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/* pngrtran.c - transforms the data in a row for PNG readers * * Last changed in libpng 1.2.38 [July 16, 2009] * Copyright (c) 1998-2010 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * This file contains functions optionally called by an application * in order to tell libpng how to handle data when reading a PNG. * Transformations that are used in both reading and writing are * in pngtrans.c. */ #define PNG_INTERNAL #include "png.h" #if defined(PNG_READ_SUPPORTED) /* Set the action on getting a CRC error for an ancillary or critical chunk. */ void PNGAPI png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action) { png_debug(1, "in png_set_crc_action"); /* Tell libpng how we react to CRC errors in critical chunks */ if (png_ptr == NULL) return; switch (crit_action) { case PNG_CRC_NO_CHANGE: /* Leave setting as is */ break; case PNG_CRC_WARN_USE: /* Warn/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE; break; case PNG_CRC_QUIET_USE: /* Quiet/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE | PNG_FLAG_CRC_CRITICAL_IGNORE; break; case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */ png_warning(png_ptr, "Can't discard critical data on CRC error."); case PNG_CRC_ERROR_QUIT: /* Error/quit */ case PNG_CRC_DEFAULT: default: png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; break; } switch (ancil_action) { case PNG_CRC_NO_CHANGE: /* Leave setting as is */ break; case PNG_CRC_WARN_USE: /* Warn/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE; break; case PNG_CRC_QUIET_USE: /* Quiet/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN; break; case PNG_CRC_ERROR_QUIT: /* Error/quit */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN; break; case PNG_CRC_WARN_DISCARD: /* Warn/discard data */ case PNG_CRC_DEFAULT: default: png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; break; } } #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ defined(PNG_FLOATING_POINT_SUPPORTED) /* Handle alpha and tRNS via a background color */ void PNGAPI png_set_background(png_structp png_ptr, png_color_16p background_color, int background_gamma_code, int need_expand, double background_gamma) { png_debug(1, "in png_set_background"); if (png_ptr == NULL) return; if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN) { png_warning(png_ptr, "Application must supply a known background gamma"); return; } png_ptr->transformations |= PNG_BACKGROUND; png_memcpy(&(png_ptr->background), background_color, png_sizeof(png_color_16)); png_ptr->background_gamma = (float)background_gamma; png_ptr->background_gamma_type = (png_byte)(background_gamma_code); png_ptr->transformations |= (need_expand ? PNG_BACKGROUND_EXPAND : 0); } #endif #if defined(PNG_READ_16_TO_8_SUPPORTED) /* Strip 16 bit depth files to 8 bit depth */ void PNGAPI png_set_strip_16(png_structp png_ptr) { png_debug(1, "in png_set_strip_16"); if (png_ptr == NULL) return; png_ptr->transformations |= PNG_16_TO_8; } #endif #if defined(PNG_READ_STRIP_ALPHA_SUPPORTED) void PNGAPI png_set_strip_alpha(png_structp png_ptr) { png_debug(1, "in png_set_strip_alpha"); if (png_ptr == NULL) return; png_ptr->flags |= PNG_FLAG_STRIP_ALPHA; } #endif #if defined(PNG_READ_DITHER_SUPPORTED) /* Dither file to 8 bit. Supply a palette, the current number * of elements in the palette, the maximum number of elements * allowed, and a histogram if possible. If the current number * of colors is greater then the maximum number, the palette will be * modified to fit in the maximum number. "full_dither" indicates * whether we need a dithering cube set up for RGB images, or if we * simply are reducing the number of colors in a paletted image. */ typedef struct png_dsort_struct { struct png_dsort_struct FAR * next; png_byte left; png_byte right; } png_dsort; typedef png_dsort FAR * png_dsortp; typedef png_dsort FAR * FAR * png_dsortpp; void PNGAPI png_set_dither(png_structp png_ptr, png_colorp palette, int num_palette, int maximum_colors, png_uint_16p histogram, int full_dither) { png_debug(1, "in png_set_dither"); if (png_ptr == NULL) return; png_ptr->transformations |= PNG_DITHER; if (!full_dither) { int i; png_ptr->dither_index = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * png_sizeof(png_byte))); for (i = 0; i < num_palette; i++) png_ptr->dither_index[i] = (png_byte)i; } if (num_palette > maximum_colors) { if (histogram != NULL) { /* This is easy enough, just throw out the least used colors. * Perhaps not the best solution, but good enough. */ int i; /* Initialize an array to sort colors */ png_ptr->dither_sort = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * png_sizeof(png_byte))); /* Initialize the dither_sort array */ for (i = 0; i < num_palette; i++) png_ptr->dither_sort[i] = (png_byte)i; /* Find the least used palette entries by starting a * bubble sort, and running it until we have sorted * out enough colors. Note that we don't care about * sorting all the colors, just finding which are * least used. */ for (i = num_palette - 1; i >= maximum_colors; i--) { int done; /* To stop early if the list is pre-sorted */ int j; done = 1; for (j = 0; j < i; j++) { if (histogram[png_ptr->dither_sort[j]] < histogram[png_ptr->dither_sort[j + 1]]) { png_byte t; t = png_ptr->dither_sort[j]; png_ptr->dither_sort[j] = png_ptr->dither_sort[j + 1]; png_ptr->dither_sort[j + 1] = t; done = 0; } } if (done) break; } /* Swap the palette around, and set up a table, if necessary */ if (full_dither) { int j = num_palette; /* Put all the useful colors within the max, but don't * move the others. */ for (i = 0; i < maximum_colors; i++) { if ((int)png_ptr->dither_sort[i] >= maximum_colors) { do j--; while ((int)png_ptr->dither_sort[j] >= maximum_colors); palette[i] = palette[j];