mirror of
https://git.code.sf.net/p/libpng/code.git
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01ff090760
PNG compression level setting API: this allows the various compression settings
controlling deflate, fitlering, and so on to be set via a single setting with
six values. This is currently documented in png.h ("Write compression
settings").
Internally the compression settings have been tuned both for the overall setting
and for any specific settings made by the original APIs.
APIs to control iCCP chunk compression separately have been added.
contrib/examples/pngcp.c has been modified to accomodate the new compression
setting and to include options for separate control of iCCP chunk compression.
The new ABI, png_setting, has been modified to accomodate a wider range of
settings and most of the old compression control ABIs have been replaced by
function-like macros with the same API which call png_setting. This is an API
check in 1.7.0 for png_setting (alone). png_setting now handles all of
png_set_option. This eliminates 19 ABIs at the cost of adding 1 (png_setting).
CRC and benign error checking has been updated internally to use bit-fields and
the CRC calculation skip when the CRC is not used has been improved slightly to
avoid the initialization of the CRC. A new png_setting based API allows more
detailed control of benign error/warning messages (this may change, the internal
error handling seems too complex.) The ERROR_NUMBERS support has been removed
with the intent of implementing proper i18n.
The memcpy-size-0 issue in png_push_fill_buffer has been fixed, with an
appropriate debug() assert if a fill for 0 bytes occurs.
Most PNG_FLAG_ values for png_struct::flags have been eliminated (as a result of
the benign error handling changes). Only one remains.
Signed-off-by: John Bowler <jbowler@acm.org>
4174 lines
141 KiB
C
4174 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_ERROR;
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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_ERROR;
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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)
|
|
return;
|
|
|
|
rp = row;
|
|
dp = display_row;
|
|
if (rp != NULL && dp != NULL)
|
|
for (i = 0; i < num_rows; i++)
|
|
{
|
|
png_bytep rptr = *rp++;
|
|
png_bytep dptr = *dp++;
|
|
|
|
png_read_row(png_ptr, rptr, dptr);
|
|
}
|
|
|
|
else if (rp != NULL)
|
|
for (i = 0; i < num_rows; i++)
|
|
{
|
|
png_bytep rptr = *rp;
|
|
png_read_row(png_ptr, rptr, NULL);
|
|
rp++;
|
|
}
|
|
|
|
else if (dp != NULL)
|
|
for (i = 0; i < num_rows; i++)
|
|
{
|
|
png_bytep dptr = *dp;
|
|
png_read_row(png_ptr, NULL, dptr);
|
|
dp++;
|
|
}
|
|
}
|
|
#endif /* SEQUENTIAL_READ */
|
|
|
|
#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;
|
|
|
|
png_set_benign_errors(png_ptr, 1/*warn*/);
|
|
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,
|
|
"a 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; check for
|
|
* (size_t) overflow here. This detects issues with the
|
|
* PNG_IMAGE_BUFFER_SIZE macro.
|
|
*/
|
|
if (image->height <= PNG_SIZE_MAX/png_row_stride)
|
|
{
|
|
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 */
|