环境：SDL2 + VC++2015
下面的代码将打开background.bmp和image.bmp，将background平铺背景，将image作为前景呈现
1 #include <iostream>
2 #include “SDL.h“
3
4 //屏幕宽度
5 const int SCREEN_WIDTH = 640;
6 const int SCREEN_HEIGHT = 480;
7
8 //全局窗口和渲染器
9 SDL_Window window = nullptr;
10 SDL_Renderer renderer = nullptr;
11
12 //加载图片
13 SDL_Texture LoadImage(std::string file)
14 {
15 SDL_Surface loadedImage = nullptr;
16 SDL_Texture texture = nullptr;
17
18 loadedImage = SDL_LoadBMP(file.c_str());
19 if (loadedImage != nullptr)
20 {
21 texture = SDL_CreateTextureFromSurface(renderer, loadedImage);
22 SDL_FreeSurface(loadedImage);
23 }
24 else
25 std::cout << SDL_GetError() << std::endl;
26 return texture;
27 }
28
29 //将表面应用到渲染器
30 void ApplySurface(int x, int y, SDL_Texture tex, SDL_Renderer rend)
31 {
32 SDL_Rect pos;
33 pos.x = x;
34 pos.y = y;
35 SDL_QueryTexture(tex, NULL, NULL, &pos.w, &pos.h);
36 SDL_RenderCopy(rend, tex, NULL, &pos);
37 }
38
39 int main(int argc, char** argv)
40 {
41 //初始化SDL
42 if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
43 {
44 std::cout << SDL_GetError() << std::endl;
45 return 1;
46 }
47
48 //创建窗口
49 window = SDL_CreateWindow(“Lesson 2“,
50 SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
51 SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
52 if (window == nullptr)
53 {
54 std::cout << SDL_GetError() << std::endl;
55 return 2;
56 }
57
58 //创建渲染器
59 renderer = SDL_CreateRenderer(window, -1,
60 SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
61 if (renderer == nullptr)
62 {
63 std::cout << SDL_GetError() << std::endl;
64 return 3;
65 }
66
67 //创建背景和前景纹理
68 SDL_Texture background = nullptr, *image = nullptr;
69 background = LoadImage(“background.bmp“);
70 image = LoadImage(“image.bmp“);
71 if (background == nullptr || image == nullptr)
72 return 4;
73
74 //清空渲染器
75 SDL_RenderClear(renderer);
76
77 //在渲染器内平铺背景
78 int bW, bH;
79 SDL_QueryTexture(background, NULL, NULL, &bW, &bH);
80 ApplySurface(0, 0, background, renderer);
81 ApplySurface(bW, 0, background, renderer);
82 ApplySurface(0, bH, background, renderer);
83 ApplySurface(bW, bH, background, renderer);
84
85 //在渲染器中央放置前景
86 int iW, iH;
87 SDL_QueryTexture(image, NULL, NULL, &iW, &iH);
88 int x = SCREEN_WIDTH / 2 - iW / 2;
89 int y = SCREEN_HEIGHT / 2 - iH / 2;
90 ApplySurface(x, y, image, renderer);
91
92 //呈现渲染器
93 SDL_RenderPresent(renderer);
94 SDL_Delay(2000);
95
96 //释放资源
97 SDL_DestroyTexture(background);
98 SDL_DestroyTexture(image);
99 SDL_DestroyRenderer(renderer);
100 SDL_DestroyWindow(window);
101
102 SDL_Quit();
103
104 return 0;
105 }
彩蛋：
如果窗口变成了1920*1080呢？上面的平铺方法就不够灵活了。试下：
1 int bW, bH;
2 SDL_QueryTexture(background, NULL, NULL, &bW, &bH);
3 for (int y = 0; y <= SCREEN_HEIGHT; y += bH)
4 for (int x = 0; x <= SCREEN_WIDTH; x += bW)
5 ApplySurface(x, y, background, renderer);