ComboListCell creates an editable combo box cell: users can type freely, rely on auto-completion, or pick from a drop-down list. Unlike DropdownListCell (selection-only), ComboListCell accepts new values typed by the user.

Namespace

using unvell.ReoGrid.CellTypes;

Create a Combo List Cell

var sheet = grid.CurrentWorksheet;
var combo = new ComboListCell("Apple", "Banana", "Orange", "Applause", "Appreciate");
sheet.Cells["C3"].Body = combo;

Constructors

Using a Mutable List

Pass a List<string> to keep items in sync. New items added to the list appear in the dropdown:

var items = new List<string> { "Alpha", "Beta", "Gamma" };
var combo = new ComboListCell(items);
sheet["B5"] = combo;

items.Add("Delta"); // immediately available in the dropdown

Using a Cell Range

Bind to a range so the list reflects current cell contents:

var combo = new ComboListCell(sheet.Ranges["A2:A20"]);
sheet["D2"] = combo;

Properties

ComboListCell Properties

Inherited from DropdownCell

Events

combo.SelectedItemChanged += (s, e) =>
{
    Console.WriteLine($"Selected: {combo.SelectedItem}");
};

Methods

Auto-Completion

Auto-completion is enabled by default. As the user types, matching items are suggested and the remaining text is auto-filled.

Disable Auto-Completion

combo.EnableAutoCompletion = false;

Custom Comparison Logic

The default comparison uses a case-insensitive prefix match (StartsWith). Override it for different behavior:

// Substring match instead of prefix match
combo.AutoCompleteComparerator = (item, text) =>
{
    if (string.IsNullOrWhiteSpace(text)) return false;
    return item.Contains(text, StringComparison.OrdinalIgnoreCase);
};

The function signature is Func<string, string, bool> where:

• First parameter: the candidate item text
• Second parameter: the text the user has typed
• Return true to include the item in suggestions

Custom Search Provider

For large or remote datasets, supply a search provider that returns filtered candidates dynamically:

combo.CandidationListSearchProvider = text =>
{
    return ProductSearch(text?.ToString())
        .Take(20)
        .ToList();
};

The function signature is Func<object, IList<string>> where:

• Parameter: the text currently typed by the user
• Return: the filtered list of candidates to display

When a search provider is set, it replaces the default filtering behavior entirely.

Capturing New Values

Since ComboListCell allows free text input, users can type values not in the original list. Capture these and add them for future suggestions:

var items = new List<string> { "Alpha", "Beta" };
var combo = new ComboListCell(items);
sheet["B5"] = combo;

sheet.AfterCellEdit += (s, e) =>
{
    if (ReferenceEquals(e.Cell.Body, combo) &&
        e.NewData is string text &&
        !string.IsNullOrWhiteSpace(text) &&
        !items.Contains(text))
    {
        items.Add(text);
    }
};

Keyboard Behavior

WPF Styling

On WPF, customize the list appearance through the Style property:

#if WPF
combo.Style.TextColor = SolidColor.DarkBlue;
combo.Style.BackColor = SolidColor.LightYellow;
combo.Style.FontSize = 14;
combo.Style.FontWeight = FontWeights.Bold;
#endif

ComboListStyle Properties (WPF Only)

Override the ListBox Template (WPF)

Swap in a custom ControlTemplate/ItemTemplate for the drop-down ListBox:

<Window.Resources>
    <ControlTemplate x:Key="ReoGridComboListTemplate" TargetType="ListBox">
        <Border Background="#101820" CornerRadius="6" Padding="4">
            <ScrollViewer Focusable="False">
                <ItemsPresenter />
            </ScrollViewer>
        </Border>
    </ControlTemplate>

    <DataTemplate x:Key="ReoGridComboItemTemplate">
        <StackPanel Orientation="Horizontal" Margin="4,2">
            <Ellipse Width="6" Height="6" Fill="#FF7A00" Margin="0,0,6,0"/>
            <TextBlock Text="{Binding}" Foreground="White"/>
        </StackPanel>
    </DataTemplate>
</Window.Resources>

Wire it up in code:

#if WPF
combo.DropdownOpened += (s, e) =>
{
    if (((ComboListCell)s).DropdownControl is ListBox listBox)
    {
        listBox.Template = (ControlTemplate)FindResource("ReoGridComboListTemplate");
        listBox.ItemTemplate = (DataTemplate)FindResource("ReoGridComboItemTemplate");
    }
};
#endif

Extending ComboListCell

Subclass ComboListCell for deeper customization:

class ProductComboCell : ComboListCell
{
    private readonly ProductService _service;

    public ProductComboCell(ProductService service) : base()
    {
        _service = service;
        CandidationListSearchProvider = text =>
            _service.Search(text?.ToString()).Select(p => p.Name).ToList();
    }
}

Comparison: DropdownListCell vs ComboListCell

Class Hierarchy

CellBody
  └─ DropdownCell (panel, button, open/close)
       └─ DropdownListBaseCell (candidate source)
            ├─ DropdownListCell (selection-only)
            └─ ComboListCell (editable + auto-complete)

Related Topics

• Built-in Cell Types — All cell type overview
• Dropdown List Cell — Selection-only dropdown
• Custom Cell — Creating custom cell bodies
• How to Create Custom Drop-down Cell — Custom drop-down tutorial