From 3663453c7d0c5ad09120dbfff183ac80d2fe97c5 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Wed, 13 Dec 2023 15:02:57 +0200
Subject: [PATCH] scene: Freeze SurfaceItem tree when the Window is closed

If the wl_surface is unmapped, the compositor should unmap the window.
Most clients don't do it, and instead destroy the wl_surface or the
surface role object or both. A very tiny fraction of clients actually
close the window by unmapping the wl_surface. Either way, it's worth
handling that case because xdg-shell protocol says that the clients are
allowed to do it.

BUG: 478297
---
 src/scene/surfaceitem.cpp         |  4 ++++
 src/scene/surfaceitem.h           |  2 ++
 src/scene/surfaceitem_wayland.cpp | 16 ++++++++++++++++
 src/scene/surfaceitem_wayland.h   |  1 +
 src/scene/windowitem.cpp          |  9 +++++++++
 src/scene/windowitem.h            |  1 +
 6 files changed, 33 insertions(+)

diff --git a/src/scene/surfaceitem.cpp b/src/scene/surfaceitem.cpp
index df54ff6101..bbd1d50e09 100644
--- a/src/scene/surfaceitem.cpp
+++ b/src/scene/surfaceitem.cpp
@@ -227,6 +227,10 @@ ContentType SurfaceItem::contentType() const
     return ContentType::None;
 }
 
+void SurfaceItem::freeze()
+{
+}
+
 SurfaceTexture::~SurfaceTexture()
 {
 }
diff --git a/src/scene/surfaceitem.h b/src/scene/surfaceitem.h
index fa85e55752..ea89e8db5a 100644
--- a/src/scene/surfaceitem.h
+++ b/src/scene/surfaceitem.h
@@ -54,6 +54,8 @@ public:
 
     virtual ContentType contentType() const;
 
+    virtual void freeze();
+
 Q_SIGNALS:
     void damaged();
 
diff --git a/src/scene/surfaceitem_wayland.cpp b/src/scene/surfaceitem_wayland.cpp
index bfbe0abdba..670168e614 100644
--- a/src/scene/surfaceitem_wayland.cpp
+++ b/src/scene/surfaceitem_wayland.cpp
@@ -168,6 +168,22 @@ ContentType SurfaceItemWayland::contentType() const
     return m_surface ? m_surface->contentType() : ContentType::None;
 }
 
+void SurfaceItemWayland::freeze()
+{
+    if (!m_surface) {
+        return;
+    }
+
+    m_surface->disconnect(this);
+    if (auto subsurface = m_surface->subSurface()) {
+        subsurface->disconnect(this);
+    }
+
+    for (auto &[subsurface, subsurfaceItem] : m_subsurfaces) {
+        subsurfaceItem->freeze();
+    }
+}
+
 void SurfaceItemWayland::handleColorDescriptionChanged()
 {
     setColorDescription(m_surface->colorDescription());
diff --git a/src/scene/surfaceitem_wayland.h b/src/scene/surfaceitem_wayland.h
index a0c4914308..26f6af9532 100644
--- a/src/scene/surfaceitem_wayland.h
+++ b/src/scene/surfaceitem_wayland.h
@@ -31,6 +31,7 @@ public:
     QList<QRectF> shape() const override;
     QRegion opaque() const override;
     ContentType contentType() const override;
+    void freeze() override;
 
     SurfaceInterface *surface() const;
 
diff --git a/src/scene/windowitem.cpp b/src/scene/windowitem.cpp
index 8a56b73294..380abd651b 100644
--- a/src/scene/windowitem.cpp
+++ b/src/scene/windowitem.cpp
@@ -55,6 +55,8 @@ WindowItem::WindowItem(Window *window, Scene *scene, Item *parent)
     connect(window, &Window::stackingOrderChanged, this, &WindowItem::updateStackingOrder);
     updateStackingOrder();
 
+    connect(window, &Window::closed, this, &WindowItem::freeze);
+
     m_effectWindow = std::make_unique<EffectWindow>(this);
 }
 
@@ -288,6 +290,13 @@ void WindowItem::markDamaged()
     Q_EMIT m_window->damaged(m_window);
 }
 
+void WindowItem::freeze()
+{
+    if (m_surfaceItem) {
+        m_surfaceItem->freeze();
+    }
+}
+
 WindowItemX11::WindowItemX11(X11Window *window, Scene *scene, Item *parent)
     : WindowItem(window, scene, parent)
 {
diff --git a/src/scene/windowitem.h b/src/scene/windowitem.h
index 442ebdda7a..9774ad38e3 100644
--- a/src/scene/windowitem.h
+++ b/src/scene/windowitem.h
@@ -74,6 +74,7 @@ private:
     bool computeVisibility() const;
     void updateVisibility();
     void markDamaged();
+    void freeze();
 
     Window *m_window;
     std::unique_ptr<SurfaceItem> m_surfaceItem;