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cwebp: extract png decoding to its own module

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Change-Id: I80dd09fe1f1c6317e9d0cdd422438bda11b43ed5
This commit is contained in:
James Zern
2012-12-06 13:06:37 -08:00
parent 4679db006c
commit 2ee228f9a5
6 changed files with 169 additions and 108 deletions
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107
examples/cwebp.c
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@ -18,12 +18,8 @@
#include "config.h"
#endif
#ifdef WEBP_HAVE_PNG
#include <png.h>
#endif
#ifdef WEBP_HAVE_JPEG
#include <setjmp.h> // note: this must be included *after* png.h
#include <setjmp.h>
#include <jpeglib.h>
#endif
@ -47,6 +43,7 @@
#include "webp/encode.h"
#include "./metadata.h"
#include "./pngdec.h"
#include "./stopwatch.h"
#ifndef WEBP_DLL
#if defined(__cplusplus) || defined(c_plusplus)
@ -388,106 +385,6 @@ static int ReadJPEG(FILE* in_file, WebPPicture* const pic) {
}
#endif
#ifdef WEBP_HAVE_PNG
static void PNGAPI error_function(png_structp png, png_const_charp dummy) {
(void)dummy; // remove variable-unused warning
longjmp(png_jmpbuf(png), 1);
}
static int ReadPNG(FILE* in_file, WebPPicture* const pic, int keep_alpha) {
png_structp png;
png_infop info;
int color_type, bit_depth, interlaced;
int has_alpha;
int num_passes;
int p;
int ok = 0;
png_uint_32 width, height, y;
int stride;
uint8_t* rgb = NULL;
png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
if (png == NULL) {
goto End;
}
png_set_error_fn(png, 0, error_function, NULL);
if (setjmp(png_jmpbuf(png))) {
Error:
png_destroy_read_struct(&png, NULL, NULL);
free(rgb);
goto End;
}
info = png_create_info_struct(png);
if (info == NULL) goto Error;
png_init_io(png, in_file);
png_read_info(png, info);
if (!png_get_IHDR(png, info,
&width, &height, &bit_depth, &color_type, &interlaced,
NULL, NULL)) goto Error;
png_set_strip_16(png);
png_set_packing(png);
if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_palette_to_rgb(png);
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
if (bit_depth < 8) {
png_set_expand_gray_1_2_4_to_8(png);
}
png_set_gray_to_rgb(png);
}
if (png_get_valid(png, info, PNG_INFO_tRNS)) {
png_set_tRNS_to_alpha(png);
has_alpha = 1;
} else {
has_alpha = !!(color_type & PNG_COLOR_MASK_ALPHA);
}
if (!keep_alpha) {
png_set_strip_alpha(png);
has_alpha = 0;
}
num_passes = png_set_interlace_handling(png);
png_read_update_info(png, info);
stride = (has_alpha ? 4 : 3) * width * sizeof(*rgb);
rgb = (uint8_t*)malloc(stride * height);
if (rgb == NULL) goto Error;
for (p = 0; p < num_passes; ++p) {
for (y = 0; y < height; ++y) {
png_bytep row = rgb + y * stride;
png_read_rows(png, &row, NULL, 1);
}
}
png_read_end(png, info);
png_destroy_read_struct(&png, &info, NULL);
pic->width = width;
pic->height = height;
ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, stride)
: WebPPictureImportRGB(pic, rgb, stride);
free(rgb);
if (ok && has_alpha && keep_alpha == 2) {
WebPCleanupTransparentArea(pic);
}
End:
return ok;
}
#else
static int ReadPNG(FILE* in_file, WebPPicture* const pic, int keep_alpha) {
(void)in_file;
(void)pic;
(void)keep_alpha;
fprintf(stderr, "PNG support not compiled. Please install the libpng "
"development package before building.\n");
return 0;
}
#endif
#ifdef WEBP_HAVE_TIFF
static int ReadTIFF(const char* const filename,
WebPPicture* const pic, int keep_alpha) {