[PATCH 1/5] cursor: Revise edge cases for the pointer moving towards barriers

[Jasper St. Pierre]

From: "Jasper St. Pierre" <jstpierre at mecheye.net>

Since barriers block the invisible line between pixels, that means
that we need to explicitly check the boundaries, or else we'll have
a potential off-by-one error. This fixes issues when trying to move
down or right across a barrier and having the pointer visibly bounce.

Signed-off-by: Jasper St. Pierre <jstpierre at mecheye.net>
---
 xfixes/cursor.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/xfixes/cursor.c b/xfixes/cursor.c
index bd175b4..ffee4d6 100644
--- a/xfixes/cursor.c
+++ b/xfixes/cursor.c
@@ -1093,7 +1093,11 @@ barrier_is_blocking(const struct PointerBarrier * barrier,
         if (dir & BarrierNegativeX && x1 == (barrier->x1 - 1))
             return FALSE;
         /* startpoint adjacent to barrier, moving towards -> block */
-        if (x1 == barrier->x1 && y1 >= barrier->y1 && y1 <= barrier->y2) {
+        if (dir & BarrierPositiveX && x1 == (barrier->x1 - 1) && y1 >= barrier->y1 && y1 <= barrier->y2) {
+            *distance = 0;
+            return TRUE;
+        }
+        if (dir & BarrierNegativeX && x1 == barrier->x1 && y1 >= barrier->y1 && y1 <= barrier->y2) {
             *distance = 0;
             return TRUE;
         }
@@ -1105,7 +1109,11 @@ barrier_is_blocking(const struct PointerBarrier * barrier,
         if (dir & BarrierNegativeY && y1 == (barrier->y1 - 1))
             return FALSE;
         /* startpoint adjacent to barrier, moving towards -> block */
-        if (y1 == barrier->y1 && x1 >= barrier->x1 && x1 <= barrier->x2) {
+        if (dir & BarrierPositiveY && y1 == (barrier->y1 - 1) && x1 >= barrier->x1 && x1 <= barrier->x2) {
+            *distance = 0;
+            return TRUE;
+        }
+        if (dir & BarrierNegativeY && y1 == barrier->y1 && x1 >= barrier->x1 && x1 <= barrier->x2) {
             *distance = 0;
             return TRUE;
         }
-- 
1.8.0