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ListControl.md

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ListControl

Scrollable list control with single selection and keyboard/mouse navigation.

Overview

ListControl displays a scrollable list of items with selection support. Users can navigate with keyboard or mouse, select items, and activate items (double-click or Enter).

Properties

Property Type Default Description
Items ObservableCollection<ListItem> Empty List of items to display
SelectedIndex int -1 Index of selected item (-1 = none)
SelectedItem ListItem? null Currently selected item
MaxVisibleItems int 10 Number of visible items
IsEnabled bool true Enable/disable list
BackgroundColor Color? null Background color (uses theme if null)
ForegroundColor Color? null Text color (uses theme if null)
HasFocus bool false Whether list has keyboard focus

Events

Event Arguments Description
SelectedIndexChanged EventHandler<int> Fired when selection index changes
SelectedItemChanged EventHandler<ListItem?> Fired when selected item changes
ItemActivated EventHandler<ListItem> Fired when item is double-clicked or Enter pressed
GotFocus EventHandler Fired when list receives focus
LostFocus EventHandler Fired when list loses focus

Creating Lists

Using Builder (Recommended)

var list = Controls.List()
    .AddItem("Apple")
    .AddItem("Banana")
    .AddItem("Cherry")
    .AddItem("Date")
    .AddItem("Elderberry")
    .WithHeight(10)
    .WithColors(Color.White, Color.Grey15)
    .WithName("fruitList")
    .OnItemActivated((sender, item, window) =>
    {
        windowSystem.NotificationStateService.ShowNotification(
            "Item Activated",
            $"You selected: {item.Text}",
            NotificationSeverity.Info
        );
    })
    .OnSelectionChanged((sender, index, window) =>
    {
        var status = window.FindControl<MarkupControl>("status");
        if (index >= 0)
        {
            status?.SetContent($"[dim]Selected: {sender.SelectedItem?.Text}[/]");
        }
    })
    .Build();

window.AddControl(list);

Using Constructor

var list = new ListControl
{
    MaxVisibleItems = 10,
    BackgroundColor = Color.Grey15,
    ForegroundColor = Color.White
};

list.Items.Add(new ListItem("Item 1"));
list.Items.Add(new ListItem("Item 2"));
list.Items.Add(new ListItem("Item 3"));

list.ItemActivated += (sender, item) =>
{
    // Handle activation
};

list.SelectedIndexChanged += (sender, index) =>
{
    // Handle selection change
};

window.AddControl(list);

Keyboard Support

Key Action
Up Arrow Move selection up
Down Arrow Move selection down
Page Up Move selection up by viewport height
Page Down Move selection down by viewport height
Home Select first item
End Select last item
Enter Activate selected item (fire ItemActivated)
Tab Move focus to next control
Shift+Tab Move focus to previous control

Mouse Support

Action Result
Left Click Select item and give focus
Double Click Activate item (fire ItemActivated)
Scroll Wheel Scroll list up/down

ListItem

Items in the list are ListItem objects:

public class ListItem
{
    public string Text { get; set; }
    public object? Tag { get; set; }  // Store custom data
}

Examples

Simple List

var list = Controls.List()
    .AddItem("Option 1")
    .AddItem("Option 2")
    .AddItem("Option 3")
    .WithHeight(5)
    .OnItemActivated((s, item, w) =>
    {
        windowSystem.NotificationStateService.ShowNotification(
            "Selected", item.Text, NotificationSeverity.Success);
    })
    .Build();

window.AddControl(list);

List with Custom Data

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

var people = new[]
{
    new Person { Name = "Alice", Age = 30 },
    new Person { Name = "Bob", Age = 25 },
    new Person { Name = "Charlie", Age = 35 }
};

var list = new ListControl { MaxVisibleItems = 10 };

foreach (var person in people)
{
    list.Items.Add(new ListItem(person.Name)
    {
        Tag = person  // Store custom data
    });
}

list.ItemActivated += (sender, item) =>
{
    var person = item.Tag as Person;
    if (person != null)
    {
        windowSystem.NotificationStateService.ShowNotification(
            "Person Details",
            $"{person.Name} is {person.Age} years old",
            NotificationSeverity.Info
        );
    }
};

window.AddControl(list);

Master-Detail Pattern

var list = Controls.List()
    .AddItem("Item 1")
    .AddItem("Item 2")
    .AddItem("Item 3")
    .WithName("masterList")
    .OnSelectionChanged((sender, index, window) =>
    {
        var detail = window.FindControl<MarkupControl>("detailView");
        if (index >= 0)
        {
            var item = sender.SelectedItem;
            detail?.SetContent(new List<string>
            {
                $"[bold yellow]{item?.Text}[/]",
                "",
                "Detailed information about this item...",
                $"Selected index: {index}"
            });
        }
    })
    .Build();

window.AddControl(list);

window.AddControl(
    Controls.Markup()
        .AddLine("[dim]Select an item to see details[/]")
        .WithName("detailView")
        .Build()
);

Searchable List

var allItems = new[] { "Apple", "Apricot", "Banana", "Blueberry", "Cherry", "Date" };

var list = Controls.List()
    .WithHeight(10)
    .WithName("searchableList")
    .Build();

// Initialize with all items
foreach (var item in allItems)
{
    list.Items.Add(new ListItem(item));
}

// Add search box
window.AddControl(
    Controls.Prompt("Search:")
        .OnInputChanged((sender, text, window) =>
        {
            var list = window.FindControl<ListControl>("searchableList");
            if (list != null)
            {
                list.Items.Clear();

                var filtered = string.IsNullOrWhiteSpace(text)
                    ? allItems
                    : allItems.Where(i => i.Contains(text, StringComparison.OrdinalIgnoreCase));

                foreach (var item in filtered)
                {
                    list.Items.Add(new ListItem(item));
                }

                list.Invalidate();
            }
        })
        .Build()
);

window.AddControl(list);

Dynamic List Updates

var list = Controls.List()
    .WithName("dynamicList")
    .WithHeight(10)
    .Build();

window.AddControl(list);

// Add button to add items
window.AddControl(
    Controls.Button("Add Item")
        .OnClick((s, e, w) =>
        {
            var list = w.FindControl<ListControl>("dynamicList");
            if (list != null)
            {
                var count = list.Items.Count + 1;
                list.Items.Add(new ListItem($"Item {count}"));
                list.Invalidate();
            }
        })
        .Build()
);

// Add button to remove selected
window.AddControl(
    Controls.Button("Remove Selected")
        .OnClick((s, e, w) =>
        {
            var list = w.FindControl<ListControl>("dynamicList");
            if (list != null && list.SelectedIndex >= 0)
            {
                list.Items.RemoveAt(list.SelectedIndex);
                list.Invalidate();
            }
        })
        .Build()
);

Formatted List Items

var list = Controls.List()
    .AddItem("[green]Available[/] - Service Running")
    .AddItem("[yellow]Warning[/] - High CPU Usage")
    .AddItem("[red]Error[/] - Service Stopped")
    .AddItem("[blue]Info[/] - Update Available")
    .WithHeight(10)
    .Build();

window.AddControl(list);

File Browser

public void ShowDirectoryContents(string path, ListControl list)
{
    list.Items.Clear();

    try
    {
        // Add parent directory option
        if (Directory.GetParent(path) != null)
        {
            list.Items.Add(new ListItem("[..] Parent Directory")
            {
                Tag = Directory.GetParent(path)?.FullName
            });
        }

        // Add directories
        foreach (var dir in Directory.GetDirectories(path))
        {
            var name = Path.GetFileName(dir);
            list.Items.Add(new ListItem($"[DIR] {name}")
            {
                Tag = dir
            });
        }

        // Add files
        foreach (var file in Directory.GetFiles(path))
        {
            var name = Path.GetFileName(file);
            list.Items.Add(new ListItem($"      {name}")
            {
                Tag = file
            });
        }
    }
    catch (Exception ex)
    {
        windowSystem.NotificationStateService.ShowNotification(
            "Error", ex.Message, NotificationSeverity.Danger);
    }

    list.Invalidate();
}

var list = Controls.List()
    .WithHeight(15)
    .OnItemActivated((sender, item, window) =>
    {
        var path = item.Tag as string;
        if (path != null && Directory.Exists(path))
        {
            ShowDirectoryContents(path, sender);
        }
    })
    .Build();

ShowDirectoryContents(Environment.CurrentDirectory, list);
window.AddControl(list);

Helper Methods

Select Item Programmatically

var list = window.FindControl<ListControl>("myList");
if (list != null)
{
    list.SelectedIndex = 0;  // Select first item
    list.Invalidate();
}

Clear Selection

var list = window.FindControl<ListControl>("myList");
if (list != null)
{
    list.SelectedIndex = -1;  // No selection
    list.Invalidate();
}

Get Selected Item

var list = window.FindControl<ListControl>("myList");
if (list != null && list.SelectedItem != null)
{
    string text = list.SelectedItem.Text;
    object? data = list.SelectedItem.Tag;
}

Best Practices

  1. Set appropriate height: Use WithHeight() to control visible items
  2. Use Tag for data: Store custom objects in ListItem.Tag
  3. Handle ItemActivated: Respond to double-click/Enter
  4. Update on selection: Use OnSelectionChanged for master-detail patterns
  5. Clear and rebuild: For filtering, clear Items and rebuild list
  6. Call Invalidate: After modifying Items collection
  7. Check selection: Always check SelectedIndex >= 0 before accessing SelectedItem

Common Patterns

Action on Selection

var list = Controls.List()
    .AddItem("View Details")
    .AddItem("Edit Item")
    .AddItem("Delete Item")
    .OnItemActivated((s, item, w) =>
    {
        switch (item.Text)
        {
            case "View Details":
                ShowDetailsDialog();
                break;
            case "Edit Item":
                ShowEditDialog();
                break;
            case "Delete Item":
                ConfirmDelete();
                break;
        }
    })
    .Build();

List with Status Bar

var list = Controls.List()
    .WithName("itemList")
    .WithHeight(10)
    .OnSelectionChanged((s, index, w) =>
    {
        var status = w.FindControl<MarkupControl>("statusBar");
        status?.SetContent($"Item {index + 1} of {s.Items.Count}");
    })
    .Build();

window.AddControl(list);
window.AddControl(
    Controls.Label("No selection")
        .WithName("statusBar")
        .StickyBottom()
        .Build()
);

See Also

Back to Controls | Back to Main Documentation