Question

In my WPF UserControl I have this resource, please observe the comments in the Xml sample.

<UserControl.Resources>
    <DataTemplate x:Key="AxisXLabelTemplate">
        <ContentPresenter Content="{Binding Path=Content}">
            <ContentPresenter.LayoutTransform>
                <RotateTransform Angle="{Binding XAxisLabelRotation, UpdateSourceTrigger=PropertyChanged}" /> <!-- This does not work -->
                <!-- <RotateTransform Angle="-90" /> This works -->
            </ContentPresenter.LayoutTransform>
        </ContentPresenter>
    </DataTemplate>
</UserControl.Resources>

In the code I have a dependency property defined as follows:

class MyChart: INotifyPropertyChanged
{
        public static readonly DependencyProperty XAxisLabelRotationProperty =
            DependencyProperty.Register("XAxisLabelRotation", typeof(RotateTransform), typeof(BarChart),
                new FrameworkPropertyMetadata((RotateTransform)new RotateTransform(-90.0)));

        public RotateTransform XAxisLabelRotation
        {
            get { return (RotateTransform)GetValue(XAxisLabelRotationProperty); }
            set { SetValue(XAxisLabelRotationProperty, value); }
        }
...
}

The AxisXLabelTemplate DataTemplate is assigned to an element farther below as follows:

<chart:AxisLabel ElementTemplate="{StaticResource AxisXLabelTemplate}"/>

The problem is that when I use the unbound value for Angle and hard-code it to -90, it works beautifully, and when I try with the bound value to XAxisLabelRotation it doesn’t.

Can anyone please help?

Answer 1

I recreated similar setting as you and it did not work for me either. Curiously there are no binding errors. I did relativesource binding too and it didnt work.

Although if I bind tooltip

  <ContentPresenter ToolTip="{Binding XAxisLabelRotation, 
                                      RelativeSource={RelativeSource
                                          AncestorType={x:Type ContentControl}},
                                             UpdateSourceTrigger=PropertyChanged}" ..>

shows the tooltip to me. So I changed the rotate transform,

  <RotateTransform Angle="{Binding XAxisLabelRotation, 
                                      RelativeSource={RelativeSource
                                          AncestorType={x:Type ContentControl}},
                                             UpdateSourceTrigger=PropertyChanged}" ..>

But still the transform did not work. Still no binding errors.

Then I introduced a dummy converter …

public class AngleConverter : IValueConverter
{
    public object Convert(...)
    {
        return value;
    }
    ....
}

<RotateTransform Angle="{Binding XAxisLabelRotation, 
                                 RelativeSource={RelativeSource
                                      AncestorType={x:Type ContentControl}},
                                 UpdateSourceTrigger=PropertyChanged,
                                 Converter={StaticResource AngleConverter}}" ..>

and it worked miraculously!!!

Unexplanable world of WPF???