ink_rect, logical_rect = playoutline:GetPixelExtents()
layout_line in device units.
This will return two tables that have the fields x, y, width, and
height initialized.
This function just calls playoutline:GetExtents() followed by
two pango.ExtentsToPixels() calls, rounding ink_rect and logical_rect
such that the rounded rectangles fully contain the unrounded one (that is,
passes them as first argument to pango.ExtentsToPixels()).