WPF Combobox: Different template in textbox and drop-downlist

Question

This is my combo-box.

Answer 1

There is a pretty good answer to your question here if you don't want to change the ComboBoxes style: https://stackoverflow.com/a/2277488/1070906

It uses a Trigger in the DataTemplate which looks if there is a ComboBoxItem somewhere above in the visual tree, which is not the case in the selection box.

Answer 2

You could override the ComboBox and change the SelectionBoxItemTemplate directly.

public class SelectionComboBox : ComboBox
{
    #region Properties

    #region Dependency Properties
    public DataTemplate AltSelectionBoxItemTemplate
    {
        get { return (DataTemplate)GetValue(AltSelectionBoxItemTemplateProperty); }
        set { SetValue(AltSelectionBoxItemTemplateProperty, value); }
    }

    public static readonly DependencyProperty AltSelectionBoxItemTemplateProperty =
        DependencyProperty.Register("AltSelectionBoxItemTemplate", typeof(DataTemplate), typeof(SelectionComboBox), new UIPropertyMetadata(null, (s, e) =>
        {
            // For new changes...
            if ((s is SelectionComboBox) && ((SelectionComboBox)s).Presenter != null && (e.NewValue is DataTemplate))
                ((SelectionComboBox)s).Presenter.ContentTemplate = (DataTemplate)e.NewValue;

            // Set the new value
            ((SelectionComboBox)s).AltSelectionBoxItemTemplate = (DataTemplate)e.NewValue;
        }));
    #endregion

    #region Internals

    #region Elements
    ContentPresenter Presenter { get; set; }
    #endregion

    #endregion

    #endregion

    #region Constructors
    #endregion

    #region Methods

    #region Overrides
    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        Presenter = this.GetTemplateChild("contentPresenter") as ContentPresenter;

        // Directly Set the selected item template
        if (AltSelectionBoxItemTemplate != null) Presenter.ContentTemplate = AltSelectionBoxItemTemplate;
    }
    #endregion

    #endregion

}

Once you define the control, you could style it.

<controls:SelectionComboBox ItemsSource="{Binding ...}" SelectedItem="{Binding ..., Mode=TwoWay}">
    <controls:SelectionComboBox.AltSelectionBoxItemTemplate>
        <DataTemplate>
            <!-- My Template Goes Here... -->
        </DataTemplate>
    </controls:SelectionComboBox.AltSelectionBoxItemTemplate>
</controls:SelectionComboBox>

Answer 3

Instead of using the read-only SelectionBoxItemTemplate property I created a new (attached, writable) property and used that one in my style. I also added a trigger to my style to not break all the comboboxes that are not using my new attached property...

Use it like this:

<ComboBox ItemsSource="{Binding ...}" SelectedItem="{Binding ..., Mode=TwoWay}">
    <controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate>
        <DataTemplate DataType="{x:Type ...}">
            ... Template for the selection box ...
        </DataTemplate>
    </controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate>
    <ComboBox.ItemTemplate>
        <DataTemplate DataType="{x:Type ...}">
            ... Template for the popup ...
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

You just have to add this class to your project:

public class ComboBoxSelectionBoxAltTemplateBehaviour
{
    public static readonly DependencyProperty SelectionBoxAltTemplateProperty = DependencyProperty.RegisterAttached(
        "SelectionBoxAltTemplate", typeof (DataTemplate), typeof (ComboBoxSelectionBoxAltTemplateBehaviour), new PropertyMetadata(default(DataTemplate)));

    public static void SetSelectionBoxAltTemplate(DependencyObject element, DataTemplate value)
    {
        element.SetValue(SelectionBoxAltTemplateProperty, value);
    }

    public static DataTemplate GetSelectionBoxAltTemplate(DependencyObject element)
    {
        return (DataTemplate) element.GetValue(SelectionBoxAltTemplateProperty);
    }

}

and change your ComboBox style to use the SelectionBoxAltTemplate attached property if set (or because I could not set a trigger to "not null", I set it back to the default SelectionBoxItemTemplate if the attached one is null):

The ContentPresenter inside the ControlTemplate of the ComboBox Style:

<ContentPresenter Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate}" />

And the Trigger to provide backwards compatibility to ComboBoxed without the attached Property:

<ControlTemplate.Triggers>
    <Trigger Property="controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate" Value="{x:Null}">
        <Setter Property="ContentTemplate" Value="{Binding SelectionBoxItemTemplate, RelativeSource={RelativeSource TemplatedParent}}" TargetName="ContentSite" />
    </Trigger>
    ...
</ControlTemplate.Triggers>

Full Style:

<Style x:Key="{x:Type ComboBox}" TargetType="{x:Type ComboBox}">
    <Setter Property="SnapsToDevicePixels" Value="true" />
    <Setter Property="HorizontalContentAlignment" Value="Stretch" />
    <Setter Property="VerticalContentAlignment" Value="Center" />
    <Setter Property="FontSize" Value="12" />
    <Setter Property="Background" Value="{StaticResource ComboBoxBackground}"/>
    <Setter Property="BorderBrush" Value="{StaticResource ComboBoxBorder}"/>
    <Setter Property="Margin" Value="6"/>
    <Setter Property="Padding" Value="3,3,5,3"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ComboBox}">
                <Grid>
                    <Grid.ColumnDefinitions>                    
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="Auto"/>
                    </Grid.ColumnDefinitions>
                    <Border Name="Border" Grid.ColumnSpan="2" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"/>
                    <ToggleButton Name="ToggleButton2" Focusable="False" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press" Grid.ColumnSpan="2" Background="Transparent"/>
                    <!-- Allows clicking anywhere on the combobox, not only the visible button on the right -->
                    <ToggleButton Focusable="false" Grid.Column="1" x:Name="ToggleButton" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press" Style="{StaticResource ComboBoxToggleButton}"/>
                    <ContentPresenter HorizontalAlignment="Left" Margin="{TemplateBinding Control.Padding}" x:Name="ContentSite" VerticalAlignment="Center" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" IsHitTestVisible="False" />

                    <TextBox Visibility="Hidden"  HorizontalAlignment="Left" Margin="{TemplateBinding Control.Padding}" x:Name="PART_EditableTextBox" Style="{x:Null}" VerticalAlignment="Center" Focusable="True" Background="Transparent"  />

                    <Popup IsOpen="{TemplateBinding IsDropDownOpen}" Placement="Bottom" x:Name="Popup" Focusable="False" AllowsTransparency="True" PopupAnimation="Slide">
                        <Grid MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}" x:Name="DropDown" SnapsToDevicePixels="True">
                            <Border x:Name="DropDownBorder" Background="{StaticResource ComboBoxBackground}" BorderBrush="{StaticResource ComboBoxBorder}" BorderThickness="1" Padding="0,4">
                                <ScrollViewer SnapsToDevicePixels="True" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" CanContentScroll="True" Style="{x:Null}" >
                                    <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained"/>
                                </ScrollViewer>
                            </Border>
                        </Grid>
                    </Popup>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate" Value="{x:Null}">
                        <Setter Property="ContentTemplate" Value="{Binding SelectionBoxItemTemplate, RelativeSource={RelativeSource TemplatedParent}}" TargetName="ContentSite" />
                    </Trigger>
                    <Trigger Property="HasItems" Value="false">
                        <Setter Property="MinHeight" Value="95" TargetName="DropDownBorder" />
                    </Trigger>
                    <Trigger Property="IsGrouping" Value="true">
                        <Setter Property="ScrollViewer.CanContentScroll" Value="false" />
                    </Trigger>
                    <Trigger Property="IsEditable" Value="true">
                        <Setter Property="IsTabStop" Value="false" />
                        <Setter Property="Visibility" Value="Visible" TargetName="PART_EditableTextBox" />
                        <Setter Property="Visibility" Value="Hidden" TargetName="ContentSite" />
                    </Trigger>

                    <Trigger Property="IsMouseOver" Value="true" SourceName="ToggleButton2">
                        <Setter Property="Background" Value="{StaticResource ComboBoxMouseOver}" />
                    </Trigger>
                    <Trigger Property="HasItems" Value="False">
                        <Setter Property="IsEnabled" Value="False"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

However this might not work with ItemTemplateSelctors, only with one single template - but you could easily add an attached property "SelectionBoxAltTemplateSelector" which provides the selector and passes that one to the style.

Answer 4

If the ComboBox's IsEditable property is set to True, you can set the "TextSearch.TextPath" property of the ComboBox to the property name you want to show. So in your case:

<ComboBox IsEditable="True" TextSearch.TextPath="FullName" .../>

Answer 5

Unfortunately, the SelectionBoxItemTemplate is a readonly property, so we have to do a bit more work. By doing the ItemTemplate to be how you want the item to appear when selected, you can edit the ItemContainerStyle to provide a ControlTemplate that includes the other fields you want to display.

<ComboBox Height="45" HorizontalAlignment="Left" Margin="184,66,0,0" Name="ComboBox1" VerticalAlignment="Top" Width="216">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <Label Content="{Binding FullName}" Width="150" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
    <ComboBox.ItemContainerStyle>
        <Style TargetType="{x:Type ComboBoxItem}">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type ComboBoxItem}">
                        <Border x:Name="Bd"
                                BorderBrush="{TemplateBinding BorderBrush}"
                                BorderThickness="{TemplateBinding BorderThickness}"
                                Background="{TemplateBinding Background}">
                            <StackPanel Orientation="Horizontal">
                                <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" 
                                                  VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
                                <Label Content="{Binding Title}" Width="100"/>
                                <Label Content="{Binding BranchName}" />
                            </StackPanel>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsHighlighted" Value="True">
                                <Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}" />
                            </Trigger>
                            <Trigger Property="IsEnabled" Value="False">
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ComboBox.ItemContainerStyle>
</ComboBox>

For the ComboBoxItem template, I just modified the default one, so it should be fully functional.