wayland: ensure at least a scale factor of 1 when drawing cursor

With the addition of fractional scaling support, wl->scaling was
converted to a double. Some compositors (Plasma) can report values under
1 for fractional scaling, so this meant wl->scaling could be some
small fractional value. This is fine except that when using the legacy
code for drawing the mouse cursor (i.e. not the cursor-shape protocol),
it still uses the old integer scaling method in core wayland. The reason
for this is simply because fractionally scaling the mouse cursor surface
is nonsense and nobody even has cursor images for anything besides a
select few sizes anyways (32x32, 48x48, etc.). The existing integer
scaling sort of works but it's pretty bad too and you can get some weird
sizes anyway. This is why cursor-shape is preferred since it fixes this.
Anyways, since buffer scaling for the cursor only takes integers, there
could be truncation to 0 in the previously mentioned fractional scale
this. This naturally causes the compositor to send us an error and mpv
quits. The fix is to always make sure that the scale value used for the
cursor is at least 1. Anything less makes no sense. Fixes #12309.

1 files changed, 3 insertions, 2 deletions

diff --git a/video/out/wayland_common.c b/video/out/wayland_common.c
index 53d3c97450..48fbbf2bca 100644
--- a/video/out/wayland_common.c
+++ b/video/out/wayland_common.c
@@ -1759,9 +1759,10 @@ static int set_cursor_visibility(struct vo_wayland_state *wl, bool on)
             struct wl_buffer *buffer = wl_cursor_image_get_buffer(img);
             if (!buffer)
                 return VO_FALSE;
+            int scale = MPMAX(wl->scaling, 1);
             wl_pointer_set_cursor(wl->pointer, wl->pointer_id, wl->cursor_surface,
-                                  img->hotspot_x/wl->scaling, img->hotspot_y/wl->scaling);
-            wl_surface_set_buffer_scale(wl->cursor_surface, wl->scaling);
+                                  img->hotspot_x / scale, img->hotspot_y / scale);
+            wl_surface_set_buffer_scale(wl->cursor_surface, scale);
             wl_surface_attach(wl->cursor_surface, buffer, 0, 0);
             wl_surface_damage_buffer(wl->cursor_surface, 0, 0, img->width, img->height);
         }