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Use SDL_PremultiplySurfaceAlpha() when creating NSImages

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This commit is contained in:
Sam Lantinga
2024-07-31 09:57:02 -07:00
parent b8f3cd0a10
commit b8dc97c577
1 changed files with 3 additions and 10 deletions
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13
src/video/cocoa/SDL_cocoavideo.m
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@@ -253,7 +253,6 @@ NSImage *Cocoa_CreateImage(SDL_Surface *surface)
SDL_Surface *converted; SDL_Surface *converted;
NSBitmapImageRep *imgrep; NSBitmapImageRep *imgrep;
Uint8 *pixels; Uint8 *pixels;
int i;
NSImage *img; NSImage *img;
converted = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_RGBA32); converted = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_RGBA32);
@@ -261,6 +260,9 @@ NSImage *Cocoa_CreateImage(SDL_Surface *surface)
return nil; return nil;
} }
/* Premultiply the alpha channel */
SDL_PremultiplySurfaceAlpha(converted, SDL_FALSE);
imgrep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL imgrep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
pixelsWide:converted->w pixelsWide:converted->w
pixelsHigh:converted->h pixelsHigh:converted->h
@@ -281,15 +283,6 @@ NSImage *Cocoa_CreateImage(SDL_Surface *surface)
SDL_memcpy(pixels, converted->pixels, (size_t)converted->h * converted->pitch); SDL_memcpy(pixels, converted->pixels, (size_t)converted->h * converted->pitch);
SDL_DestroySurface(converted); SDL_DestroySurface(converted);
/* Premultiply the alpha channel */
for (i = (surface->h * surface->w); i--;) {
Uint8 alpha = pixels[3];
pixels[0] = (Uint8)(((Uint16)pixels[0] * alpha) / 255);
pixels[1] = (Uint8)(((Uint16)pixels[1] * alpha) / 255);
pixels[2] = (Uint8)(((Uint16)pixels[2] * alpha) / 255);
pixels += 4;
}
img = [[NSImage alloc] initWithSize:NSMakeSize(surface->w, surface->h)]; img = [[NSImage alloc] initWithSize:NSMakeSize(surface->w, surface->h)];
if (img != nil) { if (img != nil) {
[img addRepresentation:imgrep]; [img addRepresentation:imgrep];