Silverlight – get insertion position in TextBox

public class AutoCompleteTextBox: TextBox
{
 public Point GetPositionFromCharacterIndex(int ​​index)
 {
 if (TextWrapping == TextWrapping.Wrap) throw new NotSupportedException();

 var text = Text.Substring(0, index);

 int lastNewLineIndex = text.LastIndexOf(' 
');

 var leftText = lastNewLineIndex != -1? text.Substring(lastNewLineIndex + 1): text;

 var block = new TextBlock
 {
 FontFamily = FontFamily,
 FontSize = FontSize,
 FontStretch = FontStretch,
 FontStyle = FontStyle,
 FontWeight = FontWeight
 };
 
 block. Text = text;
 double y = block.ActualHeight;

 block.Text = leftText;
 double x = block.ActualWidth;

 var scrollViewer = GetTemplateChild("ContentElement") as ScrollViewer;

 var point = scrollViewer != null
? New Point(x-scrollViewer.HorizontalOffset, y-scrollViewer.VerticalOffset)
: new Point(x, y);
 point.X += BorderThickness.Left + Padding.Left;
 point.Y += BorderThickness.Top + Padding.Top;

 return point;
 }
}

How to get the insertion position (x,y) in the visible client area of ​​the TextBox control? I need to add auto-completion in the text box.

I found a solution for WPF, but it cannot be applied in Silverlight.

public class AutoCompleteTextBox: TextBox
{
 public Point GetPositionFromCharacterIndex(int ​​index)
 {
 if (TextWrapping == TextWrapping.Wrap) throw new NotSupportedException( );

 var text = Text.Substring(0, index);

 int lastNewLineIndex = text.LastIndexOf('
');

 var leftText = lastNewLineIndex != -1? text.Substring(lastNewLineIndex + 1): text;

 var block = new TextBlock
 {
 FontFamily = FontFamily,
 FontSize = FontSize,
 FontStretch = FontStretch,
 FontStyle = FontStyle,
 FontWeight = FontWeight
 };

 block.Text = text;
 double y = block.ActualHei ght;

 block.Text = leftText;
 double x = block.ActualWidth;

 var scrollViewer = GetTemplateChild("ContentElement") as ScrollViewer;

 var point = scrollViewer != null
? new Point(x-scrollViewer.HorizontalOffset, y-scrollViewer.VerticalOffset)
: new Point(x, y);
 point .X += BorderThickness.Left + Padding.Left;
 point.Y += BorderThickness.Top + Padding.Top;

 return point;
 }
}