Question

I am trying to implement the following hierarchy of controls:

RoundedHandleBase:
– this will have a round border around a content presenter that will host a path defined in the template of the child controls.
– it will also provide 2 states: MouseOver and Normal (it displays a rectangle over the path when mouse is over)

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, MouseEventArgs e)
    {
        bool bRet = VisualStateManager.GoToState((Control)sender, "Normal", true);
    }
}

FlipHandle:
– this defines a Path as the template (that is the actual icon of the handle):

 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;               
        }            
    }
}

generic.xaml
*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="2,2,2,2">
            <Grid Height="Auto" Width="Auto">
                <Border Margin="0,0,0,0" BorderBrush="#FFFFFFFF" BorderThickness="2,2,2,2" CornerRadius="1,1,1,1" 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="1,1,1,1" 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  -->

My problem is:
– I cannot access the Path in the FlipHandle in order to modify its ScaleTransform in OnApplyTemplate.

Path arrowPath = this.GetTemplateChild(“Path_FlipHandle”) as Path;
-> arrowPath is allways null.

On the other hand, i can access the “content” content presenter:
ContentPresenter content = this.GetTemplateChild(“content”) as ContentPresenter;
-> the above works.

Please advice.
Thank you.

Answer 1

You can’t access path with GetTemplateChild if it is not part of the template. You could make it part of your template or you could define some visual states on your flip handle and use GoToState method.