/*

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@libsdl.org

*/

#ifdef SAVE_RCSID

static char rcsid =

"@(#) $Id$";

#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=128 special case */

static void BlitRGBtoRGBSurfaceAlpha128(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 s = *srcp++;

Uint32 d = *dstp;

*dstp++ = ((((s & 0x00fefefe) + (d & 0x00fefefe)) >> 1)

+ (s & d & 0x00010101)) | 0xff000000;

}, width);

srcp += srcskip;

dstp += dstskip;

}

}

/* fast RGB888->(A)RGB888 blending with surface alpha */

static void BlitRGBtoRGBSurfaceAlpha(SDL_BlitInfo *info)

{

unsigned alpha = info->src->alpha;

if(alpha == 128) {

BlitRGBtoRGBSurfaceAlpha128(info);

} else {

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 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;

}

}

/* 16bpp special case for per-surface alpha=50%: blend 2 pixels in parallel */

/* blend a single 16 bit pixel at 50% */

#define BLEND16_50(d, s, mask) \

((((s & mask) + (d & mask)) >> 1) + (s & d & (~mask & 0xffff)))

/* blend two 16 bit pixels at 50% */

#define BLEND2x16_50(d, s, mask) \

(((s & (mask | mask << 16)) >> 1) + ((d & (mask | mask << 16)) >> 1) \

+ (s & d & (~(mask | mask << 16))))

static void Blit16to16SurfaceAlpha128(SDL_BlitInfo *info, Uint16 mask)

{

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;

while(height--) {

if(((unsigned long)srcp ^ (unsigned long)dstp) & 2) {

/*

* Source and destination not aligned, pipeline it.

* This is mostly a win for big blits but no loss for

* small ones

*/

Uint32 prev_sw;

int w = width;

/* handle odd destination */

if((unsigned long)dstp & 2) {

Uint16 d = *dstp, s = *srcp;

*dstp = BLEND16_50(d, s, mask);

dstp++;

srcp++;

w--;

}

srcp++; /* srcp is now 32-bit aligned */

/* bootstrap pipeline with first halfword */

prev_sw = ((Uint32 *)srcp)[-1];

while(w > 1) {

Uint32 sw, dw, s;

sw = *(Uint32 *)srcp;

dw = *(Uint32 *)dstp;

if(SDL_BYTEORDER == SDL_BIG_ENDIAN)

s = (prev_sw << 16) + (sw >> 16);

else

s = (prev_sw >> 16) + (sw << 16);

prev_sw = sw;

*(Uint32 *)dstp = BLEND2x16_50(dw, s, mask);

dstp += 2;

srcp += 2;

w -= 2;

}

/* final pixel if any */

if(w) {

Uint16 d = *dstp, s;

if(SDL_BYTEORDER == SDL_BIG_ENDIAN)

s = prev_sw;

else

s = prev_sw >> 16;

*dstp = BLEND16_50(d, s, mask);

srcp++;

dstp++;

}

srcp += srcskip - 1;

dstp += dstskip;

} else {

/* source and destination are aligned */

int w = width;

/* first odd pixel? */

if((unsigned long)srcp & 2) {

Uint16 d = *dstp, s = *srcp;

*dstp = BLEND16_50(d, s, mask);

srcp++;

dstp++;

w--;

}

/* srcp and dstp are now 32-bit aligned */

while(w > 1) {

Uint32 sw = *(Uint32 *)srcp;

Uint32 dw = *(Uint32 *)dstp;

*(Uint32 *)dstp = BLEND2x16_50(dw, sw, mask);

srcp += 2;

dstp += 2;

w -= 2;

}

/* last odd pixel? */

if(w) {

Uint16 d = *dstp, s = *srcp;

*dstp = BLEND16_50(d, s, mask);

srcp++;

dstp++;

}

srcp += srcskip;

dstp += dstskip;

}

}

}

/* fast RGB565->RGB565 blending with surface alpha */

static void Blit565to565SurfaceAlpha(SDL_BlitInfo *info)

{

unsigned alpha = info->src->alpha;

if(alpha == 128) {

Blit16to16SurfaceAlpha128(info, 0xf7de);

} else {

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;

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)

{

unsigned alpha = info->src->alpha; /* downscale alpha to 5 bits */

if(alpha == 128) {

Blit16to16SurfaceAlpha128(info, 0xfbde);

} else {

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;

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;

}

}

}