Line spacing is incorrect with scaled CTM
When line-spacing is used and the context matrix is not the identity matrix, the spacing is over-corrected (at least on the cairo backend). See for example the output of the cairosimple example, with pango_layout_set_line_spacing(layout, 1.0)
added somewhere.
The opposite issue was first fixed in 66616440, then the broader problem was addressed in b2ef315e.
Reverting the first commit seems to fix the issue, but I am not familiar with the code base, so it's best if somebody else confirms this.
A workaround is to call pango_context_set_matrix(context, NULL)
after any calls to pango_cairo_update_layout()
or pango_cairo_update_context()
.