WPF Trigger binding to MVVM property

Question

I have a datatemplate containing an image that I want to be hidden if the the value of a property in a ViewModel is true. Can anyone tell me why the the xaml below does not work?

<Image x:Name="img" Source="..\Images\List_16.png" Margin="0,0,5,0">
  <Image.Style>
    <Style>
      <Style.Triggers>
        <DataTrigger Binding="{Binding CurrentListHasPendingChanges}" Value="True">
          <Setter Property="Image.Visibility" Value="Hidden" />
        </DataTrigger>
        <DataTrigger Binding="{Binding CurrentListHasPendingChanges}" Value="False">
          <Setter Property="Image.Visibility" Value="Visible" />
        </DataTrigger>
      </Style.Triggers>
    </Style>
  </Image.Style>
</Image>

Answer 1

isn't that

<Setter Property="Visibility" Value="Hidden" />

?

I assume you use INotifyProptyChanged.

EDIT I did some Googling and I think you need to use some sort of template in order to make the trigger work.

eg.: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/ae2dbfb7-5dd6-4352-bfa1-53634289329d

http://www.thejoyofcode.com/Help%5FWhy%5Fcant%5FI%5Fuse%5FDataTriggers%5Fwith%5Fcontrols%5Fin%5FWPF.aspx

Answer 2

Try removing "Image" part from Property="Image.Visibility" so you'll have:

<Setter Property="Visibility" Value="Hidden"/>

and add TargetType to your Style:

<Style TargetType="{x:Type Image}">

Answer 3

I just did something similar using a ContentControl.

<ContentControl Content="{Binding CurrentListHasPendingChanges}">
  <ContentControl.ContentTemplate>
    <DataTemplate>
      <Image x:Name="img" Source="..\Images\List_16.png" Margin="0,0,5,0" Visibility="Hidden" />
      <DataTemplate.Triggers>
        <DataTrigger Binding="{Binding}" Value="False">
          <Setter Property="Image.Visibility" Value="Visible" />
        </DataTrigger>
      </DataTemplate.Triggers>
    </DataTemplate>
  </ContentControl.ContentTemplate>
</ContentControl>

From http://karlhulme.wordpress.com/2007/03/06/using-a-contentcontrol-and-datatemplate-to-indicate-new-andor-modified-data/