SDL2.0 用SDL画图


概述:
SDL使用SDL_Surface和SDL_Texture这2种结构绘图到屏幕。SDL_Surface包含了一个像素集合(pixels成员),它使用软件渲染(非GPU);SDL_Textur可使用硬件加速器。使用SDL_Texture的示例程序:

#include "SDL.h" class Game2{public: Game2():m_pWindow(NULL),m_pRenderer(NULL), m_bRunning(false){}; ~Game2(){}; bool init(const char* title, int xpos, int ypos, int width, int height, int flags); void render(); void update(); void handleEvents(); bool running() {return m_bRunning; } void clean();private: SDL_Window *m_pWindow; SDL_Renderer *m_pRenderer; // new SDL_Texture *m_pTexture; SDL_Rect m_srcRect; // 源矩形 SDL_Rect m_dstRect; // 目标矩形 bool m_bRunning;}; bool Game2::init(const char *title, int xpos, int ypos, int height, int width, int flags){ if (SDL_Init(SDL_INIT_EVERYTHING) < 0) return false; m_pWindow = SDL_CreateWindow(title, xpos, ypos, height, width, flags); if (NULL == m_pWindow) return false; m_pRenderer = SDL_CreateRenderer(m_pWindow, -1, 0); SDL_SetRenderDrawColor(m_pRenderer, 255, 255, 255, 255); // new SDL_Surface *pTmpSurface = SDL_LoadBMP("D:\\sample.bmp"); // 按照实际更改图片名称及路径 if (NULL == pTmpSurface) return false; m_pTexture = SDL_CreateTextureFromSurface(m_pRenderer, pTmpSurface); if (NULL == m_pTexture) return false; SDL_FreeSurface(pTmpSurface); SDL_QueryTexture(m_pTexture,NULL, NULL, &m_srcRect.w, &m_srcRect.h); m_dstRect.x = m_srcRect.x = 0; m_dstRect.y = m_srcRect.y = 0; // for debug //m_srcRect.w /= 2; //m_srcRect.h /= 2; m_dstRect.w = m_srcRect.w; m_dstRect.h = m_srcRect.h; // for debug //m_dstRect.w = m_srcRect.w/2; //m_dstRect.h = m_srcRect.h/2; //m_dstRect.x = 50; //m_dstRect.y = 50; //m_srcRect.x = 50; //m_srcRect.y = 50; m_bRunning = true; return true; } void Game2::render(){ SDL_RenderClear(m_pRenderer); SDL_RenderCopy(m_pRenderer, m_pTexture, &m_srcRect, &m_dstRect); //SDL_RenderCopy(m_pRenderer, m_pTexture, NULL, NULL); // NULL means that use all texture( and renderer) //SDL_RenderCopyEx(m_pRenderer, m_pTexture, &m_srcRect, &m_dstRect,0, 0, SDL_FLIP_HORIZONTAL); //SDL_RenderCopyEx(m_pRenderer, m_pTexture, &m_srcRect, &m_dstRect,0, 0, SDL_FLIP_VERTICAL); SDL_RenderPresent(m_pRenderer);} void Game2::clean(){ SDL_DestroyWindow(m_pWindow); SDL_DestroyRenderer(m_pRenderer); SDL_DestroyTexture(m_pTexture); SDL_Quit();} void Game2::handleEvents(){ SDL_Event sdl_event; if (SDL_PollEvent(&sdl_event)) { switch(sdl_event.type) { case SDL_QUIT: m_bRunning = false; break; default: break; } }} void Game2::update(){ static int count = 0; Uint32 ticks = SDL_GetTicks(); if ((ticks % 1000) == 0) { count++; m_dstRect.y = m_dstRect.h * (count%6); }} /****************************************************************************** example03: use SDL_Texture to draw******************************************************************************/void example03(){ Game2 game; game.init("example03: drawing in SDL", 200, 200, 640, 480, 0); while (game.running()) { game.handleEvents(); game.update(); game.render(); } game.clean(); }

源矩形和目标矩形:
源矩形用于指定要拷贝到目标图像的源图像起始位置及宽高参数,即可以只拷贝源图像的某一部分到目标图像。目标矩形用于指定要拷贝到目标图像中的起始位置及宽高参数,即可以通过指定不同的目标矩形位置,让源图像拷贝到目标图像的不同位置。且目标矩形的宽高不用和源矩形一致,这可用于缩小或放大图像。
x,y为矩形的开始位置;w,h为矩形的宽高。


其余图片格式支持:
SDL2.0默认只支持.bmp图像(SDL_LoadBMP()),要想使用其它格式的图片,可在http://www.libsdl.org/projects/SDL_image页面下载SDL_image扩展组件,它支持BMP,GIF,JPEG,LBM,PCX,PNG,PNM,TGA,TIFF,WEBP,XCF,XPM,XV格式。


SDL_RenderCopyEx:
使用这个函数可实现水平和垂直翻转。
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版权声明:本文为CSDN博主「绿野耕夫」的原创文章,遵循 CC 4.0 BY-SA 版权协议,转载请附上原文出处链接及本声明。
原文链接:https://blog.csdn.net/finewind/article/details/38541193

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