How to resize a shape from code behind when selected, like rectangle or any other geometry shape?

private void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
   if (!canvas1.IsMouseCaptured)
    {
        startPoint = e.GetPosition(canvas1);
        canvas1.CaptureMouse();
        if (rbCombine.IsChecked == true)
        {
            SetCombineShapes(e);

        }
        else if (rbSelect.IsChecked == true)
        {
            if (canvas1 == e.Source)
                return;
            isDown = true;
            originalElement = (Path)e.Source;
            e.Handled = true;
        }
        else if (rbDelete.IsChecked == true)
        {
            originalElement = (Path)e.Source;
            DeleteShape(originalElement);
        }
    }
}