[mutter] cursor-renderer-native: Floor the cursor position instead of rounding

[Jonas Ådahl <jadahl src gnome org>]

commit 8d514095cbd2e3560bd76af3156733e031c70658
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Wed Dec 12 17:48:21 2018 +0800

    cursor-renderer-native: Floor the cursor position instead of rounding
    
    Which eliminates the 1px jitter that was visible when dragging windows,
    and eliminates the flickering that was visible when pushing the cursor
    against the right/bottom edges of the screen.

 src/backends/native/meta-cursor-renderer-native.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/native/meta-cursor-renderer-native.c 
b/src/backends/native/meta-cursor-renderer-native.c
index cb39bbed3..4fd7b1736 100644
--- a/src/backends/native/meta-cursor-renderer-native.c
+++ b/src/backends/native/meta-cursor-renderer-native.c
@@ -366,8 +366,8 @@ update_monitor_crtc_cursor (MetaMonitor         *monitor,
                        scaled_crtc_rect.origin.y) * scale;
       drmModeMoveCursor (kms_fd,
                          crtc->crtc_id,
-                         roundf (crtc_cursor_x),
-                         roundf (crtc_cursor_y));
+                         floorf (crtc_cursor_x),
+                         floorf (crtc_cursor_y));
 
       data->out_painted = data->out_painted || TRUE;
     }