Let SDL convert the pixels instead of doing it ourselves.

diff --git a/main.cpp b/main.cpp
index 35d5bc8df4c9f16df8ebdb5fa7371127cf2c00f9..0a92aed593826e091b82b437482ae90c6d238eeb 100644 (file)
--- a/main.cpp
+++ b/main.cpp
@@ -89,44 +89,34 @@ unsigned char *load_image(const char *filename, unsigned *w, unsigned *h)
                exit(1);
        }
 
-       // Convert to RGB.
-       SDL_PixelFormat *fmt = img->format;
-       SDL_LockSurface(img);
-       unsigned char *src_pixels = (unsigned char *)img->pixels;
-       unsigned char *dst_pixels = (unsigned char *)malloc(img->w * img->h * 4);
-       for (int i = 0; i < img->w * img->h; ++i) {
-               unsigned char r, g, b;
-               unsigned int temp;
-               unsigned int pixel = *(unsigned int *)(src_pixels + i * fmt->BytesPerPixel);
-
-               temp = pixel & fmt->Rmask;
-               temp = temp >> fmt->Rshift;
-               temp = temp << fmt->Rloss;
-               r = temp;
-
-               temp = pixel & fmt->Gmask;
-               temp = temp >> fmt->Gshift;
-               temp = temp << fmt->Gloss;
-               g = temp;
-
-               temp = pixel & fmt->Bmask;
-               temp = temp >> fmt->Bshift;
-               temp = temp << fmt->Bloss;
-               b = temp;
-
-               dst_pixels[i * 4 + 0] = b;
-               dst_pixels[i * 4 + 1] = g;
-               dst_pixels[i * 4 + 2] = r;
-               dst_pixels[i * 4 + 3] = 255;
-       }
-       SDL_UnlockSurface(img);
+       SDL_PixelFormat rgba_fmt;
+       rgba_fmt.palette = NULL;
+       rgba_fmt.BitsPerPixel = 32;
+       rgba_fmt.BytesPerPixel = 8;
+       rgba_fmt.Rloss = rgba_fmt.Gloss = rgba_fmt.Bloss = rgba_fmt.Aloss = 0;
+
+       // NOTE: Assumes little endian.
+       rgba_fmt.Rmask = 0x000000ff;
+       rgba_fmt.Gmask = 0x0000ff00;
+       rgba_fmt.Bmask = 0x00ff0000;
+       rgba_fmt.Amask = 0xff000000;
+
+       rgba_fmt.Rshift = 0;
+       rgba_fmt.Gshift = 8;
+       rgba_fmt.Bshift = 16;
+       rgba_fmt.Ashift = 24;
+       
+       rgba_fmt.colorkey = 0;
+       rgba_fmt.alpha = 255;
+
+       SDL_Surface *converted = SDL_ConvertSurface(img, &rgba_fmt, SDL_SWSURFACE);
 
        *w = img->w;
        *h = img->h;
 
        SDL_FreeSurface(img);
 
-       return dst_pixels;
+       return (unsigned char *)converted->pixels;
 }
 
 void write_ppm(const char *filename, unsigned char *screenbuf)