WPF: Alternating colors on a ItemsControl? - wpf

Question

How do I get alternating colors on a ItemsControl? I have AlternationCount set to 2, but the ItemsControl.AlternationIndex property always returns 0.
<ItemsControl ItemsSource="{Binding}" AlternationCount="2">
<ItemsControl.Resources>
<Style x:Key="FooBar" TargetType="Grid">
<Style.Triggers>
<Trigger Property="ItemsControl.AlternationIndex" Value="0">
<Setter Property="Background" Value="Blue"/>
</Trigger>
<Trigger Property="ItemsControl.AlternationIndex" Value="1">
<Setter Property="Background" Value="Red"/>
</Trigger>
</Style.Triggers>
</Style>
</ItemsControl.Resources>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid Margin="0,0,0,10" Style="{StaticResource FooBar}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="25" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions >
<RowDefinition Height="Auto" />
<!--<RowDefinition Height="Auto" />-->
</Grid.RowDefinitions>
<CheckBox IsChecked="{Binding Checked, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" />
<Label Grid.Column="1" Content="{Binding CompanyName}" />
<Label Grid.Column="2" Content="{Binding TradeKey}" />
<Label Grid.Column="3" Content="{Binding TradeDate}" ContentStringFormat="d" />
<Label Grid.Column="4" Content="{Binding Cusip}" />
<Label Grid.Column="5" Content="{Binding IssueName}" />
<Label Grid.Column="6" Content="{Binding TotalUnits}" ContentStringFormat="N0" />
<!--<Expander Grid.Row="0" Grid.Column="7" Grid.ColumnSpan="7" IsExpanded="True">
<Expander.Header>
<StackPanel Orientation="Horizontal">
<Label Content="Allocations"/>
<Button Content="Edit" Name="cmdEdit" Click="cmdEdit_Click" />
</StackPanel>
</Expander.Header>-->
<DataGrid Grid.Column="7" IsReadOnly="True" ItemsSource="{Binding Territories}" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False">
<DataGrid.Columns>
<DataGridTextColumn Header="Rep on Ticket" Binding="{Binding TradeCustomer.RepNameNotes}" />
<DataGridTextColumn Header="Rep # on Ticket" Binding="{Binding TradeCustomer.RepNumberNotes}" />
<DataGridTextColumn Header="State" Binding="{Binding TradeCustomer.AccountStateKey}" />
<DataGridTextColumn Header="Qty. on Ticket" Binding="{Binding TradeCustomer.Quantity, StringFormat=N0}" />
<DataGridTextColumn Header="Zip Code" Binding="{Binding ZipCode}" />
<DataGridTextColumn Header="State" Binding="{Binding State}" />
<DataGridTextColumn Header="Territory" Binding="{Binding Territory}" />
</DataGrid.Columns>
</DataGrid>
<!--</Expander>-->
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<VirtualizingStackPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.Template>
<ControlTemplate>
<Border BorderThickness="{TemplateBinding Border.BorderThickness}" Padding="{TemplateBinding Control.Padding}" BorderBrush="{TemplateBinding Border.BorderBrush}" Background="{TemplateBinding Panel.Background}" SnapsToDevicePixels="True">
<ScrollViewer Padding="{TemplateBinding Control.Padding}" Focusable="False">
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</ScrollViewer>
</Border>
</ControlTemplate>
</ItemsControl.Template>
</ItemsControl>

Answer 1

Check here http://www.codeproject.com/Articles/35886/WPF-ItemsControl-with-alternating-items-and-hover-.aspx
You have to change your code like this to get it working
<ItemsControl ItemsSource="{Binding DataList}" AlternationCount="2">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid x:Name="FooBar" Margin="0,0,0,10">
----------------------------
----------------------------
</Grid>
<DataTemplate.Triggers>
<Trigger Property="ItemsControl.AlternationIndex" Value="0">
<Setter Property="Background" Value="Blue" TargetName="FooBar"/>
</Trigger>
<Trigger Property="ItemsControl.AlternationIndex" Value="1">
<Setter Property="Background" Value="Red" TargetName="FooBar"/>
</Trigger>
</DataTemplate.Triggers>
</DataTemplate>
</ItemsControl.ItemTemplate>

Answer 2

Here is an alternative which may be a bit more general
<DataTemplate x:Key="AlternatingTemplate">
<Border>
<Border.Style>
<Style TargetType="{x:Type Border}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=(ItemsControl.AlternationIndex),
RelativeSource={RelativeSource AncestorType={x:Type ContentPresenter}}}"
Value="0">
<Setter Property="Background" Value="White" />
</DataTrigger>
<DataTrigger Binding="{Binding Path=(ItemsControl.AlternationIndex),
RelativeSource={RelativeSource AncestorType={x:Type ContentPresenter}}}"
Value="1">
<Setter Property="Background" Value="LightGray" />
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Style>
<ContentPresenter Content="{Binding}" />
</Border>
</DataTemplate>
Usage:
<ItemsControl AlternationCount="2"
ItemTemplate="{StaticResource AlternatingTemplate}"
ItemsSource="{Binding SourceOfData}" />

Answer 3

If you don't want to use the DataTemplate approach, you can create a custom control that uses a ContentControl as the item container, therefore allowing you to specify a background color.
Class:
public class ItemsControlAlternating : ItemsControl
{
static ItemsControlAlternating()
{
DefaultStyleKeyProperty.OverrideMetadata(typeof(ItemsControlAlternating),
new FrameworkPropertyMetadata(typeof(ItemsControlAlternating)));
}
protected override DependencyObject GetContainerForItemOverride()
{
return new ContentControl();
}
protected override bool IsItemItsOwnContainerOverride(object item)
{
return item is ContentControl;
}
}
Resource Dictionary:
<Style TargetType="{x:Type c:ItemsControlAlternating}">
<Setter Property="AlternationCount" Value="2"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type c:ItemsControlAlternating}">
<ItemsPresenter/>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="{x:Type ContentControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ContentControl}">
<Border Background="{TemplateBinding Background}">
<ContentPresenter/>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="ItemsControl.AlternationIndex" Value="0">
<Setter Property="Background" Value="Gray"/>
</Trigger>
<Trigger Property="ItemsControl.AlternationIndex" Value="1">
<Setter Property="Background" Value="White"/>
</Trigger>
</Style.Triggers>
</Style>
</Setter.Value>
</Setter>
</Style>