WPF trigger on attached property not working - wpf

Question

i'm trying to change an image which i put as button's content through an attached property, yet for some reason the image is not changing and i don't get any exceptions or anything solid in the output.
Here is my attached property class code:
public class ImageButton
{
#region Image dependency property
/// <summary>
/// An attached dependency property which provides an
/// <see cref="ImageSource" /> for arbitrary WPF elements.
/// </summary>
public static DependencyProperty ImageProperty;
/// <summary>
/// Gets the <see cref="ImageProperty"/> for a given
/// <see cref="DependencyObject"/>, which provides an
/// <see cref="ImageSource" /> for arbitrary WPF elements.
/// </summary>
public static ImageSource GetImage(DependencyObject obj)
{
return (ImageSource)obj.GetValue(ImageProperty);
}
/// <summary>
/// Sets the attached <see cref="ImageProperty"/> for a given
/// <see cref="DependencyObject"/>, which provides an
/// <see cref="ImageSource" /> for arbitrary WPF elements.
/// </summary>
public static void SetImage(DependencyObject obj, ImageSource value)
{
obj.SetValue(ImageProperty, value);
}
#endregion
static ImageButton()
{
//register attached dependency property
var metadataImage = new FrameworkPropertyMetadata((ImageSource)null);
ImageProperty = DependencyProperty.RegisterAttached("Image",
typeof(ImageSource),
typeof(ImageButton), metadataImage);
}
}
here the code for the style using the attached property(the image source is set to take the value):
<Style TargetType="{x:Type Button}" x:Key="MyImageButton">
<Setter Property="Background" Value="White"/>
<Setter Property="SnapsToDevicePixels" Value="True" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Border
x:Name="Border"
Background="White">
<ContentPresenter>
<ContentPresenter.Content>
<Grid
x:Name="Grid"
Background="White">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Image
Grid.Column="0"
Source="{Binding Path=(attachedProperties:ImageButton.Image),
RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Button}}}"
Width="30"
Height="25"
Margin="5,0,2,0"
VerticalAlignment="Center"/>
<TextBlock
x:Name="TextBlock"
Grid.Column="1"
Text="{Binding Path=(attachedProperties:ImageButton.StringContent),
RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Button}}}"
VerticalAlignment="Center"
TextAlignment="Center"
Margin="0,0,15,0"/>
</Grid>
</ContentPresenter.Content>
</ContentPresenter>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
and finally the XAML code using the style and the trigger there trying to change the image source:
<Button
Grid.Row="2"
Width="30"
attachedProperties:ImageButton.Image="..\Images\Down_Arrow_Enabled_Icon_25x25.png"
Command="{Binding PriorityDownCommand}">
<Button.Style>
<Style TargetType="{x:Type Button}"
BasedOn="{StaticResource MyImageButton}">
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="attachedProperties:ImageButton.Image" Value="..\Images\Down_Arrow_Disabled_Icon_25x25.png"/>
</Trigger>
</Style.Triggers>
</Style>
</Button.Style>
thanks ahead for anyone who can find the problem!!!

Answer 1

Please take a look at this Dependency Property Value Precedence article.
Your problem is that you are trying to override a Local Property Value from withing a Style Trigger, this cannot be done since the Local Value has a higher precedence value.
You should set the default property in style setters:
<Button
Grid.Row="2"
Width="30"
Command="{Binding PriorityDownCommand}">
<Button.Style>
<Style TargetType="{x:Type Button}" BasedOn="{StaticResource MyImageButton}">
<Setter Property="attachedProperties:ImageButton.Image" Value="..\Images\Down_Arrow_Enabled_Icon_25x25.png"/>
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="attachedProperties:ImageButton.Image" Value="..\Images\Down_Arrow_Disabled_Icon_25x25.png"/>
</Trigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>