mirror of
https://github.com/webmproject/libwebp.git
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125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// This code is licensed under the same terms as WebM:
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// Software License Agreement: http://www.webmproject.org/license/software/
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
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// -----------------------------------------------------------------------------
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//
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// PNG decode.
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#include "./pngdec.h"
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#ifdef WEBP_HAVE_PNG
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#include <png.h>
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#include <setjmp.h> // note: this must be included *after* png.h
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#include <stdlib.h>
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#include "webp/encode.h"
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static void PNGAPI error_function(png_structp png, png_const_charp dummy) {
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(void)dummy; // remove variable-unused warning
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longjmp(png_jmpbuf(png), 1);
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}
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int ReadPNG(FILE* in_file, WebPPicture* const pic, int keep_alpha) {
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png_structp png;
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png_infop info;
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int color_type, bit_depth, interlaced;
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int has_alpha;
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int num_passes;
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int p;
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int ok = 0;
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png_uint_32 width, height, y;
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int stride;
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uint8_t* rgb = NULL;
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png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
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if (png == NULL) {
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goto End;
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}
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png_set_error_fn(png, 0, error_function, NULL);
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if (setjmp(png_jmpbuf(png))) {
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Error:
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png_destroy_read_struct(&png, NULL, NULL);
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free(rgb);
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goto End;
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}
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info = png_create_info_struct(png);
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if (info == NULL) goto Error;
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png_init_io(png, in_file);
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png_read_info(png, info);
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if (!png_get_IHDR(png, info,
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&width, &height, &bit_depth, &color_type, &interlaced,
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NULL, NULL)) goto Error;
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png_set_strip_16(png);
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png_set_packing(png);
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if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_palette_to_rgb(png);
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if (color_type == PNG_COLOR_TYPE_GRAY ||
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color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
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if (bit_depth < 8) {
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png_set_expand_gray_1_2_4_to_8(png);
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}
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png_set_gray_to_rgb(png);
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}
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if (png_get_valid(png, info, PNG_INFO_tRNS)) {
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png_set_tRNS_to_alpha(png);
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has_alpha = 1;
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} else {
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has_alpha = !!(color_type & PNG_COLOR_MASK_ALPHA);
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}
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if (!keep_alpha) {
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png_set_strip_alpha(png);
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has_alpha = 0;
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}
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num_passes = png_set_interlace_handling(png);
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png_read_update_info(png, info);
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stride = (has_alpha ? 4 : 3) * width * sizeof(*rgb);
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rgb = (uint8_t*)malloc(stride * height);
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if (rgb == NULL) goto Error;
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for (p = 0; p < num_passes; ++p) {
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for (y = 0; y < height; ++y) {
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png_bytep row = rgb + y * stride;
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png_read_rows(png, &row, NULL, 1);
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}
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}
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png_read_end(png, info);
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png_destroy_read_struct(&png, &info, NULL);
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pic->width = width;
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pic->height = height;
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ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, stride)
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: WebPPictureImportRGB(pic, rgb, stride);
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free(rgb);
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if (ok && has_alpha && keep_alpha == 2) {
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WebPCleanupTransparentArea(pic);
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}
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End:
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return ok;
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}
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#else // !WEBP_HAVE_PNG
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int ReadPNG(FILE* in_file, struct WebPPicture* const pic, int keep_alpha) {
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(void)in_file;
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(void)pic;
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(void)keep_alpha;
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fprintf(stderr, "PNG support not compiled. Please install the libpng "
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"development package before building.\n");
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return 0;
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}
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#endif // WEBP_HAVE_PNG
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// -----------------------------------------------------------------------------
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