检测密钥释放的帧

Question

我试图让它检测密钥何时在关闭状态和启动状态之间切换。我需要它来显示键在恢复到 UP 状态之前释放了一帧。

如果需要，我可以添加更多信息或代码。提前谢谢你。

package engine 
{
import flash.display.Stage;
import flash.events.KeyboardEvent;

/**
 *  Input Manager
 */
public class Input 
{
    static private const UP         : uint = 0;
    static private const PRESS      : uint = 1;
    static private const HELD       : uint = 2;
    static private const END_PRESS  : uint = 3;
    static private const START_PRESS:uint = 9999;

    static private var keys     : Vector.<uint>;
    static private var active   : Vector.<KeyState>;

    static public function init( stage:Stage ):void 
    {
        stage.removeEventListener( KeyboardEvent.KEY_DOWN, onKeyDown );
        stage.removeEventListener( KeyboardEvent.KEY_UP,   onKeyUp );   
        keys    = new Vector.<uint>(255);   // state of all keys
        active  = new Vector.<KeyState>();      // only keys in a state other than up
        //time    = new Vector.<Time>();
        stage.addEventListener( KeyboardEvent.KEY_DOWN, onKeyDown );
        stage.addEventListener( KeyboardEvent.KEY_UP,   onKeyUp );  
    }

    /// Flash Event: A key was just pressed
    static public function onKeyDown( e:KeyboardEvent ):void
    {
        // If the system is sending another key down event, but the key is marked
        // as being in some other state than down; ignore it.
        if ( keys[ e.keyCode ] != UP )
            return;
        keys[ e.keyCode ] = START_PRESS;
        var keyState:KeyState = new KeyState( e.keyCode, Time.frameCount );
        active.push( keyState );
    }
    /// Flash Event: A key was raised
    static public function onKeyUp( e:KeyboardEvent ):void
    {
        keys[ e.keyCode ] = UP
        // Loop through all active keys; there is a slight chance that
        // more than one entry for a key being "down" snuck in due to
        // how Flash / OS handles input.
        var keyState:KeyState;
        for ( var i:int = active.length - 1; i > -1; i-- )
        {
            keyState = active[i];               // get next keystate in active list
            if ( keyState.code == e.keyCode )   // if the code matches
                active.splice( i, 1 );          // remove
        }
    }
    /// Call this once per frame
    static public function update():void
    {
        var code    :uint;
        var keyState:KeyState;
        // Go through all the inputs currently mark as being active...
        for ( var i:int = active.length - 1; i > -1; i-- )
        {
            keyState = active[i];
            code = keyState.code;
            // If a key is pressed and it's the frame after it was pressed,
            // change the state.
            if ( keys[code] == PRESS && keyState.frame < Time.frameCount )
            {
                keys[code] = HELD;
                continue;
            }
            // If a press is just starting, mark it as started and update
            // the frame for the press to be this frame.
            if ( keys[code] == START_PRESS )
            {
                keys[code] = PRESS;
                keyState.frame = Time.frameCount;
            }
        }
    }
    /// Has a key just been pressed in this frame?
    static public function getKeyDown( code:uint ):Boolean
    {
        return keys[ code ] == PRESS;
    }
    /// Is a key in state other than being "up"?
    static public function getKey( code:uint ):Boolean
    {
        return keys[ code ] == HELD;
    }
    static public function getKeyRelease( code:uint ):Boolean
    {
        return keys[ code ] == END_PRESS;
    }
}
}

internal class KeyState
{
public var code :uint;
public var frame:uint;
/// CTOR
function KeyState( code:uint, frame:uint ) :void
{
    this.code   = code;
    this.frame  = frame;
}
}

Answer 1

因为您希望在帧内完成某些操作，所以您必须使用侦听器Event.ENTER_FRAME。这样，您就可以将"刚刚发布"的键正确重置为"up"状态。在这种情况下，您可以：

static public function onKeyUp( e:KeyboardEvent ):void
{
    keys[ e.keyCode ] = END_PRESS;
    // I'm not sure why you need other checks in here, add them if you like
}
static public function onEnterFrame( e:Event ):void
{
    for (var i:int=keys.length-1; i>=0;i--) if (keys[i]==END_PRESS) {
        keys[i]=UP;
        // do whatever you need with i'th key, as this will be the "just released" key.
    }
}

更新：您已经有一个基本的进入框架过程，并且您已经拥有一些关于按下和保持状态的机制，因此您可以简单地将此循环添加到该过程中。