GradientFill的用法

package  {
	import flash.display.Sprite;
	import flash.geom.Matrix;
	import flash.display.GradientType;
	
	public class GradientFill extends Sprite {

		public function GradientFill() {
			// constructor code
			init();
		}
		
		public function init():void{
			graphics.lineStyle(1);
			var colors:Array = [0xffffff,0x0000ff,0xff0000];
			var alphas:Array = [1,1,1];
			var ratios:Array = [0,128,255];
			var matrix:Matrix = new Matrix();
			matrix.createGradientBox(100,100,Math.PI/4,100,100);//后面两个100要和drawRect后面的两个100相同
			graphics.beginGradientFill(GradientType.LINEAR,colors,alphas,ratios,matrix);
			graphics.drawRect(100,100,100,100);
			graphics.endFill();
		}

	}
	
}