+static void detect_edge(Rect area, ObDirection dir,
+ gint my_head, gint my_size,
+ gint my_edge_start, gint my_edge_size,
+ gint *dest, gboolean *near_edge)
+{
+ gint edge_start, edge_size, head, tail;
+ gboolean skip_head = FALSE, skip_tail = FALSE;
+
+ switch (dir) {
+ case OB_DIRECTION_NORTH:
+ case OB_DIRECTION_SOUTH:
+ edge_start = area.x;
+ edge_size = area.width;
+ break;
+ case OB_DIRECTION_EAST:
+ case OB_DIRECTION_WEST:
+ edge_start = area.y;
+ edge_size = area.height;
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ /* do we collide with this window? */
+ if (!RANGES_INTERSECT(my_edge_start, my_edge_size,
+ edge_start, edge_size))
+ return;
+
+ switch (dir) {
+ case OB_DIRECTION_NORTH:
+ head = RECT_BOTTOM(area);
+ tail = RECT_TOP(area);
+ break;
+ case OB_DIRECTION_SOUTH:
+ head = RECT_TOP(area);
+ tail = RECT_BOTTOM(area);
+ break;
+ case OB_DIRECTION_WEST:
+ head = RECT_RIGHT(area);
+ tail = RECT_LEFT(area);
+ break;
+ case OB_DIRECTION_EAST:
+ head = RECT_LEFT(area);
+ tail = RECT_RIGHT(area);
+ break;
+ default:
+ g_assert_not_reached();
+ }
+ switch (dir) {
+ case OB_DIRECTION_NORTH:
+ case OB_DIRECTION_WEST:
+ /* check if our window is past the head of this window */
+ if (my_head <= head + 1)
+ skip_head = TRUE;
+ /* check if our window's tail is past the tail of this window */
+ if (my_head + my_size - 1 <= tail)
+ skip_tail = TRUE;
+ /* check if the head of this window is closer than the previously
+ chosen edge (take into account that the previously chosen
+ edge might have been a tail, not a head) */
+ if (head + (*near_edge ? 0 : my_size) < *dest)
+ skip_head = TRUE;
+ /* check if the tail of this window is closer than the previously
+ chosen edge (take into account that the previously chosen
+ edge might have been a head, not a tail) */
+ if (tail - (!*near_edge ? 0 : my_size) < *dest)
+ skip_tail = TRUE;
+ break;
+ case OB_DIRECTION_SOUTH:
+ case OB_DIRECTION_EAST:
+ /* check if our window is past the head of this window */
+ if (my_head >= head - 1)
+ skip_head = TRUE;
+ /* check if our window's tail is past the tail of this window */
+ if (my_head - my_size + 1 >= tail)
+ skip_tail = TRUE;
+ /* check if the head of this window is closer than the previously
+ chosen edge (take into account that the previously chosen
+ edge might have been a tail, not a head) */
+ if (head - (*near_edge ? 0 : my_size) > *dest)
+ skip_head = TRUE;
+ /* check if the tail of this window is closer than the previously
+ chosen edge (take into account that the previously chosen
+ edge might have been a head, not a tail) */
+ if (tail + (!*near_edge ? 0 : my_size) > *dest)
+ skip_tail = TRUE;
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ ob_debug("my head %d size %d\n", my_head, my_size);
+ ob_debug("head %d tail %d deest %d\n", head, tail, *dest);
+ if (!skip_head) {
+ ob_debug("using near edge %d\n", head);
+ *dest = head;
+ *near_edge = TRUE;
+ }
+ else if (!skip_tail) {
+ ob_debug("using far edge %d\n", tail);
+ *dest = tail;
+ *near_edge = FALSE;
+ }
+}
+