xdg: center small fullscreen views and add black background fill

include/view.h

@@ -296,6 +296,9 @@ struct xdg_toplevel_view {
 	struct view base;
 	struct wlr_xdg_surface *xdg_surface;
 
+	/* Optional black background fill behind fullscreen view */
+	struct wlr_scene_rect *fullscreen_bg;
+
 	/* Events unique to xdg-toplevel views */
 	struct wl_listener set_app_id;
 	struct wl_listener request_show_window_menu;

src/view.c

@@ -1699,6 +1699,12 @@ view_set_fullscreen(struct view *view, bool fullscreen)
 		view_apply_special_geometry(view);
 	}
 	output_set_has_fullscreen_view(view->output, view->fullscreen);
+	/*
+	 * Entering/leaving fullscreen might result in a different
+	 * scene node ending up under the cursor even if view_moved()
+	 * isn't called. Update cursor focus explicitly for that case.
+	 */
+	cursor_update_focus(view->server);
 }
 
 static bool

src/xdg.c

@@ -10,6 +10,7 @@
 #include <wlr/types/wlr_xdg_toplevel_icon_v1.h>
 #include "buffer.h"
 #include "common/array.h"
+#include "common/box.h"
 #include "common/macros.h"
 #include "common/mem.h"
 #include "config/rcxml.h"
@@ -129,6 +130,58 @@ do_late_positioning(struct view *view)
 	}
 }
 
+static void
+disable_fullscreen_bg(struct view *view)
+{
+	struct xdg_toplevel_view *xdg_view = xdg_toplevel_view_from_view(view);
+	if (xdg_view->fullscreen_bg) {
+		wlr_scene_node_set_enabled(&xdg_view->fullscreen_bg->node, false);
+	}
+}
+
+/*
+ * Centers any fullscreen view smaller than the full output size.
+ * This should be called immediately before view_moved().
+ */
+static void
+center_fullscreen_if_needed(struct view *view)
+{
+	if (!view->fullscreen || !output_is_usable(view->output)) {
+		disable_fullscreen_bg(view);
+		return;
+	}
+
+	struct wlr_box output_box = {0};
+	wlr_output_layout_get_box(view->server->output_layout,
+		view->output->wlr_output, &output_box);
+	box_center(view->current.width, view->current.height, &output_box,
+		&output_box, &view->current.x, &view->current.y);
+
+	/* Reset pending x/y to computed position also */
+	view->pending.x = view->current.x;
+	view->pending.y = view->current.y;
+
+	if (view->current.width >= output_box.width
+			&& view->current.width >= output_box.height) {
+		disable_fullscreen_bg(view);
+		return;
+	}
+
+	struct xdg_toplevel_view *xdg_view = xdg_toplevel_view_from_view(view);
+	if (!xdg_view->fullscreen_bg) {
+		const float black[4] = {0, 0, 0, 1};
+		xdg_view->fullscreen_bg =
+			wlr_scene_rect_create(view->scene_tree, 0, 0, black);
+		wlr_scene_node_lower_to_bottom(&xdg_view->fullscreen_bg->node);
+	}
+
+	wlr_scene_node_set_position(&xdg_view->fullscreen_bg->node,
+		output_box.x - view->current.x, output_box.y - view->current.y);
+	wlr_scene_rect_set_size(xdg_view->fullscreen_bg,
+		output_box.width, output_box.height);
+	wlr_scene_node_set_enabled(&xdg_view->fullscreen_bg->node, true);
+}
+
 /* TODO: reorder so this forward declaration isn't needed */
 static void set_pending_configure_serial(struct view *view, uint32_t serial);
 
@@ -238,6 +291,7 @@ handle_commit(struct wl_listener *listener, void *data)
 
 	if (update_required) {
 		view_impl_apply_geometry(view, size.width, size.height);
+		center_fullscreen_if_needed(view);
 		view_moved(view);
 
 		/*
@@ -336,9 +390,11 @@ handle_configure_timeout(void *data)
 		}
 		view->current.x = view->pending.x;
 		view->current.y = view->pending.y;
-		view_moved(view);
 	}
 
+	center_fullscreen_if_needed(view);
+	view_moved(view);
+
 	/* Re-sync pending view with current state */
 	snap_constraints_update(view);
 	view->pending = view->current;
@@ -546,6 +602,12 @@ xdg_toplevel_view_configure(struct view *view, struct wlr_box geo)
 	} else if (view->pending_configure_serial == 0) {
 		view->current.x = geo.x;
 		view->current.y = geo.y;
+		/*
+		 * It's a bit difficult to think of a corner case where
+		 * center_fullscreen_if_needed() would actually be needed
+		 * here, but including it anyway for completeness.
+		 */
+		center_fullscreen_if_needed(view);
 		view_moved(view);
 	}
 }
@@ -664,6 +726,10 @@ xdg_toplevel_view_set_fullscreen(struct view *view, bool fullscreen)
 	if (serial > 0) {
 		set_pending_configure_serial(view, serial);
 	}
+	/* Disable background fill immediately on leaving fullscreen */
+	if (!fullscreen) {
+		disable_fullscreen_bg(view);
+	}
 }
 
 static void
@@ -786,6 +852,9 @@ handle_map(struct wl_listener *listener, void *data)
 			set_initial_position(view);
 		}
 
+		/* Disable background fill at map (paranoid?) */
+		disable_fullscreen_bg(view);
+
 		/*
 		 * Set initial "current" position directly before
 		 * calling view_moved() to reduce flicker