Question

I have a UserControl with the following Property:

public List<Rect> HotSpots
{
   get { return (List<Rect>)GetValue(HotSpotsProperty); }
   set { SetValue(HotSpotsProperty, value); }
}

public static readonly DependencyProperty HotSpotsProperty =
        DependencyProperty.Register("HotSpots", typeof(List<Rect>), typeof(ImageViewPort), new FrameworkPropertyMetadata(HotSpotsChanged));

Since compiled XAML (XAML 2006 by default) doesn’t support generics the way the 2009 specification allows, I wonder is there any chance of doing something like the following:

<WPF:ImageViewPort Grid.Row="1">
   <WPF:ImageViewPort.HotSpots>
      <Rect Location="0,0" Height="30" Width="50"></Rect>
       <Rect Location="10,35" Height="30" Width="20"></Rect>
   </WPF:ImageViewPort.HotSpots>
 </WPF:ImageViewPort>

Or is my only chance a Binding like the following?

<WPF:ImageViewPort Grid.Row="1" HotSpots="{Binding Path=HotSpots}"/>

Just out of curiosity, the limitation seems to be XAML’s support for generics, so writing a List derivate should do the trick, shouldn’t it?

Answer 1

Since XAML isn’t used to add to Collections but rather to setting them, I’ve had to create a wrapping XAML Node that initializes the Collection. Since the Collection is generic, I can’t do this as it is, but have to create a wrapper like so :

public class HotSpotList : List<Rect> {}

In my XAML then, I can set it like so:

<WPF:ImageViewPort.HotSpots>
  <HotSpotList>
   <Rect Location="0,0" Height="30" Width="50"></Rect>
   <Rect Location="10,35" Height="30" Width="20"></Rect>
  </HotSpotList>
</WPF:ImageViewPort.HotSpots>

Easy enough, once you’ve seen it work =)