1/*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2025 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#ifdef SDL_VIDEO_RENDER_SW
24
25#include "SDL_draw.h"
26#include "SDL_drawline.h"
27#include "SDL_drawpoint.h"
28
29static void SDL_DrawLine1(SDL_Surface *dst, int x1, int y1, int x2, int y2, Uint32 color,
30 bool draw_end)
31{
32 if (y1 == y2) {
33 int length;
34 int pitch = (dst->pitch / dst->fmt->bytes_per_pixel);
35 Uint8 *pixel;
36 if (x1 <= x2) {
37 pixel = (Uint8 *)dst->pixels + y1 * pitch + x1;
38 length = draw_end ? (x2 - x1 + 1) : (x2 - x1);
39 } else {
40 pixel = (Uint8 *)dst->pixels + y1 * pitch + x2;
41 if (!draw_end) {
42 ++pixel;
43 }
44 length = draw_end ? (x1 - x2 + 1) : (x1 - x2);
45 }
46 SDL_memset(pixel, color, length);
47 } else if (x1 == x2) {
48 VLINE(Uint8, DRAW_FASTSETPIXEL1, draw_end);
49 } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
50 DLINE(Uint8, DRAW_FASTSETPIXEL1, draw_end);
51 } else {
52 BLINE(x1, y1, x2, y2, DRAW_FASTSETPIXELXY1, draw_end);
53 }
54}
55
56static void SDL_DrawLine2(SDL_Surface *dst, int x1, int y1, int x2, int y2, Uint32 color,
57 bool draw_end)
58{
59 if (y1 == y2) {
60 HLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end);
61 } else if (x1 == x2) {
62 VLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end);
63 } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
64 DLINE(Uint16, DRAW_FASTSETPIXEL2, draw_end);
65 } else {
66 Uint8 _r, _g, _b, _a;
67 const SDL_PixelFormatDetails *fmt = dst->fmt;
68 SDL_GetRGBA(color, fmt, dst->palette, &_r, &_g, &_b, &_a);
69 if (fmt->Rmask == 0x7C00) {
70 AALINE(x1, y1, x2, y2,
71 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY_BLEND_RGB555,
72 draw_end);
73 } else if (fmt->Rmask == 0xF800) {
74 AALINE(x1, y1, x2, y2,
75 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY_BLEND_RGB565,
76 draw_end);
77 } else {
78 AALINE(x1, y1, x2, y2,
79 DRAW_FASTSETPIXELXY2, DRAW_SETPIXELXY2_BLEND_RGB,
80 draw_end);
81 }
82 }
83}
84
85static void SDL_DrawLine4(SDL_Surface *dst, int x1, int y1, int x2, int y2, Uint32 color,
86 bool draw_end)
87{
88 if (y1 == y2) {
89 HLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end);
90 } else if (x1 == x2) {
91 VLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end);
92 } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
93 DLINE(Uint32, DRAW_FASTSETPIXEL4, draw_end);
94 } else {
95 Uint8 _r, _g, _b, _a;
96 const SDL_PixelFormatDetails *fmt = dst->fmt;
97 SDL_GetRGBA(color, fmt, dst->palette, &_r, &_g, &_b, &_a);
98 if (fmt->Rmask == 0x00FF0000) {
99 if (!fmt->Amask) {
100 AALINE(x1, y1, x2, y2,
101 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY_BLEND_XRGB8888,
102 draw_end);
103 } else {
104 AALINE(x1, y1, x2, y2,
105 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY_BLEND_ARGB8888,
106 draw_end);
107 }
108 } else {
109 AALINE(x1, y1, x2, y2,
110 DRAW_FASTSETPIXELXY4, DRAW_SETPIXELXY4_BLEND_RGB,
111 draw_end);
112 }
113 }
114}
115
116typedef void (*DrawLineFunc)(SDL_Surface *dst,
117 int x1, int y1, int x2, int y2,
118 Uint32 color, bool draw_end);
119
120static DrawLineFunc SDL_CalculateDrawLineFunc(const SDL_PixelFormatDetails *fmt)
121{
122 switch (fmt->bytes_per_pixel) {
123 case 1:
124 if (fmt->bits_per_pixel < 8) {
125 break;
126 }
127 return SDL_DrawLine1;
128 case 2:
129 return SDL_DrawLine2;
130 case 4:
131 return SDL_DrawLine4;
132 }
133 return NULL;
134}
135
136bool SDL_DrawLine(SDL_Surface *dst, int x1, int y1, int x2, int y2, Uint32 color)
137{
138 DrawLineFunc func;
139
140 if (!SDL_SurfaceValid(dst)) {
141 return SDL_InvalidParamError("SDL_DrawLine(): dst");
142 }
143
144 func = SDL_CalculateDrawLineFunc(dst->fmt);
145 if (!func) {
146 return SDL_SetError("SDL_DrawLine(): Unsupported surface format");
147 }
148
149 // Perform clipping
150 // FIXME: We don't actually want to clip, as it may change line slope
151 if (!SDL_GetRectAndLineIntersection(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
152 return true;
153 }
154
155 func(dst, x1, y1, x2, y2, color, true);
156 return true;
157}
158
159bool SDL_DrawLines(SDL_Surface *dst, const SDL_Point *points, int count, Uint32 color)
160{
161 int i;
162 int x1, y1;
163 int x2, y2;
164 bool draw_end;
165 DrawLineFunc func;
166
167 if (!SDL_SurfaceValid(dst)) {
168 return SDL_InvalidParamError("SDL_DrawLines(): dst");
169 }
170
171 func = SDL_CalculateDrawLineFunc(dst->fmt);
172 if (!func) {
173 return SDL_SetError("SDL_DrawLines(): Unsupported surface format");
174 }
175
176 for (i = 1; i < count; ++i) {
177 x1 = points[i - 1].x;
178 y1 = points[i - 1].y;
179 x2 = points[i].x;
180 y2 = points[i].y;
181
182 // Perform clipping
183 // FIXME: We don't actually want to clip, as it may change line slope
184 if (!SDL_GetRectAndLineIntersection(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
185 continue;
186 }
187
188 // Draw the end if the whole line is a single point or it was clipped
189 draw_end = ((x1 == x2) && (y1 == y2)) || (x2 != points[i].x || y2 != points[i].y);
190
191 func(dst, x1, y1, x2, y2, color, draw_end);
192 }
193 if (points[0].x != points[count - 1].x || points[0].y != points[count - 1].y) {
194 SDL_DrawPoint(dst, points[count - 1].x, points[count - 1].y, color);
195 }
196 return true;
197}
198
199#endif // SDL_VIDEO_RENDER_SW
200