Question

I have defined a dependency propery as follows:

public static readonly DependencyProperty AnimateColumnWidthProperty =
    DependencyProperty.Register("AnimateColumnWidthProperty", typeof(double), typeof(MainWindow), new PropertyMetadata(0.0));

public double AnimateColumnWidth
{
    get { return (double)GetValue(AnimateColumnWidthProperty); }
    set { SetValue(AnimateColumnWidthProperty, value); }
}

When my application starts I do this….

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    AnimateColumnWidth = Properties.Settings.Default.ProductInfoWidthExpanded;
}

… which should initialise the value to its starting value – in this case 400.

I have then bound a column of a grid in my UI to this property…

<ColumnDefinition 
    Name="ProductInfo" 
    Width="{Binding Path=AnimateColumnWidth,
                    Converter={StaticResource doubleToGridLength},
                    Mode=TwoWay}" />

As I understand it, as the column width is bound to this property, whenever I update the property the column width should also update.

What am I doing wrong as the width does not update when I change the property? I am also trying to update it via an animation which also doesnt work. Additionally, a breakpoint set on the getter of the AnimateColumnWidth property is never hit – meaning that nothing ever tried to retrieve the property.

(This did work so clearly I have broken something somewhere!!)

Footnote:

The value converted is defined in the root namespace of my app (I believe that WPF would complain if it couldnt find it).

[ValueConversion(typeof(Double), typeof(GridLength))]
public class DoubleToGridLength : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return new GridLength((double)value);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return ((GridLength)value).Value;
    }
}

Answer 1

One thing I hadnt done was set the datacontext of the grid who’s column I wanted to affect to “this”.

public MainWindow()
{
    InitializeComponent();
    ProductsArea.DataContext = this;
}