SDL鼠标事件

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\n" );

while( SDL_PollEvent(&event)){

printf ( "WaitKeyboard: caught keyboard %x\n", event.key.keysym.sym );

switch (event.type){

case SDL_KEYDOWN:

printf ( "tracking keydown\n" );

kmode = TrackKeyDown(sw, event.key.keysym.sym, kmode);

break;

case SDL_QUIT:

printf("Stop !\n");

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\n" );

//        while( SDL_PollEvent(&event)){

SDL_WaitEvent(&event);

printf ( "WaitKeyboard: caught keyboard %x\n", event.key.keysym.sym );

switch (event.type){

case SDL_KEYDOWN:

printf ( "tracking keydown\n" );

kmode = TrackKeyDown(sw, event.key.keysym.sym, kmode);

break;

case SDL_QUIT:

printf("stop !\n");

quit = 1;

break;

}

}

endSDL();

}

http://blog.chinaunix.net/uid-26456800-id-3337795.html