关于如何移植在android上使用SDL，可以参考[原]零基础学习SDL开发之移植SDL2.0到Android 和 [原]零基础学习SDL开发之在Android使用SDL2.0显示BMP图 。
在一篇文章我们主要使用SDL2.0来加载一张BMP图来渲染显示，同时叠加一张图作为背景图。
博主的开发环境：Ubuntu 14.04 64位，Eclipse + CDT + ADT+NDK
在前面两篇文章我们知道了如何移植SDL2.0到android上面来，并且可以在Android上面来显示一张图片，这篇文章就是在前两篇文章的基础上来进行继续开发。
一、将功能模块化，将加载BMP的功能封装到一个函数中：
/* * SDL_Lesson.c * * Created on: Aug 12, 2014 * Author: clarck */ #include <jni.h> #include "SDL.h" #include "SDL_logger.h" #include "SDL_main.h" #include "SDL_cleanup.h" //The attributes of the screen const int SCREEN_WIDTH = 640; const int SCREEN_HEIGHT = 480; struct SDL_Window *window = NULL; struct SDL_Renderer *render = NULL; struct SDL_Texture *background = NULL; struct SDL_Texture *image = NULL; struct SDL_Surface *bmp = NULL; /* * Loads a BMP image into a texture on the rendering device * @param file The BMP image file to load * @param ren The renderer to load the texture onto * @return the loaded texture, or NULL if something went wrong. */ SDL_Texture* loadTexture(const char *file, SDL_Renderer *render) { struct SDL_Texture *texture = NULL; //Load the image bmp = SDL_LoadBMP(file); if (bmp == NULL) { LOGE("SDL_LoadBMP failed %s", SDL_GetError()); } //If the loading went ok, convert to texture and return the texture texture = SDL_CreateTextureFromSurface(render, bmp); SDL_FreeSurface(bmp); if (texture == NULL) { LOGE("SDL_CreateTextureFromSurface failed %s", SDL_GetError()); } return texture; }
二、将渲染功能封装到renderTexture函数中：
/* * SDL_Lesson.c * * Created on: Aug 12, 2014 * Author: clarck */ #include <jni.h> #include "SDL.h" #include "SDL_logger.h" #include "SDL_main.h" #include "SDL_cleanup.h" //The attributes of the screen const int SCREEN_WIDTH = 640; const int SCREEN_HEIGHT = 480; struct SDL_Window *window = NULL; struct SDL_Renderer *render = NULL; struct SDL_Texture *background = NULL; struct SDL_Texture *image = NULL; struct SDL_Surface *bmp = NULL; /* * Loads a BMP image into a texture on the rendering device * @param file The BMP image file to load * @param ren The renderer to load the texture onto * @return the loaded texture, or NULL if something went wrong. */ SDL_Texture* loadTexture(const char *file, SDL_Renderer *render) { struct SDL_Texture *texture = NULL; //Load the image bmp = SDL_LoadBMP(file); if (bmp == NULL) { LOGE("SDL_LoadBMP failed %s", SDL_GetError()); } //If the loading went ok, convert to texture and return the texture texture = SDL_CreateTextureFromSurface(render, bmp); SDL_FreeSurface(bmp); if (texture == NULL) { LOGE("SDL_CreateTextureFromSurface failed %s", SDL_GetError()); } return texture; } /* * Draw an SDL_Texture to an SDL_Renderer at position x, y, preserving * the texture's width and height * @param tex The source texture we want to draw * @param ren The renderer we want to draw too * @param x The x coordinate to draw too * @param y The y coordinate to draw too */ void renderTexture(SDL_Texture *tex, SDL_Renderer *ren, int x, int y) { //Setup the destination rectangle to be at the position we want SDL_Rect dst; dst.x = x; dst.y = y; //Query the texture to get its width and height to use SDL_QueryTexture(tex, NULL, NULL, &dst.w, &dst.h); SDL_RenderCopy(ren, tex, NULL, &dst); }
三、编写主函数功能：
/* * SDL_Lesson.c * * Created on: Aug 12, 2014 * Author: clarck */ #include <jni.h> #include "SDL.h" #include "SDL_logger.h" #include "SDL_main.h" #include "SDL_cleanup.h" //The attributes of the screen const int SCREEN_WIDTH = 640; const int SCREEN_HEIGHT = 480; struct SDL_Window *window = NULL; struct SDL_Renderer *render = NULL; struct SDL_Texture *background = NULL; struct SDL_Texture *image = NULL; struct SDL_Surface *bmp = NULL; /* * Loads a BMP image into a texture on the rendering device * @param file The BMP image file to load * @param ren The renderer to load the texture onto * @return the loaded texture, or NULL if something went wrong. */ SDL_Texture* loadTexture(const char *file, SDL_Renderer *render) { struct SDL_Texture *texture = NULL; //Load the image bmp = SDL_LoadBMP(file); if (bmp == NULL) { LOGE("SDL_LoadBMP failed %s", SDL_GetError()); } //If the loading went ok, convert to texture and return the texture texture = SDL_CreateTextureFromSurface(render, bmp); SDL_FreeSurface(bmp); if (texture == NULL) { LOGE("SDL_CreateTextureFromSurface failed %s", SDL_GetError()); } return texture; } /* * Draw an SDL_Texture to an SDL_Renderer at position x, y, preserving * the texture's width and height * @param tex The source texture we want to draw * @param ren The renderer we want to draw too * @param x The x coordinate to draw too * @param y The y coordinate to draw too */ void renderTexture(SDL_Texture *tex, SDL_Renderer *ren, int x, int y) { //Setup the destination rectangle to be at the position we want SDL_Rect dst; dst.x = x; dst.y = y; //Query the texture to get its width and height to use SDL_QueryTexture(tex, NULL, NULL, &dst.w, &dst.h); SDL_RenderCopy(ren, tex, NULL, &dst); } int main(int argc, char *argv[]) { char *filefolder = argv[1]; char *background_temp = "background.bmp"; char *image_temp = "image.bmp"; LOGI("natvie_SDL %s", filefolder); //char *background_file = "/storage/sdcard0/background.bmp"; char *background_file = (char*) malloc( strlen(filefolder) + strlen(background_temp) + 1); strcpy(background_file, filefolder); strcat(background_file, background_temp); //char *image_file = "/storage/sdcard0/image.bmp"; char *image_file = (char*) malloc( strlen(filefolder) + strlen(image_temp) + 1); strcpy(image_file, filefolder); strcat(image_file, image_temp); if (SDL_Init(SDL_INIT_EVERYTHING) != 0) { LOGE("SDL_Init failed %s", SDL_GetError()); } window = SDL_CreateWindow("lesson2", 100, 100, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN); if (window == NULL) { LOGE("SDL_CreateWindow failed %s", SDL_GetError()); } render = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC); if (render == NULL) { LOGE("SDL_CreateRenderer failed %s", SDL_GetError()); } background = loadTexture(background_file, render); image = loadTexture(image_file, render); //Clear the window SDL_RenderClear(render); //Get the width and height from the texture so we know how much to move x,y by //to tile it correctly int bW, bH; SDL_QueryTexture(background, NULL, NULL, &bW, &bH); //We want to tile our background so draw it 4 times renderTexture(background, render, 0, 0); renderTexture(background, render, bW, 0); renderTexture(background, render, 0, bH); renderTexture(background, render, bW, bH); //Draw our image in the center of the window //We need the foreground image's width to properly compute the position //of it's top left corner so that the image will be centered int iW, iH; SDL_QueryTexture(image, NULL, NULL, &iW, &iH); int x = SCREEN_WIDTH / 2 - iW / 2; int y = SCREEN_HEIGHT / 2 - iH / 2; renderTexture(image, render, x, y); //Update the screen SDL_RenderPresent(render); SDL_Delay(2000); cleanup_texture(background); cleanup_texture(image); cleanup_render(render); cleanup_window(window); SDL_Quit(); return 0; }
四、修改SDLActivity中的 SDLMain类，传入参数为sdcard的路径，其余修改参考上一篇文章，修改内容如下：
/** Simple nativeInit() runnable */ class SDLMain implements Runnable { @Override public void run() { // Runs SDL_main() String sdcard = Environment.getExternalStorageDirectory().getAbsolutePath(); SDLActivity.nativeInit(sdcard); //Log.v("SDL", "SDL thread terminated"); } }
五、运行效果截图
