input: add a weston_pointer_clear_focus() helper function

Valgrind has shown that in at least one place (default_grab_pointer_focus)
we're testing uninitialized values coming out of weston_compositor_pick_view.

This is happening when default_grab_pointer_focus is called when there is
nothing on the view list, and during the first repaint when only the black
surface with no input region exists.

This patch adds a function to clear pointer focus and also set the sx,sy
co-ordinates to a sentinel value we shouldn't compute with.

Assertions are added to make sure any time pointer focus is set to NULL
these values are used.

weston_compositor_pick_view() now returns these values too.

Now the values are always initialized, even when no view exists, and
they're initialized in such a way that actually doing computation
with them should fail in an obvious way, but we can compare them
safely for equality.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/src/compositor.c b/src/compositor.c
index 00b09a67..e27f44e9 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -1716,6 +1716,8 @@ weston_compositor_pick_view(struct weston_compositor *compositor,
 		return view;
 	}
 
+	*vx = wl_fixed_from_int(-1000000);
+	*vy = wl_fixed_from_int(-1000000);
 	return NULL;
 }
 
@@ -1760,10 +1762,7 @@ weston_view_unmap(struct weston_view *view)
 		if (keyboard && keyboard->focus == view->surface)
 			weston_keyboard_set_focus(keyboard, NULL);
 		if (pointer && pointer->focus == view)
-			weston_pointer_set_focus(pointer,
-						 NULL,
-						 wl_fixed_from_int(0),
-						 wl_fixed_from_int(0));
+			weston_pointer_clear_focus(pointer);
 		if (touch && touch->focus == view)
 			weston_touch_set_focus(touch, NULL);
 	}