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pngread.c
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/* pngread.c - read a PNG file
*
* Last changed in libpng 1.2.44 [June 26, 2010]
* Copyright (c) 1998-2010 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.
*/
#define PNG_INTERNAL
#define PNG_NO_PEDANTIC_WARNINGS
#include "png.h"
#ifdef PNG_READ_SUPPORTED
/* Create a PNG structure for reading, and allocate any memory needed. */
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)
{
#ifdef PNG_USER_MEM_SUPPORTED
return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
warn_fn, png_voidp_NULL, png_malloc_ptr_NULL, png_free_ptr_NULL));
}
/* Alternate create PNG structure for reading, and allocate any memory
* needed.
*/
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)
{
#endif /* PNG_USER_MEM_SUPPORTED */
#ifdef PNG_SETJMP_SUPPORTED
volatile
#endif
png_structp png_ptr;
#ifdef PNG_SETJMP_SUPPORTED
#ifdef USE_FAR_KEYWORD
jmp_buf jmpbuf;
#endif
#endif
int i;
png_debug(1, "in png_create_read_struct");
#ifdef PNG_USER_MEM_SUPPORTED
png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
(png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
#else
png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
#endif
if (png_ptr == NULL)
return (NULL);
/* Added at libpng-1.2.6 */
#ifdef PNG_USER_LIMITS_SUPPORTED
png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
# ifdef PNG_USER_CHUNK_CACHE_MAX
/* Added at libpng-1.2.43 and 1.4.0 */
png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
# endif
# ifdef PNG_SET_USER_CHUNK_MALLOC_MAX
/* Added at libpng-1.2.43 and 1.4.1 */
png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
# endif
#endif
#ifdef PNG_SETJMP_SUPPORTED
#ifdef USE_FAR_KEYWORD
if (setjmp(jmpbuf))
#else
if (setjmp(png_ptr->jmpbuf))
#endif
{
png_free(png_ptr, png_ptr->zbuf);
png_ptr->zbuf = NULL;
#ifdef PNG_USER_MEM_SUPPORTED
png_destroy_struct_2((png_voidp)png_ptr,
(png_free_ptr)free_fn, (png_voidp)mem_ptr);
#else
png_destroy_struct((png_voidp)png_ptr);
#endif
return (NULL);
}
#ifdef USE_FAR_KEYWORD
png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));
#endif
#endif /* PNG_SETJMP_SUPPORTED */
#ifdef PNG_USER_MEM_SUPPORTED
png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
#endif
png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
if (user_png_ver)
{
i = 0;
do
{
if (user_png_ver[i] != png_libpng_ver[i])
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
} while (png_libpng_ver[i++]);
}
else
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
{
/* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
* we must recompile any applications that use any older library version.
* For versions after libpng 1.0, we will be compatible, so we need
* only check the first digit.
*/
if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
(user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
(user_png_ver[0] == '0' && user_png_ver[2] < '9'))
{
#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
char msg[80];
if (user_png_ver)
{
png_snprintf(msg, 80,
"Application was compiled with png.h from libpng-%.20s",
user_png_ver);
png_warning(png_ptr, msg);
}
png_snprintf(msg, 80,
"Application is running with png.c from libpng-%.20s",
png_libpng_ver);
png_warning(png_ptr, msg);
#endif
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
png_ptr->flags = 0;
#endif
png_error(png_ptr,
"Incompatible libpng version in application and library");
}
}
/* Initialize zbuf - compression buffer */
png_ptr->zbuf_size = PNG_ZBUF_SIZE;
png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
(png_uint_32)png_ptr->zbuf_size);
png_ptr->zstream.zalloc = png_zalloc;
png_ptr->zstream.zfree = png_zfree;
png_ptr->zstream.opaque = (voidpf)png_ptr;
switch (inflateInit(&png_ptr->zstream))
{
case Z_OK: /* Do nothing */ break;
case Z_MEM_ERROR:
case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error");
break;
case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error");
break;
default: png_error(png_ptr, "Unknown zlib error");
}
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
#ifdef PNG_SETJMP_SUPPORTED
/* Applications that neglect to set up their own setjmp() and then
encounter a png_error() will longjmp here. Since the jmpbuf is
then meaningless we abort instead of returning. */
#ifdef USE_FAR_KEYWORD
if (setjmp(jmpbuf))
PNG_ABORT();
png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));
#else
if (setjmp(png_ptr->jmpbuf))
PNG_ABORT();
#endif
#endif /* PNG_SETJMP_SUPPORTED */
#ifdef PNG_INDEX_SUPPORTED
png_ptr->index = NULL;
#endif
return (png_ptr);
}
#if defined(PNG_1_0_X) || defined(PNG_1_2_X)
/* Initialize PNG structure for reading, and allocate any memory needed.
* This interface is deprecated in favour of the png_create_read_struct(),
* and it will disappear as of libpng-1.3.0.
*/
#undef png_read_init
void PNGAPI
png_read_init(png_structp png_ptr)
{
/* We only come here via pre-1.0.7-compiled applications */
png_read_init_2(png_ptr, "1.0.6 or earlier", 0, 0);
}
void PNGAPI
png_read_init_2(png_structp png_ptr, png_const_charp user_png_ver,
png_size_t png_struct_size, png_size_t png_info_size)
{
/* We only come here via pre-1.0.12-compiled applications */
if (png_ptr == NULL)
return;
#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
if (png_sizeof(png_struct) > png_struct_size ||
png_sizeof(png_info) > png_info_size)
{
char msg[80];
png_ptr->warning_fn = NULL;
if (user_png_ver)
{
png_snprintf(msg, 80,
"Application was compiled with png.h from libpng-%.20s",
user_png_ver);
png_warning(png_ptr, msg);
}
png_snprintf(msg, 80,
"Application is running with png.c from libpng-%.20s",
png_libpng_ver);
png_warning(png_ptr, msg);
}
#endif
if (png_sizeof(png_struct) > png_struct_size)
{
png_ptr->error_fn = NULL;
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
png_ptr->flags = 0;
#endif
png_error(png_ptr,
"The png struct allocated by the application for reading is"
" too small.");
}
if (png_sizeof(png_info) > png_info_size)
{
png_ptr->error_fn = NULL;
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
png_ptr->flags = 0;
#endif
png_error(png_ptr,
"The info struct allocated by application for reading is"
" too small.");
}
png_read_init_3(&png_ptr, user_png_ver, png_struct_size);
}
#endif /* PNG_1_0_X || PNG_1_2_X */
void PNGAPI
png_read_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
png_size_t png_struct_size)
{
#ifdef PNG_SETJMP_SUPPORTED
jmp_buf tmp_jmp; /* to save current jump buffer */
#endif
int i = 0;
png_structp png_ptr=*ptr_ptr;
if (png_ptr == NULL)
return;
do
{
if (user_png_ver[i] != png_libpng_ver[i])
{
#ifdef PNG_LEGACY_SUPPORTED
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
#else
png_ptr->warning_fn = NULL;
png_warning(png_ptr,
"Application uses deprecated png_read_init() and should be"
" recompiled.");
break;
#endif
}
} while (png_libpng_ver[i++]);
png_debug(1, "in png_read_init_3");
#ifdef PNG_SETJMP_SUPPORTED
/* Save jump buffer and error functions */
png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
#endif
if (png_sizeof(png_struct) > png_struct_size)
{
png_destroy_struct(png_ptr);
*ptr_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
png_ptr = *ptr_ptr;
}
/* Reset all variables to 0 */
png_memset(png_ptr, 0, png_sizeof(png_struct));
#ifdef PNG_SETJMP_SUPPORTED
/* Restore jump buffer */
png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
#endif
/* Added at libpng-1.2.6 */
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
#endif
/* Initialize zbuf - compression buffer */
png_ptr->zbuf_size = PNG_ZBUF_SIZE;
png_ptr->zstream.zalloc = png_zalloc;
png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
(png_uint_32)png_ptr->zbuf_size);
png_ptr->zstream.zalloc = png_zalloc;
png_ptr->zstream.zfree = png_zfree;
png_ptr->zstream.opaque = (voidpf)png_ptr;
switch (inflateInit(&png_ptr->zstream))
{
case Z_OK: /* Do nothing */ break;
case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break;
case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error");
break;
default: png_error(png_ptr, "Unknown zlib error");
}
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_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;
/* If we haven't checked all of the PNG signature bytes, do so now. */
if (png_ptr->sig_bytes < 8)
{
png_size_t num_checked = png_ptr->sig_bytes,
num_to_check = 8 - num_checked;
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
{
if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
png_error(png_ptr, "Not a PNG file");
else
png_error(png_ptr, "PNG file corrupted by ASCII conversion");
}
if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
for (;;)
{
#ifdef PNG_USE_LOCAL_ARRAYS
PNG_CONST PNG_IHDR;
PNG_CONST PNG_IDAT;
PNG_CONST PNG_IEND;
PNG_CONST PNG_PLTE;
#ifdef PNG_READ_bKGD_SUPPORTED
PNG_CONST PNG_bKGD;
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
PNG_CONST PNG_cHRM;
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
PNG_CONST PNG_gAMA;
#endif
#ifdef PNG_READ_hIST_SUPPORTED
PNG_CONST PNG_hIST;
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
PNG_CONST PNG_iCCP;
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
PNG_CONST PNG_iTXt;
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
PNG_CONST PNG_oFFs;
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
PNG_CONST PNG_pCAL;
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
PNG_CONST PNG_pHYs;
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
PNG_CONST PNG_sBIT;
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
PNG_CONST PNG_sCAL;
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
PNG_CONST PNG_sPLT;
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
PNG_CONST PNG_sRGB;
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
PNG_CONST PNG_tEXt;
#endif
#ifdef PNG_READ_tIME_SUPPORTED
PNG_CONST PNG_tIME;
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
PNG_CONST PNG_tRNS;
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
PNG_CONST PNG_zTXt;
#endif
#endif /* PNG_USE_LOCAL_ARRAYS */
png_uint_32 length = png_read_chunk_header(png_ptr);
PNG_CONST png_bytep 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 (!png_memcmp(chunk_name, png_IDAT, 4))
if (png_ptr->mode & PNG_AFTER_IDAT)
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
if (!png_memcmp(chunk_name, png_IHDR, 4))
png_handle_IHDR(png_ptr, info_ptr, length);
else if (!png_memcmp(chunk_name, png_IEND, 4))
png_handle_IEND(png_ptr, info_ptr, length);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if (png_handle_as_unknown(png_ptr, chunk_name))
{
if (!png_memcmp(chunk_name, png_IDAT, 4))
png_ptr->mode |= PNG_HAVE_IDAT;
png_handle_unknown(png_ptr, info_ptr, length);
if (!png_memcmp(chunk_name, png_PLTE, 4))
png_ptr->mode |= PNG_HAVE_PLTE;
else if (!png_memcmp(chunk_name, png_IDAT, 4))
{
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 (!png_memcmp(chunk_name, png_PLTE, 4))
png_handle_PLTE(png_ptr, info_ptr, length);
else if (!png_memcmp(chunk_name, png_IDAT, 4))
{
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 (!png_memcmp(chunk_name, png_bKGD, 4))
png_handle_bKGD(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
else if (!png_memcmp(chunk_name, png_cHRM, 4))
png_handle_cHRM(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
else if (!png_memcmp(chunk_name, png_gAMA, 4))
png_handle_gAMA(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (!png_memcmp(chunk_name, png_hIST, 4))
png_handle_hIST(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (!png_memcmp(chunk_name, png_oFFs, 4))
png_handle_oFFs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (!png_memcmp(chunk_name, png_pCAL, 4))
png_handle_pCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (!png_memcmp(chunk_name, png_sCAL, 4))
png_handle_sCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (!png_memcmp(chunk_name, png_pHYs, 4))
png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
else if (!png_memcmp(chunk_name, png_sBIT, 4))
png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (!png_memcmp(chunk_name, png_sRGB, 4))
png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
else if (!png_memcmp(chunk_name, png_iCCP, 4))
png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (!png_memcmp(chunk_name, png_sPLT, 4))
png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (!png_memcmp(chunk_name, png_tEXt, 4))
png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (!png_memcmp(chunk_name, png_tIME, 4))
png_handle_tIME(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (!png_memcmp(chunk_name, png_tRNS, 4))
png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (!png_memcmp(chunk_name, png_zTXt, 4))
png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (!png_memcmp(chunk_name, png_iTXt, 4))
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;
#ifdef PNG_INDEX_SUPPORTED
if (png_ptr->index) {
png_read_start_row(png_ptr);
}
#endif
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
png_read_start_row(png_ptr);
else
png_warning(png_ptr,
"Ignoring extra png_read_update_info() call; row buffer not reallocated");
png_read_transform_info(png_ptr, info_ptr);
}
#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)
return;
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
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)
{
PNG_CONST PNG_IDAT;
PNG_CONST int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
0xff};
PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
int ret;
if (png_ptr == NULL)
return;
png_debug2(1, "in png_read_row (row %lu, pass %d)",
png_ptr->row_number, png_ptr->pass);
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
png_read_start_row(png_ptr);
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 */
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,
png_pass_dsp_mask[png_ptr->pass]);
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,
png_pass_dsp_mask[png_ptr->pass]);
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,
png_pass_dsp_mask[png_ptr->pass]);
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,
png_pass_dsp_mask[png_ptr->pass]);
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,
png_pass_dsp_mask[png_ptr->pass]);
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,
png_pass_dsp_mask[png_ptr->pass]);
png_read_finish_row(png_ptr);
return;
}
break;
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)
{
#ifdef PNG_INDEX_SUPPORTED
if (png_ptr->index) {
png_opt_crc_finish(png_ptr, 0, 0);
png_ptr->index->stream_idat_position = png_ptr->total_data_read;
} else
#endif
png_crc_finish(png_ptr, 0);
png_ptr->idat_size = png_read_chunk_header(png_ptr);
if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
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_error(png_ptr, "Extra compressed data");
png_ptr->mode |= PNG_AFTER_IDAT;
png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
break;
}
if (ret != Z_OK)
#ifdef PNG_INDEX_SUPPORTED
if (png_ptr->index && png_ptr->row_number != png_ptr->height - 1)
#endif
png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
"Decompression error");
} while (png_ptr->zstream.avail_out);
png_ptr->row_info.color_type = png_ptr->color_type;
png_ptr->row_info.width = png_ptr->iwidth;
png_ptr->row_info.channels = png_ptr->channels;
png_ptr->row_info.bit_depth = png_ptr->bit_depth;
png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
png_ptr->row_info.width);
if (png_ptr->row_buf[0])
png_read_filter_row(png_ptr, &(png_ptr->row_info),
png_ptr->row_buf + 1, png_ptr->prev_row + 1,
(int)(png_ptr->row_buf[0]));
png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
png_ptr->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(&(png_ptr->row_info), png_ptr->row_buf + 1);
}
#endif
if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
png_do_read_transformations(png_ptr);
#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)
/* Old interface (pre-1.0.9):
* png_do_read_interlace(&(png_ptr->row_info),
* png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
*/
png_do_read_interlace(png_ptr);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row,
png_pass_dsp_mask[png_ptr->pass]);
if (row != NULL)
png_combine_row(png_ptr, row,
png_pass_mask[png_ptr->pass]);
}
else
#endif
{
if (row != NULL)
png_combine_row(png_ptr, row, 0xff);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 0xff);
}
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, png_bytep_NULL);
rp++;
}
else if (dp != NULL)
for (i = 0; i < num_rows; i++)
{
png_bytep dptr = *dp;
png_read_row(png_ptr, png_bytep_NULL, dptr);
dp++;
}
}
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#ifdef PNG_INDEX_SUPPORTED
#define IDAT_HEADER_SIZE 8
/* Set the png read position to a new position based on idat_position and
* offset.
*/
void
png_set_read_offset(png_structp png_ptr,
png_uint_32 idat_position, png_uint_32 bytes_left)
{
png_seek_data(png_ptr, idat_position);
png_ptr->idat_size = png_read_chunk_header(png_ptr);
// We need to add back IDAT_HEADER_SIZE because in zlib's perspective,
// IDAT_HEADER in PNG is already stripped out.
png_seek_data(png_ptr, idat_position + IDAT_HEADER_SIZE + png_ptr->idat_size - bytes_left);
png_ptr->idat_size = bytes_left;
}
/* Configure png decoder to decode the pass starting from *row.
* The requested row may be adjusted to align with an indexing row.
* The actual row for the decoder to start its decoding will be returned in
* *row.
*/
void PNGAPI
png_configure_decoder(png_structp png_ptr, int *row, int pass)
{
long row_byte_length;
png_indexp index = png_ptr->index;
int n = *row / index->step[pass];
png_line_indexp line_index = index->pass_line_index[pass][n];
// Adjust row to an indexing row.
*row = n * index->step[pass];
png_ptr->row_number = *row;
#ifdef PNG_READ_INTERLACING_SUPPORTED
if (png_ptr->interlaced)
png_set_interlaced_pass(png_ptr, pass);
#endif
row_byte_length =
PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1;
inflateEnd(&png_ptr->zstream);
inflateCopy(&png_ptr->zstream, line_index->z_state);
// Set the png read position to line_index.
png_set_read_offset(png_ptr, line_index->stream_idat_position,
line_index->bytes_left_in_idat);
png_memcpy_check(png_ptr,
png_ptr->prev_row, line_index->prev_row, row_byte_length);
png_ptr->zstream.avail_in = 0;
}
/* Build the line index and store the index in png_ptr->index.
*/
void PNGAPI
png_build_index(png_structp png_ptr)
{
// number of rows in a 8x8 block for each interlaced pass.
int number_rows_in_pass[7] = {1, 1, 1, 2, 2, 4, 4};
int ret;
png_uint_32 i, j;
png_bytep rp;
int p, pass_number = 1;
png_indexp index;
#ifdef PNG_READ_INTERLACING_SUPPORTED
pass_number = png_set_interlace_handling(png_ptr);
#endif
if (png_ptr == NULL)
return;
png_read_start_row(png_ptr);
#ifdef PNG_READ_INTERLACING_SUPPORTED
if (!png_ptr->interlaced)
#endif
{
number_rows_in_pass[0] = 8;
}
rp = png_malloc(png_ptr, png_ptr->rowbytes);