mirror of
https://git.code.sf.net/p/libpng/code.git
synced 2025-07-10 18:04:09 +02:00
673ae608ab
internal struct (png_transform_control) to replace row_info and uses
that to implement affirms correctly. The change also adds checks on
the rowbytes calculation and additional checks on most transform
implementations.
Added png_uint_16 range checking, pngvalid tRNS, fixed png_uint_16:
review of previous checks, removal of some where SAFE. pngvalid: add
testing of tRNS for better code coverage pngvalid: correct rgb-to-gray
error calculations. Code coverage is still incomplete: see /*UNTESTED*/
in pngrtran.c
537 lines
14 KiB
C
537 lines
14 KiB
C
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/* pngwtran.c - transforms the data in a row for PNG writers
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*
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* Last changed in libpng 1.6.17 [(PENDING RELEASE)]
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* Copyright (c) 1998-2015 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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#include "pngpriv.h"
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#define PNG_SRC_FILE PNG_SRC_FILE_pngwtran
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#ifdef PNG_WRITE_SUPPORTED
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#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
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#ifdef PNG_WRITE_PACK_SUPPORTED
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/* Pack pixels into bytes. Get the true bit depth from png_ptr. The
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* row_info bit depth should be 8 (one pixel per byte). The channels
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* should be 1 (this only happens on grayscale and paletted images).
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*/
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static void
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png_do_pack(png_transform_controlp row_info, png_bytep row)
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{
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png_debug(1, "in png_do_pack");
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# define png_ptr row_info->png_ptr
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/* The comment suggests the following must be true.
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* TODO: test this.
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*/
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affirm(row_info->bit_depth == 8 && row_info->channels == 1);
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{
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switch (png_ptr->bit_depth)
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{
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case 1:
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{
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png_const_bytep ep = row + png_transform_rowbytes(row_info);
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png_bytep dp = row;
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unsigned int mask = 0x80, v = 0;
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while (row < ep)
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{
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if (*row++ != 0)
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v |= mask;
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mask >>= 1;
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if (mask == 0)
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{
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mask = 0x80;
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*dp++ = (png_byte)/*SAFE*/v;
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v = 0;
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}
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}
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if (mask != 0x80)
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*dp++ = (png_byte)/*SAFE*/v;
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row_info->bit_depth = 1;
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break;
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}
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case 2:
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{
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png_const_bytep ep = row + png_transform_rowbytes(row_info);
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png_bytep dp = row;
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unsigned int shift = 8, v = 0;
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while (row < ep)
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{
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shift -= 2;
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v |= (*row++ & 0x3) << shift;
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if (shift == 0)
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{
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shift = 8;
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*dp++ = png_check_byte(png_ptr, v);
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v = 0;
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}
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}
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if (shift != 8)
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*dp++ = png_check_byte(png_ptr, v);
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row_info->bit_depth = 2;
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break;
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}
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case 4:
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{
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png_const_bytep ep = row + png_transform_rowbytes(row_info);
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png_bytep dp = row;
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unsigned int shift = 8, v = 0;
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while (row < ep)
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{
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shift -= 4;
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v |= ((*row++ & 0xf) << shift);
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if (shift == 0)
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{
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shift = 8;
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*dp++ = png_check_byte(png_ptr, v);
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v = 0;
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}
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}
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if (shift != 8)
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*dp++ = png_check_byte(png_ptr, v);
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row_info->bit_depth = 4;
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break;
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}
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default:
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break;
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}
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}
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# undef png_ptr
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}
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#endif
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#ifdef PNG_WRITE_SHIFT_SUPPORTED
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/* Shift pixel values to take advantage of whole range. Pass the
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* true number of bits in bit_depth. The row should be packed
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* according to row_info->bit_depth. Thus, if you had a row of
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* bit depth 4, but the pixels only had values from 0 to 7, you
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* would pass 3 as bit_depth, and this routine would translate the
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* data to 0 to 15.
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*
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* NOTE: this is horrible complexity for no value. Once people suggested they
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* were selling 16-bit displays with 5:6:5 bits spread R:G:B but so far as I
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* could determine these displays produced intermediate grey (uncolored) colors,
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* which is impossible with a true 5:6:5, so most likely 5:6:5 was marketing.
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*/
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static void
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png_do_shift(png_transform_controlp row_info, png_bytep row)
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{
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png_debug(1, "in png_do_shift");
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# define png_ptr row_info->png_ptr
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if (!(row_info->flags & PNG_INDEXED) && (row_info->channels-1) <= 3)
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{
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png_const_color_8p bit_depth = &png_ptr->shift;
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int shift_start[4], shift_dec[4];
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int channels = 0;
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if (row_info->channels == 3 || row_info->channels == 4)
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{
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shift_start[channels] = row_info->bit_depth - bit_depth->red;
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shift_dec[channels] = bit_depth->red;
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channels++;
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shift_start[channels] = row_info->bit_depth - bit_depth->green;
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shift_dec[channels] = bit_depth->green;
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channels++;
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shift_start[channels] = row_info->bit_depth - bit_depth->blue;
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shift_dec[channels] = bit_depth->blue;
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channels++;
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}
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else /* 1 or 2 channels */
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{
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shift_start[channels] = row_info->bit_depth - bit_depth->gray;
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shift_dec[channels] = bit_depth->gray;
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channels++;
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}
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if (row_info->channels == 2 || row_info->channels == 4)
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{
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shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
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shift_dec[channels] = bit_depth->alpha;
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channels++;
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}
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/* With low res depths, could only be grayscale, so one channel */
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if (row_info->bit_depth < 8)
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{
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png_bytep bp = row;
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png_size_t i;
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unsigned int mask;
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size_t row_bytes = png_transform_rowbytes(row_info);
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affirm(row_info->channels == 1);
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if (bit_depth->gray == 1 && row_info->bit_depth == 2)
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mask = 0x55;
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else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
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mask = 0x11;
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else
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mask = 0xff;
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for (i = 0; i < row_bytes; i++, bp++)
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{
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int j;
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unsigned int v, out;
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v = *bp;
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out = 0;
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for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
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{
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if (j > 0)
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out |= v << j;
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else
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out |= (v >> (-j)) & mask;
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}
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*bp = png_check_byte(png_ptr, out);
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}
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}
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else if (row_info->bit_depth == 8)
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{
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png_bytep bp = row;
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png_uint_32 i;
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png_uint_32 istop = channels * row_info->width;
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for (i = 0; i < istop; i++, bp++)
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{
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const unsigned int c = i%channels;
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int j;
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unsigned int v, out;
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v = *bp;
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out = 0;
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for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
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{
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if (j > 0)
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out |= v << j;
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else
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out |= v >> (-j);
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}
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*bp = png_check_byte(png_ptr, out);
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}
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}
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else
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{
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png_bytep bp;
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png_uint_32 i;
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png_uint_32 istop = channels * row_info->width;
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for (bp = row, i = 0; i < istop; i++)
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{
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const unsigned int c = i%channels;
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int j;
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unsigned int value, v;
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v = png_get_uint_16(bp);
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value = 0;
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for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
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{
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if (j > 0)
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value |= v << j;
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else
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value |= v >> (-j);
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}
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*bp++ = png_check_byte(png_ptr, value >> 8);
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*bp++ = PNG_BYTE(value);
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}
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}
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}
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# undef png_ptr
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}
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#endif
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#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
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static void
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png_do_write_swap_alpha(png_transform_controlp row_info, png_bytep row)
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{
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png_debug(1, "in png_do_write_swap_alpha");
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# define png_ptr row_info->png_ptr
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{
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if (row_info->channels == 4)
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{
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if (row_info->bit_depth == 8)
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{
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 4;
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/* This converts from ARGB to RGBA */
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while (row <= ep)
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{
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png_byte save = row[0];
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row[0] = row[1];
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row[1] = row[2];
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row[2] = row[3];
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row[3] = save;
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row += 4;
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}
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debug(row == ep+4);
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}
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#ifdef PNG_WRITE_16BIT_SUPPORTED
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else if (row_info->bit_depth == 16)
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{
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/* This converts from AARRGGBB to RRGGBBAA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 8;
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while (row <= ep)
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{
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png_byte s0 = row[0];
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png_byte s1 = row[1];
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memmove(row, row+2, 6);
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row[6] = s0;
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row[7] = s1;
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row += 8;
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}
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debug(row == ep+8);
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}
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#endif /* WRITE_16BIT */
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}
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else if (row_info->channels == 2)
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{
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if (row_info->bit_depth == 8)
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{
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/* This converts from AG to GA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2;
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/* This converts from ARGB to RGBA */
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while (row <= ep)
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{
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png_byte save = *row;
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*row = row[1], ++row;
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*row++ = save;
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}
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debug(row == ep+2);
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}
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#ifdef PNG_WRITE_16BIT_SUPPORTED
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else
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{
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/* This converts from AAGG to GGAA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 4;
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while (row <= ep)
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{
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png_byte save = row[0];
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row[0] = row[2];
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row[2] = save;
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save = row[1];
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row[1] = row[3];
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row[3] = save;
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row += 4;
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}
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debug(row == ep+4);
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}
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#endif /* WRITE_16BIT */
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}
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}
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# undef png_ptr
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}
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#endif
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#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
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static void
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png_do_write_invert_alpha(png_transform_controlp row_info, png_bytep row)
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{
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png_debug(1, "in png_do_write_invert_alpha");
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# define png_ptr row_info->png_ptr
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{
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if (row_info->channels == 4)
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{
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if (row_info->bit_depth == 8)
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{
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/* This inverts the alpha channel in RGBA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 1;
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row += 3; /* alpha channel */
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while (row <= ep)
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*row ^= 0xff, row += 4;
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}
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#ifdef PNG_WRITE_16BIT_SUPPORTED
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else if (row_info->bit_depth == 16)
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{
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/* This inverts the alpha channel in RRGGBBAA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2;
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row += 6;
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while (row <= ep)
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row[0] ^= 0xff, row[1] ^= 0xff, row += 8;
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}
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#endif /* WRITE_16BIT */
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}
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else if (row_info->channels == 2)
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{
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if (row_info->bit_depth == 8)
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{
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/* This inverts the alpha channel in GA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 1;
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++row;
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while (row <= ep)
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*row ^= 0xff, row += 2;
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}
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#ifdef PNG_WRITE_16BIT_SUPPORTED
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else
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{
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/* This inverts the alpha channel in GGAA */
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png_const_bytep ep = row + png_transform_rowbytes(row_info) - 2;
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row += 2;
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while (row <= ep)
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row[0] ^= 0xff, row[1] ^= 0xff, row += 4;
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}
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#endif /* WRITE_16BIT */
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}
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}
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# undef png_ptr
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}
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#endif
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/* Transform the data according to the user's wishes. The order of
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* transformations is significant.
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*/
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void /* PRIVATE */
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png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info_in)
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{
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png_transform_control display;
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png_debug(1, "in png_do_write_transformations");
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if (png_ptr == NULL)
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return;
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#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
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if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
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if (png_ptr->write_user_transform_fn != NULL)
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(*(png_ptr->write_user_transform_fn)) /* User write transform
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function */
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(png_ptr, /* png_ptr */
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row_info_in, /* row_info: */
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/* png_uint_32 width; width of row */
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/* png_size_t rowbytes; number of bytes in row */
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/* png_byte color_type; color type of pixels */
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/* png_byte bit_depth; bit depth of samples */
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/* png_byte channels; number of channels (1-4) */
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/* png_byte pixel_depth; bits per pixel (depth*channels) */
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png_ptr->row_buf + 1); /* start of pixel data for row */
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#endif
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png_init_transform_control(png_ptr, &display, row_info_in);
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#ifdef PNG_WRITE_FILLER_SUPPORTED
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if ((png_ptr->transformations & PNG_FILLER) != 0)
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png_do_strip_channel(&display, png_ptr->row_buf + 1,
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!(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
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#endif
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#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
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if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
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png_do_packswap(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_PACK_SUPPORTED
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if ((png_ptr->transformations & PNG_PACK) != 0)
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png_do_pack(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_SWAP_SUPPORTED
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# ifdef PNG_16BIT_SUPPORTED
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if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
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png_do_swap(&display, png_ptr->row_buf + 1);
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# endif
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#endif
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#ifdef PNG_WRITE_SHIFT_SUPPORTED
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if ((png_ptr->transformations & PNG_SHIFT) != 0)
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png_do_shift(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
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if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
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png_do_write_swap_alpha(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
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if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
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png_do_write_invert_alpha(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_BGR_SUPPORTED
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if ((png_ptr->transformations & PNG_BGR) != 0)
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png_do_bgr(&display, png_ptr->row_buf + 1);
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#endif
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#ifdef PNG_WRITE_INVERT_SUPPORTED
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if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
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png_do_invert(&display, png_ptr->row_buf + 1);
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#endif
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/* Clear the flags; they are irrelevant because the write code is
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* reversing transformations to get PNG data but the shared transformation
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* code assumes input PNG data. Only PNG_INDEXED is required.
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*/
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if ((display.flags & PNG_BAD_INDEX) != 0)
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png_error(png_ptr, "palette data has out of range index");
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display.flags &= PNG_INDEXED;
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png_end_transform_control(row_info_in, &display);
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}
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#endif /* WRITE_TRANSFORMS */
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#endif /* WRITE */
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