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Fixed alpha blending textures with the GDI renderer

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slouken committed Feb 7, 2009
1 parent d4eef17 commit 4730035cf348d99a0d26b9eacc0eb6defab13583
Showing with 165 additions and 4 deletions.
  1. +6 −0 include/SDL_pixels.h
  2. +58 −0 src/video/SDL_alphamult.c
  3. +36 −0 src/video/SDL_alphamult.h
  4. +19 −0 src/video/SDL_blit.h
  5. +46 −4 src/video/win32/SDL_gdirender.c
@@ -117,6 +117,12 @@ enum
(SDL_PIXELTYPE(format) == SDL_PIXELTYPE_INDEX4) || \
(SDL_PIXELTYPE(format) == SDL_PIXELTYPE_INDEX8))

#define SDL_ISPIXELFORMAT_ALPHA(format) \
((SDL_PIXELORDER(format) == SDL_PACKEDORDER_ARGB) || \
(SDL_PIXELORDER(format) == SDL_PACKEDORDER_RGBA) || \
(SDL_PIXELORDER(format) == SDL_PACKEDORDER_ABGR) || \
(SDL_PIXELORDER(format) == SDL_PACKEDORDER_BGRA))

#define SDL_ISPIXELFORMAT_FOURCC(format) \
((format) && !((format) & 0x80000000))

@@ -0,0 +1,58 @@
/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2009 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#include "SDL_config.h"

#include "SDL_blit.h"
#include "SDL_alphamult.h"

/* Functions to pre-multiply the alpha channel into the color channels */

#define DEFINE_PREMULTIPLY_FUNC(fmt) \
void \
SDL_PreMultiplyAlpha##fmt(int w, int h, Uint32 *pixels, int pitch) \
{ \
pitch /= 4; \
while (h--) { \
int n; \
Uint32 *row = pixels; \
Uint32 pixel; \
unsigned r, g, b, a; \
\
for (n = w; n--; ) { \
pixel = *row; \
RGBA_FROM_##fmt(pixel, r, g, b, a); \
r = (r * a) / 255; \
g = (g * a) / 255; \
b = (b * a) / 255; \
fmt##_FROM_RGBA(*row, r, g, b, a); \
++row; \
} \
pixels += pitch; \
} \
}

DEFINE_PREMULTIPLY_FUNC(ARGB8888)
DEFINE_PREMULTIPLY_FUNC(RGBA8888)
DEFINE_PREMULTIPLY_FUNC(ABGR8888)
DEFINE_PREMULTIPLY_FUNC(BGRA8888)

/* vi: set ts=4 sw=4 expandtab: */
@@ -0,0 +1,36 @@
/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2009 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/

/* Functions to pre-multiply the alpha channel into the color channels */

#define DEFINE_PREMULTIPLY_FUNC(fmt) \
void \
SDL_PreMultiplyAlpha##fmt(int w, int h, Uint32 *pixels, int pitch);

DEFINE_PREMULTIPLY_FUNC(ARGB8888)
DEFINE_PREMULTIPLY_FUNC(RGBA8888)
DEFINE_PREMULTIPLY_FUNC(ABGR8888)
DEFINE_PREMULTIPLY_FUNC(BGRA8888)

#undef DEFINE_PREMULTIPLY_FUNC

/* vi: set ts=4 sw=4 expandtab: */
@@ -240,6 +240,18 @@ do { \
{ \
Pixel = (a<<24)|(r<<16)|(g<<8)|b; \
}
#define RGBA8888_FROM_RGBA(Pixel, r, g, b, a) \
{ \
Pixel = (r<<24)|(g<<16)|(b<<8)|a; \
}
#define ABGR8888_FROM_RGBA(Pixel, r, g, b, a) \
{ \
Pixel = (a<<24)|(b<<16)|(g<<8)|r; \
}
#define BGRA8888_FROM_RGBA(Pixel, r, g, b, a) \
{ \
Pixel = (b<<24)|(g<<16)|(r<<8)|a; \
}
#define ASSEMBLE_RGB(buf, bpp, fmt, r, g, b) \
{ \
switch (bpp) { \
@@ -347,6 +359,13 @@ do { \
b = ((Pixel>>16)&0xFF); \
a = (Pixel>>24); \
}
#define RGBA_FROM_BGRA8888(Pixel, r, g, b, a) \
{ \
r = ((Pixel>>8)&0xFF); \
g = ((Pixel>>16)&0xFF); \
b = (Pixel>>24); \
a = (Pixel&0xFF); \
}
#define DISEMBLE_RGBA(buf, bpp, fmt, Pixel, r, g, b, a) \
do { \
switch (bpp) { \
@@ -26,6 +26,7 @@
#include "SDL_win32video.h"
#include "../SDL_rect_c.h"
#include "../SDL_yuv_sw_c.h"
#include "../SDL_alphamult.h"

/* GDI renderer implementation */

@@ -120,6 +121,7 @@ typedef struct
HBITMAP hbm;
void *pixels;
int pitch;
SDL_bool premultiplied;
} GDI_TextureData;

static void
@@ -463,10 +465,36 @@ GDI_SetTextureAlphaMod(SDL_Renderer * renderer, SDL_Texture * texture)
static int
GDI_SetTextureBlendMode(SDL_Renderer * renderer, SDL_Texture * texture)
{
GDI_TextureData *data = (GDI_TextureData *) texture->driverdata;

switch (texture->blendMode) {
case SDL_BLENDMODE_NONE:
if (data->premultiplied) {
/* Crap, we've lost the original pixel data... *sigh* */
}
return 0;
case SDL_BLENDMODE_MASK:
case SDL_BLENDMODE_BLEND:
if (!data->premultiplied && data->pixels) {
switch (texture->format) {
case SDL_PIXELFORMAT_ARGB8888:
SDL_PreMultiplyAlphaARGB8888(texture->w, texture->h, (Uint32 *)data->pixels, data->pitch);
data->premultiplied = SDL_TRUE;
break;
case SDL_PIXELFORMAT_RGBA8888:
SDL_PreMultiplyAlphaRGBA8888(texture->w, texture->h, (Uint32 *)data->pixels, data->pitch);
data->premultiplied = SDL_TRUE;
break;
case SDL_PIXELFORMAT_ABGR8888:
SDL_PreMultiplyAlphaABGR8888(texture->w, texture->h, (Uint32 *)data->pixels, data->pitch);
data->premultiplied = SDL_TRUE;
break;
case SDL_PIXELFORMAT_BGRA8888:
SDL_PreMultiplyAlphaBGRA8888(texture->w, texture->h, (Uint32 *)data->pixels, data->pitch);
data->premultiplied = SDL_TRUE;
break;
}
}
return 0;
default:
SDL_Unsupported();
@@ -525,6 +553,23 @@ GDI_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
src += pitch;
dst += data->pitch;
}
if (data->premultiplied) {
Uint32 *pixels = (Uint32 *) data->pixels + rect->y * (data->pitch / 4) + rect->x;
switch (texture->format) {
case SDL_PIXELFORMAT_ARGB8888:
SDL_PreMultiplyAlphaARGB8888(rect->w, rect->h, pixels, data->pitch);
break;
case SDL_PIXELFORMAT_RGBA8888:
SDL_PreMultiplyAlphaRGBA8888(rect->w, rect->h, pixels, data->pitch);
break;
case SDL_PIXELFORMAT_ABGR8888:
SDL_PreMultiplyAlphaABGR8888(rect->w, rect->h, pixels, data->pitch);
break;
case SDL_PIXELFORMAT_BGRA8888:
SDL_PreMultiplyAlphaBGRA8888(rect->w, rect->h, pixels, data->pitch);
break;
}
}
} else if (rect->w == texture->w && pitch == data->pitch) {
if (!SetDIBits
(renderdata->window_hdc, data->hbm, rect->y, rect->h, pixels,
@@ -700,16 +745,13 @@ GDI_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
SelectPalette(data->memory_hdc, texturedata->hpal, TRUE);
RealizePalette(data->memory_hdc);
}
if (texture->blendMode & SDL_BLENDMODE_MASK) {
if (texture->blendMode & (SDL_BLENDMODE_MASK|SDL_BLENDMODE_BLEND)) {
BLENDFUNCTION blendFunc = {
AC_SRC_OVER,
0,
texture->a,
AC_SRC_ALPHA
};
/* FIXME: GDI uses premultiplied alpha!
* Once we solve this and somehow support blended drawing we can enable SDL_BLENDMODE_BLEND
*/
if (!AlphaBlend
(data->current_hdc, dstrect->x, dstrect->y, dstrect->w,
dstrect->h, data->memory_hdc, srcrect->x, srcrect->y, srcrect->w,

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