Implement tab cycling using mouse wheel

Firstly, a change had to be made to the container_at functions. If you
create layout `T[view H[view view]]` and hover the second tab, the
container_at functions would return the focus_inactive child. They now
return the split container itself. To compensate for this,
dispatch_cursor_button has been adjusted to find the focus_inactive
child before focusing it.

The actual implementation of wheel scrolling is pretty straightforward.
This uses handle_cursor_axis, so I took a similar approach to
handle_cursor_button (ie. creating a dispatch_cursor_axis function).

1 files changed, 45 insertions, 4 deletions

diff --git a/sway/input/cursor.c b/sway/input/cursor.c
index 85951c09..5111e8e5 100644
--- a/sway/input/cursor.c
+++ b/sway/input/cursor.c
@@ -911,9 +911,10 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
                 return;
         }
 
-        // Handle clicking a container surface
+        // Handle clicking a container surface or decorations
         if (cont) {
-                seat_set_focus_container(seat, cont);
+                node = seat_get_focus_inactive(seat, &cont->node);
+                seat_set_focus(seat, node);
                 seat_pointer_notify_button(seat, time_msec, button, state);
                 return;
         }
@@ -930,12 +931,52 @@ static void handle_cursor_button(struct wl_listener *listener, void *data) {
         transaction_commit_dirty();
 }
 
+static void dispatch_cursor_axis(struct sway_cursor *cursor,
+                struct wlr_event_pointer_axis *event) {
+        struct sway_seat *seat = cursor->seat;
+
+        // Determine what's under the cursor
+        struct wlr_surface *surface = NULL;
+        double sx, sy;
+        struct sway_node *node = node_at_coords(seat,
+                        cursor->cursor->x, cursor->cursor->y, &surface, &sx, &sy);
+        struct sway_container *cont = node && node->type == N_CONTAINER ?
+                node->sway_container : NULL;
+        enum wlr_edges edge = cont ? find_edge(cont, cursor) : WLR_EDGE_NONE;
+        bool on_border = edge != WLR_EDGE_NONE;
+        bool on_titlebar = cont && !on_border && !surface;
+
+        // Scrolling on a tabbed or stacked title bar
+        if (on_titlebar) {
+                enum sway_container_layout layout = container_parent_layout(cont);
+                if (layout == L_TABBED || layout == L_STACKED) {
+                        struct sway_node *active =
+                                seat_get_active_tiling_child(seat, node_get_parent(node));
+                        list_t *siblings = container_get_siblings(cont);
+                        int desired = list_find(siblings, active->sway_container) +
+                                event->delta_discrete;
+                        if (desired < 0) {
+                                desired = 0;
+                        } else if (desired >= siblings->length) {
+                                desired = siblings->length - 1;
+                        }
+                        struct sway_container *new_focus = siblings->items[desired];
+                        node = seat_get_focus_inactive(seat, &new_focus->node);
+                        seat_set_focus(seat, node);
+                        return;
+                }
+        }
+
+        wlr_seat_pointer_notify_axis(cursor->seat->wlr_seat, event->time_msec,
+                event->orientation, event->delta, event->delta_discrete, event->source);
+}
+
 static void handle_cursor_axis(struct wl_listener *listener, void *data) {
         struct sway_cursor *cursor = wl_container_of(listener, cursor, axis);
         wlr_idle_notify_activity(cursor->seat->input->server->idle, cursor->seat->wlr_seat);
         struct wlr_event_pointer_axis *event = data;
-        wlr_seat_pointer_notify_axis(cursor->seat->wlr_seat, event->time_msec,
-                event->orientation, event->delta, event->delta_discrete, event->source);
+        dispatch_cursor_axis(cursor, event);
+        transaction_commit_dirty();
 }
 
 static void handle_touch_down(struct wl_listener *listener, void *data) {