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前言

前几篇我们体验了使用ffmpeg进行多媒体开发，本篇使用SDL来进行GUI相关的应用开发。通过加载位图显示的Demo来演示。

构建

下载源码https://github.com/libsdl-org/SDL/releases/https://github.com/libsdl-org/SDL/releases/download/release-2.26.4/SDL2-2.26.4.tar.gz解压tar -xvf SDL2-2.26.4.tar.gz进入工作目录cd SDL2-2.26.4/创建目录mkdir build配置./configure --prefix=$PWD/build构建安装make && make install编译完如下:Build下生成4个文件夹bin share lib include生成的库文件位于build/lib头文件位于build/include/SDL2/测试vi /etc/profile添加export C_INCLUDE_PATH=/root/SDL2-2.26.4/build/include/SDL2:$C_INCLUDE_PATHexport LIBRARY_PATH=/root/SDL2-2.26.4/build/lib:$LIBRARY_PATHexport LD_LIBRARY_PATH=/root/SDL2-2.26.4/build/lib:$LD_LIBRARY_PATH   source /etc/profile创建源文件内容如下sdltest.c

1. #include
   

2. 
   

3. #include
   

4. 
   

5. 
   

6. 
   

7. int main(int argc, char* argv[])
   

8. 
   

9. {
   

10. 
    

11.     /* 初始化SDL */
    

12. 
    

13.     if(SDL_Init(SDL_INIT_VIDEO) != 0)
    

14. 
    

15.     {
    

16. 
    

17.         printf("SDL_Init Error %s.n", SDL_GetError());
    

18. 
    

19.         return 1;
    

20. 
    

21.     }
    

22. 
    

23. 
    

24. 
    

25.     /* 打开窗口 */
    

26. 
    

27.     SDL_Window *win = SDL_CreateWindow("Hello World", 100, 100, 640, 480, SDL_WINDOW_SHOWN);
    

28. 
    

29.     if(win == NULL)
    

30. 
    

31.     {
    

32. 
    

33.         printf("SDL_CreateWindow Error %s.n",SDL_GetError());
    

34. 
    

35.         SDL_Quit();
    

36. 
    

37.         return 1;
    

38. 
    

39.     }
    

40. 
    

41. 
    

42. 
    

43.     /* 创建渲染器 */
    

44. 
    

45.     SDL_Renderer *ren = SDL_CreateRenderer(win , -1, SDL_RENDERER_SOFTWARE);
    

46. 
    

47.     if(ren == NULL)
    

48. 
    

49.     {
    

50. 
    

51.         SDL_DestroyWindow(win);
    

52. 
    

53.         printf("SDL_CreateRenderer Error %s.n",SDL_GetError());
    

54. 
    

55.         SDL_Quit();
    

56. 
    

57.         return 1;
    

58. 
    

59.     }
    

60. 
    

61. 
    

62. 
    

63.     /* 加载位图图像 */
    

64. 
    

65.     SDL_Surface *bmp = SDL_LoadBMP("hello.bmp");
    

66. 
    

67.     if(bmp == NULL)
    

68. 
    

69.     {
    

70. 
    

71.         SDL_DestroyRenderer(ren);
    

72. 
    

73.         SDL_DestroyWindow(win);
    

74. 
    

75.         printf("SDL_LoadBMP Error %s.n",SDL_GetError());
    

76. 
    

77.         SDL_Quit();
    

78. 
    

79.         return 1;
    

80. 
    

81.     }
    

82. 
    

83. 
    

84. 
    

85.     SDL_Texture *tex = SDL_CreateTextureFromSurface(ren, bmp);
    

86. 
    

87.     SDL_FreeSurface(bmp);
    

88. 
    

89.     if (tex == NULL)
    

90. 
    

91.     {
    

92. 
    

93.         SDL_DestroyRenderer(ren);
    

94. 
    

95.         SDL_DestroyWindow(win);
    

96. 
    

97.         printf("SDL_CreateTextureFromSurface Error %s.n",SDL_GetError());
    

98. 
    

99.         SDL_Quit();
    

100. 
     

101.         return 1;
     

102. 
     

103.     }
     

104. 
     

105. 
     

106. 
     

107.     //A sleepy rendering loop, wait for 3 seconds and render and present the screen each time
     

108. 
     

109.     for (int i = 0; i < 3; ++i)
     

110. 
     

111.     {
     

112. 
     

113.         //First clear the renderer
     

114. 
     

115.         SDL_RenderClear(ren);
     

116. 
     

117.         //Draw the texture
     

118. 
     

119.         SDL_RenderCopy(ren, tex, NULL, NULL);
     

120. 
     

121.         //Update the screen
     

122. 
     

123.         SDL_RenderPresent(ren);
     

124. 
     

125.         //Take a quick break after all that hard work
     

126. 
     

127.         SDL_Delay(1000);
     

128. 
     

129.     }
     

130. 
     

131. 
     

132. 
     

133.     SDL_DestroyTexture(tex);
     

134. 
     

135.     SDL_DestroyRenderer(ren);
     

136. 
     

137.     SDL_DestroyWindow(win);
     

138. 
     

139.     SDL_Quit();
     

140. 
     

141. 
     

142. 
     

143.     return 0;
     

144. 
     

145. }

编译gcc sdltest.c -o sdltest -lSDL2运行导入测试文件hello.bmp如下运行./sdltest可以看到加载显示了位图总结从以上可以看出，直接在开发板构建SDL，并进行应用编译开发，非常方便。所以使用本开发板可以任意选择各种技术栈进行开发，在进行多媒体终端开发时也有多种选择，非常方便，这得益于开发板运行完整的ubuntu系统和强劲的性能。