UWP RichEditBox equivalent of GetCharIndexFromPosition

Question

It seems like the GetCharIndexFromPosition is missing in UWP's richeditbox. I want to display a tooltip when a certain range is hovered over in a RichEditBox. Is this possible with UWP?

Answer 1

In UWP, we can use GetRangeFromPoint(Point, PointOptions) method as the equivalent of GetCharIndexFromPosition. This method retrieves the degenerate (empty) text range at, or nearest to, a particular point on the screen. It returns a ITextRange object and the StartPosition property of ITextRange is similar to the character index returned by GetCharIndexFromPosition method.

The following is a simple sample:

XAML:

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <RichEditBox x:Name="editor" />
</Grid>

Code-behind:

public MainPage()
{
    this.InitializeComponent();
    editor.Document.SetText(Windows.UI.Text.TextSetOptions.None, @"This is a text for testing.");
    editor.AddHandler(PointerMovedEvent, new PointerEventHandler(editor_PointerMoved), true);
}

private void editor_PointerMoved(object sender, PointerRoutedEventArgs e)
{
    var position = e.GetCurrentPoint(editor).Position;

    var range = editor.Document.GetRangeFromPoint(position, Windows.UI.Text.PointOptions.ClientCoordinates);

    System.Diagnostics.Debug.WriteLine(range.StartPosition);
}