SDL_drawline.c (6529B)
1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org> 4 5 This software is provided 'as-is', without any express or implied 6 warranty. In no event will the authors be held liable for any damages 7 arising from the use of this software. 8 9 Permission is granted to anyone to use this software for any purpose, 10 including commercial applications, and to alter it and redistribute it 11 freely, subject to the following restrictions: 12 13 1. The origin of this software must not be misrepresented; you must not 14 claim that you wrote the original software. If you use this software 15 in a product, an acknowledgment in the product documentation would be 16 appreciated but is not required. 17 2. Altered source versions must be plainly marked as such, and must not be 18 misrepresented as being the original software. 19 3. This notice may not be removed or altered from any source distribution. 20 */ 21 #include "../../SDL_internal.h" 22 23 #if SDL_VIDEO_RENDER_SW && !SDL_RENDER_DISABLED 24 25 #include "SDL_draw.h" 26 #include "SDL_drawline.h" 27 #include "SDL_drawpoint.h" 28 29 30 static void 31 SDL_DrawLine1(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color, 32 SDL_bool draw_end) 33 { 34 if (y1 == y2) { 35 int length; 36 int pitch = (dst->pitch / dst->format->BytesPerPixel); 37 Uint8 *pixel; 38 if (x1 <= x2) { 39 pixel = (Uint8 *)dst->pixels + y1 * pitch + x1; 40 length = draw_end ? (x2-x1+1) : (x2-x1); 41 } else { 42 pixel = (Uint8 *)dst->pixels + y1 * pitch + x2; 43 if (!draw_end) { 44 ++pixel; 45 } 46 length = draw_end ? (x1-x2+1) : (x1-x2); 47 } 48 SDL_memset(pixel, color, length); 49 } else if (x1 == x2) { 50 VLINE(Uint8, DRAW_FASTSETPIXEL1, draw_end); 51 } else if (ABS(x1 - x2) == ABS(y1 - y2)) { 52 DLINE(Uint8, DRAW_FASTSETPIXEL1, draw_end); 53 } else { 54 BLINE(x1, y1, x2, y2, DRAW_FASTSETPIXELXY1, draw_end); 55 } 56 } 57 58 static void 59 SDL_DrawLine2(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color, 60 SDL_bool draw_end) 61 { 62 if (y1 == y2) { 63 HLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end); 64 } else if (x1 == x2) { 65 VLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end); 66 } else if (ABS(x1 - x2) == ABS(y1 - y2)) { 67 DLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end); 68 } else { 69 Uint8 _r, _g, _b, _a; 70 const SDL_PixelFormat * fmt = dst->format; 71 SDL_GetRGBA(color, fmt, &_r, &_g, &_b, &_a); 72 if (fmt->Rmask == 0x7C00) { 73 AALINE(x1, y1, x2, y2, 74 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY_BLEND_RGB555, 75 draw_end); 76 } else if (fmt->Rmask == 0xF800) { 77 AALINE(x1, y1, x2, y2, 78 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY_BLEND_RGB565, 79 draw_end); 80 } else { 81 AALINE(x1, y1, x2, y2, 82 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY2_BLEND_RGB, 83 draw_end); 84 } 85 } 86 } 87 88 static void 89 SDL_DrawLine4(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color, 90 SDL_bool draw_end) 91 { 92 if (y1 == y2) { 93 HLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end); 94 } else if (x1 == x2) { 95 VLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end); 96 } else if (ABS(x1 - x2) == ABS(y1 - y2)) { 97 DLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end); 98 } else { 99 Uint8 _r, _g, _b, _a; 100 const SDL_PixelFormat * fmt = dst->format; 101 SDL_GetRGBA(color, fmt, &_r, &_g, &_b, &_a); 102 if (fmt->Rmask == 0x00FF0000) { 103 if (!fmt->Amask) { 104 AALINE(x1, y1, x2, y2, 105 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY_BLEND_RGB888, 106 draw_end); 107 } else { 108 AALINE(x1, y1, x2, y2, 109 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY_BLEND_ARGB8888, 110 draw_end); 111 } 112 } else { 113 AALINE(x1, y1, x2, y2, 114 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY4_BLEND_RGB, 115 draw_end); 116 } 117 } 118 } 119 120 typedef void (*DrawLineFunc) (SDL_Surface * dst, 121 int x1, int y1, int x2, int y2, 122 Uint32 color, SDL_bool draw_end); 123 124 static DrawLineFunc 125 SDL_CalculateDrawLineFunc(const SDL_PixelFormat * fmt) 126 { 127 switch (fmt->BytesPerPixel) { 128 case 1: 129 if (fmt->BitsPerPixel < 8) { 130 break; 131 } 132 return SDL_DrawLine1; 133 case 2: 134 return SDL_DrawLine2; 135 case 4: 136 return SDL_DrawLine4; 137 } 138 return NULL; 139 } 140 141 int 142 SDL_DrawLine(SDL_Surface * dst, int x1, int y1, int x2, int y2, Uint32 color) 143 { 144 DrawLineFunc func; 145 146 if (!dst) { 147 return SDL_SetError("SDL_DrawLine(): Passed NULL destination surface"); 148 } 149 150 func = SDL_CalculateDrawLineFunc(dst->format); 151 if (!func) { 152 return SDL_SetError("SDL_DrawLine(): Unsupported surface format"); 153 } 154 155 /* Perform clipping */ 156 /* FIXME: We don't actually want to clip, as it may change line slope */ 157 if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) { 158 return 0; 159 } 160 161 func(dst, x1, y1, x2, y2, color, SDL_TRUE); 162 return 0; 163 } 164 165 int 166 SDL_DrawLines(SDL_Surface * dst, const SDL_Point * points, int count, 167 Uint32 color) 168 { 169 int i; 170 int x1, y1; 171 int x2, y2; 172 SDL_bool draw_end; 173 DrawLineFunc func; 174 175 if (!dst) { 176 return SDL_SetError("SDL_DrawLines(): Passed NULL destination surface"); 177 } 178 179 func = SDL_CalculateDrawLineFunc(dst->format); 180 if (!func) { 181 return SDL_SetError("SDL_DrawLines(): Unsupported surface format"); 182 } 183 184 for (i = 1; i < count; ++i) { 185 x1 = points[i-1].x; 186 y1 = points[i-1].y; 187 x2 = points[i].x; 188 y2 = points[i].y; 189 190 /* Perform clipping */ 191 /* FIXME: We don't actually want to clip, as it may change line slope */ 192 if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) { 193 continue; 194 } 195 196 /* Draw the end if it was clipped */ 197 draw_end = (x2 != points[i].x || y2 != points[i].y); 198 199 func(dst, x1, y1, x2, y2, color, draw_end); 200 } 201 if (points[0].x != points[count-1].x || points[0].y != points[count-1].y) { 202 SDL_DrawPoint(dst, points[count-1].x, points[count-1].y, color); 203 } 204 return 0; 205 } 206 207 #endif /* SDL_VIDEO_RENDER_SW && !SDL_RENDER_DISABLED */ 208 209 /* vi: set ts=4 sw=4 expandtab: */