Flex 给容器设置背景渐变

时间：2011-06-03 来源：水手◎辛巴德

Flex和Severlight在一些UI方面，确实差很多，需要大大改进。目前，flex除了application支持背景渐变色外，其它控件都不支持，近日需要这个功能，在网上搜到些资料整理如下：

类文件GradientBorder.as：

View Code

/*  
=========== 背景渐变色    
 */   
package {   
       
    import flash.display.*;   
    import flash.geom.*;   
    import flash.utils.*;   
       
    import mx.core.EdgeMetrics;   
    import mx.skins.halo.HaloBorder;   
    import mx.utils.ColorUtil;   
    import mx.utils.GraphicsUtil;   
       
    public class GradientBorder extends HaloBorder    
    {   
           
        private var topCornerRadius:Number;        // top corner radius   
        private var bottomCornerRadius:Number;    // bottom corner radius   
        private var fillColors:Array;            // fill colors (two)   
        private var setup:Boolean;   
           
  
        private function setupStyles():void   
        {   
            fillColors = getStyle("fillColors") as Array;   
            if (!fillColors) fillColors = [0xFFFFFF, 0xFFFFFF];   
               
            topCornerRadius = getStyle("cornerRadius") as Number;   
            if (!topCornerRadius) topCornerRadius = 0;       
               
            bottomCornerRadius = getStyle("bottomCornerRadius") as Number;   
            if (!bottomCornerRadius) bottomCornerRadius = topCornerRadius;       
           
        }   
           
           
        override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void   
        {   
            super.updateDisplayList(unscaledWidth, unscaledHeight);       
               
            setupStyles();   
               
            var g:Graphics = graphics;   
            var b:EdgeMetrics = borderMetrics;   
            var w:Number = unscaledWidth - b.left - b.right;   
            var h:Number = unscaledHeight - b.top - b.bottom;   
            var m:Matrix = verticalGradientMatrix(0, 0, w, h);   
           
            g.beginGradientFill("linear", fillColors, [1, 1], [0, 255], m);   
               
            var tr:Number = Math.max(topCornerRadius-2, 0);   
            var br:Number = Math.max(bottomCornerRadius-2, 0);   
               
            GraphicsUtil.drawRoundRectComplex(g, b.left, b.top, w, h, tr, tr, br, br);   
            g.endFill();   
                   
        }   
           
    }   
}

调用示例：tester.mxml:

View Code

 1 <?xml version="1.0" encoding="utf-8"?>
 2  <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
 3     layout="vertical" backgroundImage="" backgroundColor="white">
 4     
 5     <mx:Style>
 6         
 7         .gradient
 8         {
 9             border-style: solid;
10             border-thickness: 0;
11             border-skin: ClassReference("GradientBorder");
12             fill-colors: #0099FF, #000099;
13             corner-radius: 10;
14             drop-shadow-enabled: true;
15         }
16         
17     </mx:Style>
18     
19     <mx:Script>
20         <![CDATA[
21             private function changeStyle():void
22             {
23                 box.setStyle("fillColors", [col1.value, col2.value]);
24                 box.setStyle("cornerRadius", corner.value);
25             }
26         ]]>
27     </mx:Script>
28     
29     <mx:VBox id="box" styleName="gradient" width="400" height="300" verticalAlign="middle" horizontalAlign="center">
30         <mx:FormItem label="Color 1:">
31             <mx:ColorPicker id="col1" change="changeStyle()" selectedColor="0x0099FF"/>
32         </mx:FormItem>
33         <mx:FormItem label="Color 2:">
34             <mx:ColorPicker id="col2" change="changeStyle()" selectedColor="0x000099"/>
35         </mx:FormItem>
36         <mx:FormItem label="Corner radius:">
37             <mx:HSlider id="corner" value="10" minimum="0" maximum="100" change="changeStyle()"/>
38         </mx:FormItem>
39     </mx:VBox>
40     
41  </mx:Application>