When will the ValueConverter's Convert method be called in wpf
- by sudarsanyes
I have an ObservableCollection bound to a list box and a boolean property bound to a button. I then defined two converters, one that operates on the collection and the other operates on the boolean property. Whenever I modify the boolean property, the converter's Convert method is called, where as the same is not called if I modify the observable collection. What am I missing??
Snippets for your reference,
xaml snipet,
<Window.Resources>
<local:WrapPanelWidthConverter x:Key="WrapPanelWidthConverter" />
<local:StateToColorConverter x:Key="StateToColorConverter" />
</Window.Resources>
<StackPanel>
<ListBox x:Name="NamesListBox" ItemsSource="{Binding Path=Names}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel x:Name="ItemWrapPanel" Width="500" Background="Gray">
<WrapPanel.RenderTransform>
<TranslateTransform x:Name="WrapPanelTranslatation" X="0" />
</WrapPanel.RenderTransform>
<WrapPanel.Triggers>
<EventTrigger RoutedEvent="WrapPanel.Loaded">
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Storyboard.TargetName="WrapPanelTranslatation" Storyboard.TargetProperty="X" To="{Binding Path=Names,Converter={StaticResource WrapPanelWidthConverter}}" From="525" Duration="0:0:2" RepeatBehavior="100" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</WrapPanel.Triggers>
</WrapPanel>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<Label Content="{Binding}" Width="50" Background="LightGray" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button Content="{Binding Path=State}" Background="{Binding Path=State, Converter={StaticResource StateToColorConverter}}" Width="100" Height="100" Click="Button_Click" />
</StackPanel>
code behind snippet
public class WrapPanelWidthConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
ObservableCollection<string> aNames = value as ObservableCollection<string>;
return -(aNames.Count * 50);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class StateToColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
bool aState = (bool)value;
if (aState)
return Brushes.Green;
else
return Brushes.Red;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
