AS3倒影算法

function createRef(picSource:DisplayObject):void
{
    // 倒置
    var bd:BitmapData = new BitmapData(picSource.width, picSource.height, true, 0x12346f);
    var mtx:Matrix = new Matrix();
    mtx.d = -1;
    mtx.ty = bd.height;
    bd.draw(picSource, mtx);
    // 添加渐变遮罩
    var width:int = bd.width;
    var height:int = bd.height;
    mtx = new Matrix();
    mtx.createGradientBox(width, height, 0.5 * Math.PI);
    var shape:Shape = new Shape();
    shape.graphics.beginGradientFill(GradientType.LINEAR, [0, 0], [0.9, 0.2], [0, 0xFF], mtx);
    shape.graphics.drawRect(0, 0, width, height);
    shape.graphics.endFill();
    var mask_bd:BitmapData = new BitmapData(width, height, true, 0);
    mask_bd.draw(shape);
    // 生成最终效果
    bd.copyPixels(bd, bd.rect, new Point(0, 0), mask_bd, new Point(0, 0), false);
    // 将倒影放置于图片下方
    var ref:Bitmap = new Bitmap();
    ref.y = picSource.height + picSource.y;
    ref.x = picSource.x;
    ref.bitmapData = bd;
    picSource.parent.addChild(ref);
}