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annotate src/video/SDL_drawline.c @ 3363:90aec03bf9fd

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Fixed bug #627 Increased accuracy of alpha blend calculation
author Sam Lantinga <slouken@libsdl.org>
date Sat, 10 Oct 2009 07:48:57 +0000
parents 27d8b12e0e8e
children 0267b8b1595c
rev   line source
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997-2009 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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6 modify it under the terms of the GNU Lesser General Public
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7 License as published by the Free Software Foundation; either
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8 version 2.1 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Lesser General Public License for more details.
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14
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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15 You should have received a copy of the GNU Lesser General Public
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16 License along with this library; if not, write to the Free Software
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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18
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19 Sam Lantinga
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20 slouken@libsdl.org
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21 */
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22 #include "SDL_config.h"
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23
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e40448bc7727 Share code between fill and line drawing
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24 #include "SDL_draw.h"
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25
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26
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27 int
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28 SDL_DrawLine(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color)
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29 {
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30 /* This function doesn't work on surfaces < 8 bpp */
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31 if (dst->format->BitsPerPixel < 8) {
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32 SDL_SetError("SDL_DrawLine(): Unsupported surface format");
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33 return (-1);
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34 }
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35
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36 /* Perform clipping */
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37 if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
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38 return (0);
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39 }
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40
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41 switch (dst->format->BytesPerPixel) {
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42 case 1:
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43 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL1);
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44 break;
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45 case 2:
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46 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL2);
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47 break;
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48 case 3:
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49 SDL_Unsupported();
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50 return -1;
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51 case 4:
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52 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL4);
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53 break;
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54 }
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55 return 0;
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56 }
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57
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58 /* vi: set ts=4 sw=4 expandtab: */