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annotate src/video/SDL_drawline.c @ 3542:97eae5a705f9

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Make sure we fully clip the first point before starting to adjust the second point.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 11 Dec 2009 09:57:54 +0000
parents 0267b8b1595c
children c8bed77b0386
rev   line source
2888
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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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
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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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
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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7 License as published by the Free Software Foundation; either
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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8 version 2.1 of the License, or (at your option) any later version.
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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9
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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10 This library is distributed in the hope that it will be useful,
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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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
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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13 Lesser General Public License for more details.
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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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
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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16 License along with this library; if not, write to the Free Software
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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18
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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19 Sam Lantinga
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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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
2898
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
2901
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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 if (!dst) {
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31 SDL_SetError("Passed NULL destination surface");
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32 return -1;
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33 }
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34
2888
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35 /* This function doesn't work on surfaces < 8 bpp */
32e8bbba1e94 Added stubs for software implementations of blending fills and line drawing
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36 if (dst->format->BitsPerPixel < 8) {
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37 SDL_SetError("SDL_DrawLine(): Unsupported surface format");
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38 return -1;
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39 }
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40
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41 /* Perform clipping */
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42 /* FIXME: We don't actually want to clip, as it may change line slope */
2910
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43 if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
2909
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44 return (0);
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45 }
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46
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47 switch (dst->format->BytesPerPixel) {
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48 case 1:
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49 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL1);
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50 break;
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51 case 2:
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52 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL2);
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53 break;
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54 case 3:
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55 SDL_Unsupported();
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56 return -1;
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57 case 4:
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58 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL4);
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59 break;
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60 }
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61 return 0;
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62 }
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63
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64 int
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65 SDL_DrawLines(SDL_Surface * dst, const SDL_Point * points, int count,
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66 Uint32 color)
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67 {
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68 int i;
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69
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70 if (!dst) {
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71 SDL_SetError("Passed NULL destination surface");
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72 return -1;
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73 }
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74
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75 /* This function doesn't work on surfaces < 8 bpp */
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76 if (dst->format->BitsPerPixel < 8) {
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77 SDL_SetError("SDL_DrawLine(): Unsupported surface format");
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78 return -1;
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79 }
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80
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81 if (count < 2) {
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82 return 0;
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83 }
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84
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85 for (i = 1; i < count; ++i) {
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86 int x1 = points[i-1].x;
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87 int y1 = points[i-1].y;
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88 int x2 = points[i].x;
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89 int y2 = points[i].y;
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90
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91 /* Perform clipping */
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92 /* FIXME: We don't actually want to clip, as it may change line slope */
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93 if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
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94 continue;
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95 }
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96
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97 switch (dst->format->BytesPerPixel) {
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98 case 1:
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99 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL1);
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100 break;
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101 case 2:
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102 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL2);
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103 break;
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104 case 3:
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105 SDL_Unsupported();
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106 return -1;
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107 case 4:
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108 DRAWLINE(x1, y1, x2, y2, DRAW_FASTSETPIXEL4);
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109 break;
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110 }
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111 }
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112 return 0;
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113 }
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114
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115 /* vi: set ts=4 sw=4 expandtab: */