mirror of
https://git.code.sf.net/p/libpng/code.git
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4186 lines
141 KiB
C
4186 lines
141 KiB
C
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/* pngread.c - read a PNG file
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*
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* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
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* Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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*
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* This file contains routines that an application calls directly to
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* read a PNG file or stream.
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*/
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#include "pngpriv.h"
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#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
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# include <errno.h>
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#endif
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#define PNG_SRC_FILE PNG_SRC_FILE_pngread
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#ifdef PNG_READ_SUPPORTED
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/* Create a PNG structure for reading, and allocate any memory needed. */
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PNG_FUNCTION(png_structp,PNGAPI
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png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
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{
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#ifndef PNG_USER_MEM_SUPPORTED
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png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
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error_fn, warn_fn, NULL, NULL, NULL);
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#else
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return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
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warn_fn, NULL, NULL, NULL);
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}
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/* Alternate create PNG structure for reading, and allocate any memory
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* needed.
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*/
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PNG_FUNCTION(png_structp,PNGAPI
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png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
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png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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{
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png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
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error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
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#endif /* USER_MEM */
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if (png_ptr != NULL)
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{
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png_ptr->read_struct = 1;
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png_ptr->critical_crc = crc_error_quit;
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png_ptr->ancillary_crc = crc_warn_discard;
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# ifdef PNG_BENIGN_ERRORS_SUPPORTED
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# if !PNG_RELEASE_BUILD
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/* Always quit on error prior to release */
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png_ptr->benign_error_action = PNG_ERROR;
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png_ptr->app_warning_action = PNG_WARN;
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png_ptr->app_error_action = PNG_ERROR;
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# else /* RELEASE_BUILD */
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/* Allow benign errors on read, subject to app control. */
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png_ptr->benign_error_action = PNG_WARN;
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# ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
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png_ptr->app_error_action = PNG_WARN;
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png_ptr->app_warning_action = PNG_WARN;
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# else /* !BENIGN_READ_ERRORS */
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/* libpng build without benign error support; the application
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* author has to be assumed to be correct, so:
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*/
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png_ptr->app_warning_action = PNG_WARN;
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png_ptr->app_error_action = PNG_ERROR;
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# endif /* !BENIGN_READ_ERRORS */
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# endif /* RELEASE_BUILD */
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/* This is always png_error unless explicitly changed: */
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png_ptr->IDAT_error_action = PNG_ERROR;
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# endif /* BENIGN_ERRORS */
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# ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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png_ptr->IDAT_size = PNG_IDAT_READ_SIZE;
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# endif /* SEQUENTIAL_READ */
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# ifdef PNG_READ_GAMMA_SUPPORTED
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/* Default gamma correction values: */
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# if 0 /*NYI*/
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png_ptr->gamma_accuracy = PNG_DEFAULT_GAMMA_ACCURACY;
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# endif /*NYI*/
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png_ptr->gamma_threshold = PNG_GAMMA_THRESHOLD_FIXED;
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# endif /* READ_GAMMA */
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}
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return png_ptr;
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}
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#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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/* Read the chunk header (length + type name).
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* Put the type name into png_ptr->chunk_name, and return the length.
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*/
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static void
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png_read_chunk_header(png_structrp png_ptr)
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{
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png_byte buf[8];
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#ifdef PNG_IO_STATE_SUPPORTED
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png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
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#endif
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/* Read the length and the chunk name.
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* This must be performed in a single I/O call.
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*/
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png_read_data(png_ptr, buf, 8);
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/* Put the chunk name into png_ptr->chunk_name. */
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png_ptr->chunk_length = png_get_uint_31(png_ptr, buf);
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png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
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png_debug2(0, "Reading %lx chunk, length = %lu",
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(unsigned long)png_ptr->chunk_name,
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(unsigned long)png_ptr->chunk_length);
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/* Reset the crc and run it over the chunk name. */
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png_reset_crc(png_ptr, buf + 4);
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#ifdef PNG_IO_STATE_SUPPORTED
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png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
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#endif
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}
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static void
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png_read_sequential_unknown(png_structrp png_ptr, png_inforp info_ptr)
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{
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#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
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/* Read the data for an unknown chunk. The read buffer is used: */
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png_bytep buffer = png_read_buffer(png_ptr, png_ptr->chunk_length,
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PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)); /* error if critical */
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if (buffer != NULL)
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{
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if (png_ptr->chunk_length > 0U)
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png_crc_read(png_ptr, buffer, png_ptr->chunk_length);
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png_crc_finish(png_ptr, 0);
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png_handle_unknown(png_ptr, info_ptr, buffer);
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}
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else /* out of memory on an ancillary chunk; skip the chunk */
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#else /* !READ_UNKNOWN_CHUNKS */
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/* or, no support for reading unknown chunks, so just skip it. */
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PNG_UNUSED(info_ptr)
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#endif /* !READ_UNKNOWN_CHUNKS */
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png_crc_finish(png_ptr, png_ptr->chunk_length);
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}
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/* Read the information before the actual image data. This has been
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* changed in v0.90 to allow reading a file that already has the magic
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* bytes read from the stream. You can tell libpng how many bytes have
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* been read from the beginning of the stream (up to the maximum of 8)
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* via png_set_sig_bytes(), and we will only check the remaining bytes
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* here. The application can then have access to the signature bytes we
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* read if it is determined that this isn't a valid PNG file.
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*/
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void PNGAPI
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png_read_info(png_structrp png_ptr, png_inforp info_ptr)
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{
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png_debug(1, "in png_read_info");
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if (png_ptr == NULL || info_ptr == NULL)
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return;
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/* Read and check the PNG file signature (this may do nothing if it has
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* already been read.)
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*/
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png_read_sig(png_ptr, info_ptr);
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/* Loop reading chunks until an IDAT is encountered or we reach the end of
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* the stream (IEND).
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*
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* Prior to 1.7.0 this function behaved very weirdly if called after the
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* IDATs had been read; it would keep on reading chunks util it found
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* another IDAT. This could cause it to read beyond IEND, damaging the
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* state in the host stream. This is now caught by the check below.
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*/
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while ((png_ptr->mode & (PNG_HAVE_IEND|PNG_HAVE_IDAT)) == 0)
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{
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png_read_chunk_header(png_ptr);
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switch (png_find_chunk_op(png_ptr))
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{
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default:
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impossible("invalid chunk op");
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/* FALL THROUGH */
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case png_chunk_skip:
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png_crc_finish(png_ptr, png_ptr->chunk_length);
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break;
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case png_chunk_unknown:
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png_read_sequential_unknown(png_ptr, info_ptr);
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break;
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case png_chunk_process_all:
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png_handle_chunk(png_ptr, info_ptr);
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break;
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case png_chunk_process_part:
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debug(png_ptr->mode & PNG_HAVE_IDAT);
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return;
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}
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}
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/* The loop was ended by IDAT or IEND, but if an IEND was seen the read code
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* (png_handle_position in pngrutil.c) should have errored out, therefore:
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*/
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#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
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affirm(png_ptr->chunk_name == png_IDAT && ((png_ptr->known_unknown)&1U));
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#else
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debug(png_ptr->chunk_name == png_IDAT);
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impossible("unknown IDAT");
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#endif
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/* And the code cannot have left it unread; it must have called one of the
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* handlers, so we are skipping IDAT.
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*/
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}
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/* Initialize palette, background, etc, after transformations
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* are set, but before any reading takes place. This allows
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* the user to obtain a gamma-corrected palette, for example.
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* If the user doesn't call this, we will do it ourselves.
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*/
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void PNGAPI
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png_start_read_image(png_structrp png_ptr)
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{
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png_debug(1, "in png_start_read_image");
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if (png_ptr != NULL)
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{
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if (png_ptr->zowner != png_IDAT)
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png_read_start_IDAT(png_ptr);
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/* New in 1.6.0 this avoids the bug of doing the initializations twice,
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* it could be a warning but in practice it indicates that the app may
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* have made png_get_ calls on png_ptr assuming that it hadn't been
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* 'started'.
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*/
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else
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png_app_error(png_ptr,
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"png_start_read_image/png_read_update_info: duplicate call");
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}
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}
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static void
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png_read_IDAT(png_structrp png_ptr)
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{
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/* Read more input data, up to png_struct::IDAT_size, stop at the end of the
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* IDAT stream. pngset.c checks png_struct::IDAT_size to ensure that it will
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* fit in a uInt.
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*/
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const uInt buffer_size = (uInt)/*SAFE*/png_ptr->IDAT_size;
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uInt IDAT_size = 0;
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png_bytep buffer =
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png_read_buffer(png_ptr, buffer_size, 0/*error*/);
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png_ptr->zstream.next_in = buffer;
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while (png_ptr->chunk_name == png_IDAT && IDAT_size < buffer_size)
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{
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png_uint_32 l = png_ptr->chunk_length;
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while (l == 0) /* end of this IDAT */
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{
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png_crc_finish(png_ptr, 0);
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png_read_chunk_header(png_ptr);
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if (png_ptr->chunk_name != png_IDAT) /* end of all IDAT */
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{
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png_ptr->mode |= PNG_AFTER_IDAT;
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goto done;
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}
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l = png_ptr->chunk_length;
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}
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/* Read from the IDAT chunk into the buffer, up to png_struct::IDAT_size:
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*/
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if (l > buffer_size - IDAT_size) /* SAFE: while check */
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l = buffer_size - IDAT_size;
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png_crc_read(png_ptr, buffer+IDAT_size, l);
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IDAT_size += (uInt)/*SAFE*/l;
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png_ptr->chunk_length -= l;
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}
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done:
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/* IDAT_size may be zero if the compressed image stream is truncated;
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* this is likely given a broken PNG.
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*/
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png_ptr->zstream.next_in = buffer;
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png_ptr->zstream.avail_in = IDAT_size;
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}
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void PNGAPI
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png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
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/* It is valid to call this API with both 'row' and 'dsp_row' NULL, all
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* the processing gets done. This is only useful for, either, performance
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* testing (but it skips png_combine_row) or if there is a user transform
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* or user row callback which actually uses the row data.
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*/
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{
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if (png_ptr == NULL)
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return;
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png_debug2(1, "in png_read_row (row %lu, pass %d)",
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(unsigned long)png_ptr->row_number, png_ptr->pass);
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/* Check the row number; if png_read_process_IDAT is called too many times
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* if issues an affirm, but, while this is appropriate for the progressive
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* reader, it is an app error if it happens here.
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*
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* Note that when the app does the interlace handling the last row will
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* typically be before the last row in the image.
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*/
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if (png_ptr->read_started &&
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(png_ptr->interlaced == PNG_INTERLACE_NONE ?
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png_ptr->row_number == png_ptr->height-1U : (
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# ifdef PNG_READ_INTERLACING_SUPPORTED
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png_ptr->do_interlace ?
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png_ptr->pass == 6U && png_ptr->row_number == png_ptr->height-1U :
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# endif /* READ_INTERLACING */
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png_ptr->pass == PNG_LAST_PASS(png_ptr->width, png_ptr->height) &&
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PNG_LAST_PASS_ROW(png_ptr->row_number, png_ptr->pass,
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png_ptr->height)
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)
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))
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{
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png_app_error(png_ptr, "Too many calls to png_read_row");
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return;
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}
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/* Check this right at the start; functions like png_read_process_IDAT
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* regard this condition as an internal error:
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*/
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if (png_ptr->zowner != png_IDAT)
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png_read_start_IDAT(png_ptr);
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/* So reading has started: */
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png_ptr->read_started = 1;
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for (;;)
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{
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if (png_ptr->zstream.avail_in == 0)
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png_read_IDAT(png_ptr);
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/* So... zstream.next_in may still be 0, but this may be enough for the
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* next row if zlib is storing enough output state (it only need be enough
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* for one byte, because png_read_process_IDAT keeps the next filter byte,
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* so on the last row of the image only one byte might be required.)
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*
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* png_read_process_IDAT handles the case where the input has ended; mode
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* has PNG_AFTER_IDAT set, by either doing png_error or using 0 bytes for
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* the data (after issuing a warning.)
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*/
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switch (png_read_process_IDAT(png_ptr, row, dsp_row, 0/*no save*/))
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{
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case png_row_incomplete:
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/* more IDAT data needed for row */
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debug(png_ptr->zstream.avail_in == 0);
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continue;
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case png_row_repeat:
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/* row not in this pass, but the existing row in row_buffer or (if
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* transforms are happening) png_struct::transformed_row is
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* available from a previous row.
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*/
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/* FALL THROUGH */
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case png_row_skip:
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/* row not in pass and no appropriate data; skip this row, nothing
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* more need be done, except the read_row_fn and then only if libpng
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* is doing the interlace handling (this is the historical
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* behavior!)
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*/
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# ifdef PNG_READ_INTERLACING_SUPPORTED
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if (!png_ptr->do_interlace) continue;
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# else /* !do_interlace */
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continue;
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# endif /* !do_interlace */
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/* FALL THROUGH */
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case png_row_process:
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/* png_read_process_IDAT has done everything we need, the only extra
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* required is to call the application row callback.
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*/
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if (png_ptr->read_row_fn != NULL)
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png_ptr->read_row_fn(png_ptr, png_ptr->row_number,
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png_ptr->pass);
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/* And return now because the next row has been processed; so there
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* is exactly one read_row_fn callback for each call to
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* png_read_process_IDAT.
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*/
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return;
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default:
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impossible("not reached");
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}
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}
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}
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/* Read one or more rows of image data. If the image is interlaced,
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* and png_set_interlace_handling() has been called, the rows need to
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* contain the contents of the rows from the previous pass. If the
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* image has alpha or transparency, and png_handle_alpha()[*] has been
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* called, the rows contents must be initialized to the contents of the
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* screen.
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*
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* "row" holds the actual image, and pixels are placed in it
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* as they arrive. If the image is displayed after each pass, it will
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* appear to "sparkle" in. "display_row" can be used to display a
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* "chunky" progressive image, with finer detail added as it becomes
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* available. If you do not want this "chunky" display, you may pass
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* NULL for display_row. If you do not want the sparkle display, and
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* you have not called png_handle_alpha(), you may pass NULL for rows.
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* If you have called png_handle_alpha(), and the image has either an
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* alpha channel or a transparency chunk, you must provide a buffer for
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* rows. In this case, you do not have to provide a display_row buffer
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* also, but you may. If the image is not interlaced, or if you have
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* not called png_set_interlace_handling(), the display_row buffer will
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* be ignored, so pass NULL to it.
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*
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* [*] png_handle_alpha() does not exist yet, as of this version of libpng
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*/
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void PNGAPI
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png_read_rows(png_structrp png_ptr, png_bytepp row,
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png_bytepp display_row, png_uint_32 num_rows)
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{
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png_uint_32 i;
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png_bytepp rp;
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png_bytepp dp;
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png_debug(1, "in png_read_rows");
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if (png_ptr == NULL)
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return;
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rp = row;
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dp = display_row;
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if (rp != NULL && dp != NULL)
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for (i = 0; i < num_rows; i++)
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{
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png_bytep rptr = *rp++;
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png_bytep dptr = *dp++;
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png_read_row(png_ptr, rptr, dptr);
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}
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else if (rp != NULL)
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for (i = 0; i < num_rows; i++)
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{
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png_bytep rptr = *rp;
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png_read_row(png_ptr, rptr, NULL);
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rp++;
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}
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else if (dp != NULL)
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for (i = 0; i < num_rows; i++)
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{
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png_bytep dptr = *dp;
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png_read_row(png_ptr, NULL, dptr);
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dp++;
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}
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}
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#endif /* SEQUENTIAL_READ */
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#ifdef PNG_READ_IMAGE_SUPPORTED
|
|
/* Read the entire image. If the image has an alpha channel or a tRNS
|
|
* chunk, and you have called png_handle_alpha()[*], you will need to
|
|
* initialize the image to the current image that PNG will be overlaying.
|
|
* We set the num_rows again here, in case it was incorrectly set in
|
|
* png_read_start_IDAT() by a call to png_read_update_info() or
|
|
* png_start_read_image() if png_set_interlace_handling() wasn't called
|
|
* prior to either of these functions like it should have been. You can
|
|
* only call this function once. If you desire to have an image for
|
|
* each pass of a interlaced image, use png_read_rows() instead.
|
|
*
|
|
* [*] png_handle_alpha() does not exist yet, as of this version of libpng
|
|
*/
|
|
void PNGAPI
|
|
png_read_image(png_structrp png_ptr, png_bytepp image)
|
|
{
|
|
png_uint_32 image_height;
|
|
int pass, j;
|
|
|
|
png_debug(1, "in png_read_image");
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
if (png_ptr->zowner != png_IDAT)
|
|
pass = png_set_interlace_handling(png_ptr);
|
|
|
|
else
|
|
{
|
|
if (png_ptr->interlaced == 0)
|
|
pass = 1;
|
|
|
|
else
|
|
pass = PNG_INTERLACE_ADAM7_PASSES;
|
|
}
|
|
|
|
for (j = 0, image_height = png_ptr->height; j < pass; ++j)
|
|
{
|
|
png_bytepp rp = image;
|
|
png_uint_32 i;
|
|
|
|
for (i = 0; i < image_height; i++)
|
|
{
|
|
png_read_row(png_ptr, *rp, NULL);
|
|
rp++;
|
|
}
|
|
}
|
|
}
|
|
#endif /* READ_IMAGE */
|
|
|
|
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
|
|
/* Read the end of the PNG file. Will not read past the end of the
|
|
* file, will verify the end is accurate, and will read any comments
|
|
* or time information at the end of the file, if info is not NULL.
|
|
*/
|
|
void PNGAPI
|
|
png_read_end(png_structrp png_ptr, png_inforp info_ptr)
|
|
{
|
|
png_debug(1, "in png_read_end");
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
/* When this routine is entered it is possible that an IDAT chunk still
|
|
* remains to be read. There are three conditions:
|
|
*
|
|
* 1) The app decided to handle IDAT as unknown, libpng will have consumed
|
|
* the first IDAT in png_read_info, the rest will be consumed as normal
|
|
* chunks by calls to png_handle_chunk below.
|
|
*
|
|
* 2) The app did not start to read an image, so png_read_start_IDAT was
|
|
* not called and png_struct::zowner is not png_IDAT. The first IDAT
|
|
* must still be skipped then the code below will skip the remainder.
|
|
*
|
|
* 3) The app did start to read the image. png_struct::zowner is png_IDAT
|
|
* and we need to close down the IDAT reading code. There may also be
|
|
* pending IDAT chunks, these are passed to png_read_finish_IDAT here so
|
|
* that error detection happens. If the app didn't read all the rows
|
|
* libpng will issue an 'extra compressed data' error, we could supress
|
|
* that by warning that not all the rows have been read and setting
|
|
* png_struct::zstream_error if necessary.
|
|
*/
|
|
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
|
|
if (!(png_ptr->known_unknown & 1U))
|
|
# endif
|
|
{
|
|
if (png_ptr->zowner == png_IDAT)
|
|
{
|
|
/* Normal case: read to the end of the IDAT chunks. In about
|
|
* 5/PNG_IDAT_READ_SIZE cases (typically that's 1:820) zlib will have
|
|
* returned all the image data but not read up to the end of the
|
|
* Adler32 because the end of the stream had not been read. Make sure
|
|
* it gets read here:
|
|
*/
|
|
if (png_ptr->zstream.avail_in == 0)
|
|
png_read_IDAT(png_ptr);
|
|
|
|
while (!png_read_finish_IDAT(png_ptr)) {
|
|
/* This will adjust zstream.next/avail_in appropriately and if
|
|
* necessary read the next chunk. After this avail_in may still
|
|
* be zero, but if it is then PNG_AFTER_IDAT should be set.
|
|
*/
|
|
debug(png_ptr->zstream.avail_in == 0);
|
|
png_read_IDAT(png_ptr);
|
|
debug(png_ptr->zstream.avail_in > 0 ||
|
|
(png_ptr->mode & PNG_AFTER_IDAT) != 0);
|
|
}
|
|
|
|
debug(png_ptr->zstream.avail_in == 0 && png_ptr->zowner == 0);
|
|
|
|
/* If this is still an IDAT then it hasn't been finished; at least
|
|
* the CRC has not been read. If there is data left in it then
|
|
* an error may need to be output. Note that the code below handles
|
|
* any additional chunks.
|
|
*/
|
|
if (png_ptr->chunk_name == png_IDAT)
|
|
{
|
|
if (png_ptr->chunk_length > 0 && !png_ptr->zstream_error)
|
|
{
|
|
png_chunk_benign_error(png_ptr, "too much IDAT data (read)");
|
|
png_ptr->zstream_error = 1;
|
|
}
|
|
|
|
png_crc_finish(png_ptr, png_ptr->chunk_length);
|
|
png_read_chunk_header(png_ptr);
|
|
}
|
|
}
|
|
|
|
else if (png_ptr->chunk_name == png_IDAT)
|
|
{
|
|
/* This IDAT has not been processed, the remainder will be finished
|
|
* in the loop. This is the case where IDAT is being skipped because
|
|
* the rows weren't read, this is OK, but warn anyway.
|
|
*/
|
|
png_crc_finish(png_ptr, png_ptr->chunk_length);
|
|
png_app_warning(png_ptr, "image reading skipped");
|
|
png_ptr->zstream_error = 1; /* Prevent 'too much IDAT' errors */
|
|
png_read_chunk_header(png_ptr);
|
|
}
|
|
|
|
else /* This might work, if the signature was read, but just in case: */
|
|
png_app_error(png_ptr, "Missing call to png_read_info");
|
|
}
|
|
|
|
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
|
|
else
|
|
{
|
|
/* IDAT is unknown, the chunk that terminated the loop must be an IDAT
|
|
* and it has been processed. Get a new chunk header.
|
|
*/
|
|
if (png_ptr->chunk_name == png_IDAT)
|
|
png_read_chunk_header(png_ptr);
|
|
|
|
else
|
|
png_app_error(png_ptr,
|
|
"Missing call to png_read_info with unknown IDAT");
|
|
}
|
|
# endif
|
|
|
|
if ((png_ptr->mode & PNG_HAVE_IEND) == 0) for (;;)
|
|
{
|
|
switch (png_find_chunk_op(png_ptr))
|
|
{
|
|
default:
|
|
impossible("invalid chunk op");
|
|
/* FALL THROUGH */
|
|
case png_chunk_skip:
|
|
png_crc_finish(png_ptr, png_ptr->chunk_length);
|
|
break;
|
|
|
|
case png_chunk_unknown:
|
|
png_read_sequential_unknown(png_ptr, info_ptr);
|
|
break;
|
|
|
|
case png_chunk_process_all:
|
|
png_handle_chunk(png_ptr, info_ptr);
|
|
break;
|
|
|
|
case png_chunk_process_part:
|
|
debug(png_ptr->chunk_name == png_IDAT);
|
|
debug(!(png_ptr->mode & PNG_AFTER_IDAT));
|
|
if (png_ptr->chunk_length > 0 && !png_ptr->zstream_error)
|
|
{
|
|
png_chunk_benign_error(png_ptr, "too many IDAT chunks");
|
|
png_ptr->zstream_error = 1;
|
|
}
|
|
|
|
/* Skip it: */
|
|
png_crc_finish(png_ptr, png_ptr->chunk_length);
|
|
return;
|
|
}
|
|
|
|
if ((png_ptr->mode & PNG_HAVE_IEND) != 0)
|
|
break;
|
|
|
|
png_read_chunk_header(png_ptr);
|
|
}
|
|
}
|
|
#endif /* SEQUENTIAL_READ */
|
|
|
|
/* Free all memory used in the read struct */
|
|
static void
|
|
png_read_destroy(png_structrp png_ptr)
|
|
{
|
|
png_debug(1, "in png_read_destroy");
|
|
|
|
png_read_free_row_buffers(png_ptr);
|
|
|
|
png_free(png_ptr, png_ptr->read_buffer);
|
|
png_ptr->read_buffer = NULL;
|
|
|
|
if (png_ptr->palette != NULL)
|
|
{
|
|
png_free(png_ptr, png_ptr->palette);
|
|
png_ptr->num_palette = 0;
|
|
png_ptr->palette = NULL;
|
|
}
|
|
|
|
#ifdef PNG_READ_tRNS_SUPPORTED
|
|
if (png_ptr->trans_alpha != NULL)
|
|
{
|
|
png_free(png_ptr, png_ptr->trans_alpha);
|
|
png_ptr->num_trans = 0;
|
|
png_ptr->trans_alpha = NULL;
|
|
}
|
|
#endif
|
|
|
|
if (png_ptr->zstream.state != NULL)
|
|
{
|
|
int ret = inflateEnd(&png_ptr->zstream);
|
|
|
|
if (ret != Z_OK)
|
|
{
|
|
png_zstream_error(&png_ptr->zstream, ret);
|
|
png_warning(png_ptr, png_ptr->zstream.msg);
|
|
}
|
|
}
|
|
|
|
#ifdef PNG_TRANSFORM_MECH_SUPPORTED
|
|
png_transform_free(png_ptr, &png_ptr->transform_list);
|
|
#endif
|
|
|
|
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
|
|
png_free(png_ptr, png_ptr->save_buffer);
|
|
png_ptr->save_buffer = NULL;
|
|
#endif
|
|
|
|
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
|
|
png_free(png_ptr, png_ptr->chunk_list);
|
|
png_ptr->chunk_list = NULL;
|
|
#endif
|
|
|
|
/* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
|
|
* callbacks are still set at this point. They are required to complete the
|
|
* destruction of the png_struct itself.
|
|
*/
|
|
}
|
|
|
|
/* Free all memory used by the read */
|
|
void PNGAPI
|
|
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
|
|
png_infopp end_info_ptr_ptr)
|
|
{
|
|
png_structrp png_ptr = NULL;
|
|
|
|
png_debug(1, "in png_destroy_read_struct");
|
|
|
|
if (png_ptr_ptr != NULL)
|
|
png_ptr = *png_ptr_ptr;
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
/* libpng 1.6.0: use the API to destroy info structs to ensure consistent
|
|
* behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
|
|
* The extra was, apparently, unnecessary yet this hides memory leak bugs.
|
|
*/
|
|
png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
|
|
png_destroy_info_struct(png_ptr, info_ptr_ptr);
|
|
|
|
*png_ptr_ptr = NULL;
|
|
png_read_destroy(png_ptr);
|
|
png_destroy_png_struct(png_ptr);
|
|
}
|
|
|
|
void PNGAPI
|
|
png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
png_ptr->read_row_fn = read_row_fn;
|
|
}
|
|
|
|
|
|
#ifdef PNG_READ_PNG_SUPPORTED
|
|
#ifdef __GNUC__
|
|
/* This exists solely to work round a warning from GNU C. */
|
|
static int /* PRIVATE */
|
|
png_gt(size_t a, size_t b)
|
|
{
|
|
return a > b;
|
|
}
|
|
#else
|
|
# define png_gt(a,b) ((a) > (b))
|
|
#endif
|
|
|
|
void PNGAPI
|
|
png_read_png(png_structrp png_ptr, png_inforp info_ptr, int transforms,
|
|
voidp params)
|
|
{
|
|
if (png_ptr == NULL || info_ptr == NULL)
|
|
return;
|
|
|
|
/* png_read_info() gives us all of the information from the
|
|
* PNG file before the first IDAT (image data chunk).
|
|
*/
|
|
png_read_info(png_ptr, info_ptr);
|
|
if (png_gt(info_ptr->height, PNG_SIZE_MAX/(sizeof (png_bytep))))
|
|
png_error(png_ptr, "Image is too high to process with png_read_png()");
|
|
|
|
/* -------------- image transformations start here ------------------- */
|
|
/* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
|
|
* is not implemented. This will only happen in de-configured (non-default)
|
|
* libpng builds. The results can be unexpected - png_read_png may return
|
|
* short or mal-formed rows because the transform is skipped.
|
|
*/
|
|
|
|
/* Tell libpng to strip 16-bit/color files down to 8 bits per color.
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
|
|
/* Added at libpng-1.5.4. "strip_16" produces the same result that it
|
|
* did in earlier versions, while "scale_16" is now more accurate.
|
|
*/
|
|
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
|
|
png_set_scale_16(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
|
|
#endif
|
|
|
|
/* If both SCALE and STRIP are required pngrtran will effectively cancel the
|
|
* latter by doing SCALE first. This is ok and allows apps not to check for
|
|
* which is supported to get the right answer.
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
|
|
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
|
|
png_set_strip_16(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
|
|
#endif
|
|
|
|
/* Strip alpha bytes from the input data without combining with
|
|
* the background (not recommended).
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
|
|
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
|
|
png_set_strip_alpha(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
|
|
#endif
|
|
|
|
/* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
|
|
* byte into separate bytes (useful for paletted and grayscale images).
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_PACKING) != 0)
|
|
#ifdef PNG_READ_PACK_SUPPORTED
|
|
png_set_packing(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
|
|
#endif
|
|
|
|
/* Change the order of packed pixels to least significant bit first
|
|
* (not useful if you are using png_set_packing).
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
|
|
#ifdef PNG_READ_PACKSWAP_SUPPORTED
|
|
png_set_packswap(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
|
|
#endif
|
|
|
|
/* Expand paletted colors into true RGB triplets
|
|
* Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
|
|
* Expand paletted or RGB images with transparency to full alpha
|
|
* channels so the data will be available as RGBA quartets.
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
|
|
#ifdef PNG_READ_EXPAND_SUPPORTED
|
|
png_set_expand(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
|
|
#endif
|
|
|
|
/* We don't handle background color, gamma transformation, or quantizing. */
|
|
|
|
/* Invert monochrome files to have 0 as white and 1 as black */
|
|
if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
|
|
#ifdef PNG_READ_INVERT_SUPPORTED
|
|
png_set_invert_mono(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
|
|
#endif
|
|
|
|
/* If you want to shift the pixel values from the range [0,255] or
|
|
* [0,65535] to the original [0,7] or [0,31], or whatever range the
|
|
* colors were originally in:
|
|
*/
|
|
if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
|
|
#ifdef PNG_READ_SHIFT_SUPPORTED
|
|
if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
|
|
png_set_shift(png_ptr, &info_ptr->sig_bit);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
|
|
#endif
|
|
|
|
/* Flip the RGB pixels to BGR (or RGBA to BGRA) */
|
|
if ((transforms & PNG_TRANSFORM_BGR) != 0)
|
|
#ifdef PNG_READ_BGR_SUPPORTED
|
|
png_set_bgr(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
|
|
#endif
|
|
|
|
/* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
|
|
if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
|
|
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
|
|
png_set_swap_alpha(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
|
|
#endif
|
|
|
|
/* Swap bytes of 16-bit files to least significant byte first */
|
|
if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
|
|
#ifdef PNG_READ_SWAP_SUPPORTED
|
|
png_set_swap(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
|
|
#endif
|
|
|
|
/* Added at libpng-1.2.41 */
|
|
/* Invert the alpha channel from opacity to transparency */
|
|
if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
|
|
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
|
|
png_set_invert_alpha(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
|
|
#endif
|
|
|
|
/* Added at libpng-1.2.41 */
|
|
/* Expand grayscale image to RGB */
|
|
if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
|
|
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
|
|
png_set_gray_to_rgb(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
|
|
#endif
|
|
|
|
/* Added at libpng-1.5.4 */
|
|
if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
|
|
#ifdef PNG_READ_EXPAND_16_SUPPORTED
|
|
png_set_expand_16(png_ptr);
|
|
#else
|
|
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
|
|
#endif
|
|
|
|
/* We don't handle adding filler bytes */
|
|
|
|
/* We use png_read_image and rely on that for interlace handling, but we also
|
|
* call png_read_update_info therefore must turn on interlace handling now:
|
|
*/
|
|
(void)png_set_interlace_handling(png_ptr);
|
|
|
|
/* Optional call to gamma correct and add the background to the palette
|
|
* and update info structure. REQUIRED if you are expecting libpng to
|
|
* update the palette for you (i.e., you selected such a transform above).
|
|
*/
|
|
png_read_update_info(png_ptr, info_ptr);
|
|
|
|
/* -------------- image transformations end here ------------------- */
|
|
|
|
png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
|
|
if (info_ptr->row_pointers == NULL)
|
|
{
|
|
png_uint_32 iptr;
|
|
png_alloc_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);
|
|
|
|
info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
|
|
info_ptr->height * (sizeof (png_bytep))));
|
|
|
|
for (iptr=0; iptr<info_ptr->height; iptr++)
|
|
info_ptr->row_pointers[iptr] = NULL;
|
|
|
|
info_ptr->free_me |= PNG_FREE_ROWS;
|
|
|
|
for (iptr = 0; iptr < info_ptr->height; iptr++)
|
|
info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
|
|
png_malloc(png_ptr, rowbytes));
|
|
}
|
|
|
|
png_read_image(png_ptr, info_ptr->row_pointers);
|
|
info_ptr->valid |= PNG_INFO_IDAT;
|
|
|
|
/* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
|
|
png_read_end(png_ptr, info_ptr);
|
|
|
|
PNG_UNUSED(params)
|
|
}
|
|
#endif /* READ_PNG */
|
|
|
|
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
|
/* SIMPLIFIED READ
|
|
*
|
|
* This code currently relies on the sequential reader, though it could easily
|
|
* be made to work with the progressive one.
|
|
*/
|
|
/* Arguments to png_image_finish_read: */
|
|
|
|
/* Encoding of PNG data (used by the color-map code) */
|
|
# define P_NOTSET 0 /* File encoding not yet known */
|
|
# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
|
|
# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
|
|
# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
|
|
# define P_LINEAR8 4 /* 8-bit linear: only from a file value */
|
|
# define P_FILE8 5 /* 8-bit encoded to file gamma but not significant bits */
|
|
|
|
/* Color-map processing: after libpng has run on the PNG image further
|
|
* processing may be needed to convert the data to color-map indices.
|
|
*/
|
|
#define PNG_CMAP_NONE 0
|
|
#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
|
|
#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
|
|
#define PNG_CMAP_RGB 3 /* Process RGB data */
|
|
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
|
|
|
|
/* The following document where the background is for each processing case. */
|
|
#define PNG_CMAP_NONE_BACKGROUND 256
|
|
#define PNG_CMAP_GA_BACKGROUND 231
|
|
#define PNG_CMAP_TRANS_BACKGROUND 254
|
|
#define PNG_CMAP_RGB_BACKGROUND 256
|
|
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
|
|
|
|
typedef struct
|
|
{
|
|
/* Arguments: */
|
|
png_imagep image;
|
|
png_voidp buffer;
|
|
ptrdiff_t row_stride;
|
|
png_voidp colormap;
|
|
png_const_colorp background;
|
|
/* Local variables: */
|
|
png_voidp local_row;
|
|
png_voidp first_row;
|
|
ptrdiff_t row_bytes; /* step between rows */
|
|
int file_encoding; /* E_ values above */
|
|
png_fixed_point file_to_sRGB; /* Cached correction factor */
|
|
int colormap_processing; /* PNG_CMAP_ values above */
|
|
png_byte sBIT[4]; /* Significant bits for channels */
|
|
} png_image_read_control;
|
|
|
|
/* Do all the *safe* initialization - 'safe' means that png_error won't be
|
|
* called, so setting up the jmp_buf is not required. This means that anything
|
|
* called from here must *not* call png_malloc - it has to call png_malloc_warn
|
|
* instead so that control is returned safely back to this routine.
|
|
*/
|
|
static int
|
|
png_image_read_init(png_imagep image)
|
|
{
|
|
if (image->opaque == NULL)
|
|
{
|
|
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
|
|
png_safe_error, png_safe_warning);
|
|
|
|
/* And set the rest of the structure to NULL to ensure that the various
|
|
* fields are consistent.
|
|
*/
|
|
memset(image, 0, (sizeof *image));
|
|
image->version = PNG_IMAGE_VERSION;
|
|
|
|
if (png_ptr != NULL)
|
|
{
|
|
png_infop info_ptr = png_create_info_struct(png_ptr);
|
|
|
|
if (info_ptr != NULL)
|
|
{
|
|
png_controlp control = png_voidcast(png_controlp,
|
|
png_malloc_warn(png_ptr, (sizeof *control)));
|
|
|
|
if (control != NULL)
|
|
{
|
|
memset(control, 0, (sizeof *control));
|
|
|
|
control->png_ptr = png_ptr;
|
|
control->info_ptr = info_ptr;
|
|
control->for_write = 0;
|
|
|
|
image->opaque = control;
|
|
return 1;
|
|
}
|
|
|
|
/* Error clean up */
|
|
png_destroy_info_struct(png_ptr, &info_ptr);
|
|
}
|
|
|
|
png_destroy_read_struct(&png_ptr, NULL, NULL);
|
|
}
|
|
|
|
return png_image_error(image, "png_image_read: out of memory");
|
|
}
|
|
|
|
return png_image_error(image, "png_image_read: opaque pointer not NULL");
|
|
}
|
|
|
|
/* Utility to find the base format of a PNG file from a png_struct. */
|
|
static png_uint_32
|
|
png_image_format(png_structrp png_ptr)
|
|
{
|
|
png_uint_32 format = 0;
|
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
|
|
format |= PNG_FORMAT_FLAG_COLOR;
|
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
|
|
format |= PNG_FORMAT_FLAG_ALPHA;
|
|
|
|
/* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
|
|
* sets the png_struct fields; that's all we are interested in here. The
|
|
* precise interaction with an app call to png_set_tRNS and PNG file reading
|
|
* is unclear.
|
|
*/
|
|
else if (png_ptr->num_trans > 0)
|
|
format |= PNG_FORMAT_FLAG_ALPHA;
|
|
|
|
if (png_ptr->bit_depth == 16)
|
|
format |= PNG_FORMAT_FLAG_LINEAR;
|
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
|
|
format |= PNG_FORMAT_FLAG_COLORMAP;
|
|
|
|
return format;
|
|
}
|
|
|
|
/* Is the given gamma significantly different from sRGB?
|
|
*/
|
|
static int
|
|
png_gamma_not_sRGB(png_fixed_point g)
|
|
{
|
|
/* An uninitialized gamma is assumed to be sRGB for the simplified API. */
|
|
return g != 0 && !PNG_GAMMA_IS_sRGB(g);
|
|
}
|
|
|
|
/* Do the main body of a 'png_image_begin_read' function; read the PNG file
|
|
* header and fill in all the information. This is executed in a safe context,
|
|
* unlike the init routine above.
|
|
*/
|
|
static int
|
|
png_image_read_header(png_voidp argument)
|
|
{
|
|
png_imagep image = png_voidcast(png_imagep, argument);
|
|
png_structrp png_ptr = image->opaque->png_ptr;
|
|
png_inforp info_ptr = image->opaque->info_ptr;
|
|
|
|
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
|
|
png_set_benign_errors(png_ptr, 1/*warn*/);
|
|
#endif
|
|
png_read_info(png_ptr, info_ptr);
|
|
|
|
/* Do this the fast way; just read directly out of png_struct. */
|
|
image->width = png_ptr->width;
|
|
image->height = png_ptr->height;
|
|
|
|
{
|
|
png_uint_32 format = png_image_format(png_ptr);
|
|
|
|
image->format = format;
|
|
|
|
#ifdef PNG_COLORSPACE_SUPPORTED
|
|
/* Does the colorspace match sRGB? If there is no color endpoint
|
|
* (colorant) information assume yes, otherwise require the
|
|
* 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
|
|
* colorspace has been determined to be invalid ignore it.
|
|
*/
|
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
|
|
& (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
|
|
PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
|
|
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
|
|
#endif
|
|
}
|
|
|
|
/* We need the maximum number of entries regardless of the format the
|
|
* application sets here.
|
|
*/
|
|
{
|
|
png_uint_32 cmap_entries;
|
|
|
|
switch (png_ptr->color_type)
|
|
{
|
|
case PNG_COLOR_TYPE_GRAY:
|
|
cmap_entries = 1U << png_ptr->bit_depth;
|
|
break;
|
|
|
|
case PNG_COLOR_TYPE_PALETTE:
|
|
cmap_entries = png_ptr->num_palette;
|
|
break;
|
|
|
|
default:
|
|
cmap_entries = 256;
|
|
break;
|
|
}
|
|
|
|
if (cmap_entries > 256)
|
|
cmap_entries = 256;
|
|
|
|
image->colormap_entries = cmap_entries;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void
|
|
png_image_get_sBIT(png_image_read_control *display)
|
|
/* Utility to cache the sBIT values. This uses the information from the
|
|
* png_struct not png_info because it may be needed after the sBIT
|
|
* information in png_info has been invalidated.
|
|
*/
|
|
{
|
|
if (display->sBIT[0] == 0)
|
|
{
|
|
const png_const_structrp png_ptr = display->image->opaque->png_ptr;
|
|
const unsigned int color_type = png_ptr->color_type;
|
|
const png_byte bit_depth =
|
|
(color_type & PNG_COLOR_MASK_PALETTE) ? 8U : png_ptr->bit_depth;
|
|
|
|
memset(display->sBIT, bit_depth, sizeof display->sBIT);
|
|
|
|
if (color_type & PNG_COLOR_MASK_COLOR)
|
|
{
|
|
if (png_ptr->sig_bit.red > 0 && png_ptr->sig_bit.red < bit_depth)
|
|
display->sBIT[0] = png_ptr->sig_bit.red;
|
|
if (png_ptr->sig_bit.green > 0 && png_ptr->sig_bit.green < bit_depth)
|
|
display->sBIT[1] = png_ptr->sig_bit.green;
|
|
if (png_ptr->sig_bit.blue > 0 && png_ptr->sig_bit.blue < bit_depth)
|
|
display->sBIT[2] = png_ptr->sig_bit.blue;
|
|
}
|
|
|
|
else
|
|
{
|
|
if (png_ptr->sig_bit.gray > 0 && png_ptr->sig_bit.gray < bit_depth)
|
|
display->sBIT[2] = display->sBIT[1] = display->sBIT[0] =
|
|
png_ptr->sig_bit.gray;
|
|
}
|
|
|
|
if (color_type & PNG_COLOR_MASK_ALPHA)
|
|
{
|
|
if (png_ptr->sig_bit.alpha > 0 && png_ptr->sig_bit.alpha < bit_depth)
|
|
display->sBIT[3] = png_ptr->sig_bit.alpha;
|
|
}
|
|
}
|
|
}
|
|
|
|
#ifdef PNG_STDIO_SUPPORTED
|
|
int PNGAPI
|
|
png_image_begin_read_from_stdio(png_imagep image, FILE* file)
|
|
{
|
|
if (image != NULL && image->version == PNG_IMAGE_VERSION)
|
|
{
|
|
if (file != NULL)
|
|
{
|
|
if (png_image_read_init(image) != 0 &&
|
|
png_image_init_io(image, file) != 0)
|
|
return png_safe_execute(image, png_image_read_header, image);
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_stdio: invalid argument");
|
|
}
|
|
|
|
else if (image != NULL)
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
|
|
|
|
return 0;
|
|
}
|
|
|
|
int PNGAPI
|
|
png_image_begin_read_from_file(png_imagep image, const char *file_name)
|
|
{
|
|
if (image != NULL && image->version == PNG_IMAGE_VERSION)
|
|
{
|
|
if (file_name != NULL)
|
|
{
|
|
FILE *fp = fopen(file_name, "rb");
|
|
|
|
if (fp != NULL)
|
|
{
|
|
if (png_image_read_init(image) != 0 &&
|
|
png_image_init_io(image, fp) != 0)
|
|
{
|
|
image->opaque->owned_file = 1;
|
|
return png_safe_execute(image, png_image_read_header, image);
|
|
}
|
|
|
|
/* Clean up: just the opened file. */
|
|
(void)fclose(fp);
|
|
}
|
|
|
|
else
|
|
return png_image_error(image, strerror(errno));
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_file: invalid argument");
|
|
}
|
|
|
|
else if (image != NULL)
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
|
|
|
|
return 0;
|
|
}
|
|
#endif /* STDIO */
|
|
|
|
static void PNGCBAPI
|
|
png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
|
|
{
|
|
if (png_ptr != NULL)
|
|
{
|
|
png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
|
|
if (image != NULL)
|
|
{
|
|
png_controlp cp = image->opaque;
|
|
if (cp != NULL)
|
|
{
|
|
png_const_bytep memory = cp->memory;
|
|
png_size_t size = cp->size;
|
|
|
|
if (memory != NULL && size >= need)
|
|
{
|
|
memcpy(out, memory, need);
|
|
cp->memory = memory + need;
|
|
cp->size = size - need;
|
|
return;
|
|
}
|
|
|
|
png_error(png_ptr, "read beyond end of data");
|
|
}
|
|
}
|
|
|
|
png_error(png_ptr, "invalid memory read");
|
|
}
|
|
}
|
|
|
|
static int
|
|
image_init_memory_io(png_voidp param)
|
|
/* Set the read function and pointer for a memory read, the io pointer is
|
|
* just the imagep so it is passed in directly.
|
|
*/
|
|
{
|
|
png_imagep image = png_voidcast(png_imagep, param);
|
|
png_set_read_fn(image->opaque->png_ptr, image, png_image_memory_read);
|
|
return 1;
|
|
}
|
|
|
|
int PNGAPI
|
|
png_image_begin_read_from_memory(png_imagep image, png_const_voidp memory,
|
|
png_size_t size)
|
|
{
|
|
if (image != NULL && image->version == PNG_IMAGE_VERSION)
|
|
{
|
|
if (memory != NULL && size > 0)
|
|
{
|
|
if (png_image_read_init(image) != 0)
|
|
{
|
|
/* Now set the IO functions to read from the memory buffer and
|
|
* store it into io_ptr. Again do this in-place to avoid calling a
|
|
* libpng function that requires error handling.
|
|
*/
|
|
image->opaque->memory = png_voidcast(png_const_bytep, memory);
|
|
image->opaque->size = size;
|
|
|
|
return png_safe_execute(image, image_init_memory_io, image) &&
|
|
png_safe_execute(image, png_image_read_header, image);
|
|
}
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_memory: invalid argument");
|
|
}
|
|
|
|
else if (image != NULL)
|
|
return png_image_error(image,
|
|
"png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Utility function to skip chunks that are not used by the simplified image
|
|
* read functions and an appropriate macro to call it.
|
|
*/
|
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
|
|
static void
|
|
png_image_skip_unused_chunks(png_structrp png_ptr)
|
|
{
|
|
/* Prepare the reader to ignore all recognized chunks whose data will not
|
|
* be used, i.e., all chunks recognized by libpng except for those
|
|
* involved in basic image reading:
|
|
*
|
|
* IHDR, PLTE, IDAT, IEND
|
|
*
|
|
* Or image data handling:
|
|
*
|
|
* tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
|
|
*
|
|
* This provides a small performance improvement and eliminates any
|
|
* potential vulnerability to security problems in the unused chunks.
|
|
*
|
|
* At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
|
|
* too. This allows the simplified API to be compiled without iCCP support,
|
|
* however if the support is there the chunk is still checked to detect
|
|
* errors (which are unfortunately quite common.)
|
|
*/
|
|
{
|
|
static PNG_CONST png_byte chunks_to_process[] = {
|
|
98, 75, 71, 68, '\0', /* bKGD */
|
|
99, 72, 82, 77, '\0', /* cHRM */
|
|
103, 65, 77, 65, '\0', /* gAMA */
|
|
# ifdef PNG_READ_iCCP_SUPPORTED
|
|
105, 67, 67, 80, '\0', /* iCCP */
|
|
# endif
|
|
115, 66, 73, 84, '\0', /* sBIT */
|
|
115, 82, 71, 66, '\0', /* sRGB */
|
|
};
|
|
|
|
/* Ignore unknown chunks and all other chunks except for the
|
|
* IHDR, PLTE, tRNS, IDAT, and IEND chunks.
|
|
*/
|
|
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
|
|
NULL, -1);
|
|
|
|
/* But do not ignore image data handling chunks */
|
|
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
|
|
chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
|
|
}
|
|
}
|
|
|
|
# define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
|
|
#else
|
|
# define PNG_SKIP_CHUNKS(p) ((void)0)
|
|
#endif /* HANDLE_AS_UNKNOWN */
|
|
|
|
/* The following macro gives the exact rounded answer for all values in the
|
|
* range 0..255 (it actually divides by 51.2, but the rounding still generates
|
|
* the correct numbers 0..5
|
|
*/
|
|
#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
|
|
|
|
/* Utility functions to make particular color-maps */
|
|
static void
|
|
set_file_encoding(png_image_read_control *display)
|
|
{
|
|
/* First test for an encoding close to linear: */
|
|
if (png_need_gamma_correction(display->image->opaque->png_ptr,
|
|
0/*PNG gamma*/, 0/*not sRGB*/))
|
|
{
|
|
png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
|
|
|
|
/* Now look for one close to sRGB: */
|
|
if (png_gamma_not_sRGB(g))
|
|
display->file_encoding = P_FILE;
|
|
|
|
else
|
|
display->file_encoding = P_sRGB;
|
|
}
|
|
|
|
else
|
|
display->file_encoding = P_LINEAR8;
|
|
}
|
|
|
|
/* For colormap entries we end up doing the gamma correction here and the
|
|
* following routines are provided to separate out the code. In all cases the
|
|
* input value is in the range 0..255 and is encoded P_FILE with the gamma value
|
|
* stored in the png_struct colorspace.
|
|
*/
|
|
static void
|
|
init_correct(png_const_structrp png_ptr, png_fixed_point *correct)
|
|
{
|
|
/* Record the convertion necessary to get from the encoding values to
|
|
* sRGB. If this overflows just store FP_1.
|
|
*
|
|
* NOTE: this code used to store, and use, a convertion factor to
|
|
* linear then use the sRGB encoding tables to get back to sRGB, but
|
|
* this smashes the low values; the ones which fall in the linear part
|
|
* of the sRGB transfer function.
|
|
*
|
|
* The new version of this code assumes an encoding which is neither
|
|
* linear nor sRGB is a power law transform of the sRGB curve, not
|
|
* linear values. This is somewhat at odds with a precise reading of
|
|
* the PNG spec, but given that we are trying to produce sRGB values
|
|
* here it is most likely to be correct.
|
|
*/
|
|
affirm(png_ptr->colorspace.gamma > 0);
|
|
|
|
if (!png_muldiv(correct, PNG_GAMMA_sRGB_INVERSE, PNG_FP_1,
|
|
png_ptr->colorspace.gamma))
|
|
*correct = PNG_FP_1;
|
|
}
|
|
|
|
static png_uint_32
|
|
update_for_sBIT(png_uint_32 value, unsigned int significant_bits,
|
|
unsigned int bit_depth)
|
|
/* Return a bit_depth value adjusted for the number of significant bits in
|
|
* the value.
|
|
*/
|
|
{
|
|
if (significant_bits < bit_depth)
|
|
{
|
|
value >>= bit_depth - significant_bits;
|
|
/* Now scale back to bit_depth, taking care not to overflow when 'value'
|
|
* is (1<<significant_bits)-1 by rounding *down* the rounding add below
|
|
* (so, e.g. rather than 2, 1 is used when significant bits is 2).
|
|
*/
|
|
value = (value * ((1U<<bit_depth)-1U) + ((1U<<(significant_bits-1U))-1U))
|
|
/ ((1U<<significant_bits)-1U);
|
|
}
|
|
|
|
return value;
|
|
|
|
}
|
|
|
|
static png_uint_32
|
|
convert_to_sRGB(png_image_read_control *display, png_uint_32 value,
|
|
unsigned int significant_bits)
|
|
{
|
|
/* Converts an 8-bit value from P_FILE to P_sRGB */
|
|
png_const_structrp png_ptr = display->image->opaque->png_ptr;
|
|
|
|
debug(value <= 255U && significant_bits <= 8U && significant_bits > 0U);
|
|
|
|
if (display->file_to_sRGB == 0)
|
|
init_correct(png_ptr, &display->file_to_sRGB);
|
|
|
|
/* Now simply apply this correction factor and scale back to 8 bits. */
|
|
if (display->file_to_sRGB != PNG_FP_1)
|
|
value = png_gamma_nxmbit_correct(value >> (8U-significant_bits),
|
|
display->file_to_sRGB, significant_bits, 8U);
|
|
|
|
else if (significant_bits < 8U)
|
|
value = update_for_sBIT(value, significant_bits, 8U);
|
|
|
|
return value;
|
|
}
|
|
|
|
static png_uint_32
|
|
convert_to_linear(png_image_read_control *display, png_uint_32 value,
|
|
unsigned int significant_bits)
|
|
{
|
|
/* Converts an 8-bit value from P_FILE to 16-bit P_LINEAR */
|
|
png_const_structrp png_ptr = display->image->opaque->png_ptr;
|
|
|
|
debug(value <= 255U && significant_bits <= 8U && significant_bits > 0U);
|
|
|
|
if (display->file_to_sRGB == 0)
|
|
init_correct(png_ptr, &display->file_to_sRGB);
|
|
|
|
/* Use this correction to get a 16-bit sRGB value: */
|
|
if (display->file_to_sRGB != PNG_FP_1)
|
|
value = png_gamma_nxmbit_correct(value >> (8U-significant_bits),
|
|
display->file_to_sRGB, significant_bits, 16U);
|
|
|
|
else
|
|
{
|
|
value *= 257U;
|
|
|
|
if (significant_bits < 8U)
|
|
value = update_for_sBIT(value, significant_bits, 16U);
|
|
}
|
|
|
|
/* Now convert this back to linear, using the correct transfer function. */
|
|
if (value <= 2650U /* 65535 * 0.04045 */)
|
|
{
|
|
/* We want to divide a 12-bit number by 12.92, do this by scaling to 32
|
|
* bits then dividing by 2^24, with rounding:
|
|
*/
|
|
value = (value * 1298546U + 649273U) >> 24;
|
|
}
|
|
|
|
else
|
|
{
|
|
/* Calculate for v in the range 0.04045..1.0 calculate:
|
|
*
|
|
* ((v + 0.055)/1.055)^2.4
|
|
*
|
|
* the gamma correction function needs a 16-bit value:
|
|
*/
|
|
value *= 62119U;
|
|
value += 223904831U+32768U; /* cannot overflow; test with 65535 */
|
|
value = png_gamma_nxmbit_correct(value >> 16, 240000, 16U, 16U);
|
|
}
|
|
|
|
return value;
|
|
}
|
|
|
|
static unsigned int
|
|
decode_gamma(png_image_read_control *display, png_uint_32 value,
|
|
unsigned int significant_bits, int encoding)
|
|
{
|
|
int do_sBIT = 0;
|
|
|
|
if (encoding == P_FILE) /* double check */
|
|
encoding = display->file_encoding, do_sBIT = 1;
|
|
|
|
if (encoding == P_NOTSET) /* must be the file encoding */
|
|
{
|
|
set_file_encoding(display);
|
|
encoding = display->file_encoding;
|
|
}
|
|
|
|
switch (encoding)
|
|
{
|
|
case P_FILE:
|
|
/* This is a file value, so the sBIT, if any, needs to be used. */
|
|
value = convert_to_linear(display, value, significant_bits);
|
|
break;
|
|
|
|
case P_sRGB:
|
|
if (do_sBIT)
|
|
value = update_for_sBIT(value, significant_bits, 8U);
|
|
|
|
value = png_sRGB_table[value];
|
|
break;
|
|
|
|
case P_LINEAR:
|
|
if (do_sBIT)
|
|
value = update_for_sBIT(value, significant_bits, 16U);
|
|
break;
|
|
|
|
case P_LINEAR8:
|
|
value *= 257;
|
|
if (do_sBIT)
|
|
value = update_for_sBIT(value, significant_bits, 16U);
|
|
break;
|
|
|
|
default:
|
|
png_impossiblepp(display->image->opaque->png_ptr,
|
|
"unexpected encoding");
|
|
break;
|
|
}
|
|
|
|
return value;
|
|
}
|
|
|
|
static png_uint_32
|
|
png_colormap_compose(png_image_read_control *display,
|
|
png_uint_32 foreground, unsigned int foreground_significant_bits,
|
|
int foreground_encoding, png_uint_32 alpha,
|
|
png_uint_32 background, int encoding)
|
|
{
|
|
/* The file value is composed on the background, the background has the given
|
|
* encoding and so does the result, the file is encoded with P_FILE and the
|
|
* file and alpha are 8-bit values. The (output) encoding will always be
|
|
* P_LINEAR or P_sRGB.
|
|
*/
|
|
png_uint_32 f = decode_gamma(display, foreground,
|
|
foreground_significant_bits, foreground_encoding);
|
|
png_uint_32 b = decode_gamma(display, background, 0U/*UNUSED*/, encoding);
|
|
|
|
/* The alpha is always an 8-bit value (it comes from the palette), the value
|
|
* scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
|
|
*/
|
|
f = f * alpha + b * (255-alpha);
|
|
|
|
if (encoding == P_LINEAR)
|
|
{
|
|
/* Scale to 65535; divide by 255, approximately (in fact this is extremely
|
|
* accurate, it divides by 255.00000005937181414556, with no overflow.)
|
|
*/
|
|
f *= 257; /* Now scaled by 65535 */
|
|
f += f >> 16;
|
|
f = (f+32768) >> 16;
|
|
}
|
|
|
|
else /* P_sRGB */
|
|
f = PNG_sRGB_FROM_LINEAR(display->image->opaque->png_ptr, f);
|
|
|
|
return f;
|
|
}
|
|
|
|
/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
|
|
* be 8-bit.
|
|
*/
|
|
static void
|
|
png_create_colormap_entry(png_image_read_control *display,
|
|
png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
|
|
png_uint_32 alpha, int encoding)
|
|
{
|
|
png_imagep image = display->image;
|
|
# define png_ptr image->opaque->png_ptr /* for error messages */
|
|
const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
|
|
P_LINEAR : P_sRGB;
|
|
const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
|
|
(red != green || green != blue);
|
|
int use_sBIT = encoding == P_FILE;
|
|
|
|
affirm(ip <= 255);
|
|
implies(encoding != P_LINEAR, red <= 255U && green <= 255U && blue <= 255U
|
|
&& display->sBIT[0] <= 8U && display->sBIT[1] <= 8U
|
|
&& display->sBIT[2] <= 8U && display->sBIT[3] <= 8U);
|
|
|
|
/* This is a hack for the grayscale colormap below. */
|
|
if (encoding == P_FILE8)
|
|
encoding = P_FILE;
|
|
|
|
/* Update the cache with whether the file gamma is significantly different
|
|
* from sRGB.
|
|
*/
|
|
if (encoding == P_FILE)
|
|
{
|
|
if (display->file_encoding == P_NOTSET)
|
|
set_file_encoding(display);
|
|
|
|
/* Note that the cached value may be P_FILE too. */
|
|
encoding = display->file_encoding;
|
|
if (use_sBIT)
|
|
png_image_get_sBIT(display);
|
|
}
|
|
|
|
if (encoding == P_FILE)
|
|
{
|
|
if (convert_to_Y != 0 || output_encoding == P_LINEAR)
|
|
{
|
|
red = convert_to_linear(display, red,
|
|
use_sBIT ? display->sBIT[0] : 8U);
|
|
green = convert_to_linear(display, green,
|
|
use_sBIT ? display->sBIT[1] : 8U);
|
|
blue = convert_to_linear(display, blue,
|
|
use_sBIT ? display->sBIT[2] : 8U);
|
|
alpha *= 257U;
|
|
if (use_sBIT)
|
|
alpha = update_for_sBIT(alpha, display->sBIT[3], 16U);
|
|
|
|
encoding = P_LINEAR;
|
|
use_sBIT = 0;
|
|
}
|
|
|
|
else
|
|
{
|
|
red = convert_to_sRGB(display, red,
|
|
use_sBIT ? display->sBIT[0] : 8U);
|
|
green = convert_to_sRGB(display, green,
|
|
use_sBIT ? display->sBIT[1] : 8U);
|
|
blue = convert_to_sRGB(display, blue,
|
|
use_sBIT ? display->sBIT[2] : 8U);
|
|
if (use_sBIT)
|
|
alpha = update_for_sBIT(alpha, display->sBIT[3], 8U);
|
|
encoding = P_sRGB;
|
|
use_sBIT = 0;
|
|
}
|
|
}
|
|
|
|
else if (encoding == P_LINEAR8)
|
|
{
|
|
/* This encoding corresponds to a colormap with linear RGB entries, this
|
|
* is not a very sensible encoding but it does happen with the PNGSuite
|
|
* test images.
|
|
*/
|
|
red *= 257;
|
|
green *= 257;
|
|
blue *= 257;
|
|
alpha *= 257;
|
|
if (use_sBIT)
|
|
{
|
|
red = update_for_sBIT(red, display->sBIT[0], 16U);
|
|
green = update_for_sBIT(green, display->sBIT[1], 16U);
|
|
blue = update_for_sBIT(blue, display->sBIT[2], 16U);
|
|
alpha = update_for_sBIT(alpha, display->sBIT[3], 16U);
|
|
use_sBIT = 0;
|
|
}
|
|
encoding = P_LINEAR;
|
|
}
|
|
|
|
else if (encoding == P_sRGB &&
|
|
(convert_to_Y != 0 || output_encoding == P_LINEAR))
|
|
{
|
|
/* The values are 8-bit sRGB values, but must be converted to 16-bit
|
|
* linear.
|
|
*/
|
|
if (use_sBIT)
|
|
{
|
|
|
|
red = convert_to_linear(display, red, display->sBIT[0]);
|
|
green = convert_to_linear(display, green, display->sBIT[1]);
|
|
blue = convert_to_linear(display, blue, display->sBIT[2]);
|
|
alpha = update_for_sBIT(alpha * 257U, display->sBIT[3], 16U);
|
|
use_sBIT = 0;
|
|
}
|
|
|
|
else
|
|
{
|
|
red = png_sRGB_table[red];
|
|
green = png_sRGB_table[green];
|
|
blue = png_sRGB_table[blue];
|
|
alpha *= 257;
|
|
}
|
|
|
|
encoding = P_LINEAR;
|
|
}
|
|
|
|
else if (encoding == P_sRGB && use_sBIT)
|
|
{
|
|
debug(output_encoding == P_sRGB); /* P_LINEAR handled above */
|
|
red = update_for_sBIT(red, display->sBIT[0], 8U);
|
|
green = update_for_sBIT(green, display->sBIT[1], 8U);
|
|
blue = update_for_sBIT(blue, display->sBIT[2], 8U);
|
|
alpha = update_for_sBIT(alpha, display->sBIT[3], 8U);
|
|
use_sBIT = 0;
|
|
}
|
|
|
|
debug(!use_sBIT); /* it should have been handled above */
|
|
|
|
/* This is set if the color isn't gray but the output is. */
|
|
if (encoding == P_LINEAR)
|
|
{
|
|
if (convert_to_Y != 0)
|
|
{
|
|
/* NOTE: these values are copied from png_do_rgb_to_gray */
|
|
png_uint_32 y = 6968 * red + 23434 * green + 2366 * blue;
|
|
|
|
if (output_encoding == P_LINEAR)
|
|
y = (y + 16384) >> 15;
|
|
|
|
else
|
|
{
|
|
/* y is scaled by 32768, we need it scaled by 255: */
|
|
y = (y + 128) >> 8;
|
|
y *= 255;
|
|
y = PNG_sRGB_FROM_LINEAR(png_ptr, (y + 64) >> 7);
|
|
alpha = PNG_DIV257(alpha);
|
|
encoding = P_sRGB;
|
|
}
|
|
|
|
blue = red = green = y;
|
|
}
|
|
|
|
else if (output_encoding == P_sRGB)
|
|
{
|
|
red = PNG_sRGB_FROM_LINEAR(png_ptr, red * 255);
|
|
green = PNG_sRGB_FROM_LINEAR(png_ptr, green * 255);
|
|
blue = PNG_sRGB_FROM_LINEAR(png_ptr, blue * 255);
|
|
alpha = PNG_DIV257(alpha);
|
|
encoding = P_sRGB;
|
|
}
|
|
}
|
|
|
|
if (encoding != output_encoding)
|
|
png_impossiblepp(png_ptr, "bad encoding");
|
|
|
|
/* Store the value. */
|
|
{
|
|
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
|
|
const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
|
|
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
|
|
# else
|
|
# define afirst 0
|
|
# endif
|
|
# ifdef PNG_FORMAT_BGR_SUPPORTED
|
|
const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
|
|
# else
|
|
# define bgr 0
|
|
# endif
|
|
|
|
if (output_encoding == P_LINEAR)
|
|
{
|
|
png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
|
|
|
|
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
|
|
|
|
/* The linear 16-bit values must be pre-multiplied by the alpha channel
|
|
* value, if less than 65535 (this is, effectively, composite on black
|
|
* if the alpha channel is removed.)
|
|
*/
|
|
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
|
|
{
|
|
case 4:
|
|
entry[afirst ? 0 : 3] = png_check_u16(png_ptr, alpha);
|
|
/* FALL THROUGH */
|
|
|
|
case 3:
|
|
if (alpha < 65535)
|
|
{
|
|
if (alpha > 0)
|
|
{
|
|
blue = (blue * alpha + 32767U)/65535U;
|
|
green = (green * alpha + 32767U)/65535U;
|
|
red = (red * alpha + 32767U)/65535U;
|
|
}
|
|
|
|
else
|
|
red = green = blue = 0;
|
|
}
|
|
entry[afirst + (2 ^ bgr)] = png_check_u16(png_ptr, blue);
|
|
entry[afirst + 1] = png_check_u16(png_ptr, green);
|
|
entry[afirst + bgr] = png_check_u16(png_ptr, red);
|
|
break;
|
|
|
|
case 2:
|
|
entry[1 ^ afirst] = png_check_u16(png_ptr, alpha);
|
|
/* FALL THROUGH */
|
|
|
|
case 1:
|
|
if (alpha < 65535)
|
|
{
|
|
if (alpha > 0)
|
|
green = (green * alpha + 32767U)/65535U;
|
|
|
|
else
|
|
green = 0;
|
|
}
|
|
entry[afirst] = png_check_u16(png_ptr, green);
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
else /* output encoding is P_sRGB */
|
|
{
|
|
png_bytep entry = png_voidcast(png_bytep, display->colormap);
|
|
|
|
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
|
|
|
|
png_affirmpp(png_ptr, output_encoding == P_sRGB);
|
|
|
|
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
|
|
{
|
|
case 4:
|
|
entry[afirst ? 0 : 3] = png_check_byte(png_ptr, alpha);
|
|
|
|
case 3:
|
|
entry[afirst + (2 ^ bgr)] = png_check_byte(png_ptr, blue);
|
|
entry[afirst + 1] = png_check_byte(png_ptr, green);
|
|
entry[afirst + bgr] = png_check_byte(png_ptr, red);
|
|
break;
|
|
|
|
case 2:
|
|
entry[1 ^ afirst] = png_check_byte(png_ptr, alpha);
|
|
|
|
case 1:
|
|
entry[afirst] = png_check_byte(png_ptr, green);
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
# ifdef afirst
|
|
# undef afirst
|
|
# endif
|
|
# ifdef bgr
|
|
# undef bgr
|
|
# endif
|
|
}
|
|
|
|
# undef png_ptr
|
|
}
|
|
|
|
static int
|
|
make_gray_file_colormap(png_image_read_control *display)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i=0; i<256; ++i)
|
|
png_create_colormap_entry(display, i, i, i, i, 255, P_FILE8);
|
|
|
|
return i;
|
|
}
|
|
|
|
static int
|
|
make_gray_colormap(png_image_read_control *display)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i=0; i<256; ++i)
|
|
png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
|
|
|
|
return i;
|
|
}
|
|
#define PNG_GRAY_COLORMAP_ENTRIES 256
|
|
|
|
static int
|
|
make_ga_colormap(png_image_read_control *display)
|
|
{
|
|
unsigned int i, a;
|
|
|
|
/* Alpha is retained, the output will be a color-map with entries
|
|
* selected by six levels of alpha. One transparent entry, 6 gray
|
|
* levels for all the intermediate alpha values, leaving 230 entries
|
|
* for the opaque grays. The color-map entries are the six values
|
|
* [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
|
|
* relevant entry.
|
|
*
|
|
* if (alpha > 229) // opaque
|
|
* {
|
|
* // The 231 entries are selected to make the math below work:
|
|
* base = 0;
|
|
* entry = (231 * gray + 128) >> 8;
|
|
* }
|
|
* else if (alpha < 26) // transparent
|
|
* {
|
|
* base = 231;
|
|
* entry = 0;
|
|
* }
|
|
* else // partially opaque
|
|
* {
|
|
* base = 226 + 6 * PNG_DIV51(alpha);
|
|
* entry = PNG_DIV51(gray);
|
|
* }
|
|
*/
|
|
i = 0;
|
|
while (i < 231)
|
|
{
|
|
unsigned int gray = (i * 256 + 115) / 231;
|
|
png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
|
|
}
|
|
|
|
/* 255 is used here for the component values for consistency with the code
|
|
* that undoes premultiplication in pngwrite.c.
|
|
*/
|
|
png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
|
|
|
|
for (a=1; a<5; ++a)
|
|
{
|
|
unsigned int g;
|
|
|
|
for (g=0; g<6; ++g)
|
|
png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
|
|
P_sRGB);
|
|
}
|
|
|
|
return i;
|
|
}
|
|
|
|
#define PNG_GA_COLORMAP_ENTRIES 256
|
|
|
|
static int
|
|
make_rgb_colormap(png_image_read_control *display)
|
|
{
|
|
unsigned int i, r;
|
|
|
|
/* Build a 6x6x6 opaque RGB cube */
|
|
for (i=r=0; r<6; ++r)
|
|
{
|
|
unsigned int g;
|
|
|
|
for (g=0; g<6; ++g)
|
|
{
|
|
unsigned int b;
|
|
|
|
for (b=0; b<6; ++b)
|
|
png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
|
|
P_sRGB);
|
|
}
|
|
}
|
|
|
|
return i;
|
|
}
|
|
|
|
#define PNG_RGB_COLORMAP_ENTRIES 216
|
|
|
|
/* Return a palette index to the above palette given three 8-bit sRGB values. */
|
|
#define PNG_RGB_INDEX(r,g,b) \
|
|
(png_check_byte(image->opaque->png_ptr,\
|
|
6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
|
|
|
|
static int
|
|
png_image_read_colormap(png_voidp argument)
|
|
{
|
|
png_image_read_control *display =
|
|
png_voidcast(png_image_read_control*, argument);
|
|
const png_imagep image = display->image;
|
|
|
|
const png_structrp png_ptr = image->opaque->png_ptr;
|
|
const png_uint_32 output_format = image->format;
|
|
const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
|
|
P_LINEAR : P_sRGB;
|
|
|
|
unsigned int cmap_entries;
|
|
unsigned int output_processing; /* Output processing option */
|
|
unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
|
|
|
|
/* Background information; the background color and the index of this color
|
|
* in the color-map if it exists (else 256).
|
|
*/
|
|
unsigned int background_index = 256;
|
|
png_uint_32 back_r, back_g, back_b;
|
|
|
|
/* Flags to accumulate things that need to be done to the input. */
|
|
int expand_tRNS = 0;
|
|
|
|
/* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
|
|
* very difficult to do, the results look awful, and it is difficult to see
|
|
* what possible use it is because the application can't control the
|
|
* color-map.
|
|
*/
|
|
if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
|
|
png_ptr->num_trans > 0) /* alpha in input */ &&
|
|
((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
|
|
{
|
|
if (output_encoding == P_LINEAR) /* compose on black */
|
|
back_b = back_g = back_r = 0;
|
|
|
|
else if (display->background == NULL /* no way to remove it */)
|
|
png_error(png_ptr,
|
|
"background color must be supplied to remove alpha/transparency");
|
|
|
|
/* Get a copy of the background color (this avoids repeating the checks
|
|
* below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
|
|
* output format.
|
|
*/
|
|
else
|
|
{
|
|
back_g = display->background->green;
|
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
|
|
{
|
|
back_r = display->background->red;
|
|
back_b = display->background->blue;
|
|
}
|
|
else
|
|
back_b = back_r = back_g;
|
|
}
|
|
}
|
|
|
|
else if (output_encoding == P_LINEAR)
|
|
back_b = back_r = back_g = 65535;
|
|
|
|
else
|
|
back_b = back_r = back_g = 255;
|
|
|
|
/* Default the input file gamma if required - this is necessary because
|
|
* libpng assumes that if no gamma information is present the data is in the
|
|
* output format, but the simplified API deduces the gamma from the input
|
|
* format.
|
|
*/
|
|
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
|
|
{
|
|
/* Do this directly, not using the png_colorspace functions, to ensure
|
|
* that it happens even if the colorspace is invalid (though probably if
|
|
* it is the setting will be ignored) Note that the same thing can be
|
|
* achieved at the application interface with png_set_gAMA.
|
|
*/
|
|
if (png_ptr->bit_depth == 16 &&
|
|
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
|
|
png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
|
|
|
|
else
|
|
png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
|
|
|
|
/* Make sure libpng doesn't ignore the setting: */
|
|
if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
|
|
png_ptr->colorspace.flags = PNG_COLORSPACE_HAVE_GAMMA;
|
|
|
|
else
|
|
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
|
|
}
|
|
|
|
/* Decide what to do based on the PNG color type of the input data. The
|
|
* utility function png_create_colormap_entry deals with most aspects of the
|
|
* output transformations; this code works out how to produce bytes of
|
|
* color-map entries from the original format.
|
|
*/
|
|
switch (png_ptr->color_type)
|
|
{
|
|
case PNG_COLOR_TYPE_GRAY:
|
|
if (png_ptr->bit_depth <= 8)
|
|
{
|
|
/* There at most 256 colors in the output, regardless of
|
|
* transparency.
|
|
*/
|
|
unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
|
|
|
|
cmap_entries = 1U << png_ptr->bit_depth;
|
|
if (cmap_entries > image->colormap_entries)
|
|
png_error(png_ptr, "gray[8] color-map: too few entries");
|
|
|
|
step = 255 / (cmap_entries - 1);
|
|
output_processing = PNG_CMAP_NONE;
|
|
|
|
/* If there is a tRNS chunk then this either selects a transparent
|
|
* value or, if the output has no alpha, the background color.
|
|
*/
|
|
if (png_ptr->num_trans > 0)
|
|
{
|
|
trans = png_ptr->trans_color.gray;
|
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
|
|
back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
|
|
}
|
|
|
|
/* png_create_colormap_entry just takes an RGBA and writes the
|
|
* corresponding color-map entry using the format from 'image',
|
|
* including the required conversion to sRGB or linear as
|
|
* appropriate. The input values are always either sRGB (if the
|
|
* gamma correction flag is 0) or 0..255 scaled file encoded values
|
|
* (if the function must gamma correct them).
|
|
*/
|
|
for (i=val=0; i<cmap_entries; ++i, val += step)
|
|
{
|
|
/* 'i' is a file value. While this will result in duplicated
|
|
* entries for 8-bit non-sRGB encoded files it is necessary to
|
|
* have non-gamma corrected values to do tRNS handling.
|
|
*/
|
|
if (i != trans)
|
|
png_create_colormap_entry(display, i, val, val, val, 255,
|
|
P_FILE/*8-bit with file gamma*/);
|
|
|
|
/* Else this entry is transparent. The colors don't matter if
|
|
* there is an alpha channel (back_alpha == 0), but it does no
|
|
* harm to pass them in; the values are not set above so this
|
|
* passes in white.
|
|
*
|
|
* NOTE: this preserves the full precision of the application
|
|
* supplied background color when it is used.
|
|
*/
|
|
else
|
|
{
|
|
#ifdef __COVERITY__
|
|
/* Coverity says back_r|g|b might be 16-bit values */
|
|
png_affirmpp(png_ptr, back_r < 256 && back_g < 256 &&
|
|
back_b < 256);
|
|
#endif
|
|
png_create_colormap_entry(display, i, back_r, back_g, back_b,
|
|
back_alpha, output_encoding);
|
|
}
|
|
}
|
|
|
|
/* We need libpng to preserve the original encoding. */
|
|
data_encoding = P_FILE;
|
|
|
|
/* The rows from libpng, while technically gray values, are now also
|
|
* color-map indices; however, they may need to be expanded to 1
|
|
* byte per pixel. This is what png_set_packing does (i.e., it
|
|
* unpacks the bit values into bytes.)
|
|
*/
|
|
if (png_ptr->bit_depth < 8)
|
|
png_set_packing(png_ptr);
|
|
}
|
|
|
|
else /* bit depth is 16 */
|
|
{
|
|
/* The 16-bit input values can be converted directly to 8-bit gamma
|
|
* encoded values; however, if a tRNS chunk is present 257 color-map
|
|
* entries are required. This means that the extra entry requires
|
|
* special processing; add an alpha channel, sacrifice gray level
|
|
* 254 and convert transparent (alpha==0) entries to that.
|
|
*
|
|
* Use libpng to chop the data to 8 bits. Convert it to sRGB at the
|
|
* same time to minimize quality loss. If a tRNS chunk is present
|
|
* this means libpng must handle it too; otherwise it is impossible
|
|
* to do the exact match on the 16-bit value.
|
|
*
|
|
* If the output has no alpha channel *and* the background color is
|
|
* gray then it is possible to let libpng handle the substitution by
|
|
* ensuring that the corresponding gray level matches the background
|
|
* color exactly.
|
|
*/
|
|
data_encoding = P_sRGB;
|
|
|
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "gray[16] color-map: too few entries");
|
|
|
|
cmap_entries = make_gray_colormap(display);
|
|
|
|
if (png_ptr->num_trans > 0)
|
|
{
|
|
unsigned int back_alpha;
|
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
back_alpha = 0;
|
|
|
|
else
|
|
{
|
|
if (back_r == back_g && back_g == back_b)
|
|
{
|
|
/* Background is gray; no special processing will be
|
|
* required.
|
|
*/
|
|
png_color_16 c;
|
|
png_uint_32 gray = back_g;
|
|
|
|
if (output_encoding == P_LINEAR)
|
|
{
|
|
gray = PNG_sRGB_FROM_LINEAR(png_ptr, gray * 255);
|
|
|
|
/* And make sure the corresponding palette entry
|
|
* matches.
|
|
*/
|
|
png_create_colormap_entry(display, gray, back_g, back_g,
|
|
back_g, 65535, P_LINEAR);
|
|
}
|
|
|
|
/* The background passed to libpng, however, must be the
|
|
* sRGB value.
|
|
*/
|
|
c.index = 0; /*unused*/
|
|
c.gray = c.red = c.green = c.blue =
|
|
png_check_u16(png_ptr, gray);
|
|
|
|
/* NOTE: does this work without expanding tRNS to alpha?
|
|
* It should be the color->gray case below apparently
|
|
* doesn't.
|
|
*/
|
|
png_set_background_fixed(png_ptr, &c,
|
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
|
|
0/*gamma: not used*/);
|
|
|
|
output_processing = PNG_CMAP_NONE;
|
|
break;
|
|
}
|
|
/* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
|
|
* here.
|
|
*/
|
|
affirm(output_encoding != P_LINEAR);
|
|
back_alpha = 255U;
|
|
}
|
|
|
|
/* output_processing means that the libpng-processed row will be
|
|
* 8-bit GA and it has to be processing to single byte color-map
|
|
* values. Entry 254 is replaced by either a completely
|
|
* transparent entry or by the background color at full
|
|
* precision (and the background color is not a simple gray
|
|
* level in this case.)
|
|
*/
|
|
expand_tRNS = 1;
|
|
output_processing = PNG_CMAP_TRANS;
|
|
background_index = 254;
|
|
|
|
/* And set (overwrite) color-map entry 254 to the actual
|
|
* background color at full precision.
|
|
*/
|
|
#ifdef __COVERITY__
|
|
/* Coverity says back_r|g|b might be 16-bit values */
|
|
png_affirmpp(png_ptr, back_r < 256 && back_g < 256 &&
|
|
back_b < 256);
|
|
#endif
|
|
png_create_colormap_entry(display, 254, back_r, back_g, back_b,
|
|
back_alpha, output_encoding);
|
|
}
|
|
|
|
else
|
|
output_processing = PNG_CMAP_NONE;
|
|
}
|
|
break;
|
|
|
|
case PNG_COLOR_TYPE_GRAY_ALPHA:
|
|
/* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
|
|
* of 65536 combinations. If, however, the alpha channel is to be
|
|
* removed there are only 256 possibilities if the background is gray.
|
|
* (Otherwise there is a subset of the 65536 possibilities defined by
|
|
* the triangle between black, white and the background color.)
|
|
*
|
|
* Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
|
|
* worry about tRNS matching - tRNS is ignored if there is an alpha
|
|
* channel.
|
|
*/
|
|
data_encoding = P_sRGB;
|
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "gray+alpha color-map: too few entries");
|
|
|
|
cmap_entries = make_ga_colormap(display);
|
|
|
|
background_index = PNG_CMAP_GA_BACKGROUND;
|
|
output_processing = PNG_CMAP_GA;
|
|
}
|
|
|
|
else /* alpha is removed */
|
|
{
|
|
/* Alpha must be removed as the PNG data is processed when the
|
|
* background is a color because the G and A channels are
|
|
* independent and the vector addition (non-parallel vectors) is a
|
|
* 2-D problem.
|
|
*
|
|
* This can be reduced to the same algorithm as above by making a
|
|
* colormap containing gray levels (for the opaque grays), a
|
|
* background entry (for a transparent pixel) and a set of four six
|
|
* level color values, one set for each intermediate alpha value.
|
|
* See the comments in make_ga_colormap for how this works in the
|
|
* per-pixel processing.
|
|
*
|
|
* If the background is gray, however, we only need a 256 entry gray
|
|
* level color map. It is sufficient to make the entry generated
|
|
* for the background color be exactly the color specified.
|
|
*/
|
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
|
|
(back_r == back_g && back_g == back_b))
|
|
{
|
|
/* Background is gray; no special processing will be required. */
|
|
png_color_16 c;
|
|
png_uint_32 gray = back_g;
|
|
|
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "gray-alpha color-map: too few entries");
|
|
|
|
cmap_entries = make_gray_colormap(display);
|
|
|
|
if (output_encoding == P_LINEAR)
|
|
{
|
|
gray = PNG_sRGB_FROM_LINEAR(png_ptr, gray * 255);
|
|
|
|
/* And make sure the corresponding palette entry matches. */
|
|
png_create_colormap_entry(display, gray, back_g, back_g,
|
|
back_g, 65535, P_LINEAR);
|
|
}
|
|
|
|
/* The background passed to libpng, however, must be the sRGB
|
|
* value.
|
|
*/
|
|
c.index = 0; /*unused*/
|
|
c.gray = c.red = c.green = c.blue = png_check_u16(png_ptr, gray);
|
|
|
|
png_set_background_fixed(png_ptr, &c,
|
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
|
|
0/*gamma: not used*/);
|
|
|
|
output_processing = PNG_CMAP_NONE;
|
|
}
|
|
|
|
else
|
|
{
|
|
png_uint_32 i, a;
|
|
|
|
/* This is the same as png_make_ga_colormap, above, except that
|
|
* the entries are all opaque.
|
|
*/
|
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "ga-alpha color-map: too few entries");
|
|
|
|
i = 0;
|
|
while (i < 231)
|
|
{
|
|
png_uint_32 gray = (i * 256 + 115) / 231;
|
|
png_create_colormap_entry(display, i++, gray, gray, gray,
|
|
255, P_sRGB);
|
|
}
|
|
|
|
/* NOTE: this preserves the full precision of the application
|
|
* background color.
|
|
*
|
|
* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
|
|
*/
|
|
affirm(output_encoding != P_LINEAR);
|
|
background_index = i;
|
|
png_create_colormap_entry(display, i++, back_r, back_g, back_b,
|
|
255U, output_encoding);
|
|
|
|
/* For non-opaque input composite on the sRGB background - this
|
|
* requires inverting the encoding for each component. The input
|
|
* is still converted to the sRGB encoding because this is a
|
|
* reasonable approximate to the logarithmic curve of human
|
|
* visual sensitivity, at least over the narrow range which PNG
|
|
* represents. Consequently 'G' is always sRGB encoded, while
|
|
* 'A' is linear. We need the linear background colors.
|
|
*/
|
|
if (output_encoding == P_sRGB) /* else already linear */
|
|
{
|
|
/* This may produce a value not exactly matching the
|
|
* background, but that's ok because these numbers are only
|
|
* used when alpha != 0
|
|
*/
|
|
back_r = png_sRGB_table[back_r];
|
|
back_g = png_sRGB_table[back_g];
|
|
back_b = png_sRGB_table[back_b];
|
|
}
|
|
|
|
for (a=1; a<5; ++a)
|
|
{
|
|
unsigned int g;
|
|
|
|
/* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
|
|
* by an 8-bit alpha value (0..255).
|
|
*/
|
|
png_uint_32 alpha = 51 * a;
|
|
png_uint_32 back_rx = (255-alpha) * back_r;
|
|
png_uint_32 back_gx = (255-alpha) * back_g;
|
|
png_uint_32 back_bx = (255-alpha) * back_b;
|
|
|
|
for (g=0; g<6; ++g)
|
|
{
|
|
png_uint_32 gray = png_sRGB_table[g*51] * alpha;
|
|
|
|
png_create_colormap_entry(display, i++,
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, gray + back_rx),
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, gray + back_gx),
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, gray + back_bx),
|
|
255, P_sRGB);
|
|
}
|
|
}
|
|
|
|
cmap_entries = i;
|
|
output_processing = PNG_CMAP_GA;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case PNG_COLOR_TYPE_RGB:
|
|
case PNG_COLOR_TYPE_RGB_ALPHA:
|
|
/* Exclude the case where the output is gray; we can always handle this
|
|
* with the cases above.
|
|
*/
|
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
|
|
{
|
|
/* The color-map will be grayscale, so we may as well convert the
|
|
* input RGB values to a simple grayscale and use the grayscale
|
|
* code above.
|
|
*
|
|
* NOTE: calling this apparently damages the recognition of the
|
|
* transparent color in background color handling; call
|
|
* png_set_tRNS_to_alpha before png_set_background_fixed.
|
|
*/
|
|
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
|
|
-1);
|
|
data_encoding = P_sRGB;
|
|
|
|
/* The output will now be one or two 8-bit gray or gray+alpha
|
|
* channels. The more complex case arises when the input has alpha.
|
|
*/
|
|
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
|
|
png_ptr->num_trans > 0) &&
|
|
(output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
/* Both input and output have an alpha channel, so no background
|
|
* processing is required; just map the GA bytes to the right
|
|
* color-map entry.
|
|
*/
|
|
expand_tRNS = 1;
|
|
|
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "rgb[ga] color-map: too few entries");
|
|
|
|
cmap_entries = make_ga_colormap(display);
|
|
background_index = PNG_CMAP_GA_BACKGROUND;
|
|
output_processing = PNG_CMAP_GA;
|
|
}
|
|
|
|
else
|
|
{
|
|
/* Either the input or the output has no alpha channel, so there
|
|
* will be no non-opaque pixels in the color-map; it will just be
|
|
* grayscale.
|
|
*/
|
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "rgb[gray] color-map: too few entries");
|
|
|
|
/* Ideally this code would use libpng to do the gamma correction,
|
|
* but if an input alpha channel is to be removed we will hit the
|
|
* libpng bug in gamma+compose+rgb-to-gray (the double gamma
|
|
* correction bug). Fix this by dropping the gamma correction in
|
|
* this case and doing it in the palette; this will result in
|
|
* duplicate palette entries, but that's better than the
|
|
* alternative of double gamma correction.
|
|
*/
|
|
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
|
|
png_ptr->num_trans > 0) &&
|
|
png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
|
|
{
|
|
cmap_entries = make_gray_file_colormap(display);
|
|
data_encoding = P_FILE;
|
|
}
|
|
|
|
else
|
|
cmap_entries = make_gray_colormap(display);
|
|
|
|
/* But if the input has alpha or transparency it must be removed
|
|
*/
|
|
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
|
|
png_ptr->num_trans > 0)
|
|
{
|
|
png_color_16 c;
|
|
png_uint_32 gray = back_g;
|
|
|
|
/* We need to ensure that the application background exists in
|
|
* the colormap and that completely transparent pixels map to
|
|
* it. Achieve this simply by ensuring that the entry
|
|
* selected for the background really is the background color.
|
|
*/
|
|
if (data_encoding == P_FILE) /* from the fixup above */
|
|
{
|
|
/* The app supplied a gray which is in output_encoding, we
|
|
* need to convert it to a value of the input (P_FILE)
|
|
* encoding then set this palette entry to the required
|
|
* output encoding.
|
|
*/
|
|
if (output_encoding == P_sRGB)
|
|
gray = png_sRGB_table[gray]; /* now P_LINEAR */
|
|
|
|
gray = png_gamma_nxmbit_correct(gray,
|
|
png_ptr->colorspace.gamma, 16U, 8U);
|
|
|
|
/* And make sure the corresponding palette entry contains
|
|
* exactly the required sRGB value.
|
|
*/
|
|
png_create_colormap_entry(display, gray, back_g, back_g,
|
|
back_g, 0/*unused*/, output_encoding);
|
|
}
|
|
|
|
else if (output_encoding == P_LINEAR)
|
|
{
|
|
gray = PNG_sRGB_FROM_LINEAR(png_ptr, gray * 255);
|
|
|
|
/* And make sure the corresponding palette entry matches.
|
|
*/
|
|
png_create_colormap_entry(display, gray, back_g, back_g,
|
|
back_g, 0/*unused*/, P_LINEAR);
|
|
}
|
|
|
|
/* The background passed to libpng, however, must be the
|
|
* output (normally sRGB) value.
|
|
*/
|
|
c.index = 0; /*unused*/
|
|
c.gray = c.red = c.green = c.blue =
|
|
png_check_u16(png_ptr, gray);
|
|
|
|
/* NOTE: the following is apparently a bug in libpng. Without
|
|
* it the transparent color recognition in
|
|
* png_set_background_fixed seems to go wrong.
|
|
*/
|
|
expand_tRNS = 1;
|
|
png_set_background_fixed(png_ptr, &c,
|
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
|
|
0/*gamma: not used*/);
|
|
}
|
|
|
|
output_processing = PNG_CMAP_NONE;
|
|
}
|
|
}
|
|
|
|
else /* output is color */
|
|
{
|
|
/* We could use png_quantize here so long as there is no transparent
|
|
* color or alpha; png_quantize ignores alpha. Easier overall just
|
|
* to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
|
|
* Consequently we always want libpng to produce sRGB data.
|
|
*/
|
|
data_encoding = P_sRGB;
|
|
|
|
/* Is there any transparency or alpha? */
|
|
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
|
|
png_ptr->num_trans > 0)
|
|
{
|
|
/* Is there alpha in the output too? If so all four channels are
|
|
* processed into a special RGB cube with alpha support.
|
|
*/
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
png_uint_32 r;
|
|
|
|
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
|
|
png_error(png_ptr, "rgb+alpha color-map: too few entries");
|
|
|
|
cmap_entries = make_rgb_colormap(display);
|
|
|
|
/* Add a transparent entry. */
|
|
png_create_colormap_entry(display, cmap_entries, 255, 255,
|
|
255, 0, P_sRGB);
|
|
|
|
/* This is stored as the background index for the processing
|
|
* algorithm.
|
|
*/
|
|
background_index = cmap_entries++;
|
|
|
|
/* Add 27 r,g,b entries each with alpha 0.5. */
|
|
for (r=0; r<256; r = (r << 1) | 0x7f)
|
|
{
|
|
png_uint_32 g;
|
|
|
|
for (g=0; g<256; g = (g << 1) | 0x7f)
|
|
{
|
|
png_uint_32 b;
|
|
|
|
/* This generates components with the values 0, 127 and
|
|
* 255
|
|
*/
|
|
for (b=0; b<256; b = (b << 1) | 0x7f)
|
|
png_create_colormap_entry(display, cmap_entries++,
|
|
r, g, b, 128, P_sRGB);
|
|
}
|
|
}
|
|
|
|
expand_tRNS = 1;
|
|
output_processing = PNG_CMAP_RGB_ALPHA;
|
|
}
|
|
|
|
else
|
|
{
|
|
/* Alpha/transparency must be removed. The background must
|
|
* exist in the color map (achieved by setting adding it after
|
|
* the 666 color-map). If the standard processing code will
|
|
* pick up this entry automatically that's all that is
|
|
* required; libpng can be called to do the background
|
|
* processing.
|
|
*/
|
|
unsigned int sample_size =
|
|
PNG_IMAGE_SAMPLE_SIZE(output_format);
|
|
png_uint_32 r, g, b; /* sRGB background */
|
|
|
|
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
|
|
png_error(png_ptr, "rgb-alpha color-map: too few entries");
|
|
|
|
cmap_entries = make_rgb_colormap(display);
|
|
|
|
png_create_colormap_entry(display, cmap_entries, back_r,
|
|
back_g, back_b, 0/*unused*/, output_encoding);
|
|
|
|
if (output_encoding == P_LINEAR)
|
|
{
|
|
r = PNG_sRGB_FROM_LINEAR(png_ptr, back_r * 255);
|
|
g = PNG_sRGB_FROM_LINEAR(png_ptr, back_g * 255);
|
|
b = PNG_sRGB_FROM_LINEAR(png_ptr, back_b * 255);
|
|
}
|
|
|
|
else
|
|
{
|
|
r = back_r;
|
|
g = back_g;
|
|
b = back_g;
|
|
}
|
|
|
|
/* Compare the newly-created color-map entry with the one the
|
|
* PNG_CMAP_RGB algorithm will use. If the two entries don't
|
|
* match, add the new one and set this as the background
|
|
* index.
|
|
*/
|
|
if (memcmp((png_const_bytep)display->colormap +
|
|
sample_size * cmap_entries,
|
|
(png_const_bytep)display->colormap +
|
|
sample_size * PNG_RGB_INDEX(r,g,b),
|
|
sample_size) != 0)
|
|
{
|
|
/* The background color must be added. */
|
|
background_index = cmap_entries++;
|
|
|
|
/* Add 27 r,g,b entries each with created by composing with
|
|
* the background at alpha 0.5.
|
|
*/
|
|
for (r=0; r<256; r = (r << 1) | 0x7f)
|
|
{
|
|
for (g=0; g<256; g = (g << 1) | 0x7f)
|
|
{
|
|
/* This generates components with the values 0, 127
|
|
* and 255
|
|
*/
|
|
for (b=0; b<256; b = (b << 1) | 0x7f)
|
|
png_create_colormap_entry(display, cmap_entries++,
|
|
png_colormap_compose(display, r, 8U, P_sRGB,
|
|
128U, back_r, output_encoding),
|
|
png_colormap_compose(display, g, 8U, P_sRGB,
|
|
128U, back_g, output_encoding),
|
|
png_colormap_compose(display, b, 8U, P_sRGB,
|
|
128U, back_b, output_encoding),
|
|
0/*unused*/, output_encoding);
|
|
}
|
|
}
|
|
|
|
expand_tRNS = 1;
|
|
output_processing = PNG_CMAP_RGB_ALPHA;
|
|
}
|
|
|
|
else /* background color is in the standard color-map */
|
|
{
|
|
png_color_16 c;
|
|
|
|
c.index = 0; /*unused*/
|
|
c.red = png_check_u16(png_ptr, back_r);
|
|
c.gray = c.green = png_check_u16(png_ptr, back_g);
|
|
c.blue = png_check_u16(png_ptr, back_b);
|
|
|
|
png_set_background_fixed(png_ptr, &c,
|
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
|
|
0/*gamma: not used*/);
|
|
|
|
output_processing = PNG_CMAP_RGB;
|
|
}
|
|
}
|
|
}
|
|
|
|
else /* no alpha or transparency in the input */
|
|
{
|
|
/* Alpha in the output is irrelevant, simply map the opaque input
|
|
* pixels to the 6x6x6 color-map.
|
|
*/
|
|
if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
|
|
png_error(png_ptr, "rgb color-map: too few entries");
|
|
|
|
cmap_entries = make_rgb_colormap(display);
|
|
output_processing = PNG_CMAP_RGB;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case PNG_COLOR_TYPE_PALETTE:
|
|
/* It's already got a color-map. It may be necessary to eliminate the
|
|
* tRNS entries though.
|
|
*/
|
|
{
|
|
unsigned int num_trans = png_ptr->num_trans;
|
|
png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
|
|
png_const_colorp colormap = png_ptr->palette;
|
|
const int do_background = trans != NULL &&
|
|
(output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
|
|
unsigned int i;
|
|
|
|
/* Just in case: */
|
|
if (trans == NULL)
|
|
num_trans = 0;
|
|
|
|
output_processing = PNG_CMAP_NONE;
|
|
data_encoding = P_FILE; /* Don't change from color-map indices */
|
|
cmap_entries = png_ptr->num_palette;
|
|
if (cmap_entries > 256)
|
|
cmap_entries = 256;
|
|
|
|
if (cmap_entries > image->colormap_entries)
|
|
png_error(png_ptr, "palette color-map: too few entries");
|
|
|
|
for (i=0; i < cmap_entries; ++i)
|
|
{
|
|
if (do_background != 0 && i < num_trans && trans[i] < 255)
|
|
{
|
|
if (trans[i] == 0)
|
|
png_create_colormap_entry(display, i, back_r, back_g,
|
|
back_b, 0, output_encoding);
|
|
|
|
else
|
|
{
|
|
unsigned int alpha;
|
|
|
|
/* Must compose the PNG file color in the color-map entry
|
|
* on the sRGB color in 'back'.
|
|
*/
|
|
png_image_get_sBIT(display);
|
|
alpha = update_for_sBIT(trans[i], display->sBIT[3], 8U);
|
|
|
|
/* Do the sBIT handling here because it only applies to the
|
|
* values from the colormap, not the background. Passing
|
|
* output_encoding to png_create_colormap_entry prevents
|
|
* this being duplicated.
|
|
*/
|
|
png_create_colormap_entry(display, i,
|
|
png_colormap_compose(display, colormap[i].red,
|
|
display->sBIT[0], P_FILE, alpha, back_r,
|
|
output_encoding),
|
|
png_colormap_compose(display, colormap[i].green,
|
|
display->sBIT[1], P_FILE, alpha, back_g,
|
|
output_encoding),
|
|
png_colormap_compose(display, colormap[i].blue,
|
|
display->sBIT[2], P_FILE, alpha, back_b,
|
|
output_encoding),
|
|
output_encoding == P_LINEAR ?
|
|
update_for_sBIT(alpha*257U, display->sBIT[3], 16U) :
|
|
trans[i],
|
|
output_encoding);
|
|
}
|
|
}
|
|
|
|
else
|
|
png_create_colormap_entry(display, i, colormap[i].red,
|
|
colormap[i].green, colormap[i].blue,
|
|
i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
|
|
}
|
|
|
|
/* The PNG data may have indices packed in fewer than 8 bits, it
|
|
* must be expanded if so.
|
|
*/
|
|
if (png_ptr->bit_depth < 8)
|
|
png_set_packing(png_ptr);
|
|
}
|
|
break;
|
|
|
|
default:
|
|
png_error(png_ptr, "invalid PNG color type");
|
|
/*NOT REACHED*/
|
|
}
|
|
|
|
/* Now deal with the output processing */
|
|
if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
|
|
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
|
|
png_set_tRNS_to_alpha(png_ptr);
|
|
|
|
switch (data_encoding)
|
|
{
|
|
default:
|
|
impossible("bad data option");
|
|
break;
|
|
|
|
case P_sRGB:
|
|
/* Change to 8-bit sRGB */
|
|
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
|
|
/* FALL THROUGH */
|
|
|
|
case P_FILE:
|
|
if (png_ptr->bit_depth > 8)
|
|
png_set_scale_16(png_ptr);
|
|
break;
|
|
}
|
|
|
|
affirm(cmap_entries <= 256 && cmap_entries <= image->colormap_entries);
|
|
|
|
image->colormap_entries = cmap_entries;
|
|
|
|
/* Double check using the recorded background index */
|
|
switch (output_processing)
|
|
{
|
|
case PNG_CMAP_NONE:
|
|
if (background_index != PNG_CMAP_NONE_BACKGROUND)
|
|
goto bad_background;
|
|
break;
|
|
|
|
case PNG_CMAP_GA:
|
|
if (background_index != PNG_CMAP_GA_BACKGROUND)
|
|
goto bad_background;
|
|
break;
|
|
|
|
case PNG_CMAP_TRANS:
|
|
if (background_index >= cmap_entries ||
|
|
background_index != PNG_CMAP_TRANS_BACKGROUND)
|
|
goto bad_background;
|
|
break;
|
|
|
|
case PNG_CMAP_RGB:
|
|
if (background_index != PNG_CMAP_RGB_BACKGROUND)
|
|
goto bad_background;
|
|
break;
|
|
|
|
case PNG_CMAP_RGB_ALPHA:
|
|
if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
|
|
goto bad_background;
|
|
break;
|
|
|
|
default:
|
|
impossible("bad processing option");
|
|
|
|
bad_background:
|
|
impossible("bad background index");
|
|
}
|
|
|
|
display->colormap_processing = output_processing;
|
|
|
|
return 1/*ok*/;
|
|
}
|
|
|
|
/* The final part of the color-map read called from png_image_finish_read. */
|
|
static int
|
|
png_image_read_and_map(png_voidp argument)
|
|
{
|
|
png_image_read_control *display = png_voidcast(png_image_read_control*,
|
|
argument);
|
|
png_imagep image = display->image;
|
|
png_structrp png_ptr = image->opaque->png_ptr;
|
|
int passes;
|
|
|
|
/* Called when the libpng data must be transformed into the color-mapped
|
|
* form. There is a local row buffer in display->local and this routine must
|
|
* do the interlace handling.
|
|
*/
|
|
switch (png_ptr->interlaced)
|
|
{
|
|
case PNG_INTERLACE_NONE:
|
|
passes = 1;
|
|
break;
|
|
|
|
case PNG_INTERLACE_ADAM7:
|
|
passes = PNG_INTERLACE_ADAM7_PASSES;
|
|
break;
|
|
|
|
default:
|
|
png_error(png_ptr, "unknown interlace type");
|
|
}
|
|
|
|
{
|
|
png_uint_32 height = image->height;
|
|
png_uint_32 width = image->width;
|
|
int proc = display->colormap_processing;
|
|
png_bytep first_row = png_voidcast(png_bytep, display->first_row);
|
|
ptrdiff_t step_row = display->row_bytes;
|
|
int pass;
|
|
|
|
for (pass = 0; pass < passes; ++pass)
|
|
{
|
|
unsigned int startx, stepx, stepy;
|
|
png_uint_32 y;
|
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
|
|
{
|
|
/* The row may be empty for a short image: */
|
|
if (PNG_PASS_COLS(width, pass) == 0)
|
|
continue;
|
|
|
|
startx = PNG_PASS_START_COL(pass);
|
|
stepx = PNG_PASS_COL_OFFSET(pass);
|
|
y = PNG_PASS_START_ROW(pass);
|
|
stepy = PNG_PASS_ROW_OFFSET(pass);
|
|
}
|
|
|
|
else
|
|
{
|
|
y = 0;
|
|
startx = 0;
|
|
stepx = stepy = 1;
|
|
}
|
|
|
|
for (; y<height; y += stepy)
|
|
{
|
|
png_bytep inrow = png_voidcast(png_bytep, display->local_row);
|
|
png_bytep outrow = first_row + y * step_row;
|
|
png_const_bytep end_row = outrow + width;
|
|
|
|
/* Read read the libpng data into the temporary buffer. */
|
|
png_read_row(png_ptr, inrow, NULL);
|
|
|
|
/* Now process the row according to the processing option, note
|
|
* that the caller verifies that the format of the libpng output
|
|
* data is as required.
|
|
*/
|
|
outrow += startx;
|
|
switch (proc)
|
|
{
|
|
case PNG_CMAP_GA:
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
/* The data is always in the PNG order */
|
|
unsigned int gray = *inrow++;
|
|
unsigned int alpha = *inrow++;
|
|
unsigned int entry;
|
|
|
|
/* NOTE: this code is copied as a comment in
|
|
* make_ga_colormap above. Please update the
|
|
* comment if you change this code!
|
|
*/
|
|
if (alpha > 229) /* opaque */
|
|
{
|
|
entry = (231 * gray + 128) >> 8;
|
|
}
|
|
else if (alpha < 26) /* transparent */
|
|
{
|
|
entry = 231;
|
|
}
|
|
else /* partially opaque */
|
|
{
|
|
entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
|
|
}
|
|
|
|
*outrow = png_check_byte(png_ptr, entry);
|
|
}
|
|
break;
|
|
|
|
case PNG_CMAP_TRANS:
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
png_byte gray = *inrow++;
|
|
png_byte alpha = *inrow++;
|
|
|
|
if (alpha == 0)
|
|
*outrow = PNG_CMAP_TRANS_BACKGROUND;
|
|
|
|
else if (gray != PNG_CMAP_TRANS_BACKGROUND)
|
|
*outrow = gray;
|
|
|
|
else
|
|
*outrow = PNG_CMAP_TRANS_BACKGROUND+1;
|
|
}
|
|
break;
|
|
|
|
case PNG_CMAP_RGB:
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
|
|
inrow += 3;
|
|
}
|
|
break;
|
|
|
|
case PNG_CMAP_RGB_ALPHA:
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
unsigned int alpha = inrow[3];
|
|
|
|
/* Because the alpha entries only hold alpha==0.5 values
|
|
* split the processing at alpha==0.25 (64) and 0.75
|
|
* (196).
|
|
*/
|
|
|
|
if (alpha >= 196)
|
|
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
|
|
inrow[2]);
|
|
|
|
else if (alpha < 64)
|
|
*outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
|
|
|
|
else
|
|
{
|
|
/* Likewise there are three entries for each of r, g
|
|
* and b. We could select the entry by popcount on
|
|
* the top two bits on those architectures that
|
|
* support it, this is what the code below does,
|
|
* crudely.
|
|
*/
|
|
unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
|
|
|
|
/* Here are how the values map:
|
|
*
|
|
* 0x00 .. 0x3f -> 0
|
|
* 0x40 .. 0xbf -> 1
|
|
* 0xc0 .. 0xff -> 2
|
|
*
|
|
* So, as above with the explicit alpha checks, the
|
|
* breakpoints are at 64 and 196.
|
|
*/
|
|
if (inrow[0] & 0x80) back_i += 9; /* red */
|
|
if (inrow[0] & 0x40) back_i += 9;
|
|
if (inrow[0] & 0x80) back_i += 3; /* green */
|
|
if (inrow[0] & 0x40) back_i += 3;
|
|
if (inrow[0] & 0x80) back_i += 1; /* blue */
|
|
if (inrow[0] & 0x40) back_i += 1;
|
|
|
|
*outrow = png_check_byte(png_ptr, back_i);
|
|
}
|
|
|
|
inrow += 4;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
png_image_read_colormapped(png_voidp argument)
|
|
{
|
|
png_image_read_control *display = png_voidcast(png_image_read_control*,
|
|
argument);
|
|
png_imagep image = display->image;
|
|
png_controlp control = image->opaque;
|
|
png_structrp png_ptr = control->png_ptr;
|
|
png_inforp info_ptr = control->info_ptr;
|
|
int color_type, bit_depth;
|
|
int passes = 0; /* As a flag */
|
|
|
|
PNG_SKIP_CHUNKS(png_ptr);
|
|
|
|
/* Update the 'info' structure and make sure the result is as required; first
|
|
* make sure to turn on the interlace handling if it will be required
|
|
* (because it can't be turned on *after* the call to png_read_update_info!)
|
|
*/
|
|
if (display->colormap_processing == PNG_CMAP_NONE)
|
|
passes = png_set_interlace_handling(png_ptr);
|
|
|
|
png_read_update_info(png_ptr, info_ptr);
|
|
|
|
/* Avoid the 'easy access' functions below because this allows them to be
|
|
* disabled; there are not useful with the simplified API.
|
|
*/
|
|
color_type = PNG_COLOR_TYPE_FROM_FORMAT(info_ptr->format);
|
|
bit_depth = info_ptr->bit_depth;
|
|
|
|
/* The expected output can be deduced from the colormap_processing option. */
|
|
switch (display->colormap_processing)
|
|
{
|
|
case PNG_CMAP_NONE:
|
|
/* Output must be one channel and one byte per pixel, the output
|
|
* encoding can be anything.
|
|
*/
|
|
if ((color_type == PNG_COLOR_TYPE_PALETTE ||
|
|
color_type == PNG_COLOR_TYPE_GRAY) && bit_depth == 8)
|
|
break;
|
|
|
|
goto bad_output;
|
|
|
|
case PNG_CMAP_TRANS:
|
|
case PNG_CMAP_GA:
|
|
/* Output must be two channels and the 'G' one must be sRGB, the latter
|
|
* can be checked with an exact number because it should have been set
|
|
* to this number above!
|
|
*/
|
|
if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA && bit_depth == 8 &&
|
|
!png_need_gamma_correction(png_ptr, png_memory_gamma(png_ptr),
|
|
1/*sRGB*/) &&
|
|
image->colormap_entries == 256)
|
|
break;
|
|
|
|
goto bad_output;
|
|
|
|
case PNG_CMAP_RGB:
|
|
/* Output must be 8-bit sRGB encoded RGB */
|
|
if (color_type == PNG_COLOR_TYPE_RGB && bit_depth == 8 &&
|
|
!png_need_gamma_correction(png_ptr, png_memory_gamma(png_ptr),
|
|
1/*sRGB*/) &&
|
|
image->colormap_entries == 216)
|
|
break;
|
|
|
|
goto bad_output;
|
|
|
|
case PNG_CMAP_RGB_ALPHA:
|
|
/* Output must be 8-bit sRGB encoded RGBA */
|
|
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA && bit_depth == 8 &&
|
|
!png_need_gamma_correction(png_ptr, png_memory_gamma(png_ptr),
|
|
1/*sRGB*/) &&
|
|
image->colormap_entries == 244 /* 216 + 1 + 27 */)
|
|
break;
|
|
|
|
/* goto bad_output; */
|
|
/* FALL THROUGH */
|
|
|
|
default:
|
|
bad_output:
|
|
impossible("bad color-map processing");
|
|
}
|
|
|
|
/* Now read the rows. Do this here if it is possible to read directly into
|
|
* the output buffer, otherwise allocate a local row buffer of the maximum
|
|
* size libpng requires and call the relevant processing routine safely.
|
|
*/
|
|
{
|
|
png_voidp first_row = display->buffer;
|
|
ptrdiff_t row_bytes = display->row_stride;
|
|
|
|
/* The following expression is designed to work correctly whether it gives
|
|
* a signed or an unsigned result.
|
|
*/
|
|
if (row_bytes < 0)
|
|
{
|
|
char *ptr = png_voidcast(char*, first_row);
|
|
ptr += (image->height-1) * (-row_bytes);
|
|
first_row = png_voidcast(png_voidp, ptr);
|
|
}
|
|
|
|
display->first_row = first_row;
|
|
display->row_bytes = row_bytes;
|
|
}
|
|
|
|
if (passes == 0)
|
|
{
|
|
int result;
|
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
|
|
|
|
display->local_row = row;
|
|
result = png_safe_execute(image, png_image_read_and_map, display);
|
|
display->local_row = NULL;
|
|
png_free(png_ptr, row);
|
|
|
|
return result;
|
|
}
|
|
|
|
else
|
|
{
|
|
png_alloc_size_t row_bytes = display->row_bytes;
|
|
|
|
while (--passes >= 0)
|
|
{
|
|
png_uint_32 y = image->height;
|
|
png_bytep row = png_voidcast(png_bytep, display->first_row);
|
|
|
|
while (y-- > 0)
|
|
{
|
|
png_read_row(png_ptr, row, NULL);
|
|
row += row_bytes;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/* Just the row reading part of png_image_read. */
|
|
static int
|
|
png_image_read_composite(png_voidp argument)
|
|
{
|
|
png_image_read_control *display = png_voidcast(png_image_read_control*,
|
|
argument);
|
|
png_imagep image = display->image;
|
|
png_structrp png_ptr = image->opaque->png_ptr;
|
|
int passes;
|
|
|
|
switch (png_ptr->interlaced)
|
|
{
|
|
case PNG_INTERLACE_NONE:
|
|
passes = 1;
|
|
break;
|
|
|
|
case PNG_INTERLACE_ADAM7:
|
|
passes = PNG_INTERLACE_ADAM7_PASSES;
|
|
break;
|
|
|
|
default:
|
|
png_error(png_ptr, "unknown interlace type");
|
|
}
|
|
|
|
{
|
|
png_uint_32 height = image->height;
|
|
png_uint_32 width = image->width;
|
|
ptrdiff_t step_row = display->row_bytes;
|
|
unsigned int channels =
|
|
(image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
|
|
int pass;
|
|
|
|
for (pass = 0; pass < passes; ++pass)
|
|
{
|
|
unsigned int startx, stepx, stepy;
|
|
png_uint_32 y;
|
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
|
|
{
|
|
/* The row may be empty for a short image: */
|
|
if (PNG_PASS_COLS(width, pass) == 0)
|
|
continue;
|
|
|
|
startx = PNG_PASS_START_COL(pass) * channels;
|
|
stepx = PNG_PASS_COL_OFFSET(pass) * channels;
|
|
y = PNG_PASS_START_ROW(pass);
|
|
stepy = PNG_PASS_ROW_OFFSET(pass);
|
|
}
|
|
|
|
else
|
|
{
|
|
y = 0;
|
|
startx = 0;
|
|
stepx = channels;
|
|
stepy = 1;
|
|
}
|
|
|
|
for (; y<height; y += stepy)
|
|
{
|
|
png_bytep inrow = png_voidcast(png_bytep, display->local_row);
|
|
png_bytep outrow;
|
|
png_const_bytep end_row;
|
|
|
|
/* Read the row, which is packed: */
|
|
png_read_row(png_ptr, inrow, NULL);
|
|
|
|
outrow = png_voidcast(png_bytep, display->first_row);
|
|
outrow += y * step_row;
|
|
end_row = outrow + width * channels;
|
|
|
|
/* Now do the composition on each pixel in this row. */
|
|
outrow += startx;
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
png_byte alpha = inrow[channels];
|
|
|
|
if (alpha > 0) /* else no change to the output */
|
|
{
|
|
unsigned int c;
|
|
|
|
for (c=0; c<channels; ++c)
|
|
{
|
|
png_uint_32 component = inrow[c];
|
|
|
|
if (alpha < 255) /* else just use component */
|
|
{
|
|
/* This is PNG_OPTIMIZED_ALPHA, the component value
|
|
* is a linear 8-bit value. Combine this with the
|
|
* current outrow[c] value which is sRGB encoded.
|
|
* Arithmetic here is 16-bits to preserve the output
|
|
* values correctly.
|
|
*/
|
|
component *= 257*255; /* =65535 */
|
|
component += (255-alpha)*png_sRGB_table[outrow[c]];
|
|
|
|
/* So 'component' is scaled by 255*65535 and is
|
|
* therefore appropriate for the sRGB to linear
|
|
* conversion table.
|
|
*/
|
|
component =
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, component);
|
|
}
|
|
|
|
outrow[c] = png_check_byte(png_ptr, component);
|
|
}
|
|
}
|
|
|
|
inrow += channels+1; /* components and alpha channel */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* The do_local_background case; called when all the following transforms are to
|
|
* be done:
|
|
*
|
|
* PNG_READ_RGB_TO_GRAY
|
|
* PNG_READ_COMPOSITE
|
|
* PNG_READ_GAMMA
|
|
*
|
|
* This is a work-around for the fact that both the PNG_READ_RGB_TO_GRAY and
|
|
* PNG_COMPOSITE code performs gamma correction, so we get double gamma
|
|
* correction. The fix-up is to prevent the PNG_COMPOSITE operation from
|
|
* happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
|
|
* row and handles the removal or pre-multiplication of the alpha channel.
|
|
*/
|
|
static int
|
|
png_image_read_background(png_voidp argument)
|
|
{
|
|
png_image_read_control *display = png_voidcast(png_image_read_control*,
|
|
argument);
|
|
png_imagep image = display->image;
|
|
png_structrp png_ptr = image->opaque->png_ptr;
|
|
png_inforp info_ptr = image->opaque->info_ptr;
|
|
png_uint_32 height = image->height;
|
|
png_uint_32 width = image->width;
|
|
int pass, passes;
|
|
|
|
/* Double check the convoluted logic below. We expect to get here with
|
|
* libpng doing rgb to gray and gamma correction but background processing
|
|
* left to the png_image_read_background function. The rows libpng produce
|
|
* might be 8 or 16-bit but should always have two channels; gray plus alpha.
|
|
*/
|
|
affirm(PNG_COLOR_TYPE_FROM_FORMAT(info_ptr->format) ==
|
|
PNG_COLOR_TYPE_GRAY_ALPHA);
|
|
debug(png_get_channels(png_ptr, info_ptr) == 2);
|
|
|
|
/* Expect the 8-bit case to always remove the alpha channel */
|
|
if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
|
|
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
png_error(png_ptr, "unexpected 8-bit transformation");
|
|
|
|
switch (png_ptr->interlaced)
|
|
{
|
|
case PNG_INTERLACE_NONE:
|
|
passes = 1;
|
|
break;
|
|
|
|
case PNG_INTERLACE_ADAM7:
|
|
passes = PNG_INTERLACE_ADAM7_PASSES;
|
|
break;
|
|
|
|
default:
|
|
png_error(png_ptr, "unknown interlace type");
|
|
}
|
|
|
|
/* Use direct access to info_ptr here because otherwise the simplified API
|
|
* would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
|
|
* checking the value after libpng expansions, not the original value in the
|
|
* PNG.
|
|
*/
|
|
switch (info_ptr->bit_depth)
|
|
{
|
|
default:
|
|
png_error(png_ptr, "unexpected bit depth");
|
|
break;
|
|
|
|
case 8:
|
|
/* 8-bit sRGB gray values with an alpha channel; the alpha channel is
|
|
* to be removed by composing on a background: either the row if
|
|
* display->background is NULL or display->background->green if not.
|
|
* Unlike the code above ALPHA_OPTIMIZED has *not* been done.
|
|
*/
|
|
{
|
|
png_bytep first_row = png_voidcast(png_bytep, display->first_row);
|
|
ptrdiff_t step_row = display->row_bytes;
|
|
|
|
for (pass = 0; pass < passes; ++pass)
|
|
{
|
|
png_bytep row = png_voidcast(png_bytep, display->first_row);
|
|
unsigned int startx, stepx, stepy;
|
|
png_uint_32 y;
|
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
|
|
{
|
|
/* The row may be empty for a short image: */
|
|
if (PNG_PASS_COLS(width, pass) == 0)
|
|
continue;
|
|
|
|
startx = PNG_PASS_START_COL(pass);
|
|
stepx = PNG_PASS_COL_OFFSET(pass);
|
|
y = PNG_PASS_START_ROW(pass);
|
|
stepy = PNG_PASS_ROW_OFFSET(pass);
|
|
}
|
|
|
|
else
|
|
{
|
|
y = 0;
|
|
startx = 0;
|
|
stepx = stepy = 1;
|
|
}
|
|
|
|
if (display->background == NULL)
|
|
{
|
|
for (; y<height; y += stepy)
|
|
{
|
|
png_bytep inrow = png_voidcast(png_bytep,
|
|
display->local_row);
|
|
png_bytep outrow = first_row + y * step_row;
|
|
png_const_bytep end_row = outrow + width;
|
|
|
|
/* Read the row, which is packed: */
|
|
png_read_row(png_ptr, inrow, NULL);
|
|
|
|
/* Now do the composition on each pixel in this row. */
|
|
outrow += startx;
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
png_byte alpha = inrow[1];
|
|
|
|
if (alpha > 0) /* else no change to the output */
|
|
{
|
|
png_uint_32 component = inrow[0];
|
|
|
|
if (alpha < 255) /* else just use component */
|
|
{
|
|
/* Since PNG_OPTIMIZED_ALPHA was not set it is
|
|
* necessary to invert the sRGB transfer
|
|
* function and multiply the alpha out.
|
|
*/
|
|
component = png_sRGB_table[component] * alpha;
|
|
component += png_sRGB_table[outrow[0]] *
|
|
(255-alpha);
|
|
component =
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, component);
|
|
}
|
|
|
|
outrow[0] = png_check_byte(png_ptr, component);
|
|
}
|
|
|
|
inrow += 2; /* gray and alpha channel */
|
|
}
|
|
}
|
|
}
|
|
|
|
else /* constant background value */
|
|
{
|
|
png_byte background8 = display->background->green;
|
|
png_uint_16 background = png_sRGB_table[background8];
|
|
|
|
for (; y<height; y += stepy)
|
|
{
|
|
png_bytep inrow = png_voidcast(png_bytep,
|
|
display->local_row);
|
|
png_bytep outrow = first_row + y * step_row;
|
|
png_const_bytep end_row = outrow + width;
|
|
|
|
/* Read the row, which is packed: */
|
|
png_read_row(png_ptr, inrow, NULL);
|
|
|
|
/* Now do the composition on each pixel in this row. */
|
|
outrow += startx;
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
png_byte alpha = inrow[1];
|
|
|
|
if (alpha > 0) /* else use background */
|
|
{
|
|
png_uint_32 component = inrow[0];
|
|
|
|
if (alpha < 255) /* else just use component */
|
|
{
|
|
component = png_sRGB_table[component] * alpha;
|
|
component += background * (255-alpha);
|
|
component =
|
|
PNG_sRGB_FROM_LINEAR(png_ptr, component);
|
|
}
|
|
|
|
outrow[0] = png_check_byte(png_ptr, component);
|
|
}
|
|
|
|
else
|
|
outrow[0] = background8;
|
|
|
|
inrow += 2; /* gray and alpha channel */
|
|
}
|
|
|
|
row += display->row_bytes;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
case 16:
|
|
/* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
|
|
* still be done and, maybe, the alpha channel removed. This code also
|
|
* handles the alpha-first option.
|
|
*/
|
|
{
|
|
png_uint_16p first_row = png_voidcast(png_uint_16p,
|
|
display->first_row);
|
|
/* The division by two is safe because the caller passed in a
|
|
* stride which was multiplied by 2 (below) to get row_bytes.
|
|
*/
|
|
ptrdiff_t step_row = display->row_bytes / 2;
|
|
int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
|
|
unsigned int outchannels = 1+preserve_alpha;
|
|
int swap_alpha = 0;
|
|
|
|
#ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
|
|
if (preserve_alpha != 0 &&
|
|
(image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
|
|
swap_alpha = 1;
|
|
#endif
|
|
|
|
for (pass = 0; pass < passes; ++pass)
|
|
{
|
|
unsigned int startx, stepx, stepy;
|
|
png_uint_32 y;
|
|
|
|
/* The 'x' start and step are adjusted to output components here.
|
|
*/
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
|
|
{
|
|
/* The row may be empty for a short image: */
|
|
if (PNG_PASS_COLS(width, pass) == 0)
|
|
continue;
|
|
|
|
startx = PNG_PASS_START_COL(pass) * outchannels;
|
|
stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
|
|
y = PNG_PASS_START_ROW(pass);
|
|
stepy = PNG_PASS_ROW_OFFSET(pass);
|
|
}
|
|
|
|
else
|
|
{
|
|
y = 0;
|
|
startx = 0;
|
|
stepx = outchannels;
|
|
stepy = 1;
|
|
}
|
|
|
|
for (; y<height; y += stepy)
|
|
{
|
|
png_const_uint_16p inrow;
|
|
png_uint_16p outrow = first_row + y*step_row;
|
|
png_uint_16p end_row = outrow + width * outchannels;
|
|
|
|
/* Read the row, which is packed: */
|
|
png_read_row(png_ptr, png_voidcast(png_bytep,
|
|
display->local_row), NULL);
|
|
inrow = png_voidcast(png_const_uint_16p, display->local_row);
|
|
|
|
/* Now do the pre-multiplication on each pixel in this row.
|
|
*/
|
|
outrow += startx;
|
|
for (; outrow < end_row; outrow += stepx)
|
|
{
|
|
png_uint_32 component = inrow[0];
|
|
png_uint_16 alpha = inrow[1];
|
|
|
|
if (alpha > 0) /* else 0 */
|
|
{
|
|
if (alpha < 65535) /* else just use component */
|
|
{
|
|
component *= alpha;
|
|
component += 32767;
|
|
component /= 65535;
|
|
}
|
|
}
|
|
|
|
else
|
|
component = 0;
|
|
|
|
outrow[swap_alpha] =
|
|
png_check_u16(png_ptr, component);
|
|
if (preserve_alpha != 0)
|
|
outrow[1 ^ swap_alpha] = alpha;
|
|
|
|
inrow += 2; /* components and alpha channel */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* The guts of png_image_finish_read as a png_safe_execute callback. */
|
|
static int
|
|
png_image_read_direct(png_voidp argument)
|
|
{
|
|
png_image_read_control *display = png_voidcast(png_image_read_control*,
|
|
argument);
|
|
png_imagep image = display->image;
|
|
png_structrp png_ptr = image->opaque->png_ptr;
|
|
png_inforp info_ptr = image->opaque->info_ptr;
|
|
|
|
png_uint_32 format = image->format;
|
|
int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
|
|
int do_local_compose = 0;
|
|
int do_local_background = 0; /* to avoid double gamma correction bug */
|
|
int passes = 0;
|
|
|
|
/* Add transforms to ensure the correct output format is produced then check
|
|
* that the required implementation support is there. Always expand; always
|
|
* need 8 bits minimum, no palette and expanded tRNS.
|
|
*/
|
|
png_set_expand(png_ptr);
|
|
|
|
/* Now check the format to see if it was modified. */
|
|
{
|
|
png_uint_32 base_format = png_image_format(png_ptr) &
|
|
PNG_BIC_MASK(PNG_FORMAT_FLAG_COLORMAP) /* removed by png_set_expand */;
|
|
png_uint_32 change = format ^ base_format;
|
|
png_fixed_point output_gamma;
|
|
int mode; /* alpha mode */
|
|
|
|
/* Do this first so that we have a record if rgb to gray is happening. */
|
|
if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
|
|
{
|
|
/* gray<->color transformation required. */
|
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
|
|
png_set_gray_to_rgb(png_ptr);
|
|
|
|
else
|
|
{
|
|
/* libpng can't do both rgb to gray and
|
|
* background/pre-multiplication if there is also significant gamma
|
|
* correction, because both operations require linear colors and
|
|
* the code only supports one transform doing the gamma correction.
|
|
* Handle this by doing the pre-multiplication or background
|
|
* operation in this code, if necessary.
|
|
*
|
|
* TODO: fix this by rewriting pngrtran.c (!)
|
|
*
|
|
* For the moment (given that fixing this in pngrtran.c is an
|
|
* enormous change) 'do_local_background' is used to indicate that
|
|
* the problem exists.
|
|
*/
|
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
do_local_background = 1/*maybe*/;
|
|
|
|
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
|
|
PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
|
|
}
|
|
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_COLOR);
|
|
}
|
|
|
|
/* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
|
|
*/
|
|
{
|
|
png_fixed_point input_gamma_default;
|
|
|
|
if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
|
|
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
|
|
input_gamma_default = PNG_GAMMA_LINEAR;
|
|
else
|
|
input_gamma_default = PNG_DEFAULT_sRGB;
|
|
|
|
/* Call png_set_alpha_mode to set the default for the input gamma; the
|
|
* output gamma is set by a second call below.
|
|
*/
|
|
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
|
|
}
|
|
|
|
if (linear != 0)
|
|
{
|
|
/* If there *is* an alpha channel in the input it must be multiplied
|
|
* out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
|
|
*/
|
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
mode = PNG_ALPHA_STANDARD; /* associated alpha */
|
|
|
|
else
|
|
mode = PNG_ALPHA_PNG;
|
|
|
|
output_gamma = PNG_GAMMA_LINEAR;
|
|
}
|
|
|
|
else
|
|
{
|
|
mode = PNG_ALPHA_PNG;
|
|
output_gamma = PNG_DEFAULT_sRGB;
|
|
}
|
|
|
|
/* If 'do_local_background' is set check for the presence of gamma
|
|
* correction; this is part of the work-round for the libpng bug
|
|
* described above.
|
|
*
|
|
* TODO: fix libpng and remove this.
|
|
*/
|
|
if (do_local_background != 0)
|
|
{
|
|
/* This is intended to be a safe check to see if libpng will perform
|
|
* gamma work in pngrtran.c; if it will *not* be performed the
|
|
* do_local_background flag is cancelled.
|
|
*/
|
|
if (!png_need_gamma_correction(png_ptr, 0/*PNG gamma*/,
|
|
output_gamma != PNG_GAMMA_LINEAR))
|
|
do_local_background = 0;
|
|
|
|
else if (mode == PNG_ALPHA_STANDARD)
|
|
{
|
|
do_local_background = 2/*required*/;
|
|
mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
|
|
}
|
|
|
|
/* else leave as 1 for the checks below */
|
|
}
|
|
|
|
/* If the bit-depth changes then handle that here. */
|
|
if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
|
|
{
|
|
if (linear != 0 /*16-bit output*/)
|
|
png_set_expand_16(png_ptr);
|
|
|
|
else /* 8-bit output */
|
|
png_set_scale_16(png_ptr);
|
|
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_LINEAR);
|
|
}
|
|
|
|
/* Now the background/alpha channel changes. */
|
|
if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
/* Removing an alpha channel requires composition for the 8-bit
|
|
* formats; for the 16-bit it is already done, above, by the
|
|
* pre-multiplication and the channel just needs to be stripped.
|
|
*/
|
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
/* If RGB->gray is happening the alpha channel must be left and the
|
|
* operation completed locally.
|
|
*
|
|
* TODO: fix libpng and remove this.
|
|
*/
|
|
if (do_local_background != 0)
|
|
do_local_background = 2/*required*/;
|
|
|
|
/* 16-bit output: just remove the channel */
|
|
else if (linear != 0) /* compose on black (well, pre-multiply) */
|
|
png_set_strip_alpha(png_ptr);
|
|
|
|
/* 8-bit output: do an appropriate compose */
|
|
else if (display->background != NULL)
|
|
{
|
|
png_color_16 c;
|
|
|
|
c.index = 0; /*unused*/
|
|
c.red = display->background->red;
|
|
c.green = display->background->green;
|
|
c.blue = display->background->blue;
|
|
c.gray = display->background->green;
|
|
|
|
/* This is always an 8-bit sRGB value, using the 'green' channel
|
|
* for gray is much better than calculating the luminance here;
|
|
* we can get off-by-one errors in that calculation relative to
|
|
* the app expectations and that will show up in transparent
|
|
* pixels.
|
|
*/
|
|
png_set_background_fixed(png_ptr, &c,
|
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
|
|
0/*gamma: not used*/);
|
|
}
|
|
|
|
else /* compose on row: implemented below. */
|
|
{
|
|
do_local_compose = 1;
|
|
/* This leaves the alpha channel in the output, so it has to be
|
|
* removed by the code below. Set the encoding to the 'OPTIMIZE'
|
|
* one so the code only has to hack on the pixels that require
|
|
* composition.
|
|
*/
|
|
mode = PNG_ALPHA_OPTIMIZED;
|
|
}
|
|
}
|
|
|
|
else /* output needs an alpha channel */
|
|
{
|
|
/* This is tricky because it happens before the swap operation has
|
|
* been accomplished; however, the swap does *not* swap the added
|
|
* alpha channel (weird API), so it must be added in the correct
|
|
* place.
|
|
*/
|
|
png_uint_32 filler; /* opaque filler */
|
|
int where;
|
|
|
|
if (linear != 0)
|
|
filler = 65535;
|
|
|
|
else
|
|
filler = 255;
|
|
|
|
#ifdef PNG_FORMAT_AFIRST_SUPPORTED
|
|
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
|
|
{
|
|
where = PNG_FILLER_BEFORE;
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_AFIRST);
|
|
}
|
|
|
|
else
|
|
#endif
|
|
where = PNG_FILLER_AFTER;
|
|
|
|
png_set_add_alpha(png_ptr, filler, where);
|
|
}
|
|
|
|
/* This stops the (irrelevant) call to swap_alpha below. */
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_ALPHA);
|
|
}
|
|
|
|
/* Now set the alpha mode correctly; this is always done, even if there is
|
|
* no alpha channel in either the input or the output because it correctly
|
|
* sets the output gamma.
|
|
*/
|
|
png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
|
|
|
|
# ifdef PNG_FORMAT_BGR_SUPPORTED
|
|
if ((change & PNG_FORMAT_FLAG_BGR) != 0)
|
|
{
|
|
/* Check only the output format; PNG is never BGR; don't do this if
|
|
* the output is gray, but fix up the 'format' value in that case.
|
|
*/
|
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
|
|
png_set_bgr(png_ptr);
|
|
|
|
else
|
|
format &= PNG_BIC_MASK(PNG_FORMAT_FLAG_BGR);
|
|
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_BGR);
|
|
}
|
|
# endif
|
|
|
|
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
|
|
if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
|
|
{
|
|
/* Only relevant if there is an alpha channel - it's particularly
|
|
* important to handle this correctly because do_local_compose may
|
|
* be set above and then libpng will keep the alpha channel for this
|
|
* code to remove.
|
|
*/
|
|
if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
/* Disable this if doing a local background,
|
|
* TODO: remove this when local background is no longer required.
|
|
*/
|
|
if (do_local_background != 2)
|
|
png_set_swap_alpha(png_ptr);
|
|
}
|
|
|
|
else
|
|
format &= PNG_BIC_MASK(PNG_FORMAT_FLAG_AFIRST);
|
|
|
|
change &= PNG_BIC_MASK(PNG_FORMAT_FLAG_AFIRST);
|
|
}
|
|
# endif
|
|
|
|
/* If the *output* is 16-bit then we need to check for a byte-swap on this
|
|
* architecture.
|
|
*/
|
|
if (linear != 0)
|
|
{
|
|
PNG_CONST png_uint_16 le = 0x0001;
|
|
|
|
if ((*(png_const_bytep) & le) != 0)
|
|
png_set_swap(png_ptr);
|
|
}
|
|
|
|
/* If change is not now 0 some transformation is missing - error out. */
|
|
if (change != 0)
|
|
png_error(png_ptr, "png_read_image: unsupported transformation");
|
|
}
|
|
|
|
PNG_SKIP_CHUNKS(png_ptr);
|
|
|
|
/* Update the 'info' structure and make sure the result is as required; first
|
|
* make sure to turn on the interlace handling if it will be required
|
|
* (because it can't be turned on *after* the call to png_read_update_info!)
|
|
*
|
|
* TODO: remove the do_local_background fixup below.
|
|
*/
|
|
if (do_local_compose == 0 && do_local_background != 2)
|
|
passes = png_set_interlace_handling(png_ptr);
|
|
|
|
png_read_update_info(png_ptr, info_ptr);
|
|
|
|
{
|
|
png_uint_32 out_format = png_memory_format(png_ptr);
|
|
|
|
/* Swapping is expected for the 16-bit format: */
|
|
out_format &= PNG_BIC_MASK(PNG_FORMAT_FLAG_SWAPPED);
|
|
|
|
/* The remaining upper bits should never be set: */
|
|
affirm(!(out_format & ~0x3FU));
|
|
|
|
if ((out_format & PNG_FORMAT_FLAG_ALPHA) != 0)
|
|
{
|
|
/* do_local_compose removes this channel below. */
|
|
if (do_local_compose != 0 ||
|
|
/* do_local_background does the same if required. */
|
|
(do_local_background == 2 &&
|
|
(format & PNG_FORMAT_FLAG_ALPHA) == 0))
|
|
out_format &= PNG_BIC_MASK(PNG_FORMAT_FLAG_ALPHA);
|
|
}
|
|
|
|
else
|
|
affirm(do_local_compose == 0 /* else alpha channel lost */);
|
|
|
|
switch (png_memory_channel_depth(png_ptr))
|
|
{
|
|
case 16: affirm((out_format & PNG_FORMAT_FLAG_LINEAR) != 0); break;
|
|
case 8: affirm((out_format & PNG_FORMAT_FLAG_LINEAR) == 0); break;
|
|
default: impossible("unexpected bit depth"); break;
|
|
}
|
|
|
|
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
|
|
if (do_local_background == 2)
|
|
{
|
|
/* do_local_background should be handling the swap: */
|
|
affirm(!(out_format & PNG_FORMAT_FLAG_AFIRST));
|
|
|
|
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
|
|
out_format |= PNG_FORMAT_FLAG_AFIRST;
|
|
}
|
|
# endif
|
|
|
|
/* This is actually an internal error. */
|
|
affirm(out_format == format /* else unimplemented transformations */);
|
|
}
|
|
|
|
/* Now read the rows. If do_local_compose is set then it is necessary to use
|
|
* a local row buffer. The output will be GA, RGBA or BGRA and must be
|
|
* converted to G, RGB or BGR as appropriate. The 'local_row' member of the
|
|
* display acts as a flag.
|
|
*/
|
|
{
|
|
png_voidp first_row = display->buffer;
|
|
ptrdiff_t row_bytes = display->row_stride;
|
|
|
|
if (linear != 0)
|
|
row_bytes *= 2;
|
|
|
|
/* The following expression is designed to work correctly whether it gives
|
|
* a signed or an unsigned result.
|
|
*/
|
|
if (row_bytes < 0)
|
|
{
|
|
char *ptr = png_voidcast(char*, first_row);
|
|
ptr += (image->height-1) * (-row_bytes);
|
|
first_row = png_voidcast(png_voidp, ptr);
|
|
}
|
|
|
|
display->first_row = first_row;
|
|
display->row_bytes = row_bytes;
|
|
}
|
|
|
|
if (do_local_compose != 0)
|
|
{
|
|
int result;
|
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
|
|
|
|
display->local_row = row;
|
|
result = png_safe_execute(image, png_image_read_composite, display);
|
|
display->local_row = NULL;
|
|
png_free(png_ptr, row);
|
|
|
|
return result;
|
|
}
|
|
|
|
else if (do_local_background == 2)
|
|
{
|
|
int result;
|
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
|
|
|
|
display->local_row = row;
|
|
result = png_safe_execute(image, png_image_read_background, display);
|
|
display->local_row = NULL;
|
|
png_free(png_ptr, row);
|
|
|
|
return result;
|
|
}
|
|
|
|
else
|
|
{
|
|
png_alloc_size_t row_bytes = display->row_bytes;
|
|
|
|
while (--passes >= 0)
|
|
{
|
|
png_uint_32 y = image->height;
|
|
png_bytep row = png_voidcast(png_bytep, display->first_row);
|
|
|
|
while (y-- > 0)
|
|
{
|
|
png_read_row(png_ptr, row, NULL);
|
|
row += row_bytes;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
int PNGAPI
|
|
png_image_finish_read(png_imagep image, png_const_colorp background,
|
|
void *buffer, ptrdiff_t row_stride, void *colormap)
|
|
{
|
|
if (image != NULL && image->version == PNG_IMAGE_VERSION)
|
|
{
|
|
/* Check for row_stride overflow. This check is not performed on the
|
|
* original PNG format because it may not occur in the output PNG format
|
|
* and libpng deals with the issues of reading the original.
|
|
*/
|
|
const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
|
|
|
|
/* The test is slightly evil: it assumes that a signed pointer difference
|
|
* (ptrdiff_t) can hold a maximum value of half, rounded down, of the
|
|
* maximum of a (size_t). This is almost certain to be true.
|
|
*/
|
|
if (image->width <= (PNG_SIZE_MAX >> 1)/channels) /* no overflow */
|
|
{
|
|
png_alloc_size_t check;
|
|
const png_alloc_size_t png_row_stride =
|
|
(png_alloc_size_t)/*SAFE*/image->width * channels;
|
|
|
|
if (row_stride == 0)
|
|
row_stride = (ptrdiff_t)png_row_stride;
|
|
|
|
if (row_stride < 0)
|
|
check = -row_stride;
|
|
|
|
else
|
|
check = row_stride;
|
|
|
|
if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
|
|
{
|
|
/* Now check for overflow of the image buffer calculation; this
|
|
* limits the whole image size to PNG_SIZE_MAX bytes.
|
|
*
|
|
* The PNG_IMAGE_BUFFER_SIZE macro is:
|
|
*
|
|
* (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
|
|
*
|
|
* We have no way of guaranteeing that the application used the
|
|
* correct type for 'row_stride' if it used the macro, so this is
|
|
* technically not completely safe, but this is the case throughout
|
|
* libpng; the app is responsible for making sure the calcualtion of
|
|
* buffer sizes does not overflow.
|
|
*/
|
|
if (image->height <= PNG_SIZE_MAX /
|
|
PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format) / check)
|
|
{
|
|
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
|
|
(image->colormap_entries > 0 && colormap != NULL))
|
|
{
|
|
int result;
|
|
png_image_read_control display;
|
|
|
|
memset(&display, 0, (sizeof display));
|
|
display.image = image;
|
|
display.buffer = buffer;
|
|
display.row_stride = row_stride;
|
|
display.colormap = colormap;
|
|
display.background = background;
|
|
display.local_row = NULL;
|
|
|
|
/* Choose the correct 'end' routine; for the color-map case
|
|
* all the setup has already been done.
|
|
*/
|
|
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
|
|
result =
|
|
png_safe_execute(image,
|
|
png_image_read_colormap, &display) &&
|
|
png_safe_execute(image,
|
|
png_image_read_colormapped, &display);
|
|
|
|
else
|
|
result =
|
|
png_safe_execute(image,
|
|
png_image_read_direct, &display);
|
|
|
|
png_image_free(image);
|
|
return result;
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_finish_read[color-map]: no color-map");
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_finish_read: image too large");
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_finish_read: invalid argument");
|
|
}
|
|
|
|
else
|
|
return png_image_error(image,
|
|
"png_image_finish_read: row_stride too large");
|
|
}
|
|
|
|
else if (image != NULL)
|
|
return png_image_error(image,
|
|
"png_image_finish_read: damaged PNG_IMAGE_VERSION");
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif /* SIMPLIFIED_READ */
|
|
#endif /* READ */
|