Add a PNG loader

1 files changed, 50 insertions, 0 deletions

diff --git a/png.c b/png.c
new file mode 100644
index 0000000..02b951a
--- /dev/null
+++ b/png.c
@@ -0,0 +1,50 @@
+#include <SDL2/SDL.h>
+#include <string.h>
+#include <png.h>
+
+SDL_Texture* imv_load_png(SDL_Renderer *r, const char* path)
+{
+  FILE *fp = fopen(path, "rb");
+
+  if(!fp) {
+    return NULL;
+  }
+
+  png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+  if(!png) {
+    fclose(fp);
+    return NULL;
+  }
+
+  png_infop info = png_create_info_struct(png);
+  if(!info) {
+    fclose(fp);
+    png_destroy_read_struct(&png, NULL, NULL);
+    return NULL;
+  }
+
+  png_init_io(png, fp);
+  png_read_png(png, info,
+      PNG_TRANSFORM_STRIP_16 | PNG_TRANSFORM_PACKING | PNG_TRANSFORM_EXPAND,
+      NULL);
+  png_uint_32 width, height;
+  png_get_IHDR(png, info, &width, &height, NULL, NULL, NULL, NULL, NULL);
+  unsigned int bytes_per_row = png_get_rowbytes(png, info);
+  png_bytepp row_ptrs = png_get_rows(png, info);
+
+  char* pixels = (char*)malloc(bytes_per_row*height);
+  for (unsigned int i = 0; i < height; i++) {
+    memcpy(pixels + bytes_per_row * i, row_ptrs[i], bytes_per_row);
+  }
+  png_destroy_read_struct(&png, &info, NULL);
+  fclose(fp);
+
+  SDL_Texture *img = SDL_CreateTexture(r,
+      SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STATIC,
+      width, height);
+
+  SDL_Rect area = {0,0,width,height};
+  SDL_UpdateTexture(img, &area, pixels, bytes_per_row);
+  free(pixels);
+  return img;
+}