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libpng/pngread.c

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/* pngread.c - read a PNG file
*
* Last changed in libpng 1.6.0 [(PENDING RELEASE)]
* Copyright (c) 1998-2011 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* This file contains routines that an application calls directly to
* read a PNG file or stream.
*/
#include "pngpriv.h"
#if defined PNG_SIMPLIFIED_READ_SUPPORTED && defined PNG_STDIO_SUPPORTED
# include <errno.h>
#endif
#ifdef PNG_READ_SUPPORTED
/* Create a PNG structure for reading, and allocate any memory needed. */
PNG_FUNCTION(png_structp,PNGAPI
png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
{
#ifndef PNG_USER_MEM_SUPPORTED
png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, NULL, NULL, NULL);
#else
return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
warn_fn, NULL, NULL, NULL);
}
/* Alternate create PNG structure for reading, and allocate any memory
* needed.
*/
PNG_FUNCTION(png_structp,PNGAPI
png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
{
png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
#endif /* PNG_USER_MEM_SUPPORTED */
if (png_ptr != NULL)
{
int ok = 0;
/* TODO: why does this happen here on read, but in png_write_IHDR on
* write?
*/
png_ptr->zstream.zalloc = png_zalloc;
png_ptr->zstream.zfree = png_zfree;
png_ptr->zstream.opaque = png_ptr;
switch (inflateInit(&png_ptr->zstream))
{
case Z_OK:
ok = 1;
break;
case Z_MEM_ERROR:
png_warning(png_ptr, "zlib memory error");
break;
case Z_STREAM_ERROR:
png_warning(png_ptr, "zlib stream error");
break;
case Z_VERSION_ERROR:
png_warning(png_ptr, "zlib version error");
break;
default:
png_warning(png_ptr, "Unknown zlib error");
break;
}
if (ok)
{
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = png_ptr->zbuf_size;
/* TODO: delay this, it can be done in png_init_io (if the app doesn't
* do it itself) avoiding setting the default function if it is not
* required.
*/
png_set_read_fn(png_ptr, NULL, NULL);
return png_ptr;
}
/* Else something went wrong in the zlib initialization above; it would
* much simplify this code if the creation of the zlib stuff was to be
* delayed until it is needed.
*/
png_destroy_read_struct(&png_ptr, NULL, NULL);
}
return NULL;
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the information before the actual image data. This has been
* changed in v0.90 to allow reading a file that already has the magic
* bytes read from the stream. You can tell libpng how many bytes have
* been read from the beginning of the stream (up to the maximum of 8)
* via png_set_sig_bytes(), and we will only check the remaining bytes
* here. The application can then have access to the signature bytes we
* read if it is determined that this isn't a valid PNG file.
*/
void PNGAPI
png_read_info(png_structp png_ptr, png_infop info_ptr)
{
png_debug(1, "in png_read_info");
if (png_ptr == NULL || info_ptr == NULL)
return;
/* Read and check the PNG file signature. */
png_read_sig(png_ptr, info_ptr);
for (;;)
{
png_uint_32 length = png_read_chunk_header(png_ptr);
png_uint_32 chunk_name = png_ptr->chunk_name;
/* This should be a binary subdivision search or a hash for
* matching the chunk name rather than a linear search.
*/
if (chunk_name == png_IDAT)
if (png_ptr->mode & PNG_AFTER_IDAT)
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
if (chunk_name == png_IHDR)
png_handle_IHDR(png_ptr, info_ptr, length);
else if (chunk_name == png_IEND)
png_handle_IEND(png_ptr, info_ptr, length);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
PNG_HANDLE_CHUNK_AS_DEFAULT)
{
if (chunk_name == png_IDAT)
png_ptr->mode |= PNG_HAVE_IDAT;
png_handle_unknown(png_ptr, info_ptr, length);
if (chunk_name == png_PLTE)
png_ptr->mode |= PNG_HAVE_PLTE;
else if (chunk_name == png_IDAT)
{
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
!(png_ptr->mode & PNG_HAVE_PLTE))
png_error(png_ptr, "Missing PLTE before IDAT");
break;
}
}
#endif
else if (chunk_name == png_PLTE)
png_handle_PLTE(png_ptr, info_ptr, length);
else if (chunk_name == png_IDAT)
{
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
!(png_ptr->mode & PNG_HAVE_PLTE))
png_error(png_ptr, "Missing PLTE before IDAT");
png_ptr->idat_size = length;
png_ptr->mode |= PNG_HAVE_IDAT;
break;
}
#ifdef PNG_READ_bKGD_SUPPORTED
else if (chunk_name == png_bKGD)
png_handle_bKGD(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
else if (chunk_name == png_cHRM)
png_handle_cHRM(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (chunk_name == png_hIST)
png_handle_hIST(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (chunk_name == png_oFFs)
png_handle_oFFs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (chunk_name == png_pCAL)
png_handle_pCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (chunk_name == png_sCAL)
png_handle_sCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (chunk_name == png_pHYs)
png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
else if (chunk_name == png_sBIT)
png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (chunk_name == png_sRGB)
png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
else if (chunk_name == png_iCCP)
png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (chunk_name == png_sPLT)
png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (chunk_name == png_tEXt)
png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (chunk_name == png_tIME)
png_handle_tIME(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (chunk_name == png_tRNS)
png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (chunk_name == png_zTXt)
png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (chunk_name == png_iTXt)
png_handle_iTXt(png_ptr, info_ptr, length);
#endif
else
png_handle_unknown(png_ptr, info_ptr, length);
}
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
/* Optional call to update the users info_ptr structure */
void PNGAPI
png_read_update_info(png_structp png_ptr, png_infop info_ptr)
{
png_debug(1, "in png_read_update_info");
if (png_ptr == NULL)
return;
png_read_start_row(png_ptr);
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
png_read_transform_info(png_ptr, info_ptr);
#else
PNG_UNUSED(info_ptr)
#endif
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Initialize palette, background, etc, after transformations
* are set, but before any reading takes place. This allows
* the user to obtain a gamma-corrected palette, for example.
* If the user doesn't call this, we will do it ourselves.
*/
void PNGAPI
png_start_read_image(png_structp png_ptr)
{
png_debug(1, "in png_start_read_image");
if (png_ptr != NULL)
png_read_start_row(png_ptr);
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
void PNGAPI
png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
{
int ret;
png_row_info row_info;
if (png_ptr == NULL)
return;
png_debug2(1, "in png_read_row (row %lu, pass %d)",
(unsigned long)png_ptr->row_number, png_ptr->pass);
/* png_read_start_row sets the information (in particular iwidth) for this
* interlace pass.
*/
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
png_read_start_row(png_ptr);
/* 1.5.6: row_info moved out of png_struct to a local here. */
row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
row_info.color_type = png_ptr->color_type;
row_info.bit_depth = png_ptr->bit_depth;
row_info.channels = png_ptr->channels;
row_info.pixel_depth = png_ptr->pixel_depth;
row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
if (png_ptr->row_number == 0 && png_ptr->pass == 0)
{
/* Check for transforms that have been set but were defined out */
#if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
if (png_ptr->transformations & PNG_INVERT_MONO)
png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
if (png_ptr->transformations & PNG_FILLER)
png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
!defined(PNG_READ_PACKSWAP_SUPPORTED)
if (png_ptr->transformations & PNG_PACKSWAP)
png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
if (png_ptr->transformations & PNG_PACK)
png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
if (png_ptr->transformations & PNG_SHIFT)
png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
if (png_ptr->transformations & PNG_BGR)
png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
if (png_ptr->transformations & PNG_SWAP_BYTES)
png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
#endif
}
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* If interlaced and we do not need a new row, combine row and return.
* Notice that the pixels we have from previous rows have been transformed
* already; we can only combine like with like (transformed or
* untransformed) and, because of the libpng API for interlaced images, this
* means we must transform before de-interlacing.
*/
if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
{
switch (png_ptr->pass)
{
case 0:
if (png_ptr->row_number & 0x07)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 1:
if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 2:
if ((png_ptr->row_number & 0x07) != 4)
{
if (dsp_row != NULL && (png_ptr->row_number & 4))
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 3:
if ((png_ptr->row_number & 3) || png_ptr->width < 3)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 4:
if ((png_ptr->row_number & 3) != 2)
{
if (dsp_row != NULL && (png_ptr->row_number & 2))
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 5:
if ((png_ptr->row_number & 1) || png_ptr->width < 2)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
default:
case 6:
if (!(png_ptr->row_number & 1))
{
png_read_finish_row(png_ptr);
return;
}
break;
}
}
#endif
if (!(png_ptr->mode & PNG_HAVE_IDAT))
png_error(png_ptr, "Invalid attempt to read row data");
png_ptr->zstream.next_out = png_ptr->row_buf;
png_ptr->zstream.avail_out =
(uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
png_ptr->iwidth) + 1);
do
{
if (!(png_ptr->zstream.avail_in))
{
while (!png_ptr->idat_size)
{
png_crc_finish(png_ptr, 0);
png_ptr->idat_size = png_read_chunk_header(png_ptr);
if (png_ptr->chunk_name != png_IDAT)
png_error(png_ptr, "Not enough image data");
}
png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
png_ptr->zstream.next_in = png_ptr->zbuf;
if (png_ptr->zbuf_size > png_ptr->idat_size)
png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
png_crc_read(png_ptr, png_ptr->zbuf,
(png_size_t)png_ptr->zstream.avail_in);
png_ptr->idat_size -= png_ptr->zstream.avail_in;
}
ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
if (ret == Z_STREAM_END)
{
if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
png_ptr->idat_size)
png_benign_error(png_ptr, "Extra compressed data");
png_ptr->mode |= PNG_AFTER_IDAT;
png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
break;
}
if (ret != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
"Decompression error");
} while (png_ptr->zstream.avail_out);
if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
{
if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
png_ptr->prev_row + 1, png_ptr->row_buf[0]);
else
png_error(png_ptr, "bad adaptive filter value");
}
/* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
* 1.5.6, while the buffer really is this big in current versions of libpng
* it may not be in the future, so this was changed just to copy the
* interlaced count:
*/
png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
#ifdef PNG_MNG_FEATURES_SUPPORTED
if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
(png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
{
/* Intrapixel differencing */
png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
}
#endif
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
if (png_ptr->transformations)
png_do_read_transformations(png_ptr, &row_info);
#endif
/* The transformed pixel depth should match the depth now in row_info. */
if (png_ptr->transformed_pixel_depth == 0)
{
png_ptr->transformed_pixel_depth = row_info.pixel_depth;
if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
png_error(png_ptr, "sequential row overflow");
}
else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
png_error(png_ptr, "internal sequential row size calculation error");
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* Blow up interlaced rows to full size */
if (png_ptr->interlaced &&
(png_ptr->transformations & PNG_INTERLACE))
{
if (png_ptr->pass < 6)
png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
png_ptr->transformations);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
if (row != NULL)
png_combine_row(png_ptr, row, 0/*row*/);
}
else
#endif
{
if (row != NULL)
png_combine_row(png_ptr, row, -1/*ignored*/);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
}
png_read_finish_row(png_ptr);
if (png_ptr->read_row_fn != NULL)
(*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data. If the image is interlaced,
* and png_set_interlace_handling() has been called, the rows need to
* contain the contents of the rows from the previous pass. If the
* image has alpha or transparency, and png_handle_alpha()[*] has been
* called, the rows contents must be initialized to the contents of the
* screen.
*
* "row" holds the actual image, and pixels are placed in it
* as they arrive. If the image is displayed after each pass, it will
* appear to "sparkle" in. "display_row" can be used to display a
* "chunky" progressive image, with finer detail added as it becomes
* available. If you do not want this "chunky" display, you may pass
* NULL for display_row. If you do not want the sparkle display, and
* you have not called png_handle_alpha(), you may pass NULL for rows.
* If you have called png_handle_alpha(), and the image has either an
* alpha channel or a transparency chunk, you must provide a buffer for
* rows. In this case, you do not have to provide a display_row buffer
* also, but you may. If the image is not interlaced, or if you have
* not called png_set_interlace_handling(), the display_row buffer will
* be ignored, so pass NULL to it.
*
* [*] png_handle_alpha() does not exist yet, as of this version of libpng
*/
void PNGAPI
png_read_rows(png_structp png_ptr, png_bytepp row,
png_bytepp display_row, png_uint_32 num_rows)
{
png_uint_32 i;
png_bytepp rp;
png_bytepp dp;
png_debug(1, "in png_read_rows");
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 /* PNG_SEQUENTIAL_READ_SUPPORTED */
#ifdef PNG_SEQUENTIAL_READ_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_row() 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_structp png_ptr, png_bytepp image)
{
png_uint_32 i, image_height;
int pass, j;
png_bytepp rp;
png_debug(1, "in png_read_image");
if (png_ptr == NULL)
return;
#ifdef PNG_READ_INTERLACING_SUPPORTED
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
{
pass = png_set_interlace_handling(png_ptr);
/* And make sure transforms are initialized. */
png_start_read_image(png_ptr);
}
else
{
if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
{
/* Caller called png_start_read_image or png_read_update_info without
* first turning on the PNG_INTERLACE transform. We can fix this here,
* but the caller should do it!
*/
png_warning(png_ptr, "Interlace handling should be turned on when "
"using png_read_image");
/* Make sure this is set correctly */
png_ptr->num_rows = png_ptr->height;
}
/* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
* the above error case.
*/
pass = png_set_interlace_handling(png_ptr);
}
#else
if (png_ptr->interlaced)
png_error(png_ptr,
"Cannot read interlaced image -- interlace handler disabled");
pass = 1;
#endif
image_height=png_ptr->height;
for (j = 0; j < pass; j++)
{
rp = image;
for (i = 0; i < image_height; i++)
{
png_read_row(png_ptr, *rp, NULL);
rp++;
}
}
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#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_structp png_ptr, png_infop info_ptr)
{
png_debug(1, "in png_read_end");
if (png_ptr == NULL)
return;
png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
do
{
png_uint_32 length = png_read_chunk_header(png_ptr);
png_uint_32 chunk_name = png_ptr->chunk_name;
if (chunk_name == png_IHDR)
png_handle_IHDR(png_ptr, info_ptr, length);
else if (chunk_name == png_IEND)
png_handle_IEND(png_ptr, info_ptr, length);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
PNG_HANDLE_CHUNK_AS_DEFAULT)
{
if (chunk_name == png_IDAT)
{
if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
png_benign_error(png_ptr, "Too many IDATs found");
}
png_handle_unknown(png_ptr, info_ptr, length);
if (chunk_name == png_PLTE)
png_ptr->mode |= PNG_HAVE_PLTE;
}
#endif
else if (chunk_name == png_IDAT)
{
/* Zero length IDATs are legal after the last IDAT has been
* read, but not after other chunks have been read.
*/
if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
png_benign_error(png_ptr, "Too many IDATs found");
png_crc_finish(png_ptr, length);
}
else if (chunk_name == png_PLTE)
png_handle_PLTE(png_ptr, info_ptr, length);
#ifdef PNG_READ_bKGD_SUPPORTED
else if (chunk_name == png_bKGD)
png_handle_bKGD(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
else if (chunk_name == png_cHRM)
png_handle_cHRM(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (chunk_name == png_hIST)
png_handle_hIST(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (chunk_name == png_oFFs)
png_handle_oFFs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (chunk_name == png_pCAL)
png_handle_pCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (chunk_name == png_sCAL)
png_handle_sCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (chunk_name == png_pHYs)
png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
else if (chunk_name == png_sBIT)
png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (chunk_name == png_sRGB)
png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
else if (chunk_name == png_iCCP)
png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (chunk_name == png_sPLT)
png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (chunk_name == png_tEXt)
png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (chunk_name == png_tIME)
png_handle_tIME(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (chunk_name == png_tRNS)
png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (chunk_name == png_zTXt)
png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (chunk_name == png_iTXt)
png_handle_iTXt(png_ptr, info_ptr, length);
#endif
else
png_handle_unknown(png_ptr, info_ptr, length);
} while (!(png_ptr->mode & PNG_HAVE_IEND));
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
/* Free all memory used in the read struct */
static void
png_read_destroy(png_structp png_ptr)
{
png_debug(1, "in png_read_destroy");
#ifdef PNG_READ_GAMMA_SUPPORTED
png_destroy_gamma_table(png_ptr);
#endif
png_free(png_ptr, png_ptr->zbuf);
png_free(png_ptr, png_ptr->big_row_buf);
png_free(png_ptr, png_ptr->big_prev_row);
png_free(png_ptr, png_ptr->chunkdata);
#ifdef PNG_READ_QUANTIZE_SUPPORTED
png_free(png_ptr, png_ptr->palette_lookup);
png_free(png_ptr, png_ptr->quantize_index);
#endif
if (png_ptr->free_me & PNG_FREE_PLTE)
png_zfree(png_ptr, png_ptr->palette);
png_ptr->free_me &= ~PNG_FREE_PLTE;
#if defined(PNG_tRNS_SUPPORTED) || \
defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->free_me & PNG_FREE_TRNS)
png_free(png_ptr, png_ptr->trans_alpha);
png_ptr->free_me &= ~PNG_FREE_TRNS;
#endif
#ifdef PNG_READ_hIST_SUPPORTED
if (png_ptr->free_me & PNG_FREE_HIST)
png_free(png_ptr, png_ptr->hist);
png_ptr->free_me &= ~PNG_FREE_HIST;
#endif
inflateEnd(&png_ptr->zstream);
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
png_free(png_ptr, png_ptr->save_buffer);
#endif
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
#ifdef PNG_TEXT_SUPPORTED
png_free(png_ptr, png_ptr->current_text);
#endif /* PNG_TEXT_SUPPORTED */
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
/* 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_structp 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_structp png_ptr, png_read_status_ptr read_row_fn)
{
if (png_ptr == NULL)
return;
png_ptr->read_row_fn = read_row_fn;
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
#ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_read_png(png_structp png_ptr, png_infop info_ptr,
int transforms,
voidp params)
{
int row;
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 (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
png_error(png_ptr, "Image is too high to process with png_read_png()");
/* -------------- image transformations start here ------------------- */
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
/* Tell libpng to strip 16-bit/color files down to 8 bits per color.
*/
if (transforms & PNG_TRANSFORM_SCALE_16)
{
/* 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.
*/
png_set_scale_16(png_ptr);
}
#endif
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
/* 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)
png_set_strip_16(png_ptr);
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
/* Strip alpha bytes from the input data without combining with
* the background (not recommended).
*/
if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
png_set_strip_alpha(png_ptr);
#endif
#if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
/* 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)
png_set_packing(png_ptr);
#endif
#ifdef PNG_READ_PACKSWAP_SUPPORTED
/* 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)
png_set_packswap(png_ptr);
#endif
#ifdef PNG_READ_EXPAND_SUPPORTED
/* 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)
if ((png_ptr->bit_depth < 8) ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
(png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
png_set_expand(png_ptr);
#endif
/* We don't handle background color or gamma transformation or quantizing.
*/
#ifdef PNG_READ_INVERT_SUPPORTED
/* Invert monochrome files to have 0 as white and 1 as black
*/
if (transforms & PNG_TRANSFORM_INVERT_MONO)
png_set_invert_mono(png_ptr);
#endif
#ifdef PNG_READ_SHIFT_SUPPORTED
/* 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)
&& png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
{
png_color_8p sig_bit;
png_get_sBIT(png_ptr, info_ptr, &sig_bit);
png_set_shift(png_ptr, sig_bit);
}
#endif
#ifdef PNG_READ_BGR_SUPPORTED
/* Flip the RGB pixels to BGR (or RGBA to BGRA) */
if (transforms & PNG_TRANSFORM_BGR)
png_set_bgr(png_ptr);
#endif
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
/* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
png_set_swap_alpha(png_ptr);
#endif
#ifdef PNG_READ_SWAP_SUPPORTED
/* Swap bytes of 16-bit files to least significant byte first */
if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
png_set_swap(png_ptr);
#endif
/* Added at libpng-1.2.41 */
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
/* Invert the alpha channel from opacity to transparency */
if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
png_set_invert_alpha(png_ptr);
#endif
/* Added at libpng-1.2.41 */
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* Expand grayscale image to RGB */
if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
png_set_gray_to_rgb(png_ptr);
#endif
/* Added at libpng-1.5.4 */
#ifdef PNG_READ_EXPAND_16_SUPPORTED
if (transforms & PNG_TRANSFORM_EXPAND_16)
png_set_expand_16(png_ptr);
#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;
info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
info_ptr->height * png_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 (row = 0; row < (int)info_ptr->height; row++)
info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
png_get_rowbytes(png_ptr, info_ptr));
}
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(transforms) /* Quiet compiler warnings */
PNG_UNUSED(params)
}
#endif /* PNG_INFO_IMAGE_SUPPORTED */
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#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.
*/
/* 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)
{
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
png_safe_error, png_safe_warning);
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)
{
png_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");
}
/* Utility to find the base format of a PNG file from a png_struct. */
static png_uint_32
png_image_format(png_structp png_ptr, png_infop info_ptr)
{
png_uint_32 format = 0;
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
format |= PNG_FORMAT_FLAG_COLOR;
if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)
format |= PNG_FORMAT_FLAG_ALPHA;
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
format |= PNG_FORMAT_FLAG_ALPHA;
if (png_ptr->bit_depth == 16)
format |= PNG_FORMAT_FLAG_LINEAR;
return format;
}
/* 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_structp png_ptr = image->opaque->png_ptr;
png_infop info_ptr = image->opaque->info_ptr;
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, info_ptr);
image->format = format;
image->flags = 0;
/* Now try to work out whether the color data does not match sRGB. */
if ((format & PNG_FORMAT_FLAG_COLOR) != 0 &&
(info_ptr->valid & PNG_INFO_sRGB) == 0)
{
/* gamma is irrelevant because libpng does gamma correction, what
* matters is if the cHRM chunk doesn't match or, in the absence of
* cRHM, if the iCCP profile appears to have different end points.
*/
if (info_ptr->valid & PNG_INFO_cHRM)
{
/* TODO: this is a copy'n'paste from pngrutil.c, make a common
* checking function. This checks for a 1% error.
*/
/* The cHRM chunk is used in preference to iCCP */
if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->y_white, 32900, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->x_red, 64000, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->y_red, 33000, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->x_green, 30000, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->y_green, 60000, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->x_blue, 15000, 1000) ||
PNG_OUT_OF_RANGE(info_ptr->y_blue, 6000, 1000))
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
}
else if (info_ptr->valid & PNG_INFO_iCCP)
{
# if 0
/* TODO: IMPLEMENT THIS! Remember to remove iCCP from
the chunks_to_ignore list */
/* Here if we just have an iCCP chunk. */
if (!png_iCCP_is_sRGB(png_ptr, info_ptr))
# endif
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
}
}
}
return 1;
}
#ifdef PNG_STDIO_SUPPORTED
int PNGAPI
png_image_begin_read_from_stdio(png_imagep image, FILE* file)
{
if (image != NULL)
{
if (file != NULL)
{
if (png_image_read_init(image))
{
/* This is slightly evil, but png_init_io doesn't do anything other
* than this and we haven't changed the standard IO functions so
* this saves a 'safe' function.
*/
image->opaque->png_ptr->io_ptr = file;
return png_safe_execute(image, png_image_read_header, image);
}
}
else
return png_image_error(image,
"png_image_begin_read_from_stdio: invalid argument");
}
return 0;
}
int PNGAPI
png_image_begin_read_from_file(png_imagep image, const char *file_name)
{
if (image != NULL)
{
if (file_name != NULL)
{
FILE *fp = fopen(file_name, "rb");
if (fp != NULL)
{
if (png_image_read_init(image))
{
image->opaque->png_ptr->io_ptr = fp;
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");
}
return 0;
}
#endif /* PNG_STDIO_SUPPORTED */
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)
{
png_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");
}
}
int PNGAPI png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, png_size_t size)
{
if (image != NULL)
{
if (memory != NULL && size > 0)
{
if (png_image_read_init(image))
{
/* 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;
image->opaque->png_ptr->io_ptr = image;
image->opaque->png_ptr->read_data_fn = png_image_memory_read;
return png_safe_execute(image, png_image_read_header, image);
}
}
else
return png_image_error(image,
"png_image_begin_read_from_memory: invalid argument");
}
return 0;
}
/* Arguments to png_image_finish_read: */
typedef struct
{
/* Arguments: */
png_imagep image;
png_voidp buffer;
png_int_32 row_stride;
png_colorp background;
/* Local variables: */
png_bytep local_row;
png_bytep first_row;
ptrdiff_t row_bytes; /* unsigned arithmetic step between rows */
} png_image_read_control;
/* 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_structp png_ptr = image->opaque->png_ptr;
png_byte interlace_type = png_ptr->interlaced;
int passes;
switch (interlace_type)
{
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;
unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
int pass;
for (pass = 0; pass < passes; ++pass)
{
png_bytep row = display->first_row;
unsigned int startx, stepx, stepy;
png_uint_32 y;
if (interlace_type == 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;
}
/* The following are invariants across all the rows: */
startx *= channels;
stepx *= channels;
for (; y<height; y += stepy)
{
png_bytep inrow = display->local_row;
png_bytep outrow = row + startx;
png_const_bytep end_row = row + width * channels;
/* Read the row, which is packed: */
png_read_row(png_ptr, inrow, NULL);
/* Now do the composition on each pixel in this row. */
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(component);
}
outrow[c] = (png_byte)component;
}
}
inrow += channels+1; /* components and alpha channel */
}
row += display->row_bytes;
}
}
}
return 1;
}
/* The do_local_background case; called when all the following transforms are to
* be done:
*
* PNG_RGB_TO_GRAY
* PNG_COMPOSITE
* PNG_GAMMA
*
* This is a work-round for the fact that both the PNG_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 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_structp png_ptr = image->opaque->png_ptr;
png_infop info_ptr = image->opaque->info_ptr;
png_byte interlace_type = png_ptr->interlaced;
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.
*/
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
png_error(png_ptr, "lost rgb to gray");
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
png_error(png_ptr, "unexpected compose");
/* The palette code zaps PNG_GAMMA in place... */
if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
(png_ptr->transformations & PNG_GAMMA) == 0)
png_error(png_ptr, "lost gamma correction");
if (png_get_channels(png_ptr, info_ptr) != 2)
png_error(png_ptr, "lost/gained channels");
switch (interlace_type)
{
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");
}
switch (png_get_bit_depth(png_ptr, info_ptr))
{
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 backgroundi: either the row if
* display->background is NULL or display->background.green if not.
* Unlike the code above ALPHA_OPTIMIZED has *not* been done.
*/
for (pass = 0; pass < passes; ++pass)
{
png_bytep row = display->first_row;
unsigned int startx, stepx, stepy;
png_uint_32 y;
if (interlace_type == 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 = display->local_row;
png_bytep outrow = row + startx;
png_const_bytep end_row = row + width;
/* Read the row, which is packed: */
png_read_row(png_ptr, inrow, NULL);
/* Now do the composition on each pixel in this row. */
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(component);
}
outrow[0] = (png_byte)component;
}
inrow += 2; /* gray and alpha channel */
}
row += display->row_bytes;
}
}
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 = display->local_row;
png_bytep outrow = row + startx;
png_const_bytep end_row = row + width;
/* Read the row, which is packed: */
png_read_row(png_ptr, inrow, NULL);
/* Now do the composition on each pixel in this row. */
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(component);
}
outrow[0] = (png_byte)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.
*/
{
unsigned int outchannels = png_get_channels(png_ptr, info_ptr);
int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
int swap_alpha = 0;
if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST))
swap_alpha = 1;
for (pass = 0; pass < passes; ++pass)
{
png_uint_16p row = (png_uint_16p)display->first_row;
unsigned int startx, stepx, stepy; /* all in pixels */
png_uint_32 y;
if (interlace_type == 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;
}
startx *= outchannels;
stepx *= outchannels;
for (; y<height; y += stepy)
{
png_uint_16p inrow;
png_uint_16p outrow = row + startx;
png_uint_16p end_row = row + width * outchannels;
/* Read the row, which is packed: */
png_read_row(png_ptr, display->local_row, NULL);
inrow = (png_uint_16p)display->local_row;
/* Now do the pre-multiplication on each pixel in this row.
*/
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_uint_16)component;
if (outchannels > 1)
outrow[1 ^ swap_alpha] = alpha;
inrow += 2; /* components and alpha channel */
}
row += display->row_bytes;
}
}
}
break;
}
return 1;
}
/* The guts of png_image_finish_read as a png_safe_execute callback. */
static int
png_image_read_end(png_voidp argument)
{
png_image_read_control *display = png_voidcast(png_image_read_control*,
argument);
png_imagep image = display->image;
png_structp png_ptr = image->opaque->png_ptr;
png_infop 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, info_ptr);
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)
{
/* gray<->color transformation required. */
if (format & PNG_FORMAT_FLAG_COLOR)
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)
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_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)
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)
{
/* 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)
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)
{
png_fixed_point gtest;
/* This is 'png_gamma_threshold' from pngrtran.c; the test used for
* gamma correction, the screen gamma hasn't been set on png_struct
* yet; it's set below. png_struct::gamma, however, is set to the
* final value.
*/
if (png_muldiv(&gtest, output_gamma, png_ptr->gamma, PNG_FP_1) &&
!png_gamma_significant(gtest))
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)
{
if (linear /*16-bit output*/)
png_set_expand_16(png_ptr);
else /* 8-bit output */
png_set_scale_16(png_ptr);
change &= ~PNG_FORMAT_FLAG_LINEAR;
}
/* Now the background/alpha channel changes. */
if (change & PNG_FORMAT_FLAG_ALPHA)
{
/* 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)
{
/* 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)
do_local_background = 2/*required*/;
/* 16-bit output: just remove the channel */
else if (linear) /* 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)
filler = 65535;
else
filler = 255;
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
if (format & PNG_FORMAT_FLAG_AFIRST)
{
where = PNG_FILLER_BEFORE;
change &= ~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_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)
{
/* 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)
png_set_bgr(png_ptr);
else
format &= ~PNG_FORMAT_FLAG_BGR;
change &= ~PNG_FORMAT_FLAG_BGR;
}
# endif
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
if (change & PNG_FORMAT_FLAG_AFIRST)
{
/* 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)
{
/* 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_FORMAT_FLAG_AFIRST;
change &= ~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)
{
PNG_CONST png_uint_16 le = 0x0001;
if (*(png_const_bytep)&le)
png_set_swap(png_ptr);
}
/* If change is not now 0 some transformation is missing - error out. */
if (change)
png_error(png_ptr, "png_read_image: unsupported transformation");
}
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
/* 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.
*
* TODO: make it so that this is an explicit list to process, not a list
* to ignore?
*/
{
static PNG_CONST png_byte chunks_to_ignore[] = {
104, 73, 83, 84, '\0', /* hIST */
105, 84, 88, 116, '\0', /* iTXt */
111, 70, 70, 115, '\0', /* oFFs */
112, 67, 65, 76, '\0', /* pCAL */
112, 72, 89, 115, '\0', /* pHYs */
115, 67, 65, 76, '\0', /* sCAL */
115, 80, 76, 84, '\0', /* sPLT */
116, 69, 88, 116, '\0', /* tEXt */
116, 73, 77, 69, '\0', /* tIME */
122, 84, 88, 116, '\0' /* zTXt */
};
/* Ignore unknown chunks */
png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */,
NULL, 0);
/* Ignore known but unused chunks */
png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */,
chunks_to_ignore, (sizeof chunks_to_ignore)/5);
}
# endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */
/* 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 && do_local_background != 2)
passes = png_set_interlace_handling(png_ptr);
png_read_update_info(png_ptr, info_ptr);
{
png_uint_32 info_format = 0;
if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
info_format |= PNG_FORMAT_FLAG_COLOR;
if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
{
/* do_local_compose removes this channel below. */
if (!do_local_compose)
{
/* do_local_background does the same if required. */
if (do_local_background != 2 ||
(format & PNG_FORMAT_FLAG_ALPHA) != 0)
info_format |= PNG_FORMAT_FLAG_ALPHA;
}
}
else if (do_local_compose) /* internal error */
png_error(png_ptr, "png_image_read: alpha channel lost");
if (info_ptr->bit_depth == 16)
info_format |= PNG_FORMAT_FLAG_LINEAR;
# ifdef PNG_FORMAT_BGR_SUPPORTED
if (png_ptr->transformations & PNG_BGR)
info_format |= PNG_FORMAT_FLAG_BGR;
# endif
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
if (png_ptr->transformations & PNG_SWAP_ALPHA ||
((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
(png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
info_format |= PNG_FORMAT_FLAG_AFIRST;
# endif
/* This is actually an internal error. */
if (info_format != format)
png_error(png_ptr, "png_read_image: invalid 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_bytep first_row = png_voidcast(png_bytep, display->buffer);
ptrdiff_t row_bytes = display->row_stride;
if (linear)
row_bytes *= sizeof (png_uint_16);
/* The following expression is designed to work correctly whether it gives
* a signed or an unsigned result.
*/
if (row_bytes < 0)
first_row += (image->height-1) * (-row_bytes);
display->first_row = first_row;
display->row_bytes = row_bytes;
}
if (do_local_compose)
{
int result;
png_bytep row = png_voidcast(png_bytep, 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_bytep row = png_voidcast(png_bytep, 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 = 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_colorp background, void *buffer,
png_int_32 row_stride)
{
if (image != NULL)
{
png_uint_32 check;
if (row_stride == 0)
row_stride = PNG_IMAGE_ROW_STRIDE(*image);
if (row_stride < 0)
check = -row_stride;
else
check = row_stride;
if (buffer != NULL && check >= PNG_IMAGE_ROW_STRIDE(*image))
{
int result;
png_image_read_control display;
png_memset(&display, 0, sizeof display);
display.image = image;
display.buffer = buffer;
display.row_stride = row_stride;
display.background = background;
display.local_row = NULL;
result = png_safe_execute(image, png_image_read_end, &display);
png_image_free(image);
return result;
}
else
return png_image_error(image,
"png_image_finish_read: invalid argument");
}
return 0;
}
#endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
#endif /* PNG_READ_SUPPORTED */
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