Computes the logical and ink extents of this.
Logical extents are usually what you want for positioning things. Note that both extents may have non-zero x and y. You may want to use those to offset where you render the layout. Not doing that is a very typical bug that shows up as right-to-left layouts not being correctly positioned in a layout with a set width.
The extents are given in layout coordinates and in Pango units; layout coordinates begin at the top left corner of the layout.
| this |
a `PangoLayout` |
| ink_rect |
rectangle used to store the extents of the layout as drawn |
| logical_rect |
rectangle used to store the logical extents of the layout |