flex 自定义TweenEffect方法

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Flex / As3

Flex Flash 设计模式 Adobe IDEA

rh 发现很久没有写BLOG了，罪过罪过，先忙着找工作，工作搞定了，又忙着毕业论文，现在终于有时间来做做Flex了，手生了些，没有项目，完全自娱自乐型。

TweenEffect，补间效果~是一种渐变的类型，像Glow,Move等都是TweenEffect的子类，自已做一个TweenEffect，应该在很多场合用得到。

首先选取一个TweenEffect来研究一下，就Glow吧，找到它的原代码，如下(去掉了注释,加上自己的注释 )：

package mx.effects
{

import mx.effects.effectClasses.GlowInstance;
import mx.styles.StyleManager;

public class Glow extends TweenEffect
{
    include "../core/Version.as";
	public function Glow(target:Object = null)
	{
		super(target);
		instanceClass = GlowInstance;
	}
   /*添加一些效果参数，用Inspectable标签声明，这样可以在MXML上设置这些属性*/
	[Inspectable(category="General", defaultValue="NaN")]
	public var alphaFrom:Number;
	[Inspectable(category="General", defaultValue="NaN")]
	public var alphaTo:Number;
	[Inspectable(category="General", defaultValue="NaN")]
	public var blurXFrom:Number;
	[Inspectable(category="General", defaultValue="NaN")]
	public var blurXTo:Number;
	[Inspectable(category="General", defaultValue="NaN")]
	public var blurYFrom:Number;
	[Inspectable(category="General", defaultValue="NaN")]
	public var blurYTo:Number;
	[Inspectable(category="General", format="Color", defaultValue="0xFFFFFFFF")]
	public var color:uint = StyleManager.NOT_A_COLOR;
	[Inspectable(category="General", defaultValue="false")]
	public var inner:Boolean;
	[Inspectable(defaultValue="false")]
	public var knockout:Boolean;
	[Inspectable(category="General", defaultValue="2")]
	public var strength:Number;

	override public function getAffectedProperties():Array /* of String */
	{
		return AFFECTED_PROPERTIES;
	}
	override protected function initInstance(instance:IEffectInstance):void
	{
		super.initInstance(instance);
		//创建效果实例
        var glowInstance:GlowInstance = GlowInstance(instance);
        //将参数传递给实例
		glowInstance.alphaFrom = alphaFrom;
		glowInstance.alphaTo = alphaTo;
		glowInstance.blurXFrom = blurXFrom;
		glowInstance.blurXTo = blurXTo;
		glowInstance.blurYFrom = blurYFrom;
		glowInstance.blurYTo = blurYTo;
		glowInstance.color = color;
		glowInstance.inner = inner;
		glowInstance.knockout = knockout;
		glowInstance.strength = strength;
	}
}

}

真的是so easy,Glow ms就是用来创建实例，外加传递参数的。在设计模式中叫工厂，看来关键还是有GlowInstance类里面，再找到GlowInstance类的代码。

package mx.effects.effectClasses
{
import flash.events.Event;
import flash.filters.GlowFilter;
import mx.core.Application;
import mx.core.mx_internal;
import mx.styles.StyleManager;
public class GlowInstance extends TweenEffectInstance
{
    include "../../core/Version.as";

	public function GlowInstance(target:Object)
	{
		super(target);
	}

	public var alphaFrom:Number;
	public var alphaTo:Number;
	public var blurXFrom:Number;
	public var blurXTo:Number;
	public var blurYFrom:Number;
	public var blurYTo:Number;
	public var color:uint = StyleManager.NOT_A_COLOR;
	public var inner:Boolean;
	public var knockout:Boolean;
	public var strength:Number;

	override public function initEffect(event:Event):void
	{
		super.initEffect(event);
	}

	override public function play():void
	{
		super.play();
		if (isNaN(alphaFrom))
			alphaFrom = 1.0;
		if (isNaN(alphaTo))
			alphaTo = 0;
		if (isNaN(blurXFrom))
			blurXFrom = 5;
		if (isNaN(blurXTo))
			blurXTo = 0;
		if (isNaN(blurYFrom))
			blurYFrom = 5;
		if (isNaN(blurYTo))
			blurYTo = 0;
		if (color == StyleManager.NOT_A_COLOR)
			color = Application.application.getStyle("themeColor");
		if (isNaN(strength))
			strength = 2;
		tween = createTween(
			this, [ color, alphaFrom, blurXFrom, blurYFrom ],
			[ color, alphaTo, blurXTo, blurYTo ], duration);

	}
	override public function onTweenUpdate(value:Object):void
	{
		setGlowFilter(value[0], value[1], value[2], value[3]);
	}
	override public function onTweenEnd(value:Object):void
	{
		setGlowFilter(value[0], value[1], value[2], value[3]);
		super.onTweenEnd(value);	
	}
	
	private function setGlowFilter (color:uint, alpha:Number,
								   blurX:Number, blurY:Number):void
	{
		var filters:Array = target.filters;
		var n:int = filters.length;
		for (var i:int = 0; i < n; i++)
		{
			if (filters[i] is GlowFilter)
				filters.splice(i, 1);
		}
		if (blurX || blurY || alpha)
			filters.push(new GlowFilter(color, alpha, blurX, blurY,
						strength, 1, inner, knockout));
		target.filters = filters;
	}
}

}

稍微有点复杂了，仔细看看，也还好，开始定义一些参数，就里面参数与Glow中定义是一致的，然后重写了一些关键函数。看看这些函数都干嘛的。

play()：动画开始播放，首先检查参数，如果没有值，就加上默认值。最后一句是关键，

tween = createTween(
			this, [ color, alphaFrom, blurXFrom, blurYFrom ],
			[ color, alphaTo, blurXTo, blurYTo ], duration);

它创建了一个Tween,参数中两个数组很有意思，是一一对应的，一个是From，另一个就是To,这个Tween动画就是这样产生的，数组中的参数，从From淅变到To,中间会停地派发TweenUpdate事件，在类中对这一事件进行处理，实现淅变的效果。

TweenUpdate事件便是在onTweenUpdate()函数中得到处理，参数value是From与To之间的中间值，我们根据这个值来做动画，Glow调用的是setGlowFilter()函数来实现。

在Tween结束时，即达到To了，就会派发TweenEnd事件，所以也要重写onTweenEnd()函数。

好了，都研究完了，ms可以动手写个自己的TweenEffect了，写了个，先看效果，

javaeye变垃圾了吗，连个flash贴进去总是出问题，（http://www.mjbox.com/r/io/ioryioryzhan/TestRound.swf ）这个是链接

点start按扭，可以看到，一个框框围着控件，一个球球在沿着框框移动，好像不怎么美观，将就一点。它是完成依照Glow编写的，叫Round，Round代码如下：

package effects
{
	import mx.effects.IEffectInstance;
	import mx.effects.TweenEffect;

	public class Round extends TweenEffect
	{
		[Inspectable(category="General", defaultValue="NaN")]
		public var lineColor:uint;
		[Inspectable(category="General", defaultValue="NaN")]
		public var lineWeight:Number;
		[Inspectable(category="General", defaultValue="NaN")]
		public var circleColor:uint;
		[Inspectable(category="General", defaultValue="NaN")]
		public var circleRadio:Number;
		[Inspectable(category="General", defaultValue="NaN")]
		public var distance:Number;
		
		
		public function Round(target:Object=null)
		{
			super(target);
			this.instanceClass = RoundInstance;
		}
		override protected function initInstance(instance:IEffectInstance):void{
			super.initInstance(instance);
			var roundInstance:RoundInstance = RoundInstance(instance);
			roundInstance.lineColor = lineColor;
			roundInstance.lineWeight = lineWeight;
			roundInstance.circleColor = circleColor;
			roundInstance.circleRadio = circleRadio;
			roundInstance.distance = distance;
		}
		
	}
}

不同点在于instanceClass不同了，还有就是参数不同。

没有注释，稍微讲讲这些参数，主要设置线的宽度，颜色，小圆圈的半径，颜色，还有框框与控件的距离。

下面是RoundInstance的代码：

package effects
{
	import flash.events.Event;
	
	import mx.core.UIComponent;
	import mx.core.UIComponentGlobals;
	import mx.effects.effectClasses.TweenEffectInstance;
	import mx.core.mx_internal;
	use namespace mx_internal;
	
	public class RoundInstance extends TweenEffectInstance
	{
		public var lineColor:uint;
		public var lineWeight:Number;
		public var circleColor:uint;
		public var circleRadio:Number;
		public var distance:Number;
		
		public function RoundInstance(target:Object)
		{
			super(target);
		}
		override public function initEffect(event:Event):void{
			super.initEffect(event);
			
		}
		override public function play():void{
			if (isNaN(lineColor))
				lineColor = 0xff0000;
			if (isNaN(circleColor))
				circleColor = 0xff0000;
			if (isNaN(distance))
				distance = 3;
			if (isNaN(lineWeight))
				lineWeight = 1;
			if (isNaN(circleRadio))
				circleRadio = 3;
			//保证参数合理性
			if(distance<=0){
				distance = 3;
			}	
			if(lineWeight > 2 * distance){
				lineWeight = 2 * distance;
			}
			if(circleRadio > distance){
				circleRadio = distance;
			}
			
			var targetUI:UIComponent = target as UIComponent;
			var w:Number = targetUI.width;
			var h:Number = targetUI.height;
			//创建Tween
			tween = createTween(this,[0],[2*(w+2*distance)+2*(h+2*distance)],duration);
		}
		override public function onTweenUpdate(value:Object):void{
			draw(value[0]);
		}
		override public function onTweenEnd(value:Object):void{
			var targetUI:UIComponent = target as UIComponent;
			targetUI.graphics.clear();
                        super.onTweenEnd(value);
		}
		
		private function draw(d:Number):void{
			var targetUI:UIComponent = target as UIComponent;
			targetUI.graphics.clear();
			
			targetUI.graphics.lineStyle(lineWeight,lineColor);
			targetUI.graphics.moveTo(-distance,-distance);
			targetUI.graphics.lineTo(-distance,targetUI.height+distance);
			targetUI.graphics.lineTo(targetUI.width + distance,targetUI.height+distance);
			targetUI.graphics.lineTo(targetUI.width + distance,-distance);
			
			var x:Number;
			var y:Number;
			var h:Number = targetUI.height + 2*distance;
			var w:Number = targetUI.width  + 2*distance;
			if(d<h){
				x = -distance;
				y = d;
			}else if(d>=h&&d<(w+h)){
				x = d - h;
				y = h - distance;
			}else if(d>=(w+h)&&d<(w+2*h)){
				x = w - distance;
				y = w + 2* h - d;
			}else{
				x = 2*w + 2* h - d;
				y = - distance;
			}
			
			targetUI.graphics.beginFill(circleColor);
			targetUI.graphics.drawCircle(x,y,circleRadio);
			targetUI.graphics.endFill();
		}
	}
}

看看Tween的创建

tween = createTween(this,[0],[2*(w+2*distance)+2*(h+2*distance)],duration);

从0开始，一直到2*(w+2*distance)+2*(h+2*distance)，进行淅变，这个长表达式就是框框的周长，

draw函数，便是以中间值，计算当前球球的位置，进行绘制。

主程序，很简单，三个按扭，

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
 creationComplete="init()" backgroundColor="0xffffff" 
 xmlns:myeffect="effects.*" width="300" height="300">
	<mx:Script>
		<![CDATA[
			import mx.effects.Effect;
			import mx.events.EffectEvent;
			import mx.effects.Glow;
			import effects.Round;
			internal function init():void{
				
			}
			internal function onClickBtn2(e:MouseEvent):void{
				round1.play();
			}
			internal function onClickBtn3(e:MouseEvent):void{
				round1.end();
			}
		]]>
	</mx:Script>
	<myeffect:Round id="round1" target="{btn}" lineColor="0xff0000" lineWeight="1" 
		circleColor="0x0000ff" circleRadio="3" distance="10" duration="2000"/>
	<mx:Button x="50" y="50" width="90" height="50" id="btn"  label="Button"/>
	<mx:Button x="50" y="200" width="90" height="50" id="btn2" label="start"click="onClickBtn2(event)"/>
	<mx:Button x="150" y="200" width="90" height="50" id="btn3" label="end" click="onClickBtn3(event)"/>
</mx:Application>

点击调试，ft，出问题了，框框也有，球也有，也转的挺好，就是转完后不消失，我记得在onTweenEnd()中已经将画布clear()了，看来是super.onTweenEnd();有问题，点进去看看，果然是它，

/*in Class TweenEffectInstance*/

public function onTweenEnd(value:Object):void 
	{
		onTweenUpdate(value);
		tween = null;
		if (mx_internal::needToLayout)
			UIComponentGlobals.layoutManager.validateNow();

		finishRepeat();
	}

它在里面最后还是调用了一次onTweenUpdate()，所以又将框框球球画了上去，会消失才怪，只好，将下面四行代码移到RoundInstance类的onTweenUpdate()里去,修改代码：

/*in Class RoundInstance*/

override public function onTweenEnd(value:Object):void{
	var targetUI:UIComponent = target as UIComponent;
	targetUI.graphics.clear();
	    //下面四行代码，是从父类中移过来的
	tween = null;
	if (mx_internal::needToLayout)
		UIComponentGlobals.layoutManager.validateNow();
	finishRepeat();

}

现在开以了，点击运行，就是上面flash所展示的程序了。

欢迎批评指教~~

另外求教：

RepeatCount是如何发挥作用的，相关代码在哪？

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JSON.decode() Unexpected ' encountered ... | 为jQuery添加自定义事件机制

2009-06-15 13:39
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评论(2)
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2 楼 yuanyang0710 2009-10-16

不错，牛！

1 楼 yhustc 2009-08-16

友情链接一下
关于自定义effect的实现，我引用了你的链接。我的文章里分析了repeatCount相关的内容

http://www.yhustc.com/flex_effect_repeatCount.html

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