How do I set MenuItem's Icon using ItemContainerStyle

Question

I'm following the example here of binding a MenuItem to a data object.

<Menu Grid.Row="0" KeyboardNavigation.TabNavigation="Cycle"
      ItemsSource="{Binding Path=MenuCommands}">  
    <Menu.ItemContainerStyle>
        <Style>
            <Setter Property="MenuItem.Header" Value="{Binding Path=DisplayName}"/>
            <Setter Property="MenuItem.ItemsSource" Value="{Binding Path=Commands}"/>
            <Setter Property="MenuItem.Command" Value="{Binding Path=Command}"/>
            <Setter Property="MenuItem.Icon" Value="{Binding Path=Icon}"/>
        </Style>
    </Menu.ItemContainerStyle>                
</Menu>

It all works swimmingly except the MenuItem's icon shows up as the string System.Drawing.Bitmap. The bitmap in question is returned by the data object from a compiled resource.

internal static System.Drawing.Bitmap folder_page
{
    get
    {
        object obj = ResourceManager.GetObject("folder_page", resourceCulture);
        return ((System.Drawing.Bitmap)(obj));
    }
}

What am I doing wrong?

Answer 1

Kent (of course) has the right answer. But I thought I would go ahead and post the code for the converter that converts from the System.Drawing.Bitmap (Windows Forms) to a System.Windows.Windows.Media.BitmapSource (WPF) ... as this is a common problem/question.

This takes three steps:

1. Use an image converter in your binding.
2. Create the converter.
3. Declare the converter in your resources.

Here is how you would use an image converter in your binding:

<Setter
    Property="MenuItem.Icon"
    Value="{Binding Path=Icon, Converter={StaticResource imageConverter}}"
/>

And, here is the code for the converter (put it into a file called ImageConverter.cs) and add it to your project:

[ValueConversion(typeof(Image), typeof(string))]
public class ImageConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        BitmapSource bitmapSource;

        IntPtr bitmap = ((Bitmap)value).GetHbitmap();
        try
        {
            bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(bitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
        }
        finally
        {
            DeleteObject(bitmap);
        }

        return bitmapSource;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }

    [DllImport("gdi32.dll", CharSet=CharSet.Auto, SetLastError=true)]
    static extern int DeleteObject(IntPtr o);
}

Here is how you declare it in your resources section (note the local namespace that you will have to add):

<Window
    x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication2"
>
    <Window.Resources>
        <local:ImageConverter x:Key="imageConverter"/>
    </Window.Resources>
    <!-- some xaml snipped for clarity -->
</Window>

And that's it!

---

Update

After doing a quick search for similar questions, I noticed that Lars Truijens pointed out here that the previous converter implementation leaks. I have updated the converter code above ... so that it doesn't leak.

For more information on the cause of the leak, see the remarks section on this MSDN link.