前幾節我們了解到，SDL基本庫只能加載普通的BMP圖像，如果我們還想加載其它格式的圖片，我們就需要用到SDL的擴展庫，它可以幫助我們加載BMP, PNM, XPM, LBM, PCX, GIF, JPEG, TGA and PNG等格式圖片。要下載SDL擴展幫助文檔，點擊此處！

使用擴展庫之前，我們需要先從網上下載適合VS2010的庫文件，點擊此處，進入下載！如下圖所示，下載該版本文件！

下載下來以后，同原來設置SDL基本庫一樣，我們設置好該擴展庫的使用環境，復制dll文件至exe同目錄下。

接著，我們修改上一節所寫的load_image子函數，代碼如下：

SDL_Surface *load_image(std::string filename) { //The image that's loaded SDL_Surface *loadedImage = NULL; ? //The optimized image that will be used SDL_Surface *optimizedImage = NULL; //Loaded the image using SDL_image loadedImage = IMG_Load(filename.c_str()); ? //If the image loaded if(loadedImage != NULL) { //Create an optimized image optimizedImage = SDL_DisplayFormat(loadedImage); ? //Free the old image SDL_FreeSurface(loadedImage); } ? //Return the optimized image return optimizedImage; ? }

然后我們就可以加載包括BMP之內其它格式圖片。在此，我準備了兩幅圖片，一幅test_png.png的png格式圖片：

還有一幅background.bmp的bmp格式背景圖片：

完整代碼如下所示：

#include "SDL.h" #include "SDL_image.h" #include <string> ? //The attributes of the screen const int SCREEN_WIDTH = 600; const int SCREEN_HEIGHT = 450; const int SCREEN_BPP = 32; ? //The surfaces that will be usede SDL_Surface *message = NULL; SDL_Surface *background = NULL; SDL_Surface *screen = NULL; ? SDL_Surface *load_image(std::string filename) { //The image that's loaded SDL_Surface *loadedImage = NULL; ? //The optimized image that will be used SDL_Surface *optimizedImage = NULL; //Loaded the image using SDL_image // loadedImage = SDL_LoadBMP(filename.c_str()); loadedImage = IMG_Load(filename.c_str()); ? //If the image loaded if(loadedImage != NULL) { //Create an optimized image optimizedImage = SDL_DisplayFormat(loadedImage); ? //Free the old image SDL_FreeSurface(loadedImage); } ? //Return the optimized image return optimizedImage; ? } ? void apply_surface(int x,int y,SDL_Surface* source,SDL_Surface *destination) { //Make a temporary rectangle to hold the offsets SDL_Rect offset; ? //Give the offset to the rectangle offset.x = x; offset.y = y; ? //Blit the surface SDL_BlitSurface(source,NULL,destination,&offset); } ? int main(int argc,char *argv[]) { //Initialize all SDL_subsystems if(SDL_Init(SDL_INIT_EVERYTHING) == -1) { return 1; } //Set up Screen screen = SDL_SetVideoMode(SCREEN_WIDTH,SCREEN_HEIGHT,SCREEN_BPP,SDL_SWSURFACE); if(screen == NULL) { return 1; } ? //Set the window caption SDL_WM_SetCaption("Hello World",NULL); ? //Load Image message = load_image("test_png.png"); background = load_image("background.bmp"); //Apply the background to the screen apply_surface(0,0,background,screen); ? ? //apply the message to the screen apply_surface(105,78,message,screen); //Update Screen if(SDL_Flip(screen) == -1) { return 1; } //Wait 2 seconds SDL_Delay(20000); ? //Free the loaded image SDL_FreeSurface(message); SDL_FreeSurface(background); ? //Quit SDL SDL_Quit(); return 0; }

最后效果如下：

轉載于:https://www.cnblogs.com/MrTan/archive/2013/02/23/2923346.html

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