input/tablet: add seatop_down entry for tablet input

Currently, when tablet input exits a window during an implicit grab, it
passes focus to another window.

For instance, this is problematic when trying to drag a scrollbar, and
exiting the window — the scrollbar motion stops. Additionally,
without `focus_follows_mouse no`, the tablet passes focus to whatever
surface it goes over regardless of if there is an active implicit.

If the tablet is over a surface that does not bind tablet handlers, sway
will fall back to pointer emulation, and all of this works fine. It
probably should have consistent behavior between emulated and
not-emulated input, though.

This commit adds a condition for entering seatop_down when a tablet's
tool tip goes down, and exiting when it goes up. Since events won't be
routed through seatop_default, this prevents windows losing focus during
implicit grabs.

Closes #5302.

1 files changed, 20 insertions, 0 deletions

diff --git a/sway/input/seatop_default.c b/sway/input/seatop_default.c
index 64a17157..32c7318b 100644
--- a/sway/input/seatop_default.c
+++ b/sway/input/seatop_default.c
@@ -198,6 +198,25 @@ static void state_add_button(struct seatop_default_event *e, uint32_t button) {
  * Functions used by handle_button  /
  *--------------------------------*/
 
+static void handle_tablet_tool_tip(struct sway_seat *seat,
+                struct sway_tablet_tool *tool, uint32_t time_msec,
+                enum wlr_tablet_tool_tip_state state) {
+        if (state != WLR_TABLET_TOOL_TIP_DOWN) {
+                return;
+        }
+
+        struct sway_cursor *cursor = seat->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);
+
+        if (surface && node && node->type == N_CONTAINER) {
+                seatop_begin_down(seat, node->sway_container, time_msec, sx, sy);
+        }
+}
+
 static void handle_button(struct sway_seat *seat, uint32_t time_msec,
                 struct wlr_input_device *device, uint32_t button,
                 enum wlr_button_state state) {
@@ -649,6 +668,7 @@ static const struct sway_seatop_impl seatop_impl = {
         .button = handle_button,
         .pointer_motion = handle_pointer_motion,
         .pointer_axis = handle_pointer_axis,
+        .tablet_tool_tip = handle_tablet_tool_tip,
         .tablet_tool_motion = handle_tablet_tool_motion,
         .rebase = handle_rebase,
         .allow_set_cursor = true,