From 375d7da2f28fbd734b235e2775b859f8df2773e1 Mon Sep 17 00:00:00 2001
From: Julian Orth <ju.orth@gmail.com>
Date: Wed, 1 Jun 2022 22:24:57 +0200
Subject: [PATCH] cursor: don't overwrite busy hardware buffers

---
 src/backends/metal/video.rs  | 7 ++++++-
 src/ifs/wl_surface.rs        | 1 +
 src/ifs/wl_surface/cursor.rs | 9 ++++++---
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/backends/metal/video.rs b/src/backends/metal/video.rs
index 5a841809..233926da 100644
--- a/src/backends/metal/video.rs
+++ b/src/backends/metal/video.rs
@@ -178,6 +178,7 @@ pub struct MetalConnector {
     pub cursor_enabled: Cell<bool>,
     pub cursor_buffers: CloneCell<Option<Rc<[RenderBuffer; 2]>>>,
     pub cursor_front_buffer: NumCell<usize>,
+    pub cursor_swap_buffer: Cell<bool>,
 }
 
 #[derive(Debug)]
@@ -228,7 +229,7 @@ impl HardwareCursor for MetalHardwareCursor {
         self.connector.cursor_x.set(self.cursor_x_pending.get());
         self.connector.cursor_y.set(self.cursor_y_pending.get());
         if self.cursor_swap_buffer.take() {
-            self.connector.cursor_front_buffer.fetch_add(1);
+            self.connector.cursor_swap_buffer.set(true);
         }
         self.connector.cursor_changed.set(true);
         if self.connector.can_present.get() {
@@ -363,6 +364,9 @@ impl MetalConnector {
         if self.cursor_changed.get() && cursor.is_some() {
             let plane = cursor.unwrap();
             if self.cursor_enabled.get() {
+                if self.cursor_swap_buffer.take() {
+                    self.cursor_front_buffer.fetch_add(1);
+                }
                 let buffers = self.cursor_buffers.get().unwrap();
                 let buffer = &buffers[self.cursor_front_buffer.get() % buffers.len()];
                 changes.change_object(plane.id, |c| {
@@ -545,6 +549,7 @@ fn create_connector(
         connect_sent: Cell::new(false),
         cursor_changed: Cell::new(false),
         cursor_front_buffer: Default::default(),
+        cursor_swap_buffer: Cell::new(false),
     });
     let futures = ConnectorFutures {
         present: backend
diff --git a/src/ifs/wl_surface.rs b/src/ifs/wl_surface.rs
index 6f1049f2..d89b5b79 100644
--- a/src/ifs/wl_surface.rs
+++ b/src/ifs/wl_surface.rs
@@ -832,6 +832,7 @@ impl WlSurface {
         if buffer_changed || transform_changed {
             for (_, cursor) in &self.cursors {
                 cursor.handle_buffer_change();
+                cursor.update_hardware_cursor();
             }
         }
         ext.post_commit();
diff --git a/src/ifs/wl_surface/cursor.rs b/src/ifs/wl_surface/cursor.rs
index 6df8b60f..146a4695 100644
--- a/src/ifs/wl_surface/cursor.rs
+++ b/src/ifs/wl_surface/cursor.rs
@@ -34,9 +34,6 @@ impl CursorSurface {
         let (hot_x, hot_y) = self.hotspot.get();
         self.extents
             .set(self.surface.extents.get().move_(-hot_x, -hot_y));
-        if self.seat.hardware_cursor() {
-            self.seat.update_hardware_cursor();
-        }
     }
 
     pub fn handle_surface_destroy(&self) {
@@ -57,6 +54,12 @@ impl CursorSurface {
         self.hotspot.set((hot_x - hotspot_dx, hot_y - hotspot_dy));
         self.update_extents();
     }
+
+    pub fn update_hardware_cursor(&self) {
+        if self.seat.hardware_cursor() {
+            self.seat.update_hardware_cursor();
+        }
+    }
 }
 
 impl Cursor for CursorSurface {