We return early from drawing functions if the surface to draw to is not
initialized properly. There is no immediate need to do so, at least no
crashes have been observed, but it mirrors the previous behavior a bit
more closely. Furthermore, i3 should not crash due to not being able to
make some rendering call, so this provides some stability.
relates to #1278
This patch migrates all decoration rendering of i3 to cairo. Using the
compile switch CAIRO_SUPPORT, rendering can be switched back to the
previous XCB behavior, just like with the previous migration to cairo
in i3bar.
This patch also fixes a bug in draw_util.c where copying one surface
to another would use incorrect coordinates if the source coordinates
are not 0, 0.
Furthermore, this patch implicitly fixes some minor issues in the
decoration rendering which would be ignored previously due to the fact
that errors would only show up in the event queue, but not cause the
rendering code path to crash. One example is zero-height pixmaps which
are not allowed. Using cairo, these would cause i3 to instantly segfault,
so this patch avoids this.
Lastly, this patch annotates other issues found but not fixed in this patch
using TODO comments, e.g., the zero-height check not working correctly
and the comment that it should probably work the same way for zero-width
pixmaps.
relates to #1278
This patch fixes a bug when copying one surface to another.
Since it only exposes itself when used with non-trivial source
coordinates, it didn't surface before when only used for i3bar.
relates to #1278
In order to prepare for using cairo for rendering i3 decorations,
we need to make the draw_util.c from i3bar available via libi3 such
that both i3bar and i3 can use it.
relates to #1278