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SDL_blit_A.c
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2001-04-29
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
slouken@devolution.com
*/
#ifdef SAVE_RCSID
static char rcsid =
"@(#) $Id: SDL_blit_A.c,v 1.3.2.9 2001/03/04 17:36:19 hercules Exp $";
#endif
#include <stdio.h>
#include "SDL_types.h"
#include "SDL_video.h"
#include "SDL_blit.h"
/* Functions to perform alpha blended blitting */
/* N->1 blending with per-surface alpha */
static void BlitNto1SurfaceAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
Uint8 *palmap = info->table;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp = srcfmt->BytesPerPixel;
const unsigned A = srcfmt->alpha;
while ( height-- ) {
DUFFS_LOOP4(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned dR;
unsigned dG;
unsigned dB;
DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
dR = dstfmt->palette->colors[*dst].r;
dG = dstfmt->palette->colors[*dst].g;
dB = dstfmt->palette->colors[*dst].b;
ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
dR &= 0xff;
dG &= 0xff;
dB &= 0xff;
/* Pack RGB into 8bit pixel */
if ( palmap == NULL ) {
*dst =((dR>>5)<<(3+2))|
((dG>>5)<<(2))|
((dB>>6)<<(0));
} else {
*dst = palmap[((dR>>5)<<(3+2))|
((dG>>5)<<(2)) |
((dB>>6)<<(0))];
}
dst++;
src += srcbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
/* N->1 blending with pixel alpha */
static void BlitNto1PixelAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
Uint8 *palmap = info->table;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp = srcfmt->BytesPerPixel;
/* FIXME: fix alpha bit field expansion here too? */
while ( height-- ) {
DUFFS_LOOP4(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned sA;
unsigned dR;
unsigned dG;
unsigned dB;
DISEMBLE_RGBA(src,srcbpp,srcfmt,pixel,sR,sG,sB,sA);
dR = dstfmt->palette->colors[*dst].r;
dG = dstfmt->palette->colors[*dst].g;
dB = dstfmt->palette->colors[*dst].b;
ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
dR &= 0xff;
dG &= 0xff;
dB &= 0xff;
/* Pack RGB into 8bit pixel */
if ( palmap == NULL ) {
*dst =((dR>>5)<<(3+2))|
((dG>>5)<<(2))|
((dB>>6)<<(0));
} else {
*dst = palmap[((dR>>5)<<(3+2))|
((dG>>5)<<(2)) |
((dB>>6)<<(0)) ];
}
dst++;
src += srcbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
/* colorkeyed N->1 blending with per-surface alpha */
static void BlitNto1SurfaceAlphaKey(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
Uint8 *palmap = info->table;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp = srcfmt->BytesPerPixel;
Uint32 ckey = srcfmt->colorkey;
const int A = srcfmt->alpha;
while ( height-- ) {
DUFFS_LOOP(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned dR;
unsigned dG;
unsigned dB;
DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
if ( pixel != ckey ) {
dR = dstfmt->palette->colors[*dst].r;
dG = dstfmt->palette->colors[*dst].g;
dB = dstfmt->palette->colors[*dst].b;
ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
dR &= 0xff;
dG &= 0xff;
dB &= 0xff;
/* Pack RGB into 8bit pixel */
if ( palmap == NULL ) {
*dst =((dR>>5)<<(3+2))|
((dG>>5)<<(2)) |
((dB>>6)<<(0));
} else {
*dst = palmap[((dR>>5)<<(3+2))|
((dG>>5)<<(2)) |
((dB>>6)<<(0)) ];
}
}
dst++;
src += srcbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
/* fast RGB888->(A)RGB888 blending with surface alpha */
static void BlitRGBtoRGBSurfaceAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint32 *srcp = (Uint32 *)info->s_pixels;
int srcskip = info->s_skip >> 2;
Uint32 *dstp = (Uint32 *)info->d_pixels;
int dstskip = info->d_skip >> 2;
SDL_PixelFormat *srcfmt = info->src;
unsigned alpha = srcfmt->alpha;
while(height--) {
DUFFS_LOOP4({
Uint32 s;
Uint32 d;
Uint32 s1;
Uint32 d1;
s = *srcp;
d = *dstp;
s1 = s & 0xff00ff;
d1 = d & 0xff00ff;
d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;
s &= 0xff00;
d &= 0xff00;
d = (d + ((s - d) * alpha >> 8)) & 0xff00;
*dstp = d1 | d | 0xff000000;
++srcp;
++dstp;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* fast ARGB888->(A)RGB888 blending with pixel alpha */
static void BlitRGBtoRGBPixelAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint32 *srcp = (Uint32 *)info->s_pixels;
int srcskip = info->s_skip >> 2;
Uint32 *dstp = (Uint32 *)info->d_pixels;
int dstskip = info->d_skip >> 2;
while(height--) {
DUFFS_LOOP4({
Uint32 dalpha;
Uint32 d;
Uint32 s1;
Uint32 d1;
Uint32 s = *srcp;
Uint32 alpha = s >> 24;
/* FIXME: Here we special-case opaque alpha since the
compositioning used (>>8 instead of /255) doesn't handle
it correctly. Also special-case alpha=0 for speed?
Benchmark this! */
if(alpha == SDL_ALPHA_OPAQUE) {
*dstp = (s & 0x00ffffff) | (*dstp & 0xff000000);
} else {
/*
* take out the middle component (green), and process
* the other two in parallel. One multiply less.
*/
d = *dstp;
dalpha = d & 0xff000000;
s1 = s & 0xff00ff;
d1 = d & 0xff00ff;
d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;
s &= 0xff00;
d &= 0xff00;
d = (d + ((s - d) * alpha >> 8)) & 0xff00;
*dstp = d1 | d | dalpha;
}
++srcp;
++dstp;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* fast RGB565->RGB565 blending with surface alpha */
static void Blit565to565SurfaceAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint16 *srcp = (Uint16 *)info->s_pixels;
int srcskip = info->s_skip >> 1;
Uint16 *dstp = (Uint16 *)info->d_pixels;
int dstskip = info->d_skip >> 1;
unsigned alpha = info->src->alpha >> 3; /* downscale alpha to 5 bits */
while(height--) {
DUFFS_LOOP4({
Uint32 s = *srcp++;
Uint32 d = *dstp;
/*
* shift out the middle component (green) to the high 16
* bits, and process all three RGB components at the same
* time.
*/
s = (s | s << 16) & 0x07e0f81f;
d = (d | d << 16) & 0x07e0f81f;
d += (s - d) * alpha >> 5;
d &= 0x07e0f81f;
*dstp++ = d | d >> 16;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* fast RGB555->RGB555 blending with surface alpha */
static void Blit555to555SurfaceAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint16 *srcp = (Uint16 *)info->s_pixels;
int srcskip = info->s_skip >> 1;
Uint16 *dstp = (Uint16 *)info->d_pixels;
int dstskip = info->d_skip >> 1;
unsigned alpha = info->src->alpha >> 3; /* downscale alpha to 5 bits */
while(height--) {
DUFFS_LOOP4({
Uint32 s = *srcp++;
Uint32 d = *dstp;
/*
* shift out the middle component (green) to the high 16
* bits, and process all three RGB components at the same
* time.
*/
s = (s | s << 16) & 0x03e07c1f;
d = (d | d << 16) & 0x03e07c1f;
d += (s - d) * alpha >> 5;
d &= 0x03e07c1f;
*dstp++ = d | d >> 16;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* fast ARGB8888->RGB565 blending with pixel alpha */
static void BlitARGBto565PixelAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint32 *srcp = (Uint32 *)info->s_pixels;
int srcskip = info->s_skip >> 2;
Uint16 *dstp = (Uint16 *)info->d_pixels;
int dstskip = info->d_skip >> 1;
while(height--) {
DUFFS_LOOP4({
Uint32 s = *srcp;
unsigned alpha = s >> 27; /* downscale alpha to 5 bits */
/* FIXME: Here we special-case opaque alpha since the
compositioning used (>>8 instead of /255) doesn't handle
it correctly. Also special-case alpha=0 for speed?
Benchmark this! */
if(alpha == (SDL_ALPHA_OPAQUE >> 3)) {
*dstp = (s >> 8 & 0xf800) + (s >> 5 & 0x7e0)
+ (s >> 3 & 0x1f);
} else {
Uint32 d = *dstp;
/*
* convert source and destination to G0RAB65565
* and blend all components at the same time
*/
s = ((s & 0xfc00) << 11) + (s >> 8 & 0xf800)
+ (s >> 3 & 0x1f);
d = (d | d << 16) & 0x07e0f81f;
d += (s - d) * alpha >> 5;
d &= 0x07e0f81f;
*dstp = d | d >> 16;
}
srcp++;
dstp++;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* fast ARGB8888->RGB555 blending with pixel alpha */
static void BlitARGBto555PixelAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint32 *srcp = (Uint32 *)info->s_pixels;
int srcskip = info->s_skip >> 2;
Uint16 *dstp = (Uint16 *)info->d_pixels;
int dstskip = info->d_skip >> 1;
while(height--) {
DUFFS_LOOP4({
unsigned alpha;
Uint32 s = *srcp;
alpha = s >> 27; /* downscale alpha to 5 bits */
/* FIXME: Here we special-case opaque alpha since the
compositioning used (>>8 instead of /255) doesn't handle
it correctly. Also special-case alpha=0 for speed?
Benchmark this! */
if(alpha == (SDL_ALPHA_OPAQUE >> 3)) {
*dstp = (s >> 9 & 0x7c00) + (s >> 6 & 0x3e0)
+ (s >> 3 & 0x1f);
} else {
Uint32 d = *dstp;
/*
* convert source and destination to G0RAB65565
* and blend all components at the same time
*/
s = ((s & 0xf800) << 10) + (s >> 9 & 0x7c00)
+ (s >> 3 & 0x1f);
d = (d | d << 16) & 0x03e07c1f;
d += (s - d) * alpha >> 5;
d &= 0x03e07c1f;
*dstp = d | d >> 16;
}
srcp++;
dstp++;
}, width);
srcp += srcskip;
dstp += dstskip;
}
}
/* General (slow) N->N blending with per-surface alpha */
static void BlitNtoNSurfaceAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp = srcfmt->BytesPerPixel;
int dstbpp = dstfmt->BytesPerPixel;
unsigned sA = srcfmt->alpha;
unsigned dA = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
while ( height-- ) {
DUFFS_LOOP4(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned dR;
unsigned dG;
unsigned dB;
DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
DISEMBLE_RGB(dst, dstbpp, dstfmt, pixel, dR, dG, dB);
ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
src += srcbpp;
dst += dstbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
/* General (slow) colorkeyed N->N blending with per-surface alpha */
static void BlitNtoNSurfaceAlphaKey(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
Uint32 ckey = srcfmt->colorkey;
int srcbpp = srcfmt->BytesPerPixel;
int dstbpp = dstfmt->BytesPerPixel;
unsigned sA = srcfmt->alpha;
unsigned dA = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
while ( height-- ) {
DUFFS_LOOP4(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned dR;
unsigned dG;
unsigned dB;
RETRIEVE_RGB_PIXEL(src, srcbpp, pixel);
if(pixel != ckey) {
RGB_FROM_PIXEL(pixel, srcfmt, sR, sG, sB);
DISEMBLE_RGB(dst, dstbpp, dstfmt, pixel, dR, dG, dB);
ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
}
src += srcbpp;
dst += dstbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
/* General (slow) N->N blending with pixel alpha */
static void BlitNtoNPixelAlpha(SDL_BlitInfo *info)
{
int width = info->d_width;
int height = info->d_height;
Uint8 *src = info->s_pixels;
int srcskip = info->s_skip;
Uint8 *dst = info->d_pixels;
int dstskip = info->d_skip;
SDL_PixelFormat *srcfmt = info->src;
SDL_PixelFormat *dstfmt = info->dst;
int srcbpp;
int dstbpp;
/* Set up some basic variables */
srcbpp = srcfmt->BytesPerPixel;
dstbpp = dstfmt->BytesPerPixel;
/* FIXME: for 8bpp source alpha, this doesn't get opaque values
quite right. for <8bpp source alpha, it gets them very wrong
(check all macros!)
It is unclear whether there is a good general solution that doesn't
need a branch (or a divide). */
while ( height-- ) {
DUFFS_LOOP4(
{
Uint32 pixel;
unsigned sR;
unsigned sG;
unsigned sB;
unsigned dR;
unsigned dG;
unsigned dB;
unsigned sA;
unsigned dA;
DISEMBLE_RGBA(src, srcbpp, srcfmt, pixel, sR, sG, sB, sA);
DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixel, dR, dG, dB, dA);
ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
src += srcbpp;
dst += dstbpp;
},
width);
src += srcskip;
dst += dstskip;
}
}
SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
{
SDL_PixelFormat *sf = surface->format;
SDL_PixelFormat *df = surface->map->dst->format;
if(sf->Amask == 0) {
if((surface->flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY) {
if(df->BytesPerPixel == 1)
return BlitNto1SurfaceAlphaKey;
else
return BlitNtoNSurfaceAlphaKey;
} else {
/* Per-surface alpha blits */
switch(df->BytesPerPixel) {
case 1:
return BlitNto1SurfaceAlpha;
case 2:
if(surface->map->identity) {
if(df->Gmask == 0x7e0)
return Blit565to565SurfaceAlpha;
else if(df->Gmask == 0x3e0)
return Blit555to555SurfaceAlpha;
}
return BlitNtoNSurfaceAlpha;
case 4:
if(sf->Rmask == df->Rmask
&& sf->Gmask == df->Gmask
&& sf->Bmask == df->Bmask
&& (sf->Rmask | sf->Gmask | sf->Bmask) == 0xffffff
&& sf->BytesPerPixel == 4)
return BlitRGBtoRGBSurfaceAlpha;
else
return BlitNtoNSurfaceAlpha;
case 3:
default:
return BlitNtoNSurfaceAlpha;
}
}
} else {
/* Per-pixel alpha blits */
switch(df->BytesPerPixel) {
case 1:
return BlitNto1PixelAlpha;
case 2:
if(sf->BytesPerPixel == 4 && sf->Amask == 0xff000000
&& sf->Gmask == 0xff00
&& ((sf->Rmask == 0xff && df->Rmask == 0x1f)
|| (sf->Bmask == 0xff && df->Bmask == 0x1f))) {
if(df->Gmask == 0x7e0)
return BlitARGBto565PixelAlpha;
else if(df->Gmask == 0x3e0)
return BlitARGBto555PixelAlpha;
}
return BlitNtoNPixelAlpha;
case 4:
if(sf->Amask == 0xff000000
&& sf->Rmask == df->Rmask
&& sf->Gmask == df->Gmask
&& sf->Bmask == df->Bmask
&& sf->BytesPerPixel == 4)
return BlitRGBtoRGBPixelAlpha;
return BlitNtoNPixelAlpha;
case 3:
default:
return BlitNtoNPixelAlpha;
}
}
}