How to reference a resource image in converter?

Question

I have a few images defined in my resource section of my UI :

<Window.Resources>
    <!-- Converters -->
    <loc:UserStatusToIconConverter x:Key="UserStatusToIconConverter" />

    <!-- Images -->
    <BitmapImage x:Key="ConnectIcon" UriSource="/WPFClient;component/Images/connect.png" />
    <BitmapImage x:Key="ActiveIcon" UriSource="/WPFClient;component/Images/active.png" />
    <BitmapImage x:Key="IdleIcon" UriSource="/WPFClient;component/Images/idle.png" />
    <BitmapImage x:Key="AwayIcon" UriSource="/WPFClient;component/Images/away.png" />
    <BitmapImage x:Key="UnknownIcon" UriSource="/WPFClient;component/Images/unknown.png" />
...

I would like to select one of these for a binding in my converter, I assume this would be more efficient than creating a new image each time (500 times) from the converter.

public class UserStatusToIconConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string userStatus = value.ToString();
        string iconName = ...;

        switch (userStatus)
        {
            case "Active":
                // select ActiveIcon;
                break;
            case "Idle":
                // select IdleIcon;
                break;
            case "Away":
                ...
                break;
        }

        return iconName;
    }

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

Here is where I use it :

            <ListBox ItemsSource="{Binding Users}">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <DockPanel>
                            <Image Source="{Binding Status, Converter={StaticResource UserStatusToIconConverter}}" Height="16" Width="16" />
                            <TextBlock Text="{Binding Nick}" />
                        </DockPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>

Answer 1

I think you're better off using DataTemplate.Triggers in this case rather than a Converter:

                 <DataTemplate>
                    <DockPanel>
                        <Image x:Name="Img" Height="16" Width="16" />
                        <TextBlock Text="{Binding Nick}" />
                    </DockPanel>

                    <DataTemplate.Triggers>
                       <DataTrigger Binding="{Binding Status}" Value="Active">
                          <Setter TargetName="Img" Property="Source" Value="{StaticResource ActiveIcon}"/>
                       </DataTrigger>

                       <DataTrigger Binding="{Binding Status}" Value="Idle">
                          <Setter TargetName="Img" Property="Source" Value="{StaticResource IdleIcon}"/>
                       </DataTrigger>

                       <!-- And So on... -->

                    </DataTemplate.Triggers>
                </DataTemplate>