WPF : Conditional templating of textblock
I have a bunch of textblocks in an itemscontrol... I need to know how can I underline the text in the textblock based on whether the text is available in a list in the data model..
Sounds very simple to me...but I have been googling since the past 8 hrs...
Can I use datatriggers and valueconverters for this purpose? If yes, then how can I execute the method which lies in the viewModel (the method which helps me to check whther a given a text exists in the data model list)...
Even if I go for conditional templating....how do I access the list which lies in my mode开发者_如何学Pythonl (the viewmodel can fetch it...but then how do i access the viewmodel?)..
This should be a fairly easy thing to do...Am I really missing something very simple here?? :)
I am following the MVVM pattern for my application..
One way is to use a multivalueconverter which is a class that implements IMultiValueConverter
. A multivalueconverter allows you to bind to several values which means that you can get a reference to both your viewmodel and the text of your TextBlock
in your valueconverter.
Assuming that your viewmodel has a method called GetIsUnderlined
that returns true or false indicating whether or not the text should be underlined your valueconverter can be implemented along these lines:
class UnderlineValueConverter : IMultiValueConverter
{
#region IMultiValueConverter Members
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var viewmodel = values[0] as Window1ViewModel;
var text = values[1] as string;
return viewmodel.GetIsUnderlined(text) ? TextDecorations.Underline : null;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
You can use this valueconverter in the following way for a TextBlock
:
<Grid x:Name="grid1" >
<Grid.Resources>
<local:UnderlineValueConverter x:Key="underlineValueConverter" />
</Grid.Resources>
<TextBlock Text="Blahblah">
<TextBlock.TextDecorations>
<MultiBinding Converter="{StaticResource underlineValueConverter}">
<Binding /> <!-- Pass in the DataContext (the viewmodel) as the first parameter -->
<Binding Path="Text" RelativeSource="{RelativeSource Mode=Self}" /> <!-- Pass in the text of the TextBlock as the second parameter -->
</MultiBinding>
</TextBlock.TextDecorations>
</TextBlock>
</Grid>
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