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DependencyProperty Precedence(3)

  • Artigo

Let’s focused on the coercion of DP value.

In the precedence list, the coercion source is the highest.

In order to verify it, I have created a class called CoercionButton.

    1: public class CoercionButton : Button

    2: {

    3:     static CoercionButton()

    4:     {

    5:         WidthProperty.OverrideMetadata(typeof(CoercionButton), new FrameworkPropertyMetadata(null, OnCoerceValueCallback));

    6:     }

    7:  

    8:     // public delegate object CoerceValueCallback(DependencyObject d, object baseValue);

    9:     public static object OnCoerceValueCallback(DependencyObject d, object baseValue)

   10:     {

   11:         return 150.0;

   12:     }

   13: }

It overrides the Metadata of WidthProperty and adds CoerceValueCallback. And in the callback, returns a constant value 150.0.

We change the “Target Button” from normal Button type to CoercionButton type.

Main-1

But the event handler for other 4 buttons remain some.

No matter which button you clicks, the Width of “Target Button” is always 150.

And the animation doesn’t work.

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