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comparison src/video/SDL_blit_N.c @ 1543:98f9b16f565c

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From: "Alex Volkov" Date: Thu, 10 Nov 2005 21:53:40 -0500 Subject: [SDL] BUG[?]: 32bpp RGBA->RGB colorkey blit, no SDL_SRCALPHA It seems there is either a documentation vs. reality mismatch or a real bug in SDL_blit_N.c:BlitNtoNKey(). The exact blit in question is a 32bpp RGBA->RGB, where RGBA has SDL_COLORKEY and *no* SDL_SRCALPHA flags. The doc in SDL_video.h states: * RGBA->RGB: * SDL_SRCALPHA not set: * copy RGB. * if SDL_SRCCOLORKEY set, only copy the pixels matching the * RGB values of the source colour key, ignoring alpha in the * comparison. BlitNtoNKey(), however, forgets to "ignore alpha in the comparison". The documentation makes perfect sense, so I think it is the code that is faulty. The attached patch corrects the code.
author Sam Lantinga <slouken@libsdl.org>
date Wed, 15 Mar 2006 15:43:15 +0000
parents dc6b59e925a2
children ab1e4c41ab71
comparison
equal deleted inserted replaced
1542:a8bf1aa21020 1543:98f9b16f565c
2192 SDL_PixelFormat *srcfmt = info->src; 2192 SDL_PixelFormat *srcfmt = info->src;
2193 SDL_PixelFormat *dstfmt = info->dst; 2193 SDL_PixelFormat *dstfmt = info->dst;
2194 int srcbpp = srcfmt->BytesPerPixel; 2194 int srcbpp = srcfmt->BytesPerPixel;
2195 int dstbpp = dstfmt->BytesPerPixel; 2195 int dstbpp = dstfmt->BytesPerPixel;
2196 unsigned alpha = dstfmt->Amask ? srcfmt->alpha : 0; 2196 unsigned alpha = dstfmt->Amask ? srcfmt->alpha : 0;
2197 Uint32 rgbmask = ~srcfmt->Amask;
2198
2199 /* Set up some basic variables */
2200 ckey &= rgbmask;
2197 2201
2198 while ( height-- ) { 2202 while ( height-- ) {
2199 DUFFS_LOOP( 2203 DUFFS_LOOP(
2200 { 2204 {
2201 Uint32 Pixel; 2205 Uint32 Pixel;
2202 unsigned sR; 2206 unsigned sR;
2203 unsigned sG; 2207 unsigned sG;
2204 unsigned sB; 2208 unsigned sB;
2205 RETRIEVE_RGB_PIXEL(src, srcbpp, Pixel); 2209 RETRIEVE_RGB_PIXEL(src, srcbpp, Pixel);
2206 if ( Pixel != ckey ) { 2210 if ( (Pixel & rgbmask) != ckey ) {
2207 RGB_FROM_PIXEL(Pixel, srcfmt, sR, sG, sB); 2211 RGB_FROM_PIXEL(Pixel, srcfmt, sR, sG, sB);
2208 ASSEMBLE_RGBA(dst, dstbpp, dstfmt, 2212 ASSEMBLE_RGBA(dst, dstbpp, dstfmt,
2209 sR, sG, sB, alpha); 2213 sR, sG, sB, alpha);
2210 } 2214 }
2211 dst += dstbpp; 2215 dst += dstbpp;