Unable to retrieve actual Width - wpf

Question

I am having one list view
<ListView Grid.Row="4" Grid.ColumnSpan="2"
Margin="{Binding ElementName=BorderContainer, Path=Margin}"
FontSize="{DynamicResource PlaceHolderFontSize}"
ItemContainerStyle="{StaticResource ListItemContainerStyle}"
Foreground="Black"
>
<ListView.View>
<GridView ColumnHeaderContainerStyle="{StaticResource BorderlessHeader}">
<GridViewColumn Header="Last Backup Date/Time" HeaderTemplate="{StaticResource BlueHeader}"
Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ListView}, Converter={StaticResource ColumnWidth},ConverterParameter=221}">
<GridViewColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Date}" ToolTip="{Binding Date}" FontSize="{DynamicResource ContentFontSize}" Style="{StaticResource GridColumText}" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
As mentioned in the code am calculating the header width using converter. and inside my converter am using like below
public object Convert(object value, Type target Type, object parameter, Culture Info culture)
{
ListView listview = value as ListView;
double width = listview.ActualWidth;
but the listview.actualwidth is always giving "0" as result. Why this is happening? any ideas?

Answer 1

Why this is happening?
Probably because the ListView actually has an actual width of 0 by the time the Convert method gets invoked.
any ideas?
You could use a MultiBinding and an IMultiValueConverter that binds to both the ListView itself and its ActualWidth property:
<GridViewColumn Header="Last Backup Date/Time" HeaderTemplate="{StaticResource BlueHeader}">
<GridViewColumn.Width>
<MultiBinding Converter="{StaticResource ColumnWidth}" ConverterParameter="221">
<Binding Path="." RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=ListView}" />
<Binding Path="ActualWidth" RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=ListView}" />
</MultiBinding>
</GridViewColumn.Width>
<GridViewColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Date}" ToolTip="{Binding Date}" FontSize="{DynamicResource ContentFontSize}" Style="{StaticResource GridColumText}" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
public class ColumnWidthConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
ListView listview = values[0] as ListView;
double width = listview.ActualWidth;
if (width == 0)
return (double)parameter;
//...
return 100.0;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
Then the converter should be invoked whenever the ActualWidth property is updated.

Answer 2

If you have for example 4 Columns, you can try the following:
XAML
<ListView x:Name="listView">
<ListView.View>
<GridView>
<GridViewColumn Width="{Binding ElementName=listView, Path=ActualWidth, Converter={StaticResource ColumnWidthConverter},ConverterParameter=4}">
</GridViewColumn>
</GridView>
</ListView.View>
</ListView>
Converter
public class ColumnWidthConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
int columns;
if (int.TryParse(parameter.ToString(), out columns))
{
double width;
if (columns > 0 && double.TryParse(value.ToString(), out width))
{
return width / columns;
}
}
return 100.0;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return null;
}
}
If you want to be more dynamic, you can write a Behavior and attach it to the ListView. There you can dynamic calculate the values based on the Columns count.