How to bind content template of text annotation in WPF Chart?
Description
WPF Chart (SfChart) allows you to customize a annotation’s appearance by defining your own template using the ContentTemplate property. In some scenarios, you may want to display or use underlying values or any other values from any object. By default, the content of a Text Annotation is treated as a plain string, which limits its binding capabilities when using complex data.
Solution
To bind complex objects to the annotation and use their properties within a content template, you must override the default behavior. This can be achieved by creating a custom annotation class derived from TextAnnotation that exposes an object-typed content property and properly sets the data binding to the internal content control.
Check out the following code example:
C#
public class CustomTextAnnotation : TextAnnotation
{
public object Content
{
get { return (object)GetValue(ContentProperty); }
set { SetValue(ContentProperty, value); }
}
// Using DependencyProperty as the backing store for TextString. This enables animation, styling, binding, etc...
public static readonly DependencyProperty ContentProperty = DependencyProperty.Register("Content", typeof(object), typeof(CustomTextAnnotation), new PropertyMetadata(null));
protected override void SetBindings()
{
base.SetBindings(); //You need to invoke this method to make all the default bindings
if (TextElement != null)
{
Binding textBinding = new Binding { Path = new PropertyPath("Content"), Source = this };
//TextElement is content control define internally to display text.
TextElement.SetBinding(ContentControl.ContentProperty, textBinding);
}
}
}
XAML
<Window x:Class="Annotation_DataContext.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:chart="http://schemas.syncfusion.com/wpf"
xmlns:local="clr-namespace:Annotation_DataContext"
Title="Annotation DataContext" Height="700" Width="1000">
<Window.Resources>
<DataTemplate x:Key="annotationTemplate1">
<TextBlock Text="{Binding Path=Annotation1}" Background="LightPink" Foreground="Black" FontSize="15" FontWeight="Medium"/>
</DataTemplate>
<DataTemplate x:Key="annotationTemplate2">
<StackPanel HorizontalAlignment="Center">
<TextBlock Text="{Binding Path=Annotation2.Name}" Background="LightPink" Foreground="Black" FontSize="15" FontWeight="Medium" Width="100"/>
<TextBlock Text="{Binding Path=Annotation2.Range}" Background="LightPink" Foreground="Black" FontSize="15" FontWeight="Medium" Width="100"/>
</StackPanel>
</DataTemplate>
</Window.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.DataContext>
<local:ViewModel/>
</Grid.DataContext>
<chart:SfChart x:Name="chart" Header="PRODUCT DETAILS" FontSize="18" FontWeight="ExtraBlack">
<!--create custom text annotation-->
<chart:SfChart.Annotations>
<local:CustomTextAnnotation X1="2" Y1="250" Content="{Binding}" ContentTemplate="{StaticResource annotationTemplate1}"/>
<local:CustomTextAnnotation X1="0" Y1="150" Content="{Binding}" ContentTemplate="{StaticResource annotationTemplate2}"/>
</chart:SfChart.Annotations>
<chart:SfChart.PrimaryAxis>
<chart:CategoryAxis/>
</chart:SfChart.PrimaryAxis>
<chart:SfChart.SecondaryAxis>
<chart:NumericalAxis Interval="50"/>
</chart:SfChart.SecondaryAxis>
<chart:ColumnSeries ItemsSource="{Binding Products}" Palette="Metro" XBindingPath="Name" YBindingPath="Range">
</chart:ColumnSeries>
</chart:SfChart>
</Grid>
</Window>
Output
Conclusion
I hope you enjoyed learning about how to bind the content template of TextAnnotation in WPF Chart (SfChart).
You can refer to our WPF Chart feature tour page to know about its other groundbreaking feature representations. You can also explore our WPF Chart documentation to understand how to create and manipulate data.
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