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authorJörg Frings-Fürst <debian@jff-webhosting.net>2015-08-23 12:17:05 +0200
committerJörg Frings-Fürst <debian@jff-webhosting.net>2015-08-23 12:17:05 +0200
commitc0b89ac5bfb90835ef01573267020e42d4fe070c (patch)
tree733c16852d964d84b7565af4bdaff0bcca901b88 /png/pngread.c
parent094535c010320967639e8e86f974d878e80baa72 (diff)
Imported Upstream version 1.8.0upstream/1.8.0
Diffstat (limited to 'png/pngread.c')
-rw-r--r--png/pngread.c4098
1 files changed, 0 insertions, 4098 deletions
diff --git a/png/pngread.c b/png/pngread.c
deleted file mode 100644
index 4bf2021..0000000
--- a/png/pngread.c
+++ /dev/null
@@ -1,4098 +0,0 @@
-
-/* pngread.c - read a PNG file
- *
- * Last changed in libpng 1.6.11 [June 12, 2014]
- * Copyright (c) 1998-2014 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
-#ifdef PNG_MNG_FEATURES_SUPPORTED
-/* Undoes intrapixel differencing,
- * NOTE: this is apparently only supported in the 'sequential' reader.
- */
-static void
-png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
-{
- png_debug(1, "in png_do_read_intrapixel");
-
- if (
- (row_info->color_type & PNG_COLOR_MASK_COLOR))
- {
- int bytes_per_pixel;
- png_uint_32 row_width = row_info->width;
-
- if (row_info->bit_depth == 8)
- {
- png_bytep rp;
- png_uint_32 i;
-
- if (row_info->color_type == PNG_COLOR_TYPE_RGB)
- bytes_per_pixel = 3;
-
- else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- bytes_per_pixel = 4;
-
- else
- return;
-
- for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
- {
- *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
- *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
- }
- }
- else if (row_info->bit_depth == 16)
- {
- png_bytep rp;
- png_uint_32 i;
-
- if (row_info->color_type == PNG_COLOR_TYPE_RGB)
- bytes_per_pixel = 6;
-
- else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- bytes_per_pixel = 8;
-
- else
- return;
-
- for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
- {
- png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
- png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
- png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
- png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
- png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
- *(rp ) = (png_byte)((red >> 8) & 0xff);
- *(rp + 1) = (png_byte)(red & 0xff);
- *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
- *(rp + 5) = (png_byte)(blue & 0xff);
- }
- }
- }
-}
-#endif /* PNG_MNG_FEATURES_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
- /* Expand 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_IEND)
- png_handle_IEND(png_ptr, info_ptr, length);
-
- else if (chunk_name == png_IHDR)
- png_handle_IHDR(png_ptr, info_ptr, length);
-
- else if (info_ptr == NULL)
- png_crc_finish(png_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)
-{
- 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 ------------------- */
- /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
- * is not implemented. This will only happen in de-configured (non-default)
- * libpng builds. The results can be unexpected - png_read_png may return
- * short or mal-formed rows because the transform is skipped.
- */
-
- /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
- */
- if (transforms & PNG_TRANSFORM_SCALE_16)
- /* Added at libpng-1.5.4. "strip_16" produces the same result that it
- * did in earlier versions, while "scale_16" is now more accurate.
- */
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
- png_set_scale_16(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
-#endif
-
- /* If both SCALE and STRIP are required pngrtran will effectively cancel the
- * latter by doing SCALE first. This is ok and allows apps not to check for
- * which is supported to get the right answer.
- */
- if (transforms & PNG_TRANSFORM_STRIP_16)
-#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
- png_set_strip_16(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
-#endif
-
- /* Strip alpha bytes from the input data without combining with
- * the background (not recommended).
- */
- if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
-#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
- png_set_strip_alpha(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
-#endif
-
- /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
- * byte into separate bytes (useful for paletted and grayscale images).
- */
- if (transforms & PNG_TRANSFORM_PACKING)
-#ifdef PNG_READ_PACK_SUPPORTED
- png_set_packing(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
-#endif
-
- /* Change the order of packed pixels to least significant bit first
- * (not useful if you are using png_set_packing).
- */
- if (transforms & PNG_TRANSFORM_PACKSWAP)
-#ifdef PNG_READ_PACKSWAP_SUPPORTED
- png_set_packswap(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
-#endif
-
- /* Expand paletted colors into true RGB triplets
- * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
- * Expand paletted or RGB images with transparency to full alpha
- * channels so the data will be available as RGBA quartets.
- */
- if (transforms & PNG_TRANSFORM_EXPAND)
-#ifdef PNG_READ_EXPAND_SUPPORTED
- png_set_expand(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
-#endif
-
- /* We don't handle background color or gamma transformation or quantizing.
- */
-
- /* Invert monochrome files to have 0 as white and 1 as black
- */
- if (transforms & PNG_TRANSFORM_INVERT_MONO)
-#ifdef PNG_READ_INVERT_SUPPORTED
- png_set_invert_mono(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
-#endif
-
- /* If you want to shift the pixel values from the range [0,255] or
- * [0,65535] to the original [0,7] or [0,31], or whatever range the
- * colors were originally in:
- */
- if (transforms & PNG_TRANSFORM_SHIFT)
-#ifdef PNG_READ_SHIFT_SUPPORTED
- if (info_ptr->valid & PNG_INFO_sBIT)
- png_set_shift(png_ptr, &info_ptr->sig_bit);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
-#endif
-
- /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
- if (transforms & PNG_TRANSFORM_BGR)
-#ifdef PNG_READ_BGR_SUPPORTED
- png_set_bgr(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
-#endif
-
- /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
- if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
-#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
- png_set_swap_alpha(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
-#endif
-
- /* Swap bytes of 16-bit files to least significant byte first */
- if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
-#ifdef PNG_READ_SWAP_SUPPORTED
- png_set_swap(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
-#endif
-
-/* Added at libpng-1.2.41 */
- /* Invert the alpha channel from opacity to transparency */
- if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
-#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
- png_set_invert_alpha(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
-#endif
-
-/* Added at libpng-1.2.41 */
- /* Expand grayscale image to RGB */
- if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
- png_set_gray_to_rgb(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
-#endif
-
-/* Added at libpng-1.5.4 */
- if (transforms & PNG_TRANSFORM_EXPAND_16)
-#ifdef PNG_READ_EXPAND_16_SUPPORTED
- png_set_expand_16(png_ptr);
-#else
- png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
-#endif
-
- /* We don't handle adding filler bytes */
-
- /* We use png_read_image and rely on that for interlace handling, but we also
- * call png_read_update_info therefore must turn on interlace handling now:
- */
- (void)png_set_interlace_handling(png_ptr);
-
- /* Optional call to gamma correct and add the background to the palette
- * and update info structure. REQUIRED if you are expecting libpng to
- * update the palette for you (i.e., you selected such a transform above).
- */
- png_read_update_info(png_ptr, info_ptr);
-
- /* -------------- image transformations end here ------------------- */
-
- png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
- if (info_ptr->row_pointers == NULL)
- {
- png_uint_32 iptr;
-
- info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
- info_ptr->height * (sizeof (png_bytep))));
-
- for (iptr=0; iptr<info_ptr->height; iptr++)
- info_ptr->row_pointers[iptr] = NULL;
-
- info_ptr->free_me |= PNG_FREE_ROWS;
-
- for (iptr = 0; iptr < info_ptr->height; iptr++)
- info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
- png_malloc(png_ptr, info_ptr->rowbytes));
- }
-
- png_read_image(png_ptr, info_ptr->row_pointers);
- info_ptr->valid |= PNG_INFO_IDAT;
-
- /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
- png_read_end(png_ptr, info_ptr);
-
- PNG_UNUSED(params)
-}
-#endif /* 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) */
-# define P_NOTSET 0 /* File encoding not yet known */
-# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
-# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
-# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
-# define P_LINEAR8 4 /* 8-bit linear: only from a file value */
-
-/* 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 P_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_MATCHP_sRGB' colorspace flag to have been set. If the
- * colorspace has been determined to be invalid ignore it.
- */
- if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
- & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
- PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
- image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
-#endif
- }
-
- /* We need the maximum number of entries regardless of the format the
- * application sets here.
- */
- {
- png_uint_32 cmap_entries;
-
- switch (png_ptr->color_type)
- {
- case PNG_COLOR_TYPE_GRAY:
- cmap_entries = 1U << png_ptr->bit_depth;
- break;
-
- case PNG_COLOR_TYPE_PALETTE:
- cmap_entries = png_ptr->num_palette;
- break;
-
- default:
- cmap_entries = 256;
- break;
- }
-
- if (cmap_entries > 256)
- cmap_entries = 256;
-
- image->colormap_entries = cmap_entries;
- }
-
- return 1;
-}
-
-#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.
- *
- * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
- * too. This allows the simplified API to be compiled without iCCP support,
- * however if the support is there the chunk is still checked to detect
- * errors (which are unfortunately quite common.)
- */
- {
- static PNG_CONST png_byte chunks_to_process[] = {
- 98, 75, 71, 68, '\0', /* bKGD */
- 99, 72, 82, 77, '\0', /* cHRM */
- 103, 65, 77, 65, '\0', /* gAMA */
-# ifdef PNG_READ_iCCP_SUPPORTED
- 105, 67, 67, 80, '\0', /* iCCP */
-# endif
- 115, 66, 73, 84, '\0', /* sBIT */
- 115, 82, 71, 66, '\0', /* sRGB */
- };
-
- /* Ignore unknown chunks and all other chunks except for the
- * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
- */
- png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
- NULL, -1);
-
- /* But do not ignore image data handling chunks */
- png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
- chunks_to_process, (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 = P_FILE;
- display->gamma_to_linear = png_reciprocal(g);
- }
-
- else
- display->file_encoding = P_sRGB;
- }
-
- else
- display->file_encoding = P_LINEAR8;
-}
-
-static unsigned int
-decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
-{
- if (encoding == P_FILE) /* double check */
- encoding = display->file_encoding;
-
- if (encoding == P_NOTSET) /* must be the file encoding */
- {
- set_file_encoding(display);
- encoding = display->file_encoding;
- }
-
- switch (encoding)
- {
- case P_FILE:
- value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
- break;
-
- case P_sRGB:
- value = png_sRGB_table[value];
- break;
-
- case P_LINEAR:
- break;
-
- case P_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 P_FILE and the
- * file and alpha are 8-bit values. The (output) encoding will always be
- * P_LINEAR or P_sRGB.
- */
- png_uint_32 f = decode_gamma(display, foreground, foreground_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 == P_LINEAR)
- {
- /* Scale to 65535; divide by 255, approximately (in fact this is extremely
- * accurate, it divides by 255.00000005937181414556, with no overflow.)
- */
- f *= 257; /* Now scaled by 65535 */
- f += f >> 16;
- f = (f+32768) >> 16;
- }
-
- else /* P_sRGB */
- f = PNG_sRGB_FROM_LINEAR(f);
-
- return f;
-}
-
-/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
- * be 8-bit.
- */
-static void
-png_create_colormap_entry(png_image_read_control *display,
- png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
- png_uint_32 alpha, int encoding)
-{
- png_imagep image = display->image;
- const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) ?
- P_LINEAR : P_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 == P_FILE)
- {
- if (display->file_encoding == P_NOTSET)
- set_file_encoding(display);
-
- /* Note that the cached value may be P_FILE too, but if it is then the
- * gamma_to_linear member has been set.
- */
- encoding = display->file_encoding;
- }
-
- if (encoding == P_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 == P_LINEAR)
- {
- alpha *= 257;
- encoding = P_LINEAR;
- }
-
- else
- {
- red = PNG_sRGB_FROM_LINEAR(red * 255);
- green = PNG_sRGB_FROM_LINEAR(green * 255);
- blue = PNG_sRGB_FROM_LINEAR(blue * 255);
- encoding = P_sRGB;
- }
- }
-
- else if (encoding == P_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 = P_LINEAR;
- }
-
- else if (encoding == P_sRGB && (convert_to_Y || output_encoding == P_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 = P_LINEAR;
- }
-
- /* This is set if the color isn't gray but the output is. */
- if (encoding == P_LINEAR)
- {
- if (convert_to_Y != 0)
- {
- /* NOTE: these values are copied from png_do_rgb_to_gray */
- png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
- (png_uint_32)2366 * blue;
-
- if (output_encoding == P_LINEAR)
- y = (y + 16384) >> 15;
-
- else
- {
- /* y is scaled by 32768, we need it scaled by 255: */
- y = (y + 128) >> 8;
- y *= 255;
- y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
- encoding = P_sRGB;
- }
-
- blue = red = green = y;
- }
-
- else if (output_encoding == P_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 = P_sRGB;
- }
- }
-
- if (encoding != output_encoding)
- png_error(image->opaque->png_ptr, "bad encoding (internal error)");
-
- /* Store the value. */
- {
-# ifdef PNG_FORMAT_AFIRST_SUPPORTED
- const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
- (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
-# else
-# define afirst 0
-# endif
-# ifdef PNG_FORMAT_BGR_SUPPORTED
- const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
-# else
-# define bgr 0
-# endif
-
- if (output_encoding == P_LINEAR)
- {
- png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
-
- entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
-
- /* The linear 16-bit values must be pre-multiplied by the alpha channel
- * value, if less than 65535 (this is, effectively, composite on black
- * if the alpha channel is removed.)
- */
- switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
- {
- case 4:
- entry[afirst ? 0 : 3] = (png_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 P_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, P_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, P_sRGB);
-
- return i;
-}
-#define PNG_GRAY_COLORMAP_ENTRIES 256
-
-static int
-make_ga_colormap(png_image_read_control *display)
-{
- unsigned int i, a;
-
- /* Alpha is retained, the output will be a color-map with entries
- * selected by six levels of alpha. One transparent entry, 6 gray
- * levels for all the intermediate alpha values, leaving 230 entries
- * for the opaque grays. The color-map entries are the six values
- * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
- * relevant entry.
- *
- * if (alpha > 229) // opaque
- * {
- * // The 231 entries are selected to make the math below work:
- * base = 0;
- * entry = (231 * gray + 128) >> 8;
- * }
- * else if (alpha < 26) // transparent
- * {
- * base = 231;
- * entry = 0;
- * }
- * else // partially opaque
- * {
- * base = 226 + 6 * PNG_DIV51(alpha);
- * entry = PNG_DIV51(gray);
- * }
- */
- i = 0;
- while (i < 231)
- {
- unsigned int gray = (i * 256 + 115) / 231;
- png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
- }
-
- /* 255 is used here for the component values for consistency with the code
- * that undoes premultiplication in pngwrite.c.
- */
- png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
-
- for (a=1; a<5; ++a)
- {
- unsigned int g;
-
- for (g=0; g<6; ++g)
- png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
- P_sRGB);
- }
-
- return i;
-}
-
-#define PNG_GA_COLORMAP_ENTRIES 256
-
-static int
-make_rgb_colormap(png_image_read_control *display)
-{
- unsigned int i, r;
-
- /* Build a 6x6x6 opaque RGB cube */
- for (i=r=0; r<6; ++r)
- {
- unsigned int g;
-
- for (g=0; g<6; ++g)
- {
- unsigned int b;
-
- for (b=0; b<6; ++b)
- png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
- P_sRGB);
- }
- }
-
- return i;
-}
-
-#define PNG_RGB_COLORMAP_ENTRIES 216
-
-/* Return a palette index to the above palette given three 8-bit sRGB values. */
-#define PNG_RGB_INDEX(r,g,b) \
- ((png_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) ?
- P_LINEAR : P_sRGB;
-
- unsigned int cmap_entries;
- unsigned int output_processing; /* Output processing option */
- unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
-
- /* Background information; the background color and the index of this color
- * in the color-map if it exists (else 256).
- */
- unsigned int background_index = 256;
- png_uint_32 back_r, back_g, back_b;
-
- /* Flags to accumulate things that need to be done to the input. */
- int expand_tRNS = 0;
-
- /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
- * very difficult to do, the results look awful, and it is difficult to see
- * what possible use it is because the application can't control the
- * color-map.
- */
- if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
- png_ptr->num_trans > 0) /* alpha in input */ &&
- ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
- {
- if (output_encoding == P_LINEAR) /* compose on black */
- back_b = back_g = back_r = 0;
-
- else if (display->background == NULL /* no way to remove it */)
- png_error(png_ptr,
- "a background color must be supplied to remove alpha/transparency");
-
- /* Get a copy of the background color (this avoids repeating the checks
- * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
- * output format.
- */
- else
- {
- back_g = display->background->green;
- if (output_format & PNG_FORMAT_FLAG_COLOR)
- {
- back_r = display->background->red;
- back_b = display->background->blue;
- }
- else
- back_b = back_r = back_g;
- }
- }
-
- else if (output_encoding == P_LINEAR)
- back_b = back_r = back_g = 65535;
-
- else
- back_b = back_r = back_g = 255;
-
- /* Default the input file gamma if required - this is necessary because
- * libpng assumes that if no gamma information is present the data is in the
- * output format, but the simplified API deduces the gamma from the input
- * format.
- */
- if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
- {
- /* Do this directly, not using the png_colorspace functions, to ensure
- * that it happens even if the colorspace is invalid (though probably if
- * it is the setting will be ignored) Note that the same thing can be
- * achieved at the application interface with png_set_gAMA.
- */
- if (png_ptr->bit_depth == 16 &&
- (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
- png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
-
- else
- png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
-
- png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
- }
-
- /* Decide what to do based on the PNG color type of the input data. The
- * utility function png_create_colormap_entry deals with most aspects of the
- * output transformations; this code works out how to produce bytes of
- * color-map entries from the original format.
- */
- switch (png_ptr->color_type)
- {
- case PNG_COLOR_TYPE_GRAY:
- if (png_ptr->bit_depth <= 8)
- {
- /* There at most 256 colors in the output, regardless of
- * transparency.
- */
- unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
-
- cmap_entries = 1U << png_ptr->bit_depth;
- if (cmap_entries > image->colormap_entries)
- png_error(png_ptr, "gray[8] color-map: too few entries");
-
- step = 255 / (cmap_entries - 1);
- output_processing = PNG_CMAP_NONE;
-
- /* If there is a tRNS chunk then this either selects a transparent
- * value or, if the output has no alpha, the background color.
- */
- if (png_ptr->num_trans > 0)
- {
- trans = png_ptr->trans_color.gray;
-
- if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
- back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
- }
-
- /* png_create_colormap_entry just takes an RGBA and writes the
- * corresponding color-map entry using the format from 'image',
- * including the required conversion to sRGB or linear as
- * appropriate. The input values are always either sRGB (if the
- * gamma correction flag is 0) or 0..255 scaled file encoded values
- * (if the function must gamma correct them).
- */
- for (i=val=0; i<cmap_entries; ++i, val += step)
- {
- /* 'i' is a file value. While this will result in duplicated
- * entries for 8-bit non-sRGB encoded files it is necessary to
- * have non-gamma corrected values to do tRNS handling.
- */
- if (i != trans)
- png_create_colormap_entry(display, i, val, val, val, 255,
- P_FILE/*8-bit with file gamma*/);
-
- /* Else this entry is transparent. The colors don't matter if
- * there is an alpha channel (back_alpha == 0), but it does no
- * harm to pass them in; the values are not set above so this
- * passes in white.
- *
- * NOTE: this preserves the full precision of the application
- * supplied background color when it is used.
- */
- else
- png_create_colormap_entry(display, i, back_r, back_g, back_b,
- back_alpha, output_encoding);
- }
-
- /* We need libpng to preserve the original encoding. */
- data_encoding = P_FILE;
-
- /* The rows from libpng, while technically gray values, are now also
- * color-map 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 = P_sRGB;
-
- if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
- png_error(png_ptr, "gray[16] color-map: too few entries");
-
- cmap_entries = make_gray_colormap(display);
-
- if (png_ptr->num_trans > 0)
- {
- unsigned int back_alpha;
-
- if (output_format & PNG_FORMAT_FLAG_ALPHA)
- back_alpha = 0;
-
- else
- {
- if (back_r == back_g && back_g == back_b)
- {
- /* Background is gray; no special processing will be
- * required.
- */
- png_color_16 c;
- png_uint_32 gray = back_g;
-
- if (output_encoding == P_LINEAR)
- {
- gray = PNG_sRGB_FROM_LINEAR(gray * 255);
-
- /* And make sure the corresponding palette entry
- * matches.
- */
- png_create_colormap_entry(display, gray, back_g, back_g,
- back_g, 65535, P_LINEAR);
- }
-
- /* The background passed to libpng, however, must be the
- * sRGB value.
- */
- c.index = 0; /*unused*/
- c.gray = c.red = c.green = c.blue = (png_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 == P_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 = P_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 == P_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, P_LINEAR);
- }
-
- /* The background passed to libpng, however, must be the sRGB
- * value.
- */
- c.index = 0; /*unused*/
- c.gray = c.red = c.green = c.blue = (png_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, P_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 == P_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 == P_sRGB) /* else already linear */
- {
- /* This may produce a value not exactly matching the
- * background, but that's ok because these numbers are only
- * used when alpha != 0
- */
- back_r = png_sRGB_table[back_r];
- back_g = png_sRGB_table[back_g];
- back_b = png_sRGB_table[back_b];
- }
-
- for (a=1; a<5; ++a)
- {
- unsigned int g;
-
- /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
- * by an 8-bit alpha value (0..255).
- */
- png_uint_32 alpha = 51 * a;
- png_uint_32 back_rx = (255-alpha) * back_r;
- png_uint_32 back_gx = (255-alpha) * back_g;
- png_uint_32 back_bx = (255-alpha) * back_b;
-
- for (g=0; g<6; ++g)
- {
- png_uint_32 gray = png_sRGB_table[g*51] * alpha;
-
- png_create_colormap_entry(display, i++,
- PNG_sRGB_FROM_LINEAR(gray + back_rx),
- PNG_sRGB_FROM_LINEAR(gray + back_gx),
- PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
- }
- }
-
- cmap_entries = i;
- output_processing = PNG_CMAP_GA;
- }
- }
- break;
-
- case PNG_COLOR_TYPE_RGB:
- case PNG_COLOR_TYPE_RGB_ALPHA:
- /* Exclude the case where the output is gray; we can always handle this
- * with the cases above.
- */
- if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
- {
- /* The color-map will be grayscale, so we may as well convert the
- * input RGB values to a simple grayscale and use the grayscale
- * code above.
- *
- * NOTE: calling this apparently damages the recognition of the
- * transparent color in background color handling; call
- * png_set_tRNS_to_alpha before png_set_background_fixed.
- */
- png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
- -1);
- data_encoding = P_sRGB;
-
- /* The output will now be one or two 8-bit gray or gray+alpha
- * channels. The more complex case arises when the input has alpha.
- */
- if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
- png_ptr->num_trans > 0) &&
- (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
- {
- /* Both input and output have an alpha channel, so no background
- * processing is required; just map the GA bytes to the right
- * color-map entry.
- */
- expand_tRNS = 1;
-
- if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
- png_error(png_ptr, "rgb[ga] color-map: too few entries");
-
- cmap_entries = make_ga_colormap(display);
- background_index = PNG_CMAP_GA_BACKGROUND;
- output_processing = PNG_CMAP_GA;
- }
-
- else
- {
- /* Either the input or the output has no alpha channel, so there
- * will be no non-opaque pixels in the color-map; it will just be
- * grayscale.
- */
- if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
- png_error(png_ptr, "rgb[gray] color-map: too few entries");
-
- /* Ideally this code would use libpng to do the gamma correction,
- * but if an input alpha channel is to be removed we will hit the
- * libpng bug in gamma+compose+rgb-to-gray (the double gamma
- * correction bug). Fix this by dropping the gamma correction in
- * this case and doing it in the palette; this will result in
- * duplicate palette entries, but that's better than the
- * alternative of double gamma correction.
- */
- if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
- png_ptr->num_trans > 0) &&
- png_gamma_not_sRGB(png_ptr->colorspace.gamma))
- {
- cmap_entries = make_gray_file_colormap(display);
- data_encoding = P_FILE;
- }
-
- else
- cmap_entries = make_gray_colormap(display);
-
- /* But if the input has alpha or transparency it must be removed
- */
- if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
- png_ptr->num_trans > 0)
- {
- png_color_16 c;
- png_uint_32 gray = back_g;
-
- /* We need to ensure that the application background exists in
- * the colormap and that completely transparent pixels map to
- * it. Achieve this simply by ensuring that the entry
- * selected for the background really is the background color.
- */
- if (data_encoding == P_FILE) /* from the fixup above */
- {
- /* The app supplied a gray which is in output_encoding, we
- * need to convert it to a value of the input (P_FILE)
- * encoding then set this palette entry to the required
- * output encoding.
- */
- if (output_encoding == P_sRGB)
- gray = png_sRGB_table[gray]; /* now P_LINEAR */
-
- gray = PNG_DIV257(png_gamma_16bit_correct(gray,
- png_ptr->colorspace.gamma)); /* now P_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 == P_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*/, P_LINEAR);
- }
-
- /* The background passed to libpng, however, must be the
- * output (normally sRGB) value.
- */
- c.index = 0; /*unused*/
- c.gray = c.red = c.green = c.blue = (png_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 = P_sRGB;
-
- /* Is there any transparency or alpha? */
- if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
- png_ptr->num_trans > 0)
- {
- /* Is there alpha in the output too? If so all four channels are
- * processed into a special RGB cube with alpha support.
- */
- if (output_format & PNG_FORMAT_FLAG_ALPHA)
- {
- png_uint_32 r;
-
- if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
- png_error(png_ptr, "rgb+alpha color-map: too few entries");
-
- cmap_entries = make_rgb_colormap(display);
-
- /* Add a transparent entry. */
- png_create_colormap_entry(display, cmap_entries, 255, 255,
- 255, 0, P_sRGB);
-
- /* This is stored as the background index for the processing
- * algorithm.
- */
- background_index = cmap_entries++;
-
- /* Add 27 r,g,b entries each with alpha 0.5. */
- for (r=0; r<256; r = (r << 1) | 0x7f)
- {
- png_uint_32 g;
-
- for (g=0; g<256; g = (g << 1) | 0x7f)
- {
- png_uint_32 b;
-
- /* This generates components with the values 0, 127 and
- * 255
- */
- for (b=0; b<256; b = (b << 1) | 0x7f)
- png_create_colormap_entry(display, cmap_entries++,
- r, g, b, 128, P_sRGB);
- }
- }
-
- expand_tRNS = 1;
- output_processing = PNG_CMAP_RGB_ALPHA;
- }
-
- else
- {
- /* Alpha/transparency must be removed. The background must
- * exist in the color map (achieved by setting adding it after
- * the 666 color-map). If the standard processing code will
- * pick up this entry automatically that's all that is
- * required; libpng can be called to do the background
- * processing.
- */
- unsigned int sample_size =
- PNG_IMAGE_SAMPLE_SIZE(output_format);
- png_uint_32 r, g, b; /* sRGB background */
-
- if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
- png_error(png_ptr, "rgb-alpha color-map: too few entries");
-
- cmap_entries = make_rgb_colormap(display);
-
- png_create_colormap_entry(display, cmap_entries, back_r,
- back_g, back_b, 0/*unused*/, output_encoding);
-
- if (output_encoding == P_LINEAR)
- {
- r = PNG_sRGB_FROM_LINEAR(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, P_sRGB, 128,
- back_r, output_encoding),
- png_colormap_compose(display, g, P_sRGB, 128,
- back_g, output_encoding),
- png_colormap_compose(display, b, P_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 = P_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, P_FILE,
- trans[i], back_r, output_encoding),
- png_colormap_compose(display, colormap[i].green, P_FILE,
- trans[i], back_g, output_encoding),
- png_colormap_compose(display, colormap[i].blue, P_FILE,
- trans[i], back_b, output_encoding),
- output_encoding == P_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, P_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 P_sRGB:
- /* Change to 8-bit sRGB */
- png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
- /* FALL THROUGH */
-
- case P_FILE:
- if (png_ptr->bit_depth > 8)
- png_set_scale_16(png_ptr);
- break;
- }
-
- 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:
- 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:
- 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-around 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 from
- * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
- * row and handles the removal or pre-multiplication of the alpha channel.
- */
-static int
-png_image_read_background(png_voidp argument)
-{
- png_image_read_control *display = png_voidcast(png_image_read_control*,
- argument);
- png_imagep image = display->image;
- png_structrp png_ptr = image->opaque->png_ptr;
- png_inforp info_ptr = image->opaque->info_ptr;
- png_uint_32 height = image->height;
- png_uint_32 width = image->width;
- int pass, passes;
-
- /* Double check the convoluted logic below. We expect to get here with
- * libpng doing rgb to gray and gamma correction but background processing
- * left to the png_image_read_background function. The rows libpng produce
- * might be 8 or 16-bit but should always have two channels; gray plus alpha.
- */
- 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:
- png_error(png_ptr, "unknown interlace type");
- }
-
- /* Use direct access to info_ptr here because otherwise the simplified API
- * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
- * checking the value after libpng expansions, not the original value in the
- * PNG.
- */
- switch (info_ptr->bit_depth)
- {
- default:
- png_error(png_ptr, "unexpected bit depth");
- break;
-
- case 8:
- /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
- * to be removed by composing on a background: either the row if
- * display->background is NULL or display->background->green if not.
- * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
- */
- {
- png_bytep first_row = png_voidcast(png_bytep, display->first_row);
- ptrdiff_t step_row = display->row_bytes;
-
- for (pass = 0; pass < passes; ++pass)
- {
- png_bytep row = png_voidcast(png_bytep,
- display->first_row);
- unsigned int startx, stepx, stepy;
- png_uint_32 y;
-
- if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
- {
- /* The row may be empty for a short image: */
- if (PNG_PASS_COLS(width, pass) == 0)
- continue;
-
- startx = PNG_PASS_START_COL(pass);
- stepx = PNG_PASS_COL_OFFSET(pass);
- y = PNG_PASS_START_ROW(pass);
- stepy = PNG_PASS_ROW_OFFSET(pass);
- }
-
- else
- {
- y = 0;
- startx = 0;
- stepx = stepy = 1;
- }
-
- if (display->background == NULL)
- {
- for (; y<height; y += stepy)
- {
- png_bytep inrow = png_voidcast(png_bytep,
- display->local_row);
- png_bytep outrow = first_row + y * step_row;
- png_const_bytep end_row = outrow + width;
-
- /* Read the row, which is packed: */
- png_read_row(png_ptr, inrow, NULL);
-
- /* Now do the composition on each pixel in this row. */
- outrow += startx;
- for (; outrow < end_row; outrow += stepx)
- {
- png_byte alpha = inrow[1];
-
- if (alpha > 0) /* else no change to the output */
- {
- png_uint_32 component = inrow[0];
-
- if (alpha < 255) /* else just use component */
- {
- /* Since PNG_OPTIMIZED_ALPHA was not set it is
- * necessary to invert the sRGB transfer
- * function and multiply the alpha out.
- */
- component = png_sRGB_table[component] * alpha;
- component += png_sRGB_table[outrow[0]] *
- (255-alpha);
- component = PNG_sRGB_FROM_LINEAR(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;
-
-# ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
- if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST))
- swap_alpha = 1;
-# endif
-
- for (pass = 0; pass < passes; ++pass)
- {
- unsigned int startx, stepx, stepy;
- png_uint_32 y;
-
- /* The 'x' start and step are adjusted to output components here.
- */
- if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
- {
- /* The row may be empty for a short image: */
- if (PNG_PASS_COLS(width, pass) == 0)
- continue;
-
- startx = PNG_PASS_START_COL(pass) * outchannels;
- stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
- y = PNG_PASS_START_ROW(pass);
- stepy = PNG_PASS_ROW_OFFSET(pass);
- }
-
- else
- {
- y = 0;
- startx = 0;
- stepx = outchannels;
- stepy = 1;
- }
-
- for (; y<height; y += stepy)
- {
- png_const_uint_16p inrow;
- png_uint_16p outrow = first_row + y*step_row;
- png_uint_16p end_row = outrow + width * outchannels;
-
- /* Read the row, which is packed: */
- png_read_row(png_ptr, png_voidcast(png_bytep,
- display->local_row), NULL);
- inrow = png_voidcast(png_const_uint_16p, display->local_row);
-
- /* Now do the pre-multiplication on each pixel in this row.
- */
- outrow += startx;
- for (; outrow < end_row; outrow += stepx)
- {
- png_uint_32 component = inrow[0];
- png_uint_16 alpha = inrow[1];
-
- if (alpha > 0) /* else 0 */
- {
- if (alpha < 65535) /* else just use component */
- {
- component *= alpha;
- component += 32767;
- component /= 65535;
- }
- }
-
- else
- component = 0;
-
- outrow[swap_alpha] = (png_uint_16)component;
- if (preserve_alpha != 0)
- outrow[1 ^ swap_alpha] = alpha;
-
- inrow += 2; /* components and alpha channel */
- }
- }
- }
- }
- break;
- }
-
- return 1;
-}
-
-/* The guts of png_image_finish_read as a png_safe_execute callback. */
-static int
-png_image_read_direct(png_voidp argument)
-{
- png_image_read_control *display = png_voidcast(png_image_read_control*,
- argument);
- png_imagep image = display->image;
- png_structrp png_ptr = image->opaque->png_ptr;
- png_inforp info_ptr = image->opaque->info_ptr;
-
- png_uint_32 format = image->format;
- int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
- int do_local_compose = 0;
- int do_local_background = 0; /* to avoid double gamma correction bug */
- int passes = 0;
-
- /* Add transforms to ensure the correct output format is produced then check
- * that the required implementation support is there. Always expand; always
- * need 8 bits minimum, no palette and expanded tRNS.
- */
- png_set_expand(png_ptr);
-
- /* Now check the format to see if it was modified. */
- {
- png_uint_32 base_format = png_image_format(png_ptr) &
- ~PNG_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 != 0)
- {
- /* If there *is* an alpha channel in the input it must be multiplied
- * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
- */
- if (base_format & PNG_FORMAT_FLAG_ALPHA)
- mode = PNG_ALPHA_STANDARD; /* associated alpha */
-
- else
- mode = PNG_ALPHA_PNG;
-
- output_gamma = PNG_GAMMA_LINEAR;
- }
-
- else
- {
- mode = PNG_ALPHA_PNG;
- output_gamma = PNG_DEFAULT_sRGB;
- }
-
- /* If 'do_local_background' is set check for the presence of gamma
- * correction; this is part of the work-round for the libpng bug
- * described above.
- *
- * TODO: fix libpng and remove this.
- */
- if (do_local_background != 0)
- {
- png_fixed_point gtest;
-
- /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
- * gamma correction, the screen gamma hasn't been set on png_struct
- * yet; it's set below. png_struct::gamma, however, is set to the
- * final value.
- */
- if (png_muldiv(&gtest, output_gamma, png_ptr->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 != 0)
- do_local_background = 2/*required*/;
-
- /* 16-bit output: just remove the channel */
- else if (linear != 0) /* compose on black (well, pre-multiply) */
- png_set_strip_alpha(png_ptr);
-
- /* 8-bit output: do an appropriate compose */
- else if (display->background != NULL)
- {
- png_color_16 c;
-
- c.index = 0; /*unused*/
- c.red = display->background->red;
- c.green = display->background->green;
- c.blue = display->background->blue;
- c.gray = display->background->green;
-
- /* This is always an 8-bit sRGB value, using the 'green' channel
- * for gray is much better than calculating the luminance here;
- * we can get off-by-one errors in that calculation relative to
- * the app expectations and that will show up in transparent
- * pixels.
- */
- png_set_background_fixed(png_ptr, &c,
- PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
- 0/*gamma: not used*/);
- }
-
- else /* compose on row: implemented below. */
- {
- do_local_compose = 1;
- /* This leaves the alpha channel in the output, so it has to be
- * removed by the code below. Set the encoding to the 'OPTIMIZE'
- * one so the code only has to hack on the pixels that require
- * composition.
- */
- mode = PNG_ALPHA_OPTIMIZED;
- }
- }
-
- else /* output needs an alpha channel */
- {
- /* This is tricky because it happens before the swap operation has
- * been accomplished; however, the swap does *not* swap the added
- * alpha channel (weird API), so it must be added in the correct
- * place.
- */
- png_uint_32 filler; /* opaque filler */
- int where;
-
- if (linear != 0)
- filler = 65535;
-
- else
- filler = 255;
-
-# ifdef PNG_FORMAT_AFIRST_SUPPORTED
- if (format & PNG_FORMAT_FLAG_AFIRST)
- {
- 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 != 0)
- {
- 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 != 0)
- png_error(png_ptr, "png_read_image: unsupported transformation");
- }
-
- PNG_SKIP_CHUNKS(png_ptr);
-
- /* Update the 'info' structure and make sure the result is as required; first
- * make sure to turn on the interlace handling if it will be required
- * (because it can't be turned on *after* the call to png_read_update_info!)
- *
- * TODO: remove the do_local_background fixup below.
- */
- if (do_local_compose == 0 && do_local_background != 2)
- passes = png_set_interlace_handling(png_ptr);
-
- png_read_update_info(png_ptr, info_ptr);
-
- {
- png_uint_32 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 == 0)
- {
- /* 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 != 0) /* 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 != 0)
- row_bytes *= 2;
-
- /* The following expression is designed to work correctly whether it gives
- * a signed or an unsigned result.
- */
- if (row_bytes < 0)
- {
- char *ptr = png_voidcast(char*, first_row);
- ptr += (image->height-1) * (-row_bytes);
- first_row = png_voidcast(png_voidp, ptr);
- }
-
- display->first_row = first_row;
- display->row_bytes = row_bytes;
- }
-
- if (do_local_compose != 0)
- {
- int result;
- png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
-
- display->local_row = row;
- result = png_safe_execute(image, png_image_read_composite, display);
- display->local_row = NULL;
- png_free(png_ptr, row);
-
- return result;
- }
-
- else if (do_local_background == 2)
- {
- int result;
- png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
-
- display->local_row = row;
- result = png_safe_execute(image, png_image_read_background, display);
- display->local_row = NULL;
- png_free(png_ptr, row);
-
- return result;
- }
-
- else
- {
- png_alloc_size_t row_bytes = display->row_bytes;
-
- while (--passes >= 0)
- {
- png_uint_32 y = image->height;
- png_bytep row = png_voidcast(png_bytep, display->first_row);
-
- while (y-- > 0)
- {
- png_read_row(png_ptr, row, NULL);
- row += row_bytes;
- }
- }
-
- return 1;
- }
-}
-
-int PNGAPI
-png_image_finish_read(png_imagep image, png_const_colorp background,
- void *buffer, 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 */