ComboBox

Introduction

The ComboBox control provides a compact way for users to select from a list of options.

Code Example: Adding a ComboBox

// Initialize
var comboBox = new ComboBox();
comboBox.AddToRoot();
for(int i = 0; i < 10; i++)
{
    comboBox.Items.Add($"Item {i}");
}

Try on XnaFiddle.NET

ComboBox displaying a list of items

Adjusting the Drop-Down ListBox

ComboBox provides a ListBox property which can be used to customize the ListBox instance.

This can be modified, even if it hasn't yet been shown. The following code shows how to modify the default size of the ListBox:

// Initialize
var comboBox = new ComboBox();
comboBox.AddToRoot();
comboBox.Anchor(Gum.Wireframe.Anchor.Top);
comboBox.ListBox.Height = 400;

for(int i = 0; i < 40; i++)
{
    comboBox.Items.Add($"Item {i+1}");
}

Try on XnaFiddle.NET

ComboBox ListBox with custom Height

SelectedObject and SelectedIndex

Use SelectedIndex to select an item by its zero-based position in Items, or read it back to find which item is currently selected. Use SelectedObject to get or set the selected item directly as an object.

// Initialize
var comboBox = new ComboBox();
comboBox.AddToRoot();
for(int i = 0; i < 5; i++)
{
    comboBox.Items.Add($"Item {i}");
}
comboBox.SelectedIndex = 2;

Try on XnaFiddle.NET

SelectionChanged

The SelectionChanged event fires whenever the user picks a different item. The handler receives a SelectionChangedEventArgs with information about the previously and newly selected items. You can also read SelectedObject or SelectedIndex directly inside the handler.

// Initialize
var label = new Label();
label.AddToRoot();

var comboBox = new ComboBox();
comboBox.AddToRoot();
comboBox.Y = 24;
for(int i = 0; i < 5; i++)
{
    comboBox.Items.Add($"Item {i}");
}
comboBox.SelectionChanged += (sender, args) =>
{
    // comboBox.SelectedObject holds the newly selected item
    label.Text = $"Selected: {comboBox.SelectedObject}";
};

Try on XnaFiddle.NET