From 452f45cd3d6695299d8014c271db094da11fad05 Mon Sep 17 00:00:00 2001
From: John Lindgren <john@jlindgren.net>
Date: Tue, 1 Oct 2024 10:16:29 -0400
Subject: [PATCH] xdg: try to handle slow un-maximize with empty natural
 geometry better

In the case of an initially-maximized view which is taking a long time
to un-maximize (seen for example with Thunderbird on slow machines), we
may end up in handle_configure_timeout() with an empty pending geometry.
In that case we have no great options (we can't center the view since we
don't know the un-maximized size yet), so set a fallback position.

v2: check wlr_box_empty() before comparing pending and current

Fixes: #2191
---
 include/view.h | 10 ++++++++++
 src/view.c     | 10 ++--------
 src/xdg.c      | 39 +++++++++++++++++++++++++++++----------
 3 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/include/view.h b/include/view.h
index 296b4845..7a1b5dde 100644
--- a/include/view.h
+++ b/include/view.h
@@ -13,6 +13,16 @@
 
 #define LAB_MIN_VIEW_HEIGHT 60
 
+/*
+ * Fallback view geometry used in some cases where a better position
+ * and/or size can't be determined. Try to avoid using these except as
+ * a last resort.
+ */
+#define VIEW_FALLBACK_X 100
+#define VIEW_FALLBACK_Y 100
+#define VIEW_FALLBACK_WIDTH  640
+#define VIEW_FALLBACK_HEIGHT 480
+
 /*
  * In labwc, a view is a container for surfaces which can be moved around by
  * the user. In practice this means XDG toplevel and XWayland windows.
diff --git a/src/view.c b/src/view.c
index 00618a18..c1b8bfca 100644
--- a/src/view.c
+++ b/src/view.c
@@ -29,9 +29,6 @@
 #include <wlr/xwayland.h>
 #endif
 
-#define LAB_FALLBACK_WIDTH  640
-#define LAB_FALLBACK_HEIGHT 480
-
 struct view *
 view_from_wlr_surface(struct wlr_surface *surface)
 {
@@ -827,8 +824,8 @@ adjust_floating_geometry(struct view *view, struct wlr_box *geometry,
 void
 view_set_fallback_natural_geometry(struct view *view)
 {
-	view->natural_geometry.width = LAB_FALLBACK_WIDTH;
-	view->natural_geometry.height = LAB_FALLBACK_HEIGHT;
+	view->natural_geometry.width = VIEW_FALLBACK_WIDTH;
+	view->natural_geometry.height = VIEW_FALLBACK_HEIGHT;
 	view_compute_centered_position(view, NULL,
 		view->natural_geometry.width,
 		view->natural_geometry.height,
@@ -836,9 +833,6 @@ view_set_fallback_natural_geometry(struct view *view)
 		&view->natural_geometry.y);
 }
 
-#undef LAB_FALLBACK_WIDTH
-#undef LAB_FALLBACK_HEIGHT
-
 void
 view_store_natural_geometry(struct view *view)
 {
diff --git a/src/xdg.c b/src/xdg.c
index 92a99fdc..f8939ddd 100644
--- a/src/xdg.c
+++ b/src/xdg.c
@@ -251,16 +251,35 @@ handle_configure_timeout(void *data)
 	view->pending_configure_serial = 0;
 	view->pending_configure_timeout = NULL;
 
-	/*
-	 * We do not use view_impl_apply_geometry() here since in the timeout
-	 * case we prefer to always put the top-left corner of the view at the
-	 * desired position rather than anchoring some other edge or corner
-	 */
-	bool moved = view->current.x != view->pending.x
-		|| view->current.y != view->pending.y;
-	view->current.x = view->pending.x;
-	view->current.y = view->pending.y;
-	if (moved) {
+	bool empty_pending = wlr_box_empty(&view->pending);
+	if (empty_pending || view->pending.x != view->current.x
+			|| view->pending.y != view->current.y) {
+		/*
+		 * This is a pending move + resize and the client is
+		 * taking too long to respond to the resize. Apply the
+		 * move now (while keeping the current size) so that the
+		 * desktop doesn't appear unresponsive.
+		 *
+		 * We do not use view_impl_apply_geometry() here since
+		 * in this case we prefer to always put the top-left
+		 * corner of the view at the desired position rather
+		 * than anchoring some other edge or corner.
+		 *
+		 * Corner case: we may get here with an empty pending
+		 * geometry in the case of an initially-maximized view
+		 * which is taking a long time to un-maximize (seen for
+		 * example with Thunderbird on slow machines). In that
+		 * case we have no great options (we can't center the
+		 * view since we don't know the un-maximized size yet),
+		 * so set a fallback position.
+		 */
+		if (empty_pending) {
+			wlr_log(WLR_INFO, "using fallback position");
+			view->pending.x = VIEW_FALLBACK_X;
+			view->pending.y = VIEW_FALLBACK_Y;
+		}
+		view->current.x = view->pending.x;
+		view->current.y = view->pending.y;
 		view_moved(view);
 	}