替换TWaver中Tree展开合并图标

class="baidu_pl">

class="article_content clearfix">

class="htmledit_views"> TWaver最大的优点之一是“ 灵活的定制功能”。光说不练不行，来个例子演练一下：定制Tree节点的标签。

默认Tree和Network上的标签显示的是网元的name属性，设置Styles.TREE_LABEL属性后，可以让Tree显示Styles.TREE_LABEL的值，以达到Tree和Network显示不同标签的目的
如果觉得这样还不够，可以设置Tree#labelFunction，比如下面的代码可以让Node显示name，Link显示Styles.TREE_LABEL：

class="language-javascript">class="tags" href="/tags/TREE.html" title=tree>tree.labelFunction = function(e:IElement):String{
	if(e is Link){
		return e.getStyle(Styles.TREE_LABEL);
	}else{
		return e.name;
	}
}

既然TWaver这么灵活，那Tree的展开合并图标能定制么？

class class="alignnone size-thumbnail wp-image-4352" title="disclosure2" src="http://twaver.servasoft.com/wp-content/uploads/2012/06/disclosure2-644x121.png" alt="" width="644" height="121" style="border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; max-width:649px" />

先来看看用最原始的方式：

先定义2个class：

class="language-javascript">[Embed(source="assets/plus.png")]
[Bindable]
public var plus:Class;

[Embed(source="assets/minus.png")]
[Bindable]
public var minus:Class;

再设置Tree的disclosureOpenIcon和disclosureClosedIcon属性为上面定义的class

class="language-javascript"><tw:Tree id="class="tags" href="/tags/TREE.html" title=tree>tree2" width="100%" height="100%" disclosureOpenIcon="{minus}" disclosureClosedIcon="{plus}"/>

效果如下：

class="alignnone size-thumbnail wp-image-4348" title="disclosure1" src="http://twaver.servasoft.com/wp-content/uploads/2012/06/disclosure1-644x194.png" alt="" width="644" height="194" style="border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; max-width:649px" />

有同学就要问了，这样还是不够灵活，资源文件直接嵌入了SWF中，如果想换个图标，还得重新编译打包上传一把。这好说，可以用css定制组件样式（其实css也要编译成swf，这点adobe完全没有考虑到用户的实际需求，换个颜色还得编译swf，以后有时间给大家说说如何不编译swf也能用css定制样式），但是偏偏disclosureOpenIcon和disclosureClosedIcon无法用css定制样式。从mx.controls.Tree的源代码中可以看到

class="language-javascript">[Style(name="disclosureOpenIcon", type="Class", format="EmbeddedFile", inherit="no")]
[Style(name="disclosureClosedIcon", type="Class", format="EmbeddedFile", inherit="no")]

这说明，disclosureOpenIcon和disclosureClosedIcon的style类型为class，css可以加载class？肯定不行，不信邪的同学可以试试:

class="language-javascript"><mx:Style>
	Tree {
		disclosureOpenIcon: "assets/minus.png";
		disclosureClosedIcon: "assets/plus.png";
	}
</mx:Style>

运行程序会得到下面的错误：

TypeError: Error #1034: Type Coercion failed: cannot convert “assets/plus.png” to Class.
at mx.controls::Tree/initListData()[C:\autobuild\3.5.0\frameworks\projects\framework\src\mx\controls\Tree.as:2663]

那我们就定义两个class，但是这两个class是什么class？我们来分析一下：

既然是图片，我们就继承Image组件吧。
既然是class，说明mx内部会不停地new这个class，所以图片资源要缓存起来。
加载图片是异步的，所以要等图片加载完成后，再注册这个class。

因此就有了这2个类的定义：

class="language-javascript">package {
	import flash.display.Bitmap;
	import flash.display.Loader;

	import mx.controls.Image;

	public class disclosureOpenIcon extends Image {
		public static const loader:Loader = new Loader();

		public function disclosureOpenIcon() {
			this.source = new Bitmap(Bitmap(loader.content).bitmapData);
			this.width = loader.content.width;
			this.height = loader.content.height;
		}
	}
}

package {
	import flash.display.Bitmap;
	import flash.display.Loader;

	import mx.controls.Image;

	public class disclosureClosedIcon extends Image {
		public static const loader:Loader = new Loader();

		public function disclosureClosedIcon() {
			this.source = new Bitmap(Bitmap(loader.content).bitmapData);
			this.width = loader.content.width;
			this.height = loader.content.height;
		}
	}
}

下面是定制Tree展开合并图标的代码：

class="language-javascript">private static function registTreeDisclosureIcon(class="tags" href="/tags/TREE.html" title=tree>tree:UIComponent):void {
	registClassStyle(class="tags" href="/tags/TREE.html" title=tree>tree, disclosureOpenIcon, "assets/minus.png");
	registClassStyle(class="tags" href="/tags/TREE.html" title=tree>tree, disclosureClosedIcon, "assets/plus.png");
}

private static function registClassStyle(component:UIComponent, clazz:Class, value:String):void {
	if(clazz["loader"].content == null){
		clazz["loader"].contentLoaderInfo.addEventListener(Event.COMPLETE, function(e:Event):void {
			component.setStyle(getQualifiedClassName(clazz), clazz);
		});
		clazz["loader"].load(new URLRequest(value), new LoaderContext(true));
	}
}

如果想全局注册，可以考虑下面的代码：

class="language-javascript">private static function registTreeDisclosureIcon():void {
	var css:CSSStyleDeclaration = StyleManager.getStyleDeclaration("Tree");
	registClassStyle(css, disclosureOpenIcon, "assets/minus.png");
	registClassStyle(css, disclosureClosedIcon, "assets/plus.png");
}

private static function registClassStyle(css:CSSStyleDeclaration, clazz:Class, value:String):void {
	if(clazz["loader"].content == null){
		clazz["loader"].contentLoaderInfo.addEventListener(Event.COMPLETE, function(e:Event):void {
			css.setStyle(getQualifiedClassName(clazz), clazz);
		});
		clazz["loader"].load(new URLRequest(value), new LoaderContext(true));
	}
}

最后看看摆脱mx.controls.Tree的FastTree怎么定制展开合并图标，比如下面的代码就让展开合并图标颠倒了：

class="language-javascript">class="tags" href="/tags/TREE.html" title=tree>tree4.expandIcon = "collapsed_icon";
class="tags" href="/tags/TREE.html" title=tree>tree4.collapseIcon = "expanded_icon";

本文完整代码见附件：TreeDisclosureIcon

class="tags" href="/tags/TREE.html" title=tree>treeSkill">