Use Data Triggers to Change the Appearance of Bound Data : Binding « Windows Presentation Foundation « VB.Net






Use Data Triggers to Change the Appearance of Bound Data

Use Data Triggers to Change the Appearance of Bound Data
      
<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:WpfApplication1="clr-namespace:WpfApplication1"
    x:Name="thisWindow" Title="WPF" Height="240" Width="280">

    <Window.Resources>
        <WpfApplication1:DataItems x:Key="dataItems"/>
        <WpfApplication1:AmountToHeightConverter x:Key="amountToHeightConverter" />
        <DataTemplate x:Key="dataItemtemplate">
            <Rectangle x:Name="rectangle" Width="30"
                VerticalAlignment="Bottom"
                Fill="Green"
                Height="{Binding Path=Amount,Converter={StaticResource amountToHeightConverter}}"/>
            <DataTemplate.Triggers>
                <DataTrigger Binding="{Binding Path=IsPositive}" Value="False">
                    <Setter TargetName="rectangle" Property="Fill" Value="Red"/>
                </DataTrigger>
            </DataTemplate.Triggers>
        </DataTemplate>
    </Window.Resources>
    <StackPanel>
        <ItemsControl ItemsSource="{Binding Source={StaticResource dataItems}}"
            ItemTemplate="{StaticResource dataItemtemplate}">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Horizontal"/>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
        </ItemsControl>

        <Line Stroke="Black" StrokeThickness="2" X1="0" Y1="0" X2="0" Y2="{Binding ElementName=thisWindow, Path=ActualHeight}"/>
        <Line Stroke="Black" StrokeThickness="2" X1="0" Y1="0" X2="{Binding ElementName=thisWindow, Path=ActualWidth}" Y2="0"/>
    </StackPanel>
</Window>
//File:Window.xaml.vb
Imports System
Imports System.Windows.Data
Imports System.Globalization
Imports System.Collections.ObjectModel
Namespace WpfApplication1
  <ValueConversion(GetType(Double), GetType(Double))> _
  Public Class AmountToHeightConverter
    Implements IValueConverter
    Public Function Convert(value As [Object], targetType As Type, parameter As [Object], culture As CultureInfo) As [Object] Implements IValueConverter.Convert
      Dim amount As Double = System.Convert.ToDouble(value)
      If amount < 0 Then
        amount = 0
      End If

      Return amount
    End Function
    Public Function ConvertBack(value As Object, targetType As Type, parameter As Object, culture As CultureInfo) As Object Implements IValueConverter.ConvertBack
      Throw New NotImplementedException()
    End Function
  End Class
  Public Class DataItem
    Public Property Amount() As Double
      Get
        Return m_Amount
      End Get
      Set
        m_Amount = Value
      End Set
    End Property
    Private m_Amount As Double

    Public ReadOnly Property IsPositive() As Boolean
      Get
        Return Amount >= 0
      End Get
    End Property
  End Class

  Public Class DataItems
    Inherits Collection(Of DataItem)
    Public Sub New()
      Me.Add(New DataItem() With { _
        .Amount = 5 _
      })
      Me.Add(New DataItem() With { _
        .Amount = 8 _
      })
      Me.Add(New DataItem() With { _
        .Amount = -5 _
      })
      Me.Add(New DataItem() With { _
        .Amount = 2 _
      })
      Me.Add(New DataItem() With { _
        .Amount = -5 _
      })
      Me.Add(New DataItem() With { _
        .Amount = -5 _
      })
    End Sub
  End Class
End Namespace

   
    
    
    
    
    
  








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