CODEWITHSUNDEEP
wpfxaml
BlackMat
BlackMat

Reputation: 41

RenderTransform is not updated in resource dictionary in WPF

I want to implement a knob in resource dictionary that could receive an image as template. When I implemented it in the same library, it worked well :

knob.xaml :

<UserControl x:Class="SwitchesLibrary.Knob"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="96" Width="96" x:Name="This">
<Grid>
    <Image RenderTransformOrigin=".5,.5" Source="Images/Knobs/Knob.png" Height="96" Width="96" >
        <Image.RenderTransform>
            <RotateTransform Angle="{Binding Angle, ElementName=This}"/>
        </Image.RenderTransform>
    </Image>
</Grid>

knob.cs

public static readonly DependencyProperty AngleProperty =
       DependencyProperty.Register("Angle",
                                   typeof(double),
                                   typeof(ExampleKnobLocklessAnalogLarge),
                                    new FrameworkPropertyMetadata(0.0,
                                        FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                                            null,
                                            coerceValueCallback));
public double Angle
{
    get { return (double)GetValue(AngleProperty); }
    set { SetValue(AngleProperty, value); }
}

but when I moved it to resource dictionary :

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:SwitchesLibrary">
<Style TargetType="local:Knob">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:Knob">
                <Border BorderBrush="{TemplateBinding BorderBrush}"
                BorderThickness="{TemplateBinding BorderThickness}">
                    <Grid>
                        <Image 
                            x:Name="image"
                            Source="{TemplateBinding KnobImage}"
                            RenderTransformOrigin=".5,.5" 
                            Stretch="Fill"
                            HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                            <Image.RenderTransform>
                                <RotateTransform Angle="{TemplateBinding Angle}"/>
                            </Image.RenderTransform>
                        </Image>
                        <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

It's seem to work well (the angle value is updated correctly), but the knob image is not rotating. Why ?

Upvotes: 0

Views: 205

Answers (1)

mm8
mm8

Reputation: 169420

Try to replace the TemplateBinding with a RelativeSource binding;

<RotateTransform Angle="{Binding Angle, RelativeSource={RelativeSource AncestorType=local:Know}, Mode=OneWay}"/>

{TemplateBinding} is an optimized version of a binding that doesn't work very well in all scenarios.

Upvotes: 3

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