I am fairly new to WPF so forgive me if I am missing something obvious. I'm having a pr开发者_如何学Coblem where I have a collection of AggregatedLabels and I am trying to bind the ItemCount of each AggregatedLabel to the FontSize in my DataTemplate so that if the ItemCount of an AggregatedLabel is large then a larger fontSize will be displayed in my listBox etc. The part that I am struggling with is the binding to the ValueConverter. Can anyone assist? Many thanks!
XAML Snippet
<DataTemplate x:Key="TagsTemplate">
<WrapPanel>
<TextBlock Text="{Binding Name, Mode=Default}"
TextWrapping="Wrap"
FontSize="{Binding ItemCount,
Converter={StaticResource CountToFontSizeConverter},
Mode=Default}"
Foreground="#FF0D0AF7"/>
</WrapPanel>
</DataTemplate>
<ListBox x:Name="tagsList"
ItemsSource="{Binding AggregatedLabels, Mode=Default}"
ItemTemplate="{StaticResource TagsTemplate}"
Style="{StaticResource tagsStyle}"
Margin="200,10,16.171,11.88" />
With your CollectionView
in place you might be able to bind to the Groups
property, i've never used that, will try it and clarify if possible...
Edit: Allright, here's one way to do it:
The data you bind to needs to be the CollectionView.Groups
, the CollectionView
should be defined like this:
CollectionView view = (ListCollectionView) CollectionViewSource.
GetDefaultView(LabelData);
view.GroupDescriptions.Add(new PropertyGroupDescription("Name"));
Then you can bind to the respective properties of CollectionViewGroup
in code, what you need are probably:
ItemCount
Name
That being said your original binding should work.
Note: You only pass one value to the converter, the ItemCount, thus it should look like this:
public class CountToFontSizeConverter : IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter,
CultureInfo culture)
{
const int minFontSize = 6;
const int maxFontSize = 38;
const int increment = 3;
if ((minFontSize + (int)value + increment) < maxFontSize)
{
return (double)(minFontSize + (int)value + increment);
}
return (double)maxFontSize;
}
public object ConvertBack(object value, Type targetType,
object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
Edit: Further clarifications...
Just add the CollectionView
to your ViewModel
as a property and create it in its constructor:
public class TagCloudViewModel//:INotifyPropertyChanged
{
public ObservableCollection<AggregatedLabelModel> AggregatedLabels
{get; set;}
public CollectionView AggregatedLabelsView {get; set;} // <-This...
public TagCloudViewModel()
{
var data = new DataAccess();
AggregatedLabels = data.GetData();
//...and this:
AggregatedLabelsView = (ListCollectionView)CollectionViewSource.
GetDefaultView(AggregatedLabels);
AggregatedLabelsView.GroupDescriptions.Add(
new PropertyGroupDescription("Name"));
}
}
Then bind to AggregatedLabelsView.Groups
.
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