layer.centerFrame()

The calculated frame, centered within its parent. If there is no parent, it will be centered relative to the screen.
译：计算框架，以其超级图层。如果没有超级图层，这将是中心相对于屏幕。

layerA = new Layer
    width: 500
    height: 500

layerB = new Layer
    parent: layerA
    width: 100
    height: 100

print layerB.centerFrame()
# Output: { x: 200, y: 200, width: 100, height: 100 }