flash as3 放大（按比例放大）到剪辑中的特定点

Question

我正在尝试放大容器/父影片剪辑，以便有效地放大到其子级之一引用的点。我已经弄清楚如何使用 globalToLocal 来获得舞台中心的该点，但问题是容器剪辑的注册点是（并且需要保持）在左上角，所以当我缩放容器剪辑时向上时，该点不会停留在屏幕中心。这是我的代码：

//修订：

var stageCenter = new Point(int(stage.stageWidth/2),int(stage.stageHeight)/2);
    var parPointLocal = parRef.globalToLocal(stageCenter);
    TweenMax.to(treeClip,.5,{x:parPointLocal.x,y:parPointLocal.y,onComplete:doZoom});

    function doZoom():void {
        var zoomPoint = zoomToMember(treeClip,stageCenter,2);

        function zoomToMember(target:MovieClip, center:Point, scale:Number):Point {
            var m:Matrix = new Matrix();
            m.translate(-center.x, -center.y);//move the center into (0,0)
            m.scale(scale, scale);//scale relatively to (0,0) (which is where our center is now)
            m.translate(center.x, center.y);//move the center back to its original position
            return m.transformPoint(new Point());//transform (0,0) using the whole transformation matrix to calculate the destination of the upper left corner
        }

        TweenMax.to (treeClip,.5,{x:zoomPoint.x,y:zoomPoint.y,scaleX:2,scaleY:2})

    }

当我这样做时，缩放点最终位于“Mabel Greer's Toy Shop”周围的某个地方 - 我想象这是在树剪辑补间之前舞台的中心点，以便“Jon Anderson”会处于舞台中央。

Answer 1

您需要在缩放并补间 x 和 y 属性后计算左上角的目标位置。

最简单的方法是使用矩阵：

function scale(target:MovieClip, center:Point, scale:Number):Point {
    var m:Matrix = new Matrix();
    m.translate(-center.x, -center.y);//move the center into (0,0)
    m.scale(scale, scale);//scale relatively to (0,0) (which is where our center is now)
    m.translate(center.x, center.y);//move the center back to its original position
    return m.transformPoint(new Point());//transform (0,0) using the whole transformation matrix to calculate the destination of the upper left corner
}