如何在WPF处理Canvas.Top更改事件？

问题描述

我定位在画布使用附加属性的元素 Canvas.Top 和画布。左。然后用动画的元素被移动到不同的组坐标，像这样的：

I have an element positioned on Canvas using attached properties Canvas.Top and Canvas.Left. Then using animations the element is moved to different set of coordinates, like this:

DoubleAnimation left = new DoubleAnimation( oldLeft, newLeft );
DoubleAnimation top = new DoubleAnimation( oldTop, newTop );

element.BeginAnimation( Canvas.LeftProperty, left );
element.BeginAnimation( Canvas.TopProperty, top );

有没有办法接收事件时 Canvas.Top 或 Canvas.Left 被改变？最好不涉及动画。

Is there a way to receive events whenever Canvas.Top or Canvas.Left is changed? Preferably without relation to animation.

推荐答案

人们可以的使用 DependencyPropertyDescriptor 小号 AddValueChanged 方法：

One can catch attached property changed event using DependencyPropertyDescriptor's AddValueChanged method:

var descriptor 
    = DependencyPropertyDescriptor.FromProperty( 
        Canvas.LeftProperty, typeof( YourControlType ) 
      );
descriptor.AddValueChanged( this, OnCanvasLeftChanged );

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