Divides the vertical space in the `PangoLayout` being iterated over between the lines in the layout, and returns the space belonging to the current line.
A line's range includes the line's logical extents. plus half of the spacing above and below the line, if [ [email protected]_spacing] has been called to set layout spacing. The Y positions are in layout coordinates (origin at top left of the entire layout).
Note: Since 1.44, Pango uses line heights for placing lines, and there may be gaps between the ranges returned by this function.
| this |
a `PangoLayoutIter` |
| y0_ |
start of line |
| y1_ |
end of line |