ext/webp_ffi/jpegdec.c
#include "./jpegdec.h"
#include <stdio.h>
#include <jpeglib.h>
#include <setjmp.h>
#include <stdlib.h>
#include <string.h>
struct my_error_mgr {
struct jpeg_error_mgr pub;
jmp_buf setjmp_buffer;
};
static void my_error_exit(j_common_ptr dinfo) {
struct my_error_mgr* myerr = (struct my_error_mgr*) dinfo->err;
(*dinfo->err->output_message) (dinfo);
longjmp(myerr->setjmp_buffer, 1);
}
int UtilReadJPEG(FILE* in_file, WebPPicture* const pic) {
int ok = 0;
int stride, width, height;
uint8_t* rgb = NULL;
struct jpeg_decompress_struct dinfo;
struct my_error_mgr jerr;
JSAMPROW buffer[1];
dinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit;
if (setjmp(jerr.setjmp_buffer)) {
Error:
jpeg_destroy_decompress(&dinfo);
goto End;
}
jpeg_create_decompress(&dinfo);
jpeg_stdio_src(&dinfo, in_file);
jpeg_read_header(&dinfo, TRUE);
dinfo.out_color_space = JCS_RGB;
dinfo.do_fancy_upsampling = TRUE;
jpeg_start_decompress(&dinfo);
if (dinfo.output_components != 3) {
goto Error;
}
width = dinfo.output_width;
height = dinfo.output_height;
stride = dinfo.output_width * dinfo.output_components * sizeof(*rgb);
rgb = (uint8_t*)malloc(stride * height);
if (rgb == NULL) {
goto End;
}
buffer[0] = (JSAMPLE*)rgb;
while (dinfo.output_scanline < dinfo.output_height) {
if (jpeg_read_scanlines(&dinfo, buffer, 1) != 1) {
goto End;
}
buffer[0] += stride;
}
jpeg_finish_decompress(&dinfo);
jpeg_destroy_decompress(&dinfo);
// WebP conversion.
pic->width = width;
pic->height = height;
ok = WebPPictureImportRGB(pic, rgb, stride);
if (!ok) goto Error;
End:
free(rgb);
return ok;
}