Question

I need to force uppercase input inside AutoCompleteBox in Silverlight 4 app.

In TextBox this could be done by replacing Text property on KeyDown event like:

            control.Text += enteredChar;
            control.Select(control.Text.Length, 0); //To maintain caret position

However AutoCompleteBox doesn’t provide text selection function, and I found no way to move caret to string end.

Answer 1

You need to change AutoCompleteBox template and add UpperCaseBehavior to the TextBox within:

<TextBox x:Name="Text" ...>
    <i:Interaction.Behaviors>
        <behaviors:UpperCaseBehavior/>
    </i:Interaction.Behaviors>
</TextBox>

where UpperCaseBehavior is:

public class UpperCaseBehavior: Behavior<TextBox>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.TextChanged += AssociatedObject_TextChanged;
    }

    private void AssociatedObject_TextChanged(object sender, TextChangedEventArgs args)
    {
        var selectionStart = AssociatedObject.SelectionStart;
        var selectionLength = AssociatedObject.SelectionLength;

        AssociatedObject.Text = AssociatedObject.Text.ToUpper();

        AssociatedObject.SelectionStart = selectionStart;
        AssociatedObject.SelectionLength = selectionLength;
    }

    protected override void OnDetaching()
    {
        AssociatedObject.TextChanged -= AssociatedObject_TextChanged;
        base.OnDetaching();
    }
}