SDL2 中使用多线程绘图

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最新推荐文章于 2025-03-30 20:59:02 发布

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分类专栏：移动开发文章标签： Android ucGUI SDL2

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本文介绍如何在Android平台上使用ucGUI配合SDL实现多线程绘图和刷新，通过一个示例展示了如何在一个子线程中进行绘图操作，而在主线程中完成屏幕更新。

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SDL的中文资料比较少，推荐一个英文的网站里面讲的非常详细点击打开链接解决了我不少的疑惑。

最近在移植ucGUI到Android上，ucGUI的windows Demo中可以实现在一个线程中绘图，在另一个线程中刷新。在Android中使用ucGUI也是可以实现的用SDL 当画布，在子线程中绘画，在主线程中刷新。代码如下:

/*This source code copyrighted by Lazy Foo' Productions (2004-2013)
 and may not be redistributed without written permission.*/

//Using SDL and standard IO
#include <SDL.h>
#include <stdio.h>
#include <stdbool.h>
#include "GUI.h"
//Screen dimension constants

extern int SCREEN_WIDTH;
extern int SCREEN_HEIGHT;
//Starts up SDL and creates window


//Loads media
bool loadMedia();//加载图片

//Frees media and shuts down SDL
void close();

//The window we'll be rendering to
extern SDL_Window* g_screen_window;

//The surface contained by the window
extern SDL_Surface* g_screen_surface;

//The image we will load and show on the screen
SDL_Surface* gXOut = NULL;

bool loadMedia() {
	//Loading success flag
	bool success = true;

	//Load splash image
	gXOut = SDL_LoadBMP("x.bmp");
	if (gXOut == NULL) {
		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
				"Unable to load image %s! SDL Error: %s\n",
				"03_event_driven_programming/x.bmp", SDL_GetError());
		success = false;
	}

	return success;
}

void close() {
	//Deallocate surface
	SDL_FreeSurface(gXOut);
	gXOut = NULL;

	//Destroy window
	SDL_DestroyWindow(g_screen_window);
	g_screen_window = NULL;

	//Quit SDL subsystems
	SDL_Quit();
}
void Thread1(void *pdata) {

	MainTask(0);//子线程中的绘画函数都在这里

	SDL_Log("Thread runing");
}
int SDL_main(int argc, char* args[]) {

	//Start up SDL and create window
	GUI_Init();//初始化windows 以及surface

	//Load media
	if (!loadMedia()) {
		printf("Failed to load media!\n");
	} else {
		//Main loop flag
		bool quit = false;

		//Event handler
		SDL_Event e;

		SDL_Thread *thread = SDL_CreateThread(Thread1, "TestThread",
				(void *) NULL);

		//While application is running

		while (!quit) {
			//Handle events on queue
			while (SDL_PollEvent(&e) != 0) {
				//User requests quit
				if (e.type == SDL_QUIT) {
					quit = true;
				}
				if (e.type == SDL_FINGERUP) {
					quit = true;
				}
			}

			//Apply the image

			//Update the surface
			SDL_UpdateWindowSurface(g_screen_window);
			SDL_Log("Invalidate");
		}
	}

	//Free resources and close SDL
	close();

	return 0;
}