From a53ed33d2fa50bcb494fd0df7f6f717151e2c172 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 29 Jul 2022 22:01:59 -0700
Subject: [PATCH] Fixed loading grayscale images with stb_image
Fixes https://github.com/libsdl-org/SDL_image/issues/294
---
IMG_stb.c | 97 +++++++++++++++++++++++++++++++++----------------------
1 file changed, 59 insertions(+), 38 deletions(-)
diff --git a/IMG_stb.c b/IMG_stb.c
index 95150b42..79826381 100644
--- a/IMG_stb.c
+++ b/IMG_stb.c
@@ -86,10 +86,6 @@ SDL_Surface *IMG_LoadSTB_RW(SDL_RWops *src)
{
Sint64 start;
int w, h, format;
-#if SDL_BYTEORDER == SDL_BIG_ENDIAN
- int shift;
-#endif
- Uint32 rmask, gmask, bmask, amask;
stbi_uc *pixels;
stbi_io_callbacks rw_callbacks;
SDL_Surface *surface = NULL;
@@ -117,44 +113,69 @@ SDL_Surface *IMG_LoadSTB_RW(SDL_RWops *src)
return NULL;
}
- /* Determine the surface format */
- SDL_assert(format == STBI_rgb || format == STBI_rgb_alpha);
-#if SDL_BYTEORDER == SDL_BIG_ENDIAN
- shift = (format == STBI_rgb) ? 8 : 0;
- rmask = 0xFF000000 >> shift;
- gmask = 0x00FF0000 >> shift;
- bmask = 0x0000FF00 >> shift;
- amask = 0x000000FF >> shift;
-#else /* little endian, like x86 */
- rmask = 0x000000FF;
- gmask = 0x0000FF00;
- bmask = 0x00FF0000;
- amask = (format == STBI_rgb) ? 0 : 0xFF000000;
-#endif
+ if (format == STBI_rgb || format == STBI_rgb_alpha) {
+ surface = SDL_CreateRGBSurfaceWithFormatFrom(
+ pixels,
+ w,
+ h,
+ 8 * format,
+ w * format,
+ (format == STBI_rgb) ? SDL_PIXELFORMAT_RGB24 : SDL_PIXELFORMAT_RGBA32
+ );
+ if (surface) {
+ /* FIXME: This sucks. It'd be better to allocate the surface first, then
+ * write directly to the pixel buffer:
+ * https://github.com/nothings/stb/issues/58
+ * -flibit
+ */
+ surface->flags &= ~SDL_PREALLOC;
+ }
+
+ } else if (format == STBI_grey || format == STBI_grey_alpha) {
+ surface = SDL_CreateRGBSurfaceWithFormat(
+ 0,
+ w,
+ h,
+ 8 * (2 + format),
+ (format == STBI_grey) ? SDL_PIXELFORMAT_RGB24 : SDL_PIXELFORMAT_RGBA32
+ );
+ if (surface) {
+ Uint8 *src = pixels;
+ Uint8 *dst = (Uint8 *)surface->pixels;
+ int skip = surface->pitch - (surface->w * (2 + format));
+ int row, col;
+
+ if (format == STBI_grey) {
+ for (row = 0; row < h; ++row) {
+ for (col = 0; col < w; ++col) {
+ Uint8 c = *src++;
+ *dst++ = c;
+ *dst++ = c;
+ *dst++ = c;
+ }
+ dst += skip;
+ }
+ } else {
+ for (row = 0; row < h; ++row) {
+ for (col = 0; col < w; ++col) {
+ Uint8 c = *src++;
+ Uint8 a = *src++;
+ *dst++ = c;
+ *dst++ = c;
+ *dst++ = c;
+ *dst++ = a;
+ }
+ dst += skip;
+ }
+ }
+ stbi_image_free(pixels);
+ }
+ }
- /* Allocate the surface */
- surface = SDL_CreateRGBSurfaceFrom(
- pixels,
- w,
- h,
- 8 * format,
- w * format,
- rmask,
- gmask,
- bmask,
- amask
- );
- if ( !surface ) {
+ if (!surface) {
/* The error message should already be set */
stbi_image_free(pixels); /* calls SDL_free() */
SDL_RWseek(src, start, RW_SEEK_SET);
- } else {
- /* FIXME: This sucks. It'd be better to allocate the surface first, then
- * write directly to the pixel buffer:
- * https://github.com/nothings/stb/issues/58
- * -flibit
- */
- surface->flags &= ~SDL_PREALLOC;
}
return surface;
}