AutoCompleteComboBox for WPF

Provides a lightweight combobox with filtering (auto-complete).

Screenshot

Usage

Install via NuGet.

Declare XML namespace.

<Window
    ...
    xmlns:dotNetKitControls="clr-namespace:DotNetKit.Windows.Controls;assembly=DotNetKit.Wpf.AutoCompleteComboBox"
    ... >

Then you can use AutoCompleteComboBox. It's like a normal ComboBox because of inheritance.

<dotNetKitControls:AutoCompleteComboBox
    SelectedValuePath="Id"
    TextSearch.TextPath="Name"
    ItemsSource="{Binding Items}"
    SelectedItem="{Binding SelectedItem}"
    SelectedValue="{Binding SelectedValue}"
    />

Note that:

• Set a property path to TextSearch.TextPath property.
  • The path leads to a property whose getter produces a string value to identify items. For example, assume each item is an instance of Person, which has Name property, and the property path is "Name". If the user input "va", the combobox filters the items to remove ones (persons) whose Name don't contain "va".
  • No support for TextSeach.Text.
• Don't use ComboBox.Items property directly. Use ItemsSource instead.
• Although the Demo project uses DataTemplate to display items, you can also use DisplayMemberPath.

Configuration

This library works fine in the default setting, however, it also provides how to configure.

• Define a class derived from DotNetKit.Windows.Controls.AutoCompleteComboBoxSetting to override some of properties.
• Set the instance to AutoCompleteComboBox.Setting property.

<dotNetKitControls:AutoCompleteComboBox
    Setting="..."
    ...
    />

• Or set to AutoCompleteComboBoxSetting.Default to apply to all comboboxes.

Performance

Filtering allows you to add a lot of items to a combobox without loss of usability, however, that makes the performance poor. To get rid of the issue, we recommend you to use VirtualizingStackPanel as the panel.

Use ItemsPanel property:

<dotNetKitControls:AutoCompleteComboBox ...>
    <dotNetKitControls:AutoCompleteComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </dotNetKitControls:AutoCompleteComboBox.ItemsPanel>
</dotNetKitControls:AutoCompleteComboBox>

or declare a style in resources as the Demo app does.

See also WPF: Using a VirtualizingStackPanel to Improve ComboBox Performance for more detailed explanation.

Internals

This library is basically a thin wrapper of the standard ComboBox with some behaviors.

What Happens Under the Hood

• Finds the TextBox part (in the ComboBox) to listen to the TextChanged event
• Opens or close the dropdown whenever the text changed (and then the debounce timer fired)
  • TextBox selection is carefully saved and restored to not disturb the user
• Filters the ComboBox items based on the input
• Defines ItemsSource DependencyProperty that shadows the ItemsControl.ItemsProperty (see also #26)
• Handles PreviewKeyDown events (Ctrl+Space) to open the dropdown