WPF Label adapt FontSize to it's Width and Height

Question

Hi all,

I need to develop a Label control in WPF, on .net 3.5 and VisualStudio 2010, which FontSize automatically makes the text fill the control area.

I dont know if create a CustomControl inheriting from label or create a UserControl which contains a Label control.

I've seen an example here using a ValueConverter, but I'am not understanding right its behavior, here: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/89167931-0813-4d6a-92b7-42a3323a5bd2

Can anyone give me a clue about that?

Thanks.

I found the solutiion using the DoubleConverter from the example I've posted before:

The soultion is using a ValueConverter, which I extracted from the example, but added the NumerFormat IFormatProvider to correctly parse "0.1" value, i found that at bytes.com/topic/c-sharp/answers/495594-decimal-d1-decimal-parse-0-1-1-a:

 [ValueConversion(typeof(object), typeof(double))]
 public class DoubleConverter : IValueConverter
 {
  public object Convert(object value, Type targetType,
   object parameter, CultureInfo culture)
  {
   double dblValue = (double)value;
   double scale = Double.Parse(((string)parameter), System.Globalization.CultureInfo.InvariantCulture.NumberFormat);
   return dblValue * scale;
  }

  public object ConvertBack(object value, Type targetType,
   object parameter, CultureInfo culture)
  {
   throw new NotImplementedException();
  }
 }

Then, you have to instantiate in XAML the DoubleConverter, and specify the binding in the FonSize Property:

<UserControl x:Class="<Namespace>.LabelAutoFontSize"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
  xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
  xmlns:me="clr-namespace:<Namespace>"
  mc:Ignorable="d" 
  d:DesignHeight="60" d:DesignWidth="278">
 <UserControl.Resources>
 <me:DoubleConverter x:Key="doubleConverter" />
 </UserControl.Resources>
 <Grid>
 <Label
  x:Name="lbl"
  FontSize="{
   Binding Path=Width,
    RelativeSource={RelativeSource AncestorType={x:Type UserControl}},
   Converter={StaticResource doubleConverter},
   ConverterParameter=0.116}"

  VerticalAlignment="Stretch"
  HorizontalAlignment="Stretch"
  Content="LabelAutoFontSize"
  d:LayoutOverrides="Width"
  HorizontalContentAlignment="Center"
  VerticalContentAlignment="Center" />
 </Grid>
</UserControl>

An important point is that the value for ConverterParameter depends absolutely from the font assigned. Each font may need a different value and you have to "play around" to get the correct value to fit exactly.