This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
SDL_drawline.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"
#include "SDL_video.h"
#include "SDL_blit.h"
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#define ABS(x) (x < 0 ? -x : x)
#define SWAP(x, y) (x ^= y ^= x ^= y)
#define BRESENHAM(x0, y0, x1, y1, op, color) \
{ \
int deltax, deltay, steep, error, xstep, ystep, x, y; \
\
deltax = ABS(x1 - x0); \
deltay = ABS(y1 - y0); \
steep = deltay > deltax; \
error = deltax / 2; \
if (steep) { \
SWAP(x0, y0); \
SWAP(x1, y1); \
} \
y = y0; \
if (x0 > x1) { \
xstep = -1; \
deltax = -deltax; \
} else { \
xstep = 1; \
} \
if (y0 < y1) { \
ystep = 1; \
} else { \
ystep = -1; \
} \
if (!steep) { \
for (x = x0; x != x1; x += xstep) { \
op(x, y, color); \
error -= deltay; \
if (error < 0) { \
y = y + ystep; \
error += deltax; \
} \
} \
} else { \
for (x = x0; x != x1; x += xstep) { \
op(y, x, color); \
error -= deltay; \
if (error < 0) { \
y = y + ystep; \
error += deltax; \
} \
} \
} \
}
#define SETPIXEL(x, y, type, bpp, color) \
*(type *)(dst->pixels + y * dst->pitch + x * bpp) = (type) color
#define SETPIXEL1(x, y, color) SETPIXEL(x, y, Uint8, 1, color);
#define SETPIXEL2(x, y, color) SETPIXEL(x, y, Uint16, 2, color);
#define SETPIXEL4(x, y, color) SETPIXEL(x, y, Uint32, 4, color);
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SDL_DrawLine(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color)
{
/* This function doesn't work on surfaces < 8 bpp */
if (dst->format->BitsPerPixel < 8) {
SDL_SetError("SDL_DrawLine(): Unsupported surface format");
return (-1);
}
/* Perform clipping */
/* FIXME
if (!SDL_IntersectRect(dstrect, &dst->clip_rect, dstrect)) {
return (0);
}
*/
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switch (dst->format->BytesPerPixel) {
case 1:
BRESENHAM(x1, y1, x2, y2, SETPIXEL1, color);
break;
case 2:
BRESENHAM(x1, y1, x2, y2, SETPIXEL2, color);
break;
case 3:
SDL_Unsupported();
return -1;
case 4:
BRESENHAM(x1, y1, x2, y2, SETPIXEL4, color);
break;
}
return 0;
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}
/* vi: set ts=4 sw=4 expandtab: */