/* pngread.c - read a PNG file | |
* | |
* Last changed in libpng 1.6.1 [March 28, 2013] | |
* Copyright (c) 1998-2013 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) | |
{ | |
png_ptr->mode = PNG_IS_READ_STRUCT; | |
/* Added in libpng-1.6.0; this can be used to detect a read structure if | |
* required (it will be zero in a write structure.) | |
*/ | |
# ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; | |
# endif | |
# ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED | |
png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; | |
/* In stable builds only warn if an application error can be completely | |
* handled. | |
*/ | |
# if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC | |
png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; | |
# endif | |
# endif | |
/* 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; | |
} | |
#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_structrp png_ptr, png_inforp info_ptr) | |
{ | |
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
int keep; | |
#endif | |
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; | |
/* IDAT logic needs to happen here to simplify getting the two flags | |
* right. | |
*/ | |
if (chunk_name == png_IDAT) | |
{ | |
if (!(png_ptr->mode & PNG_HAVE_IHDR)) | |
png_chunk_error(png_ptr, "Missing IHDR before IDAT"); | |
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && | |
!(png_ptr->mode & PNG_HAVE_PLTE)) | |
png_chunk_error(png_ptr, "Missing PLTE before IDAT"); | |
else if (png_ptr->mode & PNG_AFTER_IDAT) | |
png_chunk_benign_error(png_ptr, "Too many IDATs found"); | |
png_ptr->mode |= PNG_HAVE_IDAT; | |
} | |
else if (png_ptr->mode & PNG_HAVE_IDAT) | |
png_ptr->mode |= PNG_AFTER_IDAT; | |
/* This should be a binary subdivision search or a hash for | |
* matching the chunk name rather than a linear search. | |
*/ | |
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 ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) | |
{ | |
png_handle_unknown(png_ptr, info_ptr, length, keep); | |
if (chunk_name == png_PLTE) | |
png_ptr->mode |= PNG_HAVE_PLTE; | |
else if (chunk_name == png_IDAT) | |
{ | |
png_ptr->idat_size = 0; /* It has been consumed */ | |
break; | |
} | |
} | |
#endif | |
else if (chunk_name == png_PLTE) | |
png_handle_PLTE(png_ptr, info_ptr, length); | |
else if (chunk_name == png_IDAT) | |
{ | |
png_ptr->idat_size = length; | |
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, | |
PNG_HANDLE_CHUNK_AS_DEFAULT); | |
} | |
} | |
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
/* Optional call to update the users info_ptr structure */ | |
void PNGAPI | |
png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) | |
{ | |
png_debug(1, "in png_read_update_info"); | |
if (png_ptr != NULL) | |
{ | |
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) | |
{ | |
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 | |
} | |
/* New in 1.6.0 this avoids the bug of doing the initializations twice */ | |
else | |
png_app_error(png_ptr, | |
"png_read_update_info/png_start_read_image: duplicate call"); | |
} | |
} | |
#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_structrp png_ptr) | |
{ | |
png_debug(1, "in png_start_read_image"); | |
if (png_ptr != NULL) | |
{ | |
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) | |
png_read_start_row(png_ptr); | |
/* New in 1.6.0 this avoids the bug of doing the initializations twice */ | |
else | |
png_app_error(png_ptr, | |
"png_start_read_image/png_read_update_info: duplicate call"); | |
} | |
} | |
#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
void PNGAPI | |
png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) | |
{ | |
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"); | |
/* Fill the row with IDAT data: */ | |
png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); | |
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: | |
*/ | |
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_structrp 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_structrp 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_structrp png_ptr, png_inforp info_ptr) | |
{ | |
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
int keep; | |
#endif | |
png_debug(1, "in png_read_end"); | |
if (png_ptr == NULL) | |
return; | |
/* If png_read_end is called in the middle of reading the rows there may | |
* still be pending IDAT data and an owned zstream. Deal with this here. | |
*/ | |
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
if (!png_chunk_unknown_handling(png_ptr, png_IDAT)) | |
#endif | |
png_read_finish_IDAT(png_ptr); | |
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED | |
/* Report invalid palette index; added at libng-1.5.10 */ | |
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && | |
png_ptr->num_palette_max > png_ptr->num_palette) | |
png_benign_error(png_ptr, "Read palette index exceeding num_palette"); | |
#endif | |
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 ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) | |
{ | |
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, keep); | |
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, | |
PNG_HANDLE_CHUNK_AS_DEFAULT); | |
} 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_structrp 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->big_row_buf); | |
png_free(png_ptr, png_ptr->big_prev_row); | |
png_free(png_ptr, png_ptr->read_buffer); | |
#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 | |
inflateEnd(&png_ptr->zstream); | |
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED | |
png_free(png_ptr, png_ptr->save_buffer); | |
#endif | |
#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) &&\ | |
defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) | |
png_free(png_ptr, png_ptr->unknown_chunk.data); | |
#endif | |
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED | |
png_free(png_ptr, png_ptr->chunk_list); | |
#endif | |
/* NOTE: the 'setjmp' buffer may still be allocated and the memory and error | |
* callbacks are still set at this point. They are required to complete the | |
* destruction of the png_struct itself. | |
*/ | |
} | |
/* Free all memory used by the read */ | |
void PNGAPI | |
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, | |
png_infopp end_info_ptr_ptr) | |
{ | |
png_structrp png_ptr = NULL; | |
png_debug(1, "in png_destroy_read_struct"); | |
if (png_ptr_ptr != NULL) | |
png_ptr = *png_ptr_ptr; | |
if (png_ptr == NULL) | |
return; | |
/* libpng 1.6.0: use the API to destroy info structs to ensure consistent | |
* behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. | |
* The extra was, apparently, unnecessary yet this hides memory leak bugs. | |
*/ | |
png_destroy_info_struct(png_ptr, end_info_ptr_ptr); | |
png_destroy_info_struct(png_ptr, info_ptr_ptr); | |
*png_ptr_ptr = NULL; | |
png_read_destroy(png_ptr); | |
png_destroy_png_struct(png_ptr); | |
} | |
void PNGAPI | |
png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) | |
{ | |
if (png_ptr == NULL) | |
return; | |
png_ptr->read_row_fn = read_row_fn; | |
} | |
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
#ifdef PNG_INFO_IMAGE_SUPPORTED | |
void PNGAPI | |
png_read_png(png_structrp png_ptr, png_inforp 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/(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 * (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. | |
*/ | |
/* Arguments to png_image_finish_read: */ | |
/* Encoding of PNG data (used by the color-map code) */ | |
/* TODO: change these, dang, ANSI-C reserves the 'E' namespace. */ | |
# define E_NOTSET 0 /* File encoding not yet known */ | |
# define E_sRGB 1 /* 8-bit encoded to sRGB gamma */ | |
# define E_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ | |
# define E_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ | |
# define E_LINEAR8 4 /* 8-bit linear: only from a file value */ | |
/* Color-map processing: after libpng has run on the PNG image further | |
* processing may be needed to conver the data to color-map indicies. | |
*/ | |
#define PNG_CMAP_NONE 0 | |
#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ | |
#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ | |
#define PNG_CMAP_RGB 3 /* Process RGB data */ | |
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ | |
/* The following document where the background is for each processing case. */ | |
#define PNG_CMAP_NONE_BACKGROUND 256 | |
#define PNG_CMAP_GA_BACKGROUND 231 | |
#define PNG_CMAP_TRANS_BACKGROUND 254 | |
#define PNG_CMAP_RGB_BACKGROUND 256 | |
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 | |
typedef struct | |
{ | |
/* Arguments: */ | |
png_imagep image; | |
png_voidp buffer; | |
png_int_32 row_stride; | |
png_voidp colormap; | |
png_const_colorp background; | |
/* Local variables: */ | |
png_voidp local_row; | |
png_voidp first_row; | |
ptrdiff_t row_bytes; /* step between rows */ | |
int file_encoding; /* E_ values above */ | |
png_fixed_point gamma_to_linear; /* For E_FILE, reciprocal of gamma */ | |
int colormap_processing; /* PNG_CMAP_ values above */ | |
} png_image_read_control; | |
/* Do all the *safe* initialization - 'safe' means that png_error won't be | |
* called, so setting up the jmp_buf is not required. This means that anything | |
* called from here must *not* call png_malloc - it has to call png_malloc_warn | |
* instead so that control is returned safely back to this routine. | |
*/ | |
static int | |
png_image_read_init(png_imagep image) | |
{ | |
if (image->opaque == NULL) | |
{ | |
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, | |
png_safe_error, png_safe_warning); | |
/* And set the rest of the structure to NULL to ensure that the various | |
* fields are consistent. | |
*/ | |
memset(image, 0, (sizeof *image)); | |
image->version = PNG_IMAGE_VERSION; | |
if (png_ptr != NULL) | |
{ | |
png_infop info_ptr = png_create_info_struct(png_ptr); | |
if (info_ptr != NULL) | |
{ | |
png_controlp control = png_voidcast(png_controlp, | |
png_malloc_warn(png_ptr, (sizeof *control))); | |
if (control != NULL) | |
{ | |
memset(control, 0, (sizeof *control)); | |
control->png_ptr = png_ptr; | |
control->info_ptr = info_ptr; | |
control->for_write = 0; | |
image->opaque = control; | |
return 1; | |
} | |
/* Error clean up */ | |
png_destroy_info_struct(png_ptr, &info_ptr); | |
} | |
png_destroy_read_struct(&png_ptr, NULL, NULL); | |
} | |
return png_image_error(image, "png_image_read: out of memory"); | |
} | |
return png_image_error(image, "png_image_read: opaque pointer not NULL"); | |
} | |
/* Utility to find the base format of a PNG file from a png_struct. */ | |
static png_uint_32 | |
png_image_format(png_structrp png_ptr) | |
{ | |
png_uint_32 format = 0; | |
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) | |
format |= PNG_FORMAT_FLAG_COLOR; | |
if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) | |
format |= PNG_FORMAT_FLAG_ALPHA; | |
/* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS | |
* sets the png_struct fields; that's all we are interested in here. The | |
* precise interaction with an app call to png_set_tRNS and PNG file reading | |
* is unclear. | |
*/ | |
else if (png_ptr->num_trans > 0) | |
format |= PNG_FORMAT_FLAG_ALPHA; | |
if (png_ptr->bit_depth == 16) | |
format |= PNG_FORMAT_FLAG_LINEAR; | |
if (png_ptr->color_type & PNG_COLOR_MASK_PALETTE) | |
format |= PNG_FORMAT_FLAG_COLORMAP; | |
return format; | |
} | |
/* Is the given gamma significantly different from sRGB? The test is the same | |
* one used in pngrtran.c when deciding whether to do gamma correction. The | |
* arithmetic optimizes the division by using the fact that the inverse of the | |
* file sRGB gamma is 2.2 | |
*/ | |
static int | |
png_gamma_not_sRGB(png_fixed_point g) | |
{ | |
if (g < PNG_FP_1) | |
{ | |
/* An uninitialized gamma is assumed to be sRGB for the simplified API. */ | |
if (g == 0) | |
return 0; | |
return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); | |
} | |
return 1; | |
} | |
/* Do the main body of a 'png_image_begin_read' function; read the PNG file | |
* header and fill in all the information. This is executed in a safe context, | |
* unlike the init routine above. | |
*/ | |
static int | |
png_image_read_header(png_voidp argument) | |
{ | |
png_imagep image = png_voidcast(png_imagep, argument); | |
png_structrp png_ptr = image->opaque->png_ptr; | |
png_inforp info_ptr = image->opaque->info_ptr; | |
png_set_benign_errors(png_ptr, 1/*warn*/); | |
png_read_info(png_ptr, info_ptr); | |
/* Do this the fast way; just read directly out of png_struct. */ | |
image->width = png_ptr->width; | |
image->height = png_ptr->height; | |
{ | |
png_uint_32 format = png_image_format(png_ptr); | |
image->format = format; | |
#ifdef PNG_COLORSPACE_SUPPORTED | |
/* Does the colorspace match sRGB? If there is no color endpoint | |
* (colorant) information assume yes, otherwise require the | |
* 'ENDPOINTS_MATCHE_sRGB' colorspace flag to have been set. If the | |
* colorspace has been determined to be invalid ignore it. | |
*/ | |
if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags | |
& (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB| | |
PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS)) | |
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; | |
#endif | |
} | |
/* We need the maximum number of entries regardless of the format the | |
* application sets here. | |
*/ | |
{ | |
png_uint_32 cmap_entries; | |
switch (png_ptr->color_type) | |
{ | |
case PNG_COLOR_TYPE_GRAY: | |
cmap_entries = 1U << png_ptr->bit_depth; | |
break; | |
case PNG_COLOR_TYPE_PALETTE: | |
cmap_entries = png_ptr->num_palette; | |
break; | |
default: | |
cmap_entries = 256; | |
break; | |
} | |
if (cmap_entries > 256) | |
cmap_entries = 256; | |
image->colormap_entries = cmap_entries; | |
} | |
return 1; | |
} | |
#ifdef PNG_STDIO_SUPPORTED | |
int PNGAPI | |
png_image_begin_read_from_stdio(png_imagep image, FILE* file) | |
{ | |
if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
{ | |
if (file != NULL) | |
{ | |
if (png_image_read_init(image)) | |
{ | |
/* 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"); | |
} | |
else if (image != NULL) | |
return png_image_error(image, | |
"png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); | |
return 0; | |
} | |
int PNGAPI | |
png_image_begin_read_from_file(png_imagep image, const char *file_name) | |
{ | |
if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
{ | |
if (file_name != NULL) | |
{ | |
FILE *fp = fopen(file_name, "rb"); | |
if (fp != NULL) | |
{ | |
if (png_image_read_init(image)) | |
{ | |
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"); | |
} | |
else if (image != NULL) | |
return png_image_error(image, | |
"png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); | |
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) | |
{ | |
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 && image->version == PNG_IMAGE_VERSION) | |
{ | |
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"); | |
} | |
else if (image != NULL) | |
return png_image_error(image, | |
"png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); | |
return 0; | |
} | |
/* Utility function to skip chunks that are not used by the simplified image | |
* read functions and an appropriate macro to call it. | |
*/ | |
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
static void | |
png_image_skip_unused_chunks(png_structrp png_ptr) | |
{ | |
/* Prepare the reader to ignore all recognized chunks whose data will not | |
* be used, i.e., all chunks recognized by libpng except for those | |
* involved in basic image reading: | |
* | |
* IHDR, PLTE, IDAT, IEND | |
* | |
* Or image data handling: | |
* | |
* tRNS, bKGD, gAMA, cHRM, sRGB, iCCP and sBIT. | |
* | |
* This provides a small performance improvement and eliminates any | |
* potential vulnerability to security problems in the unused chunks. | |
*/ | |
{ | |
static PNG_CONST png_byte chunks_to_process[] = { | |
98, 75, 71, 68, '\0', /* bKGD */ | |
99, 72, 82, 77, '\0', /* cHRM */ | |
103, 65, 77, 65, '\0', /* gAMA */ | |
105, 67, 67, 80, '\0', /* iCCP */ | |
115, 66, 73, 84, '\0', /* sBIT */ | |
115, 82, 71, 66, '\0', /* sRGB */ | |
}; | |
/* Ignore unknown chunks and all other chunks except for the | |
* IHDR, PLTE, tRNS, IDAT, and IEND chunks. | |
*/ | |
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, | |
NULL, -1); | |
/* But do not ignore image data handling chunks */ | |
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, | |
chunks_to_process, (sizeof chunks_to_process)/5); | |
} | |
} | |
# define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) | |
#else | |
# define PNG_SKIP_CHUNKS(p) ((void)0) | |
#endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */ | |
/* The following macro gives the exact rounded answer for all values in the | |
* range 0..255 (it actually divides by 51.2, but the rounding still generates | |
* the correct numbers 0..5 | |
*/ | |
#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) | |
/* Utility functions to make particular color-maps */ | |
static void | |
set_file_encoding(png_image_read_control *display) | |
{ | |
png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma; | |
if (png_gamma_significant(g)) | |
{ | |
if (png_gamma_not_sRGB(g)) | |
{ | |
display->file_encoding = E_FILE; | |
display->gamma_to_linear = png_reciprocal(g); | |
} | |
else | |
display->file_encoding = E_sRGB; | |
} | |
else | |
display->file_encoding = E_LINEAR8; | |
} | |
static unsigned int | |
decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) | |
{ | |
if (encoding == E_FILE) /* double check */ | |
encoding = display->file_encoding; | |
if (encoding == E_NOTSET) /* must be the file encoding */ | |
{ | |
set_file_encoding(display); | |
encoding = display->file_encoding; | |
} | |
switch (encoding) | |
{ | |
case E_FILE: | |
value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); | |
break; | |
case E_sRGB: | |
value = png_sRGB_table[value]; | |
break; | |
case E_LINEAR: | |
break; | |
case E_LINEAR8: | |
value *= 257; | |
break; | |
default: | |
png_error(display->image->opaque->png_ptr, | |
"unexpected encoding (internal error)"); | |
break; | |
} | |
return value; | |
} | |
static png_uint_32 | |
png_colormap_compose(png_image_read_control *display, | |
png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, | |
png_uint_32 background, int encoding) | |
{ | |
/* The file value is composed on the background, the background has the given | |
* encoding and so does the result, the file is encoded with E_FILE and the | |
* file and alpha are 8-bit values. The (output) encoding will always be | |
* E_LINEAR or E_sRGB. | |
*/ | |
png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); | |
png_uint_32 b = decode_gamma(display, background, encoding); | |
/* The alpha is always an 8-bit value (it comes from the palette), the value | |
* scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. | |
*/ | |
f = f * alpha + b * (255-alpha); | |
if (encoding == E_LINEAR) | |
{ | |
/* Scale to 65535; divide by 255, approximately (in fact this is extremely | |
* accurate, it divides by 255.00000005937181414556, with no overflow.) | |
*/ | |
f *= 257; /* Now scaled by 65535 */ | |
f += f >> 16; | |
f = (f+32768) >> 16; | |
} | |
else /* E_sRGB */ | |
f = PNG_sRGB_FROM_LINEAR(f); | |
return f; | |
} | |
/* NOTE: E_LINEAR values to this routine must be 16-bit, but E_FILE values must | |
* be 8-bit. | |
*/ | |
static void | |
png_create_colormap_entry(png_image_read_control *display, | |
png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, | |
png_uint_32 alpha, int encoding) | |
{ | |
png_imagep image = display->image; | |
const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) ? | |
E_LINEAR : E_sRGB; | |
const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && | |
(red != green || green != blue); | |
if (ip > 255) | |
png_error(image->opaque->png_ptr, "color-map index out of range"); | |
/* Update the cache with whether the file gamma is significantly different | |
* from sRGB. | |
*/ | |
if (encoding == E_FILE) | |
{ | |
if (display->file_encoding == E_NOTSET) | |
set_file_encoding(display); | |
/* Note that the cached value may be E_FILE too, but if it is then the | |
* gamma_to_linear member has been set. | |
*/ | |
encoding = display->file_encoding; | |
} | |
if (encoding == E_FILE) | |
{ | |
png_fixed_point g = display->gamma_to_linear; | |
red = png_gamma_16bit_correct(red*257, g); | |
green = png_gamma_16bit_correct(green*257, g); | |
blue = png_gamma_16bit_correct(blue*257, g); | |
if (convert_to_Y || output_encoding == E_LINEAR) | |
{ | |
alpha *= 257; | |
encoding = E_LINEAR; | |
} | |
else | |
{ | |
red = PNG_sRGB_FROM_LINEAR(red * 255); | |
green = PNG_sRGB_FROM_LINEAR(green * 255); | |
blue = PNG_sRGB_FROM_LINEAR(blue * 255); | |
encoding = E_sRGB; | |
} | |
} | |
else if (encoding == E_LINEAR8) | |
{ | |
/* This encoding occurs quite frequently in test cases because PngSuite | |
* includes a gAMA 1.0 chunk with most images. | |
*/ | |
red *= 257; | |
green *= 257; | |
blue *= 257; | |
alpha *= 257; | |
encoding = E_LINEAR; | |
} | |
else if (encoding == E_sRGB && (convert_to_Y || output_encoding == E_LINEAR)) | |
{ | |
/* The values are 8-bit sRGB values, but must be converted to 16-bit | |
* linear. | |
*/ | |
red = png_sRGB_table[red]; | |
green = png_sRGB_table[green]; | |
blue = png_sRGB_table[blue]; | |
alpha *= 257; | |
encoding = E_LINEAR; | |
} | |
/* This is set if the color isn't gray but the output is. */ | |
if (encoding == E_LINEAR) | |
{ | |
if (convert_to_Y) | |
{ | |
/* NOTE: these values are copied from png_do_rgb_to_gray */ | |
png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + | |
(png_uint_32)2366 * blue; | |
if (output_encoding == E_LINEAR) | |
y = (y + 16384) >> 15; | |
else | |
{ | |
/* y is scaled by 32768, we need it scaled by 255: */ | |
y = (y + 128) >> 8; | |
y *= 255; | |
y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); | |
encoding = E_sRGB; | |
} | |
blue = red = green = y; | |
} | |
else if (output_encoding == E_sRGB) | |
{ | |
red = PNG_sRGB_FROM_LINEAR(red * 255); | |
green = PNG_sRGB_FROM_LINEAR(green * 255); | |
blue = PNG_sRGB_FROM_LINEAR(blue * 255); | |
alpha = PNG_DIV257(alpha); | |
encoding = E_sRGB; | |
} | |
} | |
if (encoding != output_encoding) | |
png_error(image->opaque->png_ptr, "bad encoding (internal error)"); | |
/* Store the value. */ | |
{ | |
# ifdef PNG_FORMAT_BGR_SUPPORTED | |
const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && | |
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0; | |
# else | |
# define afirst 0 | |
# endif | |
# ifdef PNG_FORMAT_BGR_SUPPORTED | |
const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) ? 2 : 0; | |
# else | |
# define bgr 0 | |
# endif | |
if (output_encoding == E_LINEAR) | |
{ | |
png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); | |
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); | |
/* The linear 16-bit values must be pre-multiplied by the alpha channel | |
* value, if less than 65535 (this is, effectively, composite on black | |
* if the alpha channel is removed.) | |
*/ | |
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) | |
{ | |
case 4: | |
entry[afirst ? 0 : 3] = (png_uint_16)alpha; | |
/* FALL THROUGH */ | |
case 3: | |
if (alpha < 65535) | |
{ | |
if (alpha > 0) | |
{ | |
blue = (blue * alpha + 32767U)/65535U; | |
green = (green * alpha + 32767U)/65535U; | |
red = (red * alpha + 32767U)/65535U; | |
} | |
else | |
red = green = blue = 0; | |
} | |
entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; | |
entry[afirst + 1] = (png_uint_16)green; | |
entry[afirst + bgr] = (png_uint_16)red; | |
break; | |
case 2: | |
entry[1 ^ afirst] = (png_uint_16)alpha; | |
/* FALL THROUGH */ | |
case 1: | |
if (alpha < 65535) | |
{ | |
if (alpha > 0) | |
green = (green * alpha + 32767U)/65535U; | |
else | |
green = 0; | |
} | |
entry[afirst] = (png_uint_16)green; | |
break; | |
default: | |
break; | |
} | |
} | |
else /* output encoding is E_sRGB */ | |
{ | |
png_bytep entry = png_voidcast(png_bytep, display->colormap); | |
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); | |
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) | |
{ | |
case 4: | |
entry[afirst ? 0 : 3] = (png_byte)alpha; | |
case 3: | |
entry[afirst + (2 ^ bgr)] = (png_byte)blue; | |
entry[afirst + 1] = (png_byte)green; | |
entry[afirst + bgr] = (png_byte)red; | |
break; | |
case 2: | |
entry[1 ^ afirst] = (png_byte)alpha; | |
case 1: | |
entry[afirst] = (png_byte)green; | |
break; | |
default: | |
break; | |
} | |
} | |
# ifdef afirst | |
# undef afirst | |
# endif | |
# ifdef bgr | |
# undef bgr | |
# endif | |
} | |
} | |
static int | |
make_gray_file_colormap(png_image_read_control *display) | |
{ | |
unsigned int i; | |
for (i=0; i<256; ++i) | |
png_create_colormap_entry(display, i, i, i, i, 255, E_FILE); | |
return i; | |
} | |
static int | |
make_gray_colormap(png_image_read_control *display) | |
{ | |
unsigned int i; | |
for (i=0; i<256; ++i) | |
png_create_colormap_entry(display, i, i, i, i, 255, E_sRGB); | |
return i; | |
} | |
#define PNG_GRAY_COLORMAP_ENTRIES 256 | |
static int | |
make_ga_colormap(png_image_read_control *display) | |
{ | |
unsigned int i, a; | |
/* Alpha is retained, the output will be a color-map with entries | |
* selected by six levels of alpha. One transparent entry, 6 gray | |
* levels for all the intermediate alpha values, leaving 230 entries | |
* for the opaque grays. The color-map entries are the six values | |
* [0..5]*51, the GA processing uses PNG_DIV51(value) to find the | |
* relevant entry. | |
* | |
* if (alpha > 229) // opaque | |
* { | |
* // The 231 entries are selected to make the math below work: | |
* base = 0; | |
* entry = (231 * gray + 128) >> 8; | |
* } | |
* else if (alpha < 26) // transparent | |
* { | |
* base = 231; | |
* entry = 0; | |
* } | |
* else // partially opaque | |
* { | |
* base = 226 + 6 * PNG_DIV51(alpha); | |
* entry = PNG_DIV51(gray); | |
* } | |
*/ | |
i = 0; | |
while (i < 231) | |
{ | |
unsigned int gray = (i * 256 + 115) / 231; | |
png_create_colormap_entry(display, i++, gray, gray, gray, 255, E_sRGB); | |
} | |
/* 255 is used here for the component values for consistency with the code | |
* that undoes premultiplication in pngwrite.c. | |
*/ | |
png_create_colormap_entry(display, i++, 255, 255, 255, 0, E_sRGB); | |
for (a=1; a<5; ++a) | |
{ | |
unsigned int g; | |
for (g=0; g<6; ++g) | |
png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, | |
E_sRGB); | |
} | |
return i; | |
} | |
#define PNG_GA_COLORMAP_ENTRIES 256 | |
static int | |
make_rgb_colormap(png_image_read_control *display) | |
{ | |
unsigned int i, r; | |
/* Build a 6x6x6 opaque RGB cube */ | |
for (i=r=0; r<6; ++r) | |
{ | |
unsigned int g; | |
for (g=0; g<6; ++g) | |
{ | |
unsigned int b; | |
for (b=0; b<6; ++b) | |
png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, | |
E_sRGB); | |
} | |
} | |
return i; | |
} | |
#define PNG_RGB_COLORMAP_ENTRIES 216 | |
/* Return a palette index to the above palette given three 8-bit sRGB values. */ | |
#define PNG_RGB_INDEX(r,g,b) \ | |
((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) | |
static int | |
png_image_read_colormap(png_voidp argument) | |
{ | |
png_image_read_control *display = | |
png_voidcast(png_image_read_control*, argument); | |
const png_imagep image = display->image; | |
const png_structrp png_ptr = image->opaque->png_ptr; | |
const png_uint_32 output_format = image->format; | |
const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) ? | |
E_LINEAR : E_sRGB; | |
unsigned int cmap_entries; | |
unsigned int output_processing; /* Output processing option */ | |
unsigned int data_encoding = E_NOTSET; /* Encoding libpng must produce */ | |
/* Background information; the background color and the index of this color | |
* in the color-map if it exists (else 256). | |
*/ | |
unsigned int background_index = 256; | |
png_uint_32 back_r, back_g, back_b; | |
/* Flags to accumulate things that need to be done to the input. */ | |
int expand_tRNS = 0; | |
/* Exclude the NYI feature of compositing onto a color-mapped buffer; it is | |
* very difficult to do, the results look awful, and it is difficult to see | |
* what possible use it is because the application can't control the | |
* color-map. | |
*/ | |
if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || | |
png_ptr->num_trans > 0) /* alpha in input */ && | |
((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) | |
{ | |
if (output_encoding == E_LINEAR) /* compose on black */ | |
back_b = back_g = back_r = 0; | |
else if (display->background == NULL /* no way to remove it */) | |
png_error(png_ptr, | |
"a background color must be supplied to remove alpha/transparency"); | |
/* Get a copy of the background color (this avoids repeating the checks | |
* below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the | |
* output format. | |
*/ | |
else | |
{ | |
back_g = display->background->green; | |
if (output_format & PNG_FORMAT_FLAG_COLOR) | |
{ | |
back_r = display->background->red; | |
back_b = display->background->blue; | |
} | |
else | |
back_b = back_r = back_g; | |
} | |
} | |
else if (output_encoding == E_LINEAR) | |
back_b = back_r = back_g = 65535; | |
else | |
back_b = back_r = back_g = 255; | |
/* Default the input file gamma if required - this is necessary because | |
* libpng assumes that if no gamma information is present the data is in the | |
* output format, but the simplified API deduces the gamma from the input | |
* format. | |
*/ | |
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0) | |
{ | |
/* Do this directly, not using the png_colorspace functions, to ensure | |
* that it happens even if the colorspace is invalid (though probably if | |
* it is the setting will be ignored) Note that the same thing can be | |
* achieved at the application interface with png_set_gAMA. | |
*/ | |
if (png_ptr->bit_depth == 16 && | |
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) | |
png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR; | |
else | |
png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE; | |
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; | |
} | |
/* Decide what to do based on the PNG color type of the input data. The | |
* utility function png_create_colormap_entry deals with most aspects of the | |
* output transformations; this code works out how to produce bytes of | |
* color-map entries from the original format. | |
*/ | |
switch (png_ptr->color_type) | |
{ | |
case PNG_COLOR_TYPE_GRAY: | |
if (png_ptr->bit_depth <= 8) | |
{ | |
/* There at most 256 colors in the output, regardless of | |
* transparency. | |
*/ | |
unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; | |
cmap_entries = 1U << png_ptr->bit_depth; | |
if (cmap_entries > image->colormap_entries) | |
png_error(png_ptr, "gray[8] color-map: too few entries"); | |
step = 255 / (cmap_entries - 1); | |
output_processing = PNG_CMAP_NONE; | |
/* If there is a tRNS chunk then this either selects a transparent | |
* value or, if the output has no alpha, the background color. | |
*/ | |
if (png_ptr->num_trans > 0) | |
{ | |
trans = png_ptr->trans_color.gray; | |
if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) | |
back_alpha = output_encoding == E_LINEAR ? 65535 : 255; | |
} | |
/* png_create_colormap_entry just takes an RGBA and writes the | |
* corresponding color-map entry using the format from 'image', | |
* including the required conversion to sRGB or linear as | |
* appropriate. The input values are always either sRGB (if the | |
* gamma correction flag is 0) or 0..255 scaled file encoded values | |
* (if the function must gamma correct them). | |
*/ | |
for (i=val=0; i<cmap_entries; ++i, val += step) | |
{ | |
/* 'i' is a file value. While this will result in duplicated | |
* entries for 8-bit non-sRGB encoded files it is necessary to | |
* have non-gamma corrected values to do tRNS handling. | |
*/ | |
if (i != trans) | |
png_create_colormap_entry(display, i, val, val, val, 255, | |
E_FILE/*8-bit with file gamma*/); | |
/* Else this entry is transparent. The colors don't matter if | |
* there is an alpha channel (back_alpha == 0), but it does no | |
* harm to pass them in; the values are not set above so this | |
* passes in white. | |
* | |
* NOTE: this preserves the full precision of the application | |
* supplied background color when it is used. | |
*/ | |
else | |
png_create_colormap_entry(display, i, back_r, back_g, back_b, | |
back_alpha, output_encoding); | |
} | |
/* We need libpng to preserve the original encoding. */ | |
data_encoding = E_FILE; | |
/* The rows from libpng, while technically gray values, are now also | |
* color-map indicies; however, they may need to be expanded to 1 | |
* byte per pixel. This is what png_set_packing does (i.e., it | |
* unpacks the bit values into bytes.) | |
*/ | |
if (png_ptr->bit_depth < 8) | |
png_set_packing(png_ptr); | |
} | |
else /* bit depth is 16 */ | |
{ | |
/* The 16-bit input values can be converted directly to 8-bit gamma | |
* encoded values; however, if a tRNS chunk is present 257 color-map | |
* entries are required. This means that the extra entry requires | |
* special processing; add an alpha channel, sacrifice gray level | |
* 254 and convert transparent (alpha==0) entries to that. | |
* | |
* Use libpng to chop the data to 8 bits. Convert it to sRGB at the | |
* same time to minimize quality loss. If a tRNS chunk is present | |
* this means libpng must handle it too; otherwise it is impossible | |
* to do the exact match on the 16-bit value. | |
* | |
* If the output has no alpha channel *and* the background color is | |
* gray then it is possible to let libpng handle the substitution by | |
* ensuring that the corresponding gray level matches the background | |
* color exactly. | |
*/ | |
data_encoding = E_sRGB; | |
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "gray[16] color-map: too few entries"); | |
cmap_entries = make_gray_colormap(display); | |
if (png_ptr->num_trans > 0) | |
{ | |
unsigned int back_alpha; | |
if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
back_alpha = 0; | |
else | |
{ | |
if (back_r == back_g && back_g == back_b) | |
{ | |
/* Background is gray; no special processing will be | |
* required. | |
*/ | |
png_color_16 c; | |
png_uint_32 gray = back_g; | |
if (output_encoding == E_LINEAR) | |
{ | |
gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
/* And make sure the corresponding palette entry | |
* matches. | |
*/ | |
png_create_colormap_entry(display, gray, back_g, back_g, | |
back_g, 65535, E_LINEAR); | |
} | |
/* The background passed to libpng, however, must be the | |
* sRGB value. | |
*/ | |
c.index = 0; /*unused*/ | |
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
/* NOTE: does this work without expanding tRNS to alpha? | |
* It should be the color->gray case below apparently | |
* doesn't. | |
*/ | |
png_set_background_fixed(png_ptr, &c, | |
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
0/*gamma: not used*/); | |
output_processing = PNG_CMAP_NONE; | |
break; | |
} | |
back_alpha = output_encoding == E_LINEAR ? 65535 : 255; | |
} | |
/* output_processing means that the libpng-processed row will be | |
* 8-bit GA and it has to be processing to single byte color-map | |
* values. Entry 254 is replaced by either a completely | |
* transparent entry or by the background color at full | |
* precision (and the background color is not a simple gray leve | |
* in this case.) | |
*/ | |
expand_tRNS = 1; | |
output_processing = PNG_CMAP_TRANS; | |
background_index = 254; | |
/* And set (overwrite) color-map entry 254 to the actual | |
* background color at full precision. | |
*/ | |
png_create_colormap_entry(display, 254, back_r, back_g, back_b, | |
back_alpha, output_encoding); | |
} | |
else | |
output_processing = PNG_CMAP_NONE; | |
} | |
break; | |
case PNG_COLOR_TYPE_GRAY_ALPHA: | |
/* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum | |
* of 65536 combinations. If, however, the alpha channel is to be | |
* removed there are only 256 possibilities if the background is gray. | |
* (Otherwise there is a subset of the 65536 possibilities defined by | |
* the triangle between black, white and the background color.) | |
* | |
* Reduce 16-bit files to 8-bit and sRGB encode the result. No need to | |
* worry about tRNS matching - tRNS is ignored if there is an alpha | |
* channel. | |
*/ | |
data_encoding = E_sRGB; | |
if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
{ | |
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "gray+alpha color-map: too few entries"); | |
cmap_entries = make_ga_colormap(display); | |
background_index = PNG_CMAP_GA_BACKGROUND; | |
output_processing = PNG_CMAP_GA; | |
} | |
else /* alpha is removed */ | |
{ | |
/* Alpha must be removed as the PNG data is processed when the | |
* background is a color because the G and A channels are | |
* independent and the vector addition (non-parallel vectors) is a | |
* 2-D problem. | |
* | |
* This can be reduced to the same algorithm as above by making a | |
* colormap containing gray levels (for the opaque grays), a | |
* background entry (for a transparent pixel) and a set of four six | |
* level color values, one set for each intermediate alpha value. | |
* See the comments in make_ga_colormap for how this works in the | |
* per-pixel processing. | |
* | |
* If the background is gray, however, we only need a 256 entry gray | |
* level color map. It is sufficient to make the entry generated | |
* for the background color be exactly the color specified. | |
*/ | |
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || | |
(back_r == back_g && back_g == back_b)) | |
{ | |
/* Background is gray; no special processing will be required. */ | |
png_color_16 c; | |
png_uint_32 gray = back_g; | |
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "gray-alpha color-map: too few entries"); | |
cmap_entries = make_gray_colormap(display); | |
if (output_encoding == E_LINEAR) | |
{ | |
gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
/* And make sure the corresponding palette entry matches. */ | |
png_create_colormap_entry(display, gray, back_g, back_g, | |
back_g, 65535, E_LINEAR); | |
} | |
/* The background passed to libpng, however, must be the sRGB | |
* value. | |
*/ | |
c.index = 0; /*unused*/ | |
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
png_set_background_fixed(png_ptr, &c, | |
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
0/*gamma: not used*/); | |
output_processing = PNG_CMAP_NONE; | |
} | |
else | |
{ | |
png_uint_32 i, a; | |
/* This is the same as png_make_ga_colormap, above, except that | |
* the entries are all opaque. | |
*/ | |
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "ga-alpha color-map: too few entries"); | |
i = 0; | |
while (i < 231) | |
{ | |
png_uint_32 gray = (i * 256 + 115) / 231; | |
png_create_colormap_entry(display, i++, gray, gray, gray, | |
255, E_sRGB); | |
} | |
/* NOTE: this preserves the full precision of the application | |
* background color. | |
*/ | |
background_index = i; | |
png_create_colormap_entry(display, i++, back_r, back_g, back_b, | |
output_encoding == E_LINEAR ? 65535U : 255U, output_encoding); | |
/* For non-opaque input composite on the sRGB background - this | |
* requires inverting the encoding for each component. The input | |
* is still converted to the sRGB encoding because this is a | |
* reasonable approximate to the logarithmic curve of human | |
* visual sensitivity, at least over the narrow range which PNG | |
* represents. Consequently 'G' is always sRGB encoded, while | |
* 'A' is linear. We need the linear background colors. | |
*/ | |
if (output_encoding == E_sRGB) /* else already linear */ | |
{ | |
/* This may produce a value not exactly matching the | |
* background, but that's ok because these numbers are only | |
* used when alpha != 0 | |
*/ | |
back_r = png_sRGB_table[back_r]; | |
back_g = png_sRGB_table[back_g]; | |
back_b = png_sRGB_table[back_b]; | |
} | |
for (a=1; a<5; ++a) | |
{ | |
unsigned int g; | |
/* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled | |
* by an 8-bit alpha value (0..255). | |
*/ | |
png_uint_32 alpha = 51 * a; | |
png_uint_32 back_rx = (255-alpha) * back_r; | |
png_uint_32 back_gx = (255-alpha) * back_g; | |
png_uint_32 back_bx = (255-alpha) * back_b; | |
for (g=0; g<6; ++g) | |
{ | |
png_uint_32 gray = png_sRGB_table[g*51] * alpha; | |
png_create_colormap_entry(display, i++, | |
PNG_sRGB_FROM_LINEAR(gray + back_rx), | |
PNG_sRGB_FROM_LINEAR(gray + back_gx), | |
PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, E_sRGB); | |
} | |
} | |
cmap_entries = i; | |
output_processing = PNG_CMAP_GA; | |
} | |
} | |
break; | |
case PNG_COLOR_TYPE_RGB: | |
case PNG_COLOR_TYPE_RGB_ALPHA: | |
/* Exclude the case where the output is gray; we can always handle this | |
* with the cases above. | |
*/ | |
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) | |
{ | |
/* The color-map will be grayscale, so we may as well convert the | |
* input RGB values to a simple grayscale and use the grayscale | |
* code above. | |
* | |
* NOTE: calling this apparently damages the recognition of the | |
* transparent color in background color handling; call | |
* png_set_tRNS_to_alpha before png_set_background_fixed. | |
*/ | |
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, | |
-1); | |
data_encoding = E_sRGB; | |
/* The output will now be one or two 8-bit gray or gray+alpha | |
* channels. The more complex case arises when the input has alpha. | |
*/ | |
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
png_ptr->num_trans > 0) && | |
(output_format & PNG_FORMAT_FLAG_ALPHA) != 0) | |
{ | |
/* Both input and output have an alpha channel, so no background | |
* processing is required; just map the GA bytes to the right | |
* color-map entry. | |
*/ | |
expand_tRNS = 1; | |
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "rgb[ga] color-map: too few entries"); | |
cmap_entries = make_ga_colormap(display); | |
background_index = PNG_CMAP_GA_BACKGROUND; | |
output_processing = PNG_CMAP_GA; | |
} | |
else | |
{ | |
/* Either the input or the output has no alpha channel, so there | |
* will be no non-opaque pixels in the color-map; it will just be | |
* grayscale. | |
*/ | |
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "rgb[gray] color-map: too few entries"); | |
/* Ideally this code would use libpng to do the gamma correction, | |
* but if an input alpha channel is to be removed we will hit the | |
* libpng bug in gamma+compose+rgb-to-gray (the double gamma | |
* correction bug). Fix this by dropping the gamma correction in | |
* this case and doing it in the palette; this will result in | |
* duplicate palette entries, but that's better than the | |
* alternative of double gamma correction. | |
*/ | |
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
png_ptr->num_trans > 0) && | |
png_gamma_not_sRGB(png_ptr->colorspace.gamma)) | |
{ | |
cmap_entries = make_gray_file_colormap(display); | |
data_encoding = E_FILE; | |
} | |
else | |
cmap_entries = make_gray_colormap(display); | |
/* But if the input has alpha or transparency it must be removed | |
*/ | |
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
png_ptr->num_trans > 0) | |
{ | |
png_color_16 c; | |
png_uint_32 gray = back_g; | |
/* We need to ensure that the application background exists in | |
* the colormap and that completely transparent pixels map to | |
* it. Achieve this simply by ensuring that the entry | |
* selected for the background really is the background color. | |
*/ | |
if (data_encoding == E_FILE) /* from the fixup above */ | |
{ | |
/* The app supplied a gray which is in output_encoding, we | |
* need to convert it to a value of the input (E_FILE) | |
* encoding then set this palette entry to the required | |
* output encoding. | |
*/ | |
if (output_encoding == E_sRGB) | |
gray = png_sRGB_table[gray]; /* now E_LINEAR */ | |
gray = PNG_DIV257(png_gamma_16bit_correct(gray, | |
png_ptr->colorspace.gamma)); /* now E_FILE */ | |
/* And make sure the corresponding palette entry contains | |
* exactly the required sRGB value. | |
*/ | |
png_create_colormap_entry(display, gray, back_g, back_g, | |
back_g, 0/*unused*/, output_encoding); | |
} | |
else if (output_encoding == E_LINEAR) | |
{ | |
gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
/* And make sure the corresponding palette entry matches. | |
*/ | |
png_create_colormap_entry(display, gray, back_g, back_g, | |
back_g, 0/*unused*/, E_LINEAR); | |
} | |
/* The background passed to libpng, however, must be the | |
* output (normally sRGB) value. | |
*/ | |
c.index = 0; /*unused*/ | |
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
/* NOTE: the following is apparently a bug in libpng. Without | |
* it the transparent color recognition in | |
* png_set_background_fixed seems to go wrong. | |
*/ | |
expand_tRNS = 1; | |
png_set_background_fixed(png_ptr, &c, | |
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
0/*gamma: not used*/); | |
} | |
output_processing = PNG_CMAP_NONE; | |
} | |
} | |
else /* output is color */ | |
{ | |
/* We could use png_quantize here so long as there is no transparent | |
* color or alpha; png_quantize ignores alpha. Easier overall just | |
* to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. | |
* Consequently we always want libpng to produce sRGB data. | |
*/ | |
data_encoding = E_sRGB; | |
/* Is there any transparency or alpha? */ | |
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
png_ptr->num_trans > 0) | |
{ | |
/* Is there alpha in the output too? If so all four channels are | |
* processed into a special RGB cube with alpha support. | |
*/ | |
if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
{ | |
png_uint_32 r; | |
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) | |
png_error(png_ptr, "rgb+alpha color-map: too few entries"); | |
cmap_entries = make_rgb_colormap(display); | |
/* Add a transparent entry. */ | |
png_create_colormap_entry(display, cmap_entries, 255, 255, | |
255, 0, E_sRGB); | |
/* This is stored as the background index for the processing | |
* algorithm. | |
*/ | |
background_index = cmap_entries++; | |
/* Add 27 r,g,b entries each with alpha 0.5. */ | |
for (r=0; r<256; r = (r << 1) | 0x7f) | |
{ | |
png_uint_32 g; | |
for (g=0; g<256; g = (g << 1) | 0x7f) | |
{ | |
png_uint_32 b; | |
/* This generates components with the values 0, 127 and | |
* 255 | |
*/ | |
for (b=0; b<256; b = (b << 1) | 0x7f) | |
png_create_colormap_entry(display, cmap_entries++, | |
r, g, b, 128, E_sRGB); | |
} | |
} | |
expand_tRNS = 1; | |
output_processing = PNG_CMAP_RGB_ALPHA; | |
} | |
else | |
{ | |
/* Alpha/transparency must be removed. The background must | |
* exist in the color map (achieved by setting adding it after | |
* the 666 color-map). If the standard processing code will | |
* pick up this entry automatically that's all that is | |
* required; libpng can be called to do the background | |
* processing. | |
*/ | |
unsigned int sample_size = | |
PNG_IMAGE_SAMPLE_SIZE(output_format); | |
png_uint_32 r, g, b; /* sRGB background */ | |
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) | |
png_error(png_ptr, "rgb-alpha color-map: too few entries"); | |
cmap_entries = make_rgb_colormap(display); | |
png_create_colormap_entry(display, cmap_entries, back_r, | |
back_g, back_b, 0/*unused*/, output_encoding); | |
if (output_encoding == E_LINEAR) | |
{ | |
r = PNG_sRGB_FROM_LINEAR(back_r * 255); | |
g = PNG_sRGB_FROM_LINEAR(back_g * 255); | |
b = PNG_sRGB_FROM_LINEAR(back_b * 255); | |
} | |
else | |
{ | |
r = back_r; | |
g = back_g; | |
b = back_g; | |
} | |
/* Compare the newly-created color-map entry with the one the | |
* PNG_CMAP_RGB algorithm will use. If the two entries don't | |
* match, add the new one and set this as the background | |
* index. | |
*/ | |
if (memcmp((png_const_bytep)display->colormap + | |
sample_size * cmap_entries, | |
(png_const_bytep)display->colormap + | |
sample_size * PNG_RGB_INDEX(r,g,b), | |
sample_size) != 0) | |
{ | |
/* The background color must be added. */ | |
background_index = cmap_entries++; | |
/* Add 27 r,g,b entries each with created by composing with | |
* the background at alpha 0.5. | |
*/ | |
for (r=0; r<256; r = (r << 1) | 0x7f) | |
{ | |
for (g=0; g<256; g = (g << 1) | 0x7f) | |
{ | |
/* This generates components with the values 0, 127 | |
* and 255 | |
*/ | |
for (b=0; b<256; b = (b << 1) | 0x7f) | |
png_create_colormap_entry(display, cmap_entries++, | |
png_colormap_compose(display, r, E_sRGB, 128, | |
back_r, output_encoding), | |
png_colormap_compose(display, g, E_sRGB, 128, | |
back_g, output_encoding), | |
png_colormap_compose(display, b, E_sRGB, 128, | |
back_b, output_encoding), | |
0/*unused*/, output_encoding); | |
} | |
} | |
expand_tRNS = 1; | |
output_processing = PNG_CMAP_RGB_ALPHA; | |
} | |
else /* background color is in the standard color-map */ | |
{ | |
png_color_16 c; | |
c.index = 0; /*unused*/ | |
c.red = (png_uint_16)back_r; | |
c.gray = c.green = (png_uint_16)back_g; | |
c.blue = (png_uint_16)back_b; | |
png_set_background_fixed(png_ptr, &c, | |
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
0/*gamma: not used*/); | |
output_processing = PNG_CMAP_RGB; | |
} | |
} | |
} | |
else /* no alpha or transparency in the input */ | |
{ | |
/* Alpha in the output is irrelevant, simply map the opaque input | |
* pixels to the 6x6x6 color-map. | |
*/ | |
if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) | |
png_error(png_ptr, "rgb color-map: too few entries"); | |
cmap_entries = make_rgb_colormap(display); | |
output_processing = PNG_CMAP_RGB; | |
} | |
} | |
break; | |
case PNG_COLOR_TYPE_PALETTE: | |
/* It's already got a color-map. It may be necessary to eliminate the | |
* tRNS entries though. | |
*/ | |
{ | |
unsigned int num_trans = png_ptr->num_trans; | |
png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; | |
png_const_colorp colormap = png_ptr->palette; | |
const int do_background = trans != NULL && | |
(output_format & PNG_FORMAT_FLAG_ALPHA) == 0; | |
unsigned int i; | |
/* Just in case: */ | |
if (trans == NULL) | |
num_trans = 0; | |
output_processing = PNG_CMAP_NONE; | |
data_encoding = E_FILE; /* Don't change from color-map indicies */ | |
cmap_entries = png_ptr->num_palette; | |
if (cmap_entries > 256) | |
cmap_entries = 256; | |
if (cmap_entries > image->colormap_entries) | |
png_error(png_ptr, "palette color-map: too few entries"); | |
for (i=0; i < cmap_entries; ++i) | |
{ | |
if (do_background && i < num_trans && trans[i] < 255) | |
{ | |
if (trans[i] == 0) | |
png_create_colormap_entry(display, i, back_r, back_g, | |
back_b, 0, output_encoding); | |
else | |
{ | |
/* Must compose the PNG file color in the color-map entry | |
* on the sRGB color in 'back'. | |
*/ | |
png_create_colormap_entry(display, i, | |
png_colormap_compose(display, colormap[i].red, E_FILE, | |
trans[i], back_r, output_encoding), | |
png_colormap_compose(display, colormap[i].green, E_FILE, | |
trans[i], back_g, output_encoding), | |
png_colormap_compose(display, colormap[i].blue, E_FILE, | |
trans[i], back_b, output_encoding), | |
output_encoding == E_LINEAR ? trans[i] * 257U : | |
trans[i], | |
output_encoding); | |
} | |
} | |
else | |
png_create_colormap_entry(display, i, colormap[i].red, | |
colormap[i].green, colormap[i].blue, | |
i < num_trans ? trans[i] : 255U, E_FILE/*8-bit*/); | |
} | |
/* The PNG data may have indicies packed in fewer than 8 bits, it | |
* must be expanded if so. | |
*/ | |
if (png_ptr->bit_depth < 8) | |
png_set_packing(png_ptr); | |
} | |
break; | |
default: | |
png_error(png_ptr, "invalid PNG color type"); | |
/*NOT REACHED*/ | |
break; | |
} | |
/* Now deal with the output processing */ | |
if (expand_tRNS && png_ptr->num_trans > 0 && | |
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) | |
png_set_tRNS_to_alpha(png_ptr); | |
switch (data_encoding) | |
{ | |
default: | |
png_error(png_ptr, "bad data option (internal error)"); | |
break; | |
case E_sRGB: | |
/* Change to 8-bit sRGB */ | |
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); | |
/* FALL THROUGH */ | |
case E_FILE: | |
if (png_ptr->bit_depth > 8) | |
png_set_scale_16(png_ptr); | |
break; | |
} | |
if (cmap_entries > 256 || cmap_entries > image->colormap_entries) | |
png_error(png_ptr, "color map overflow (BAD internal error)"); | |
image->colormap_entries = cmap_entries; | |
/* Double check using the recorded background index */ | |
switch (output_processing) | |
{ | |
case PNG_CMAP_NONE: | |
if (background_index != PNG_CMAP_NONE_BACKGROUND) | |
goto bad_background; | |
break; | |
case PNG_CMAP_GA: | |
if (background_index != PNG_CMAP_GA_BACKGROUND) | |
goto bad_background; | |
break; | |
case PNG_CMAP_TRANS: | |
if (background_index >= cmap_entries || | |
background_index != PNG_CMAP_TRANS_BACKGROUND) | |
goto bad_background; | |
break; | |
case PNG_CMAP_RGB: | |
if (background_index != PNG_CMAP_RGB_BACKGROUND) | |
goto bad_background; | |
break; | |
case PNG_CMAP_RGB_ALPHA: | |
if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) | |
goto bad_background; | |
break; | |
default: | |
png_error(png_ptr, "bad processing option (internal error)"); | |
bad_background: | |
png_error(png_ptr, "bad background index (internal error)"); | |
} | |
display->colormap_processing = output_processing; | |
return 1/*ok*/; | |
} | |
/* The final part of the color-map read called from png_image_finish_read. */ | |
static int | |
png_image_read_and_map(png_voidp argument) | |
{ | |
png_image_read_control *display = png_voidcast(png_image_read_control*, | |
argument); | |
png_imagep image = display->image; | |
png_structrp png_ptr = image->opaque->png_ptr; | |
int passes; | |
/* Called when the libpng data must be transformed into the color-mapped | |
* form. There is a local row buffer in display->local and this routine must | |
* do the interlace handling. | |
*/ | |
switch (png_ptr->interlaced) | |
{ | |
case PNG_INTERLACE_NONE: | |
passes = 1; | |
break; | |
case PNG_INTERLACE_ADAM7: | |
passes = PNG_INTERLACE_ADAM7_PASSES; | |
break; | |
default: | |
passes = 0; | |
png_error(png_ptr, "unknown interlace type"); | |
} | |
{ | |
png_uint_32 height = image->height; | |
png_uint_32 width = image->width; | |
int proc = display->colormap_processing; | |
png_bytep first_row = png_voidcast(png_bytep, display->first_row); | |
ptrdiff_t step_row = display->row_bytes; | |
int pass; | |
for (pass = 0; pass < passes; ++pass) | |
{ | |
unsigned int startx, stepx, stepy; | |
png_uint_32 y; | |
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
{ | |
/* The row may be empty for a short image: */ | |
if (PNG_PASS_COLS(width, pass) == 0) | |
continue; | |
startx = PNG_PASS_START_COL(pass); | |
stepx = PNG_PASS_COL_OFFSET(pass); | |
y = PNG_PASS_START_ROW(pass); | |
stepy = PNG_PASS_ROW_OFFSET(pass); | |
} | |
else | |
{ | |
y = 0; | |
startx = 0; | |
stepx = stepy = 1; | |
} | |
for (; y<height; y += stepy) | |
{ | |
png_bytep inrow = png_voidcast(png_bytep, display->local_row); | |
png_bytep outrow = first_row + y * step_row; | |
png_const_bytep end_row = outrow + width; | |
/* Read read the libpng data into the temporary buffer. */ | |
png_read_row(png_ptr, inrow, NULL); | |
/* Now process the row according to the processing option, note | |
* that the caller verifies that the format of the libpng output | |
* data is as required. | |
*/ | |
outrow += startx; | |
switch (proc) | |
{ | |
case PNG_CMAP_GA: | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
/* The data is always in the PNG order */ | |
unsigned int gray = *inrow++; | |
unsigned int alpha = *inrow++; | |
unsigned int entry; | |
/* NOTE: this code is copied as a comment in | |
* make_ga_colormap above. Please update the | |
* comment if you change this code! | |
*/ | |
if (alpha > 229) /* opaque */ | |
{ | |
entry = (231 * gray + 128) >> 8; | |
} | |
else if (alpha < 26) /* transparent */ | |
{ | |
entry = 231; | |
} | |
else /* partially opaque */ | |
{ | |
entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); | |
} | |
*outrow = (png_byte)entry; | |
} | |
break; | |
case PNG_CMAP_TRANS: | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
png_byte gray = *inrow++; | |
png_byte alpha = *inrow++; | |
if (alpha == 0) | |
*outrow = PNG_CMAP_TRANS_BACKGROUND; | |
else if (gray != PNG_CMAP_TRANS_BACKGROUND) | |
*outrow = gray; | |
else | |
*outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); | |
} | |
break; | |
case PNG_CMAP_RGB: | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); | |
inrow += 3; | |
} | |
break; | |
case PNG_CMAP_RGB_ALPHA: | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
unsigned int alpha = inrow[3]; | |
/* Because the alpha entries only hold alpha==0.5 values | |
* split the processing at alpha==0.25 (64) and 0.75 | |
* (196). | |
*/ | |
if (alpha >= 196) | |
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1], | |
inrow[2]); | |
else if (alpha < 64) | |
*outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; | |
else | |
{ | |
/* Likewise there are three entries for each of r, g | |
* and b. We could select the entry by popcount on | |
* the top two bits on those architectures that | |
* support it, this is what the code below does, | |
* crudely. | |
*/ | |
unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; | |
/* Here are how the values map: | |
* | |
* 0x00 .. 0x3f -> 0 | |
* 0x40 .. 0xbf -> 1 | |
* 0xc0 .. 0xff -> 2 | |
* | |
* So, as above with the explicit alpha checks, the | |
* breakpoints are at 64 and 196. | |
*/ | |
if (inrow[0] & 0x80) back_i += 9; /* red */ | |
if (inrow[0] & 0x40) back_i += 9; | |
if (inrow[0] & 0x80) back_i += 3; /* green */ | |
if (inrow[0] & 0x40) back_i += 3; | |
if (inrow[0] & 0x80) back_i += 1; /* blue */ | |
if (inrow[0] & 0x40) back_i += 1; | |
*outrow = (png_byte)back_i; | |
} | |
inrow += 4; | |
} | |
break; | |
default: | |
break; | |
} | |
} | |
} | |
} | |
return 1; | |
} | |
static int | |
png_image_read_colormapped(png_voidp argument) | |
{ | |
png_image_read_control *display = png_voidcast(png_image_read_control*, | |
argument); | |
png_imagep image = display->image; | |
png_controlp control = image->opaque; | |
png_structrp png_ptr = control->png_ptr; | |
png_inforp info_ptr = control->info_ptr; | |
int passes = 0; /* As a flag */ | |
PNG_SKIP_CHUNKS(png_ptr); | |
/* Update the 'info' structure and make sure the result is as required; first | |
* make sure to turn on the interlace handling if it will be required | |
* (because it can't be turned on *after* the call to png_read_update_info!) | |
*/ | |
if (display->colormap_processing == PNG_CMAP_NONE) | |
passes = png_set_interlace_handling(png_ptr); | |
png_read_update_info(png_ptr, info_ptr); | |
/* The expected output can be deduced from the colormap_processing option. */ | |
switch (display->colormap_processing) | |
{ | |
case PNG_CMAP_NONE: | |
/* Output must be one channel and one byte per pixel, the output | |
* encoding can be anything. | |
*/ | |
if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || | |
info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && | |
info_ptr->bit_depth == 8) | |
break; | |
goto bad_output; | |
case PNG_CMAP_TRANS: | |
case PNG_CMAP_GA: | |
/* Output must be two channels and the 'G' one must be sRGB, the latter | |
* can be checked with an exact number because it should have been set | |
* to this number above! | |
*/ | |
if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && | |
info_ptr->bit_depth == 8 && | |
png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
image->colormap_entries == 256) | |
break; | |
goto bad_output; | |
case PNG_CMAP_RGB: | |
/* Output must be 8-bit sRGB encoded RGB */ | |
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && | |
info_ptr->bit_depth == 8 && | |
png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
image->colormap_entries == 216) | |
break; | |
goto bad_output; | |
case PNG_CMAP_RGB_ALPHA: | |
/* Output must be 8-bit sRGB encoded RGBA */ | |
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && | |
info_ptr->bit_depth == 8 && | |
png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
image->colormap_entries == 244 /* 216 + 1 + 27 */) | |
break; | |
/* goto bad_output; */ | |
/* FALL THROUGH */ | |
default: | |
bad_output: | |
png_error(png_ptr, "bad color-map processing (internal error)"); | |
} | |
/* Now read the rows. Do this here if it is possible to read directly into | |
* the output buffer, otherwise allocate a local row buffer of the maximum | |
* size libpng requires and call the relevant processing routine safely. | |
*/ | |
{ | |
png_voidp first_row = display->buffer; | |
ptrdiff_t row_bytes = display->row_stride; | |
/* The following expression is designed to work correctly whether it gives | |
* a signed or an unsigned result. | |
*/ | |
if (row_bytes < 0) | |
{ | |
char *ptr = png_voidcast(char*, first_row); | |
ptr += (image->height-1) * (-row_bytes); | |
first_row = png_voidcast(png_voidp, ptr); | |
} | |
display->first_row = first_row; | |
display->row_bytes = row_bytes; | |
} | |
if (passes == 0) | |
{ | |
int result; | |
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
display->local_row = row; | |
result = png_safe_execute(image, png_image_read_and_map, display); | |
display->local_row = NULL; | |
png_free(png_ptr, row); | |
return result; | |
} | |
else | |
{ | |
png_alloc_size_t row_bytes = display->row_bytes; | |
while (--passes >= 0) | |
{ | |
png_uint_32 y = image->height; | |
png_bytep row = png_voidcast(png_bytep, display->first_row); | |
while (y-- > 0) | |
{ | |
png_read_row(png_ptr, row, NULL); | |
row += row_bytes; | |
} | |
} | |
return 1; | |
} | |
} | |
/* Just the row reading part of png_image_read. */ | |
static int | |
png_image_read_composite(png_voidp argument) | |
{ | |
png_image_read_control *display = png_voidcast(png_image_read_control*, | |
argument); | |
png_imagep image = display->image; | |
png_structrp png_ptr = image->opaque->png_ptr; | |
int passes; | |
switch (png_ptr->interlaced) | |
{ | |
case PNG_INTERLACE_NONE: | |
passes = 1; | |
break; | |
case PNG_INTERLACE_ADAM7: | |
passes = PNG_INTERLACE_ADAM7_PASSES; | |
break; | |
default: | |
passes = 0; | |
png_error(png_ptr, "unknown interlace type"); | |
} | |
{ | |
png_uint_32 height = image->height; | |
png_uint_32 width = image->width; | |
ptrdiff_t step_row = display->row_bytes; | |
unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1; | |
int pass; | |
for (pass = 0; pass < passes; ++pass) | |
{ | |
unsigned int startx, stepx, stepy; | |
png_uint_32 y; | |
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
{ | |
/* The row may be empty for a short image: */ | |
if (PNG_PASS_COLS(width, pass) == 0) | |
continue; | |
startx = PNG_PASS_START_COL(pass) * channels; | |
stepx = PNG_PASS_COL_OFFSET(pass) * channels; | |
y = PNG_PASS_START_ROW(pass); | |
stepy = PNG_PASS_ROW_OFFSET(pass); | |
} | |
else | |
{ | |
y = 0; | |
startx = 0; | |
stepx = channels; | |
stepy = 1; | |
} | |
for (; y<height; y += stepy) | |
{ | |
png_bytep inrow = png_voidcast(png_bytep, display->local_row); | |
png_bytep outrow; | |
png_const_bytep end_row; | |
/* Read the row, which is packed: */ | |
png_read_row(png_ptr, inrow, NULL); | |
outrow = png_voidcast(png_bytep, display->first_row); | |
outrow += y * step_row; | |
end_row = outrow + width * channels; | |
/* Now do the composition on each pixel in this row. */ | |
outrow += startx; | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
png_byte alpha = inrow[channels]; | |
if (alpha > 0) /* else no change to the output */ | |
{ | |
unsigned int c; | |
for (c=0; c<channels; ++c) | |
{ | |
png_uint_32 component = inrow[c]; | |
if (alpha < 255) /* else just use component */ | |
{ | |
/* This is PNG_OPTIMIZED_ALPHA, the component value | |
* is a linear 8-bit value. Combine this with the | |
* current outrow[c] value which is sRGB encoded. | |
* Arithmetic here is 16-bits to preserve the output | |
* values correctly. | |
*/ | |
component *= 257*255; /* =65535 */ | |
component += (255-alpha)*png_sRGB_table[outrow[c]]; | |
/* So 'component' is scaled by 255*65535 and is | |
* therefore appropriate for the sRGB to linear | |
* conversion table. | |
*/ | |
component = PNG_sRGB_FROM_LINEAR(component); | |
} | |
outrow[c] = (png_byte)component; | |
} | |
} | |
inrow += channels+1; /* components and alpha channel */ | |
} | |
} | |
} | |
} | |
return 1; | |
} | |
/* The do_local_background case; called when all the following transforms are to | |
* be done: | |
* | |
* PNG_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_structrp png_ptr = image->opaque->png_ptr; | |
png_inforp info_ptr = image->opaque->info_ptr; | |
png_uint_32 height = image->height; | |
png_uint_32 width = image->width; | |
int pass, passes; | |
/* Double check the convoluted logic below. We expect to get here with | |
* libpng doing rgb to gray and gamma correction but background processing | |
* left to the png_image_read_background function. The rows libpng produce | |
* might be 8 or 16-bit but should always have two channels; gray plus alpha. | |
*/ | |
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"); | |
if (png_get_channels(png_ptr, info_ptr) != 2) | |
png_error(png_ptr, "lost/gained channels"); | |
/* Expect the 8-bit case to always remove the alpha channel */ | |
if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && | |
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0) | |
png_error(png_ptr, "unexpected 8-bit transformation"); | |
switch (png_ptr->interlaced) | |
{ | |
case PNG_INTERLACE_NONE: | |
passes = 1; | |
break; | |
case PNG_INTERLACE_ADAM7: | |
passes = PNG_INTERLACE_ADAM7_PASSES; | |
break; | |
default: | |
passes = 0; | |
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. | |
*/ | |
{ | |
png_bytep first_row = png_voidcast(png_bytep, display->first_row); | |
ptrdiff_t step_row = display->row_bytes; | |
for (pass = 0; pass < passes; ++pass) | |
{ | |
png_bytep row = png_voidcast(png_bytep, | |
display->first_row); | |
unsigned int startx, stepx, stepy; | |
png_uint_32 y; | |
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
{ | |
/* The row may be empty for a short image: */ | |
if (PNG_PASS_COLS(width, pass) == 0) | |
continue; | |
startx = PNG_PASS_START_COL(pass); | |
stepx = PNG_PASS_COL_OFFSET(pass); | |
y = PNG_PASS_START_ROW(pass); | |
stepy = PNG_PASS_ROW_OFFSET(pass); | |
} | |
else | |
{ | |
y = 0; | |
startx = 0; | |
stepx = stepy = 1; | |
} | |
if (display->background == NULL) | |
{ | |
for (; y<height; y += stepy) | |
{ | |
png_bytep inrow = png_voidcast(png_bytep, | |
display->local_row); | |
png_bytep outrow = first_row + y * step_row; | |
png_const_bytep end_row = outrow + width; | |
/* Read the row, which is packed: */ | |
png_read_row(png_ptr, inrow, NULL); | |
/* Now do the composition on each pixel in this row. */ | |
outrow += startx; | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
png_byte alpha = inrow[1]; | |
if (alpha > 0) /* else no change to the output */ | |
{ | |
png_uint_32 component = inrow[0]; | |
if (alpha < 255) /* else just use component */ | |
{ | |
/* Since PNG_OPTIMIZED_ALPHA was not set it is | |
* necessary to invert the sRGB transfer | |
* function and multiply the alpha out. | |
*/ | |
component = png_sRGB_table[component] * alpha; | |
component += png_sRGB_table[outrow[0]] * | |
(255-alpha); | |
component = PNG_sRGB_FROM_LINEAR(component); | |
} | |
outrow[0] = (png_byte)component; | |
} | |
inrow += 2; /* gray and alpha channel */ | |
} | |
} | |
} | |
else /* constant background value */ | |
{ | |
png_byte background8 = display->background->green; | |
png_uint_16 background = png_sRGB_table[background8]; | |
for (; y<height; y += stepy) | |
{ | |
png_bytep inrow = png_voidcast(png_bytep, | |
display->local_row); | |
png_bytep outrow = first_row + y * step_row; | |
png_const_bytep end_row = outrow + width; | |
/* Read the row, which is packed: */ | |
png_read_row(png_ptr, inrow, NULL); | |
/* Now do the composition on each pixel in this row. */ | |
outrow += startx; | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
png_byte alpha = inrow[1]; | |
if (alpha > 0) /* else use background */ | |
{ | |
png_uint_32 component = inrow[0]; | |
if (alpha < 255) /* else just use component */ | |
{ | |
component = png_sRGB_table[component] * alpha; | |
component += background * (255-alpha); | |
component = PNG_sRGB_FROM_LINEAR(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. | |
*/ | |
{ | |
png_uint_16p first_row = png_voidcast(png_uint_16p, | |
display->first_row); | |
/* The division by two is safe because the caller passed in a | |
* stride which was multiplied by 2 (below) to get row_bytes. | |
*/ | |
ptrdiff_t step_row = display->row_bytes / 2; | |
int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; | |
unsigned int outchannels = 1+preserve_alpha; | |
int swap_alpha = 0; | |
if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST)) | |
swap_alpha = 1; | |
for (pass = 0; pass < passes; ++pass) | |
{ | |
unsigned int startx, stepx, stepy; | |
png_uint_32 y; | |
/* The 'x' start and step are adjusted to output components here. | |
*/ | |
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
{ | |
/* The row may be empty for a short image: */ | |
if (PNG_PASS_COLS(width, pass) == 0) | |
continue; | |
startx = PNG_PASS_START_COL(pass) * outchannels; | |
stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; | |
y = PNG_PASS_START_ROW(pass); | |
stepy = PNG_PASS_ROW_OFFSET(pass); | |
} | |
else | |
{ | |
y = 0; | |
startx = 0; | |
stepx = outchannels; | |
stepy = 1; | |
} | |
for (; y<height; y += stepy) | |
{ | |
png_const_uint_16p inrow; | |
png_uint_16p outrow = first_row + y*step_row; | |
png_uint_16p end_row = outrow + width * outchannels; | |
/* Read the row, which is packed: */ | |
png_read_row(png_ptr, png_voidcast(png_bytep, | |
display->local_row), NULL); | |
inrow = png_voidcast(png_const_uint_16p, display->local_row); | |
/* Now do the pre-multiplication on each pixel in this row. | |
*/ | |
outrow += startx; | |
for (; outrow < end_row; outrow += stepx) | |
{ | |
png_uint_32 component = inrow[0]; | |
png_uint_16 alpha = inrow[1]; | |
if (alpha > 0) /* else 0 */ | |
{ | |
if (alpha < 65535) /* else just use component */ | |
{ | |
component *= alpha; | |
component += 32767; | |
component /= 65535; | |
} | |
} | |
else | |
component = 0; | |
outrow[swap_alpha] = (png_uint_16)component; | |
if (preserve_alpha) | |
outrow[1 ^ swap_alpha] = alpha; | |
inrow += 2; /* components and alpha channel */ | |
} | |
} | |
} | |
} | |
break; | |
} | |
return 1; | |
} | |
/* The guts of png_image_finish_read as a png_safe_execute callback. */ | |
static int | |
png_image_read_direct(png_voidp argument) | |
{ | |
png_image_read_control *display = png_voidcast(png_image_read_control*, | |
argument); | |
png_imagep image = display->image; | |
png_structrp png_ptr = image->opaque->png_ptr; | |
png_inforp info_ptr = image->opaque->info_ptr; | |
png_uint_32 format = image->format; | |
int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; | |
int do_local_compose = 0; | |
int do_local_background = 0; /* to avoid double gamma correction bug */ | |
int passes = 0; | |
/* Add transforms to ensure the correct output format is produced then check | |
* that the required implementation support is there. Always expand; always | |
* need 8 bits minimum, no palette and expanded tRNS. | |
*/ | |
png_set_expand(png_ptr); | |
/* Now check the format to see if it was modified. */ | |
{ | |
png_uint_32 base_format = png_image_format(png_ptr) & | |
~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; | |
png_uint_32 change = format ^ base_format; | |
png_fixed_point output_gamma; | |
int mode; /* alpha mode */ | |
/* Do this first so that we have a record if rgb to gray is happening. */ | |
if (change & PNG_FORMAT_FLAG_COLOR) | |
{ | |
/* 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) && | |
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) | |
input_gamma_default = PNG_GAMMA_LINEAR; | |
else | |
input_gamma_default = PNG_DEFAULT_sRGB; | |
/* Call png_set_alpha_mode to set the default for the input gamma; the | |
* output gamma is set by a second call below. | |
*/ | |
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); | |
} | |
if (linear) | |
{ | |
/* 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(>est, output_gamma, png_ptr->colorspace.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"); | |
} | |
PNG_SKIP_CHUNKS(png_ptr); | |
/* Update the 'info' structure and make sure the result is as required; first | |
* make sure to turn on the interlace handling if it will be required | |
* (because it can't be turned on *after* the call to png_read_update_info!) | |
* | |
* TODO: remove the do_local_background fixup below. | |
*/ | |
if (!do_local_compose && 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 (do_local_background == 2) | |
{ | |
if (format & PNG_FORMAT_FLAG_AFIRST) | |
info_format |= PNG_FORMAT_FLAG_AFIRST; | |
} | |
if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || | |
((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && | |
(png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) | |
{ | |
if (do_local_background == 2) | |
png_error(png_ptr, "unexpected alpha swap transformation"); | |
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_voidp first_row = display->buffer; | |
ptrdiff_t row_bytes = display->row_stride; | |
if (linear) | |
row_bytes *= 2; | |
/* The following expression is designed to work correctly whether it gives | |
* a signed or an unsigned result. | |
*/ | |
if (row_bytes < 0) | |
{ | |
char *ptr = png_voidcast(char*, first_row); | |
ptr += (image->height-1) * (-row_bytes); | |
first_row = png_voidcast(png_voidp, ptr); | |
} | |
display->first_row = first_row; | |
display->row_bytes = row_bytes; | |
} | |
if (do_local_compose) | |
{ | |
int result; | |
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
display->local_row = row; | |
result = png_safe_execute(image, png_image_read_composite, display); | |
display->local_row = NULL; | |
png_free(png_ptr, row); | |
return result; | |
} | |
else if (do_local_background == 2) | |
{ | |
int result; | |
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
display->local_row = row; | |
result = png_safe_execute(image, png_image_read_background, display); | |
display->local_row = NULL; | |
png_free(png_ptr, row); | |
return result; | |
} | |
else | |
{ | |
png_alloc_size_t row_bytes = display->row_bytes; | |
while (--passes >= 0) | |
{ | |
png_uint_32 y = image->height; | |
png_bytep row = png_voidcast(png_bytep, display->first_row); | |
while (y-- > 0) | |
{ | |
png_read_row(png_ptr, row, NULL); | |
row += row_bytes; | |
} | |
} | |
return 1; | |
} | |
} | |
int PNGAPI | |
png_image_finish_read(png_imagep image, png_const_colorp background, | |
void *buffer, png_int_32 row_stride, void *colormap) | |
{ | |
if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
{ | |
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 (image->opaque != NULL && buffer != NULL && | |
check >= PNG_IMAGE_ROW_STRIDE(*image)) | |
{ | |
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || | |
(image->colormap_entries > 0 && colormap != NULL)) | |
{ | |
int result; | |
png_image_read_control display; | |
memset(&display, 0, (sizeof display)); | |
display.image = image; | |
display.buffer = buffer; | |
display.row_stride = row_stride; | |
display.colormap = colormap; | |
display.background = background; | |
display.local_row = NULL; | |
/* Choose the correct 'end' routine; for the color-map case all the | |
* setup has already been done. | |
*/ | |
if (image->format & PNG_FORMAT_FLAG_COLORMAP) | |
result = | |
png_safe_execute(image, png_image_read_colormap, &display) && | |
png_safe_execute(image, png_image_read_colormapped, &display); | |
else | |
result = | |
png_safe_execute(image, png_image_read_direct, &display); | |
png_image_free(image); | |
return result; | |
} | |
else | |
return png_image_error(image, | |
"png_image_finish_read[color-map]: no color-map"); | |
} | |
else | |
return png_image_error(image, | |
"png_image_finish_read: invalid argument"); | |
} | |
else if (image != NULL) | |
return png_image_error(image, | |
"png_image_finish_read: damaged PNG_IMAGE_VERSION"); | |
return 0; | |
} | |
#endif /* PNG_SIMPLIFIED_READ_SUPPORTED */ | |
#endif /* PNG_READ_SUPPORTED */ |