wpf - How do I databind a ColumnDefinition's Width or RowDefinition's Height?

Question

Under the View-Model-ViewModel pattern for WPF, I am trying to databind the Heights and Widths of various definitions for grid controls, so I can store the values the user sets them to after using a GridSplitter. However, the normal pattern doesn't seem to work for these particular properties.

Note: I'm posting this as a reference question that I'm posting as Google failed me and I had to work this out myself. My own answer to follow.

Answer 1

Create a IValueConverter as follows:

public class GridLengthConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        double val = (double)value;
        GridLength gridLength = new GridLength(val);

        return gridLength;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        GridLength val = (GridLength)value;

        return val.Value;
    }
}

You can then utilize the converter in your Binding:

<UserControl.Resources>
    <local:GridLengthConverter x:Key="gridLengthConverter" />
</UserControl.Resources>
...
<ColumnDefinition Width="{Binding Path=LeftPanelWidth, 
                                  Mode=TwoWay,
                                  Converter={StaticResource gridLengthConverter}}" />