截取位图的某一部分 (像素)

var bmd1: BitmapData = new BitmapData(40,
	40,
	false,
	0x000000FF);
var bmd2: BitmapData = new BitmapData(80,
	40,
	false,
	0x0000CC44);

var rect: Rectangle = new Rectangle(0,
	0,
	20,
	20);
var pt: Point = new Point(10,
	10);
bmd2.copyPixels(bmd1,
	rect, pt); //将bmd1中以pt为左上顶点的rect矩形像素复制到bmd2中

var bm1: Bitmap = new Bitmap(bmd1);
this.addChild(bm1);
var bm2: Bitmap = new Bitmap(bmd2);
this.addChild(bm2);
bm2.x = 50;