How to have a property of a view model set the height/width for all associate child controls

Here's the scenario: I have a flickr photo viewer, and the PhotoBrowserViewModel has a property named Image Source. The View that is bound to my PhotoBrowserViewModel contains the following XAML. My goal is to get the child controls to have the height/width of the ImageSource property.

        <ItemsControl ItemsSource="{Binding Photos}">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel/>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemTemplate>
                <DataTemplate DataType="viewmodel:FlickrPhotoViewModel">
                    <con开发者_高级运维trols:FlickrPhotoControl Margin="10"/> 
<!-- I want to set this control's Width/Height to {Binding PhotoSize}-->
<!-- on the same data context as ItemsControl, not as the data template.-->
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>

Use relative source binding:

{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.PhotoSize}