Question

In Silverlight (though I think this is applicable to WPF as well) I have an Items Control that has a List of Uris bound to it.

The ItemsPanel is a WrapPanel (from the Silverlight Toolkit) and the DataTemplate contains an Image with it’s Source bound.

The databound images display fine.

In xaml for each bound Image I have a storyboard which is started by The Image.Loaded RoutedEvent on an EventTrigger for each Image.

The Storyboard increases the images opacity from 0 to 1 over a period of 1 second.

When this runs all images ‘fade in’ at the same time.

Question : How can I build in a delay so that the subsequent images animation starts a short while after the previous? (Think of a mexican wave)

Update : Code example coming soon

<ItemsControl x:Name="Items1" ItemsSource="{Binding}">
        <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
                <toolkit:WrapPanel></toolkit:WrapPanel>
            </ItemsPanelTemplate>
        </ItemsControl.ItemsPanel>
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Border BorderBrush="#cccccc" BorderThickness="1" Margin="5">
                    <Image x:Name="myImage" Source="{Binding}" Width="100" Height="100" Stretch="Fill">
                        <Image.Triggers>
                            <EventTrigger RoutedEvent="Image.Loaded">
                                <BeginStoryboard>
                                    <Storyboard x:Name="myStoryboard">
                                        <DoubleAnimation Duration="00:00:03"
                            Storyboard.TargetName="myImage" 
                            Storyboard.TargetProperty="Opacity" 
                            From="0" To="1" />
                                    </Storyboard>
                                </BeginStoryboard>

                            </EventTrigger>
                        </Image.Triggers>
                    </Image>
                </Border>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>

Answer 1

You could bind DoubleAnimation.BeginTime to the index of ImageUri in your UriList.
Of course you have to use a converter.

class UriIndexConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        int seconds = YourUriList.IndexOf(value); /* or something similar */

        return new TimeSpan(0, 0, seconds);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

In your DoubleAnimation:

BeginTime="{Binding Converter={StaticResource UriIndexConverter}}"