3.25.测量并改变容器尺寸

<mx:HBox xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
import mx.core.Container;
import mx.core.UIComponent;
override protected function measure():void
{
super.measure();
var childrenWidth:int = 0;
var childrenHeight:int = 0;
//loop through all children, and determine the
height and width
//of all the children components
for(var i:int = 0; i<this.numChildren; i++)
{
var obj:UIComponent = (getChildAt(i) as
UIComponent);
if(obj is Container)
{
//here we are using the viewMetricsAndPadding
//so that we get any style information
affiliated
//with the child as well as its actual width
childrenWidth +=
Container(obj).viewMetricsAndPadding.left+
Container(obj).viewMetricsAndPadding.right+obj.width;
childrenHeight +=
Container(obj).viewMetricsAndPadding.top+
Container(obj).viewMetricsAndPadding.bottom+obj.height;
}e
else
{
childrenWidth += obj.width;
childrenHeight += obj.height;
}
} //set this components measured height based on our
calculations
measuredHeight = childrenHeight;
measuredWidth = childrenWidth;
}

]]>
</mx:Script>
</mx:HBox>

<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" width="1400"
height="500" xmlns:cookbook="oreilly.cookbook.*">
<mx:Script>
<![CDATA[
import mx.containers.Panel;
private function addChildToExtendableCanvas():void
{
var panel:Panel = new Panel();
panel.height = 100 + Math.random()*200;
panel.width = 100 + Math.random()*200;
extCanvas.addChild(panel);
}

]]>
</mx:Script>
<mx:Button click="addChildToExtendableCanvas()"
label="add child"/>
<cookbook:ExtendableCanvas id="extCanvas" y="50"
verticalScrollPolicy="off" horizontalScrollPolicy="off"/>
</mx:Canvas>