Add JPEG support

1 files changed, 42 insertions, 0 deletions

diff --git a/jpeg.c b/jpeg.c
new file mode 100644
index 0000000..5ec3b5f
--- /dev/null
+++ b/jpeg.c
@@ -0,0 +1,42 @@
+#include <SDL2/SDL.h>
+#include <string.h>
+#include <jpeglib.h>
+#include <setjmp.h>
+
+SDL_Texture* imv_load_jpeg(SDL_Renderer *r, const char* path)
+{
+  FILE *fp = fopen(path, "rb");
+  if(!fp) {
+    return NULL;
+  }
+
+  struct jpeg_decompress_struct cinfo;
+  jpeg_create_decompress(&cinfo);
+  struct jpeg_error_mgr jerr;
+  cinfo.err = jpeg_std_error(&jerr);
+
+  jpeg_stdio_src(&cinfo, fp);
+  jpeg_read_header(&cinfo, TRUE);
+  jpeg_start_decompress(&cinfo);
+  int row_stride = cinfo.output_width * cinfo.output_components;
+  JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray)
+                ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
+  char* pixels = (char*)malloc(row_stride*cinfo.output_height);
+  while (cinfo.output_scanline < cinfo.output_height) {
+    jpeg_read_scanlines(&cinfo, buffer, 1);
+    void *out_row = pixels + row_stride * (cinfo.output_scanline-1);
+    memcpy(out_row, buffer[0], row_stride);
+  }
+  jpeg_finish_decompress(&cinfo);
+  jpeg_destroy_decompress(&cinfo);
+  fclose(fp);
+
+  SDL_Texture *img = SDL_CreateTexture(r,
+      SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STATIC,
+      cinfo.output_width, cinfo.output_height);
+
+  SDL_Rect area = {0,0,cinfo.output_width,cinfo.output_height};
+  SDL_UpdateTexture(img, &area, pixels, row_stride);
+  free(pixels);
+  return img;
+}