2014-08-31 129 views
2

我創建了簡單的自定義控件,該控件從Control派生。模板綁定到ScaleTransform不能在自定義控件中工作

這個控件有2個DP,我在ScaleTransform中綁定xaml。

後面的代碼。

public class MyControl : Control 
{ 
     public static readonly DependencyProperty ScaleXProperty = DependencyProperty.Register(
     "ScaleX", typeof (double), typeof (MyControl), new FrameworkPropertyMetadata(OnScaleXChanged)); 

    public static readonly DependencyProperty ScaleYProperty = DependencyProperty.Register(
     "ScaleY", typeof (double), typeof (MyControl), new FrameworkPropertyMetadata(OnScaleYChanged)); 

       public double ScaleX 
    { 
     get { return (double) GetValue(ScaleXProperty); } 
     set { SetValue(ScaleXProperty, value); } 
    } 

    public double ScaleY 
    { 
     get { return (double) GetValue(ScaleYProperty); } 
     set { SetValue(ScaleYProperty, value); } 
    } 
} 

XAML。

<Style TargetType="{x:Type local:MyControl}"> 
    <Setter Property="Template"> 
     <Setter.Value> 
      <ControlTemplate TargetType="{x:Type local:MyControl}"> 
       <Border Background="{TemplateBinding Background}" 
         BorderBrush="{TemplateBinding BorderBrush}" 
         BorderThickness="{TemplateBinding BorderThickness}"> 

        <Border.LayoutTransform> 
         <ScaleTransform ScaleX="{TemplateBinding ScaleX}" ScaleY="{TemplateBinding ScaleY}" /> 
        </Border.LayoutTransform> 


        <Image HorizontalAlignment="Stretch" 
          VerticalAlignment="Stretch" 
          Source="{TemplateBinding Icon}" 
          StretchDirection="Both" /> 
       </Border> 
      </ControlTemplate> 
     </Setter.Value> 
    </Setter> 
</Style> 

我在Window中使用MyControl。在Window代碼後面更改ScaleX和ScaleY屬性之後,LayoutTransform不會觸發。

所以我爲MyX for ScaleX和ScaleY添加了處理程序。我這些處理程序我manualy做ScaleTransform。這工作。那麼TemplateBinding中的問題在哪裏?

使用此變通辦法ScaleTransform的作品。

private static void OnScaleXChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
    { 
     if (d is MyControl) 
     { 
      var ctrl = d as MyControl; 

      var x = (double) e.NewValue; 

      ctrl.LayoutTransform = new ScaleTransform(x, ctrl.ScaleY); 

     } 
    } 

回答

2

你可能打的TemplateBinding許多限制之一。

因此,而不是使用相當於Binding相對源模板父這是語義上等同於TemplateBinding但(略)重:

<ScaleTransform ScaleX="{Binding ScaleX,RelativeSource={RelativeSource TemplatedParent}}" ScaleY="{Binding ScaleY,RelativeSource={RelativeSource TemplatedParent}}" /> 
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