Skip to content
Permalink
Browse files

Fixed SDL_DisplayFormatAlpha() on RGB surfaces with alpha

  • Loading branch information
slouken committed Aug 1, 2002
1 parent 12574f2 commit 755583323194fef003148253faa9f1974aec380a
Showing with 63 additions and 6 deletions.
  1. +1 −0 docs.html
  2. +1 −1 include/SDL_video.h
  3. +2 −2 src/video/SDL_blit_N.c
  4. +59 −3 src/video/SDL_surface.c
@@ -16,6 +16,7 @@ <H2>
Major changes since SDL 1.0.0:
</H2>
<UL>
<LI> 1.2.5: Fixed SDL_DisplayFormatAlpha() on RGB surfaces with alpha
<LI> 1.2.5: Fixed setting OpenGL mode multiple times on Windows
<LI> 1.2.5: Added support for Qtopia on embedded systems (thanks David!)
<LI> 1.2.4: Added initial support for Atari (thanks Patrice!)
@@ -645,7 +645,7 @@ extern DECLSPEC SDL_Surface * SDLCALL SDL_ConvertSurface
* alpha-blend (using the source per-surface alpha value);
* set destination alpha to opaque.
* SDL_SRCALPHA not set:
* copy RGB, set destination alpha to opaque.
* copy RGB, set destination alpha to source per-surface alpha value.
* both:
* if SDL_SRCCOLORKEY set, only copy the pixels matching the
* source colour key.
@@ -1202,7 +1202,7 @@ static void BlitNtoN(SDL_BlitInfo *info)
int srcbpp = srcfmt->BytesPerPixel;
SDL_PixelFormat *dstfmt = info->dst;
int dstbpp = dstfmt->BytesPerPixel;
unsigned alpha = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
unsigned alpha = dstfmt->Amask ? srcfmt->alpha : 0;

while ( height-- ) {
DUFFS_LOOP(
@@ -1358,7 +1358,7 @@ static void BlitNtoNKey(SDL_BlitInfo *info)
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp = srcfmt->BytesPerPixel;
int dstbpp = dstfmt->BytesPerPixel;
unsigned alpha = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
unsigned alpha = dstfmt->Amask ? srcfmt->alpha : 0;

while ( height-- ) {
DUFFS_LOOP(
@@ -211,6 +211,7 @@ int SDL_SetColorKey (SDL_Surface *surface, Uint32 flag, Uint32 key)
SDL_InvalidateMap(surface->map);
return(0);
}
/* This function sets the alpha channel of a surface */
int SDL_SetAlpha (SDL_Surface *surface, Uint32 flag, Uint8 value)
{
Uint32 oldflags = surface->flags;
@@ -269,6 +270,52 @@ int SDL_SetAlpha (SDL_Surface *surface, Uint32 flag, Uint8 value)
SDL_InvalidateMap(surface->map);
return(0);
}
int SDL_SetAlphaChannel(SDL_Surface *surface, Uint8 value)
{
int row, col;
int offset;
Uint8 *buf;

if ( (surface->format->Amask != 0xFF000000) &&
(surface->format->Amask != 0x000000FF) ) {
SDL_SetError("Unsupported surface alpha mask format");
return -1;
}

#if SDL_BYTEORDER == SDL_LIL_ENDIAN
if ( surface->format->Amask == 0xFF000000 ) {
offset = 3;
} else {
offset = 0;
}
#else
if ( surface->format->Amask == 0xFF000000 ) {
offset = 0;
} else {
offset = 3;
}
#endif /* Byte ordering */

/* Quickly set the alpha channel of an RGBA or ARGB surface */
if ( SDL_MUSTLOCK(surface) ) {
if ( SDL_LockSurface(surface) < 0 ) {
return -1;
}
}
row = surface->h;
while (row--) {
col = surface->w;
buf = (Uint8 *)surface->pixels + row * surface->pitch + offset;
while(col--) {
*buf = value;
buf += 4;
}
}
if ( SDL_MUSTLOCK(surface) ) {
SDL_UnlockSurface(surface);
}
return 0;
}

/*
* A function to calculate the intersection of two rectangles:
@@ -748,8 +795,13 @@ SDL_Surface * SDL_ConvertSurface (SDL_Surface *surface,
}
}
if ( (surface_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
alpha = surface->format->alpha;
SDL_SetAlpha(surface, 0, 0);
/* Copy over the alpha channel to RGBA if requested */
if ( format->Amask ) {
surface->flags &= ~SDL_SRCALPHA;
} else {
alpha = surface->format->alpha;
SDL_SetAlpha(surface, 0, 0);
}
}

/* Copy over the image data */
@@ -780,7 +832,11 @@ SDL_Surface * SDL_ConvertSurface (SDL_Surface *surface,
SDL_SetAlpha(convert, aflags|(flags&SDL_RLEACCELOK),
alpha);
}
SDL_SetAlpha(surface, aflags, alpha);
if ( format->Amask ) {
surface->flags |= SDL_SRCALPHA;
} else {
SDL_SetAlpha(surface, aflags, alpha);
}
}

/* We're ready to go! */

0 comments on commit 7555833

Please sign in to comment.