通过SDL_Window、SDL_Renderer、SDL_Texture三者实现了简单的几何图形绘画。
包括了SDL_RenderDrawPoint、SDL_RenderFillRect、SDL_RenderDrawLine、SDL_SetRenderDrawColor等。
具体看代码吧（VS2012运行）：
1 #include <stdio.h>
2 #include <string.h>
3 #include <time.h>
4 #include <SDL2SDL.h>
5 #include <SDL2SDL_image.h>
6 #include <SDL2exSDLex.h>
7
8 SDL_Window *sdlWindow = NULL;
9 SDL_Renderer *sdlRender = NULL;
10 SDL_Texture *sdlTexture = NULL;
11 SDL srcRect;
12 int w = 500;
13 int h = 500;
14
15 void DrawCircle(SDL_Renderer *ren,int radius){
16 int st=clock(),tx=0,ty=radius,d=3-(radius<<1),x=radius,y=radius;
17 while(tx<ty){
18 for (int i=x-ty;i<=x+ty;++i){
19 SDL_RenderDrawPoint(ren,i,y-tx);
20 if (tx)
21 SDL_RenderDrawPoint(ren,i,y+tx);
22 }
23 if (d<0)
24 d+=(tx<<2)+6;
25 else{
26 for (int i=x-tx;i<=x+tx;++i){
27 SDL_RenderDrawPoint(ren,i,y-ty);
28 SDL_RenderDrawPoint(ren,i,y+ty);
29 }
30 d+=((tx - ty)<<2)+10,ty--;
31 }
32 tx++;
33 }
34 if (tx==ty)
35 for (int i=x-ty;i<=x+ty;++i){
36 SDL_RenderDrawPoint(ren,i,y-tx);
37 SDL_RenderDrawPoint(ren,i,y+tx);
38 }
39 int en=clock();
40 }
41
42 bool InitView(int width, int height, const char *iconName)
43 {
44 //初始化窗体
45 SDL_Init(SDL_INIT_VIDEO);
46
47 sdlWindow = SDL_CreateWindow(
48 "The First SDL Program",
49 SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width, height,
50 SDL_WINDOW_RESIZABLE);
51 if (sdlWindow == NULL) return false;
52
53 //加载窗体图标
54 SDL_Surface *iconSurface = IMG_Load(iconName);
55 if (iconSurface == NULL) return false;
56
57 SDL_SetWindowIcon(sdlWindow, iconSurface);
58
59 return true;
60 }
61
62 bool InitDraw()
63 {
64 //加载渲染器
65 sdlRender = SDL_CreateRenderer(sdlWindow, -1, 0);
66 if (sdlRender == NULL) return false;
67
68 sdlTexture = SDL_CreateTexture(sdlRender, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, w, h);
69 if (sdlTexture == NULL) return false;
70 //SDL_SetTextureBlendMode(sdlTexture, SDL_BLENDMODE_BLEND);
71 //SDL_SetRenderTarget(sdlRender, sdlTexture);
72
73 return true;
74 }
75
76 void UpdateDraw()
77 {
78 //设置背景颜色
79 SDL_SetRenderDrawColor(sdlRender, 255, 153, 153, 0xFF);
80 SDL_RenderClear(sdlRender);
81
82 //左眼
83 SDL_SetRenderDrawColor(sdlRender, 0x00, 0xFF, 0xFF, 0xFF);
84 srcRect = SDLMake(w/7*2, h/7, w/8, h/8);
85 SDL_RenderFillRect(sdlRender, &srcRect);
86
87 //左眉毛
88 SDL_SetRenderDrawColor(sdlRender, 0x00, 0x00, 0x00, 0xFF);
89 SDL_RenderDrawLine(sdlRender, srcRect.x, srcRect.y - 10, SDLMaxX(srcRect), srcRect.y - 10);
90
91 //右眼
92 SDL_SetRenderDrawColor(sdlRender, 0xFF, 0x00, 0xFF, 0xFF);
93 srcRect = SDLMake(w/7*4, srcRect.y, srcRect.w, srcRect.h);
94 SDL_RenderDrawRect(sdlRender, &srcRect);
95
96 //右眉毛
97 SDL_SetRenderDrawColor(sdlRender, 0x00, 0x00, 0x00, 0xFF);
98 SDL_RenderDrawLine(sdlRender, srcRect.x, srcRect.y - 10, SDLMaxX(srcRect), srcRect.y - 10);
99
100 //嘴巴
101 SDL_SetRenderDrawColor(sdlRender, 0xFF, 0xFF, 0x00, 0xFF);
102 srcRect = SDLMake(w/8*3, h/7*3, w/8*2, h/8);
103 SDL_RenderFillRect(sdlRender, &srcRect);
104
105 SDL_SetRenderDrawColor(sdlRender, 0xFF, 0x00, 0x00, 0xFF);
106 DrawCircle(sdlRender, 10);
107
108 SDL_RenderPresent(sdlRender);
109 }
110
111 void Quit(int code)
112 {
113 const char *errMsg = SDL_GetError();
114 if (errMsg && strlen(errMsg)) {
115 SDL_Log("Error : %s
", errMsg);
116 }
117
118 //销毁窗口、渲染器、纹理
119 if (sdlWindow) SDL_DestroyWindow(sdlWindow);
120 if (sdlRender) SDL_DestroyRenderer(sdlRender);
121 if (sdlTexture) SDL_DestroyTexture(sdlTexture);
122 SDL_Quit();
123 exit(code);
124 }
125
126 void HandleKeyEvent(const SDL_Keysym* keysym)
127 {
128 int key = keysym->sym;
129 switch(key)
130 {
131 case SDLK_ESCAPE:
132 Quit(0);
133 break;
134 case SDLK_SPACE:
135 break;
136 case SDLK_UP:
137 case SDLK_DOWN:
138 case SDLK_LEFT:
139 case SDLK_RIGHT:
140 int x, y;
141 SDL_GetWindowPosition(sdlWindow, &x, &y);
142 x = (key == SDLK_LEFT ? x-2 : (key == SDLK_RIGHT ? x+2 : x));
143 y = (key == SDLK_UP ? y-2 : (key == SDLK_DOWN ? y+2 : y));
144 SDL_SetWindowPosition(sdlWindow, x, y);
145 SDL_Log("x=%d, y=%d
", x, y);
146 break;
147 case SDLK_KP_PLUS:
148 case SDLK_KP_MINUS:
149 w = (key == SDLK_KP_PLUS ? w+2 : w-2);
150 h = (key == SDLK_KP_PLUS ? h+2 : h-2);
151 SDL_SetWindowSize(sdlWindow, w, h);
152 SDL_Log("w=%d, h=%d
", w, h);
153 break;
154 default:
155 break;
156 }
157 }
158
159 void HandleEvents()
160 {
161 //Our SDL event placeholder.
162 SDL_Event event;
163 //Grab all the events off the queue.
164 while(SDL_PollEvent(&event)) {
165 switch(event.type) {
166 case SDL_KEYDOWN:
167 //Handle key Event
168 HandleKeyEvent(&event.key.keysym);
169 break;
170 case SDL_QUIT:
171 //Handle quit requests (like Ctrl-c).
172 Quit(0);
173 break;
174 }
175 }
176 }
177
178 int main(int argc, char* argv[])
179 {
180 printf("可以通过↑↓←→+ -按键控制移动和大小
");
181 if (InitView(w, h, "yp.ico") == false) {
182 SDL_Log("sdlWindow is null @_@
");
183 Quit(0);
184 return -1;
185 }
186
187 if (InitDraw() == false) {
188 SDL_Log("Init Fail @_@
");
189 Quit(0);
190 return -1;
191 }
192
193 //配置客户区大小
194 SDL_QueryTexture(sdlTexture,NULL, NULL, &w, &h);
195 SDL_SetWindowSize(sdlWindow, w + 2, h);
196 SDL_Log("w=%d, h=%d
", w, h);
197
198 while (1) {
199 HandleEvents();
200 UpdateDraw();
201 }
202
203 SDL_DestroyWindow(sdlWindow);
204 SDL_Quit();
205 return 0;
206 }
效果图：
