Implement relative pointer mode on Wayland

yasl_surface_set_pointer_mode(YASL_POINTER_RELATIVE) now takes a
persistent zwp_locked_pointer_v1 on the surface and hides its cursor.
While the compositor keeps the lock engaged, zwp_relative_pointer_v1
motion is pushed as POINTER_MOTION with pos frozen and delta in device
pixels. When the lock disengages, as on focus loss, motion is absolute
again with a delta derived by the input queue.

The lock follows the pointer's seat: it moves to another seat when its
seat loses the pointer, and is released on NORMAL and on surface
destruction. Compositors without both protocols return false.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/platform/wayland/shell.c b/src/platform/wayland/shell.c
index 92c89d1..a12bd4d 100644
--- a/src/platform/wayland/shell.c
+++ b/src/platform/wayland/shell.c
@@ -208,6 +208,12 @@ static void registry_global(void *data, struct wl_registry *registry,
     } else if (strcmp(interface, wp_cursor_shape_manager_v1_interface.name) == 0) {
         c->cursor_shape_mgr = wl_registry_bind(registry, name,
                 &wp_cursor_shape_manager_v1_interface, 1);
+    } else if (strcmp(interface, zwp_relative_pointer_manager_v1_interface.name) == 0) {
+        c->relative_pointer_mgr = wl_registry_bind(registry, name,
+                &zwp_relative_pointer_manager_v1_interface, 1);
+    } else if (strcmp(interface, zwp_pointer_constraints_v1_interface.name) == 0) {
+        c->pointer_constraints = wl_registry_bind(registry, name,
+                &zwp_pointer_constraints_v1_interface, 1);
     } else if (strcmp(interface, wp_fractional_scale_manager_v1_interface.name) == 0) {
         c->scale_mgr = wl_registry_bind(registry, name,
                 &wp_fractional_scale_manager_v1_interface, 1);