Silverlight：子控件的默认模板内部的访问控件从模板控件派生

问题描述

| 我正在尝试实现以下控件层次结构： RoundedHandleBase： -这将在内容演示者周围有一个圆形边框，该边框将承载子控件模板中定义的路径。 -它还将提供2种状态：MouseOver和Normal（鼠标悬停时会在路径上显示一个矩形）

public class RoundedHandleBase : ContentControl
{        
    public RoundedHandleBase()
        : base()
    {
        base.DefaultStyleKey = typeof(RoundedHandleBase);

        this.MouseEnter += new MouseEventHandler(RoundedHandleBase_MouseEnter);
        this.MouseLeave += new MouseEventHandler(RoundedHandleBase_MouseLeave);
    }

    void RoundedHandleBase_MouseEnter(object sender,MouseEventArgs e)
    {
        bool bRet = VisualStateManager.GoToState((Control)sender,\"MouseOver\",true);            
    }
    void RoundedHandleBase_MouseLeave(object sender,\"Normal\",true);
    }
}

FlipHandle： -这将Path定义为模板（即手柄的实际图标）：

 public class FlipHandle : RoundedHandleBase
{
    private bool bFlipPath;

    public bool FlipPath
    {
        get { return bFlipPath; }
        set 
        {
            bFlipPath = value; 
        }
    }

    public FlipHandle()
        : base()
    {
        base.DefaultStyleKey = typeof(FlipHandle);
        bFlipPath = false;
    }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        if (bFlipPath)
        {
            ContentPresenter content = this.GetTemplateChild(\"content\") as ContentPresenter;
            Path arrowPath = this.GetTemplateChild(\"Path_FlipHandle\") as Path;               
        }            
    }
}

泛型 * generic.xaml *

 <!--ROUNDED HANDLES -->
<ControlTemplate x:Key=\"RoundedHandleBaseTemplate\" TargetType=\"local:RoundedHandleBase\">
    <Viewbox>
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name=\"CommonStates\">
                <VisualState x:Name=\"Normal\"/>
                <VisualState x:Name=\"MouseOver\">
                    <Storyboard>
                        <DoubleAnimationUsingKeyFrames BeginTime=\"00:00:00\" Storyboard.TargetName=\"rectangleOver\" Storyboard.TargetProperty=\"(UIElement.Opacity)\">
                            <SplineDoubleKeyFrame KeyTime=\"00:00:00\" Value=\"0.6\"/>
                            <SplineDoubleKeyFrame KeyTime=\"00:00:00.2000000\" Value=\"0.3\"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
                <VisualState x:Name=\"Pressed\">
                    <Storyboard>
                        <DoubleAnimationUsingKeyFrames BeginTime=\"00:00:00\" Duration=\"00:00:00.0010000\" Storyboard.TargetName=\"rectangleOver\" Storyboard.TargetProperty=\"(UIElement.Opacity)\">
                            <SplineDoubleKeyFrame KeyTime=\"00:00:00\" Value=\"0.15\"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>
        <Border CornerRadius=\"2,2,2\">
            <Grid Height=\"Auto\" Width=\"Auto\">
                <Border Margin=\"0,0\" BorderBrush=\"#FFFFFFFF\" BorderThickness=\"2,2\" CornerRadius=\"1,1,1\" Width=\"20\" Height=\"20\">
                    <Grid>
                        <Viewbox Width=\"14\" Height=\"14\">
                            <ContentPresenter x:Name=\"content\" Content=\"{TemplateBinding Content}\" ContentTemplate=\"{TemplateBinding ContentTemplate}\" HorizontalAlignment=\"Center\" VerticalAlignment=\"Center\"></ContentPresenter>
                        </Viewbox>
                        <Rectangle x:Name=\"rectangleOver\" Fill=\"#FFFFFFFF\" RadiusX=\"2\" RadiusY=\"2\" Margin=\"1,1\" Opacity=\"0\"/>
                    </Grid>
                </Border>
            </Grid>
        </Border>
    </Viewbox>
</ControlTemplate>

<Style TargetType=\"local:RoundedHandleBase\" x:Key=\"RoundedHandleStyle\">
    <Setter Property=\"Template\" Value=\"{StaticResource RoundedHandleBaseTemplate}\">
    </Setter>
</Style>


<Style TargetType=\"local:FlipHandle\" BasedOn=\"{StaticResource RoundedHandleStyle}\">
    <Setter Property=\"ContentTemplate\">
        <Setter.Value>
            <DataTemplate>
                <Path x:Name=\"Path_FlipHandle\" Width=\"47.5646\" Height=\"49.2324\" Canvas.Left=\"472.184\" Canvas.Top=\"584.534\" Stretch=\"Fill\" Fill=\"#FFFFFFFF\" Data=\"M 494.718,633.76C 508.77,634.067 520.133,622.527 519.738,608.563C 519.534,601.327 516.378,595.502 512.286,591.527C 508.354,587.711 502.225,583.955 493.832,584.608C 482.414,585.496 475.704,591.912 472.184,601.111L 501.638,601.111C 501.668,599.118 501.62,595.698 501.638,593.124C 505.862,596.766 509.822,601.13 513.884,605.191C 514.376,605.684 517.992,608.638 517.965,609.272C 517.962,609.336 516.478,610.758 516.013,611.224C 513.753,613.483 511.846,615.214 509.802,617.258C 506.906,620.154 504.43,623.172 501.638,625.066C 501.618,622.551 501.669,619.192 501.638,617.258L 472.184,617.258C 475.668,626.822 483.53,633.515 494.718,633.76 Z \">
                    <Path.RenderTransform>
                        <ScaleTransform CenterX=\"23.7823\" CenterY=\"24.6162\" ScaleX=\"1\" ScaleY=\"1\"></ScaleTransform>
                    </Path.RenderTransform>
                </Path>
            </DataTemplate>
        </Setter.Value>
    </Setter>
</Style>
<!--/ROUNDED HANDLES  -->

我的问题是： -我无法在FlipHandle中访问Path以便在OnApplyTemplate中修改其ScaleTransform。 路径arrowPath = this.GetTemplateChild（\“ Path_FlipHandle \”）作为路径； -> arrowPath始终为null。 另一方面，我可以访问\“ content \”内容演示者： ContentPresenter content = this.GetTemplateChild（\“ content \”）as ContentPresenter; ->以上作品。 请指教。 谢谢。     

解决方法

如果GetTemplateChild不属于模板，则无法访问该路径。您可以将其作为模板的一部分，也可以在翻转手柄上定义一些视觉状态并使用GoToState方法。