鼠标事件有这么多种，手柄的可以忽视，Sdl.SDL_KEYDOWN，Sdl.SDL_KEYUP，Sdl.SDL_MOUSEMOTION，Sdl.SDL_MOUSEBUTTONDOWN，Sdl.SDL_MOUSEBUTTONUP应该是常用的。
public enum EventTypes { /// <summary> /// No event /// </summary> None = Sdl.SDL_NOEVENT, /// <summary> /// Active event /// </summary> ActiveEvent = Sdl.SDL_ACTIVEEVENT, /// <summary> /// Key down event /// </summary> KeyDown = Sdl.SDL_KEYDOWN, /// <summary> /// Key up event /// </summary> KeyUp = Sdl.SDL_KEYUP, /// <summary> /// Mouse Motion event /// </summary> MouseMotion = Sdl.SDL_MOUSEMOTION, /// <summary> /// Mouse button down event /// </summary> MouseButtonDown = Sdl.SDL_MOUSEBUTTONDOWN, /// <summary> /// Mouse button up event /// </summary> MouseButtonUp = Sdl.SDL_MOUSEBUTTONUP, /// <summary> /// Joystick Axis motion event /// </summary> JoystickAxisMotion = Sdl.SDL_JOYAXISMOTION, /// <summary> /// Joystick ball motion event /// </summary> JoystickBallMotion = Sdl.SDL_JOYBALLMOTION, /// <summary> /// Joystick hat motion event /// </summary> JoystickHatMotion = Sdl.SDL_JOYHATMOTION, /// <summary> /// Joystick button down event /// </summary> JoystickButtonDown = Sdl.SDL_JOYBUTTONDOWN, /// <summary> /// joystick button up event /// </summary> JoystickButtonUp = Sdl.SDL_JOYBUTTONUP, /// <summary> /// Video resize event /// </summary> VideoResize = Sdl.SDL_VIDEORESIZE, /// <summary> /// Video expose event /// </summary> VideoExpose = Sdl.SDL_VIDEOEXPOSE, /// <summary> /// Quit event /// </summary> Quit = Sdl.SDL_QUIT, /// <summary> /// Window manager event /// </summary> WindowManagerEvent = Sdl.SDL_SYSWMEVENT, /// <summary> /// user-defined event /// </summary> UserEvent = Sdl.SDL_USEREVENT }
鼠标点击后的button：
public enum MouseButton { /// <summary> /// None /// </summary> None = 0, /// <summary> /// Primary button. Typically the left button /// </summary> PrimaryButton = Sdl.SDL_BUTTON_LEFT, /// <summary> /// Secondary button. typically the right button /// </summary> SecondaryButton = Sdl.SDL_BUTTON_RIGHT, /// <summary> /// Middle button /// </summary> MiddleButton = Sdl.SDL_BUTTON_MIDDLE, /// <summary> /// Wheel up /// </summary> WheelUp = Sdl.SDL_BUTTON_WHEELUP, /// <summary> /// Wheel down /// </summary> WheelDown = Sdl.SDL_BUTTON_WHEELDOWN }
常用的代码写法
while (!quit) //建立事件主循环 { while (Sdl.SDL_PollEvent(out ev) == 0)//从队列里取出事件 { Sdl.SDL_WaitEvent(out ev); //必须等待 if (ev.type == Sdl.SDL_MOUSEBUTTONDOWN) { if (ev.button.button == Sdl.SDL_BUTTON_LEFT) { MouseDown(ev.button); } else if (ev.button.button ==Sdl.SDL_BUTTON_RIGHT) { } } else if (ev.type == Sdl.SDL_MOUSEMOTION) { MouseMove (ev.button); } else if (ev.type == Sdl.SDL_MOUSEBUTTONUP) { if (ev.button.button ==Sdl.SDL_BUTTON_LEFT) { MouseUp (ev.button); } } else if (ev.type ==Sdl.SDL_VIDEORESIZE) { } else if (ev.type ==Sdl.SDL_QUIT) { quit = true; break; } } }
在处理SDL的事件有两种模式，一种是等待 SDL_WaitEvent,另一种是轮询SDL_PollEvent
目前，在网上可以查到的文章，大多数都使用了轮询，还有人指出等待有时会导致事件处理延迟。但是我在实际coding中，使用SDL_PollEvent，一运行就风扇不停的转，用top看了下，cpu占用到了99%。
实际上，使用wait已经足够，我不大清楚这种轮询机制在什么时候会用到。
以下是一个SDL_PollEvent的原型。分析一下这段程序：
在while(quit!=1)这个循环中，如果没有发生任何事件，quit始终为0,那么在用户没有任何操作的情况下，这里会无限循环，直到event发生，进入了SDL_PollEvent的循环中。
这就导致了cpu占用率达到了100%. 因此，这种方法是不可取的。
在外层有循环时，SDL_PollEvent论询是不能用的。如果单独使用，用户无操作的时候，又无法进入处理事件的部分。实在不能明白它有什么用。
我考虑是不是这个应该用在非实时处理的时候，比如while(quit!=1)循环中嵌入一个sleep(1)之类。
void WaitKeyboard(SubWin sw){ int quit = 0; SDL_Event event; KEYBOARDMODE kmode = COMMAND; while(quit!=1){ // printf ( "waiting for keyboard action " ); while( SDL_PollEvent(&event)){ printf ( "WaitKeyboard: caught keyboard %x ", event.key.keysym.sym ); switch (event.type){ case SDL_KEYDOWN: printf ( "tracking keydown " ); kmode = TrackKeyDown(sw, event.key.keysym.sym, kmode); break; case SDL_QUIT: printf("Stop ! "); quit = 1; break; } } } endSDL(); }
接下来是SDL_WaitEvent的原型
在while(quit!=1)的循环中，由于SDL_WaitEvent语句，在用户未发生任何操作前，程序处于等待状态，不会进入下一次循环，这样就避免了cpu占用的问题。
这样的做法才是正确处理SDL事件的方法。
void WaitKeyboard(SubWin sw){ int quit = 0; SDL_Event event; KEYBOARDMODE kmode = COMMAND; while(quit!=1){ // printf ( "waiting for keyboard action " ); // while( SDL_PollEvent(&event)){ SDL_WaitEvent(&event); printf ( "WaitKeyboard: caught keyboard %x ", event.key.keysym.sym ); switch (event.type){ case SDL_KEYDOWN: printf ( "tracking keydown " ); kmode = TrackKeyDown(sw, event.key.keysym.sym, kmode); break; case SDL_QUIT: printf("stop ! "); quit = 1; break; } } endSDL(); }
http://blog.chinaunix.net/uid-26456800-id-3337795.html