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SDL_blendline.c
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/*
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"
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#include "SDL_draw.h"
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static int
SDL_BlendLine_RGB555(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
unsigned inva = 0xff - a;
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switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_BLEND_RGB555);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_ADD_RGB555);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_MOD_RGB555);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_RGB555);
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break;
}
return 0;
}
static int
SDL_BlendLine_RGB565(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
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unsigned inva = 0xff - a;
switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_BLEND_RGB565);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_ADD_RGB565);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_MOD_RGB565);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_RGB565);
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return 0;
}
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static int
SDL_BlendLine_RGB888(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
unsigned inva = 0xff - a;
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switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_BLEND_RGB888);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_ADD_RGB888);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_MOD_RGB888);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_RGB888);
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return 0;
}
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static int
SDL_BlendLine_ARGB8888(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
unsigned inva = 0xff - a;
switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_BLEND_ARGB8888);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_ADD_ARGB8888);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_MOD_ARGB8888);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY_ARGB8888);
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break;
}
return 0;
}
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static int
SDL_BlendLine_RGB(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
SDL_PixelFormat *fmt = dst->format;
unsigned inva = 0xff - a;
switch (fmt->BytesPerPixel) {
case 2:
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switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY2_BLEND_RGB);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY2_ADD_RGB);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY2_MOD_RGB);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY2_RGB);
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break;
}
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return 0;
case 4:
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switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_BLEND_RGB);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_ADD_RGB);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_MOD_RGB);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_RGB);
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break;
}
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return 0;
default:
SDL_Unsupported();
return -1;
}
}
static int
SDL_BlendLine_RGBA(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
SDL_PixelFormat *fmt = dst->format;
unsigned inva = 0xff - a;
switch (fmt->BytesPerPixel) {
case 4:
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switch (blendMode) {
case SDL_BLENDMODE_BLEND:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_BLEND_RGBA);
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break;
case SDL_BLENDMODE_ADD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_ADD_RGBA);
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break;
case SDL_BLENDMODE_MOD:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_MOD_RGBA);
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break;
default:
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DRAWLINE(x1, y1, x2, y2, DRAW_SETPIXELXY4_RGBA);
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break;
}
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return 0;
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default:
SDL_Unsupported();
return -1;
}
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}
int
SDL_BlendLine(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
/* This function doesn't work on surfaces < 8 bpp */
if (dst->format->BitsPerPixel < 8) {
SDL_SetError("SDL_BlendLine(): Unsupported surface format");
return (-1);
}
/* Perform clipping */
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if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
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return (0);
}
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if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
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r = DRAW_MUL(r, a);
g = DRAW_MUL(g, a);
b = DRAW_MUL(b, a);
}
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switch (dst->format->BitsPerPixel) {
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case 15:
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switch (dst->format->Rmask) {
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case 0x7C00:
return SDL_BlendLine_RGB555(dst, x1, y1, x2, y2, blendMode, r, g,
b, a);
}
break;
case 16:
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switch (dst->format->Rmask) {
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case 0xF800:
return SDL_BlendLine_RGB565(dst, x1, y1, x2, y2, blendMode, r, g,
b, a);
}
break;
case 32:
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switch (dst->format->Rmask) {
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case 0x00FF0000:
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if (!dst->format->Amask) {
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return SDL_BlendLine_RGB888(dst, x1, y1, x2, y2, blendMode, r,
g, b, a);
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} else {
return SDL_BlendLine_ARGB8888(dst, x1, y1, x2, y2, blendMode,
r, g, b, a);
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}
break;
}
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default:
break;
}
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if (!dst->format->Amask) {
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return SDL_BlendLine_RGB(dst, x1, y1, x2, y2, blendMode, r, g, b, a);
} else {
return SDL_BlendLine_RGBA(dst, x1, y1, x2, y2, blendMode, r, g, b, a);
}
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int
SDL_BlendLines(SDL_Surface * dst, const SDL_Point * points, int count,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
int i;
int x1, y1;
int x2, y2;
int (*func)(SDL_Surface * dst, int x1, int y1, int x2, int y2,
int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a) = NULL;
int status = 0;
if (!dst) {
SDL_SetError("Passed NULL destination surface");
return -1;
}
/* This function doesn't work on surfaces < 8 bpp */
if (dst->format->BitsPerPixel < 8) {
SDL_SetError("SDL_BlendLines(): Unsupported surface format");
return -1;
}
if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
r = DRAW_MUL(r, a);
g = DRAW_MUL(g, a);
b = DRAW_MUL(b, a);
}
/* FIXME: Does this function pointer slow things down significantly? */
switch (dst->format->BitsPerPixel) {
case 15:
switch (dst->format->Rmask) {
case 0x7C00:
func = SDL_BlendLine_RGB555;
}
break;
case 16:
switch (dst->format->Rmask) {
case 0xF800:
func = SDL_BlendLine_RGB565;
}
break;
case 32:
switch (dst->format->Rmask) {
case 0x00FF0000:
if (!dst->format->Amask) {
func = SDL_BlendLine_RGB888;
} else {
func = SDL_BlendLine_ARGB8888;
}
break;
}
default:
break;
}
if (!func) {
if (!dst->format->Amask) {
func = SDL_BlendLine_RGB;
} else {
func = SDL_BlendLine_RGBA;
}
}
for (i = 1; i < count; ++i) {
x1 = points[i-1].x;
y1 = points[i-1].y;
x2 = points[i].x;
y2 = points[i].y;
/* Perform clipping */
/* FIXME: We don't actually want to clip, as it may change line slope */
if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
continue;
}
status = func(dst, x1, y1, x2, y2, blendMode, r, g, b, a);
}
return status;
}
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/* vi: set ts=4 sw=4 expandtab: */