如何在ControlTemplate中引用顶部UIElement？

Question

In my custom control I have ControlTemplate propety

public ControlTemplate ControlTemplate

It can be something like this:

<map:IdattMapLayer.ControlTemplate>
    <ControlTemplate>
        <Canvas
            DataContext="{Binding
                Converter={StaticResource ObjectToTrackedAssetConverter}}">
            <Button                                
                Style="{StaticResource LooklessButtonStyle}"
                Width="{Binding PushpinWidth}" Height="{Binding PushpinWidth}"
                Margin="{Binding PushpinMargin}"
                Command="{Binding
                    Path=DataContext.SelectedPushpinChangedCommand,
                    ElementName=LayoutRoot}"
                CommandParameter="{Binding}"
                Cursor="Hand">
                <Ellipse
                  Width="{Binding PushpinWidth}"
                  Height="{Binding PushpinWidth}"
                  Stroke="Black"
                  Fill="{Binding IsGPSDataRecent,
                      Converter={StaticResource BoolToGreenRedBrushConverter}}"
                  StrokeThickness="1">
                </Ellipse>
            </Button>
        </Canvas>
    </ControlTemplate>
</map:IdattMapLayer.ControlTemplate>

I would like to set Canvas 's data context myself rather than doing it in XAML.

So, If I have ControlTemplate - how do I find first child (Canvas in this case) programmatically?

Answer 1

1) set x:Name attribute for Canvas.

2) override OnApplyTemplate.

3) use (Canvas)GetTemplateChild("CanvasName") for get Canvas.

ofcourse this class should inherit from Control.