[原]零基础学习SDL开发之在Android使用SDL2.0显示BMP叠加图
2014-08-21 23:38
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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:
二、将渲染功能封装到renderTexture函数中:
三、编写主函数功能:
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:
五、运行效果截图
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
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