From 846961bfaec98ba88a2a34c5408bfd22cf109dd3 Mon Sep 17 00:00:00 2001
From: Roman Gilg <subdiff@gmail.com>
Date: Thu, 6 Jun 2019 23:17:01 +0200
Subject: [PATCH] Delayed focus updates for Toplevels without surface

Summary:
XWayland clients have a surface associated with them asynchronously. In this
case we don't directly want to set focus on this Toplevel, but wait until the
surface is set.

This patch aims in conjunction with an unrelated fix to SDL at improving Steam
Big Picture Mode in our Wayland session.

Test Plan: Steam BPM regains focus on game close.

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: anthonyfieroni, davidedmundson, zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D19262
---
 input.cpp | 27 +++++++++++++++++++++------
 input.h   |  8 ++++++--
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/input.cpp b/input.cpp
index 5013cb2869..253200795d 100644
--- a/input.cpp
+++ b/input.cpp
@@ -2249,11 +2249,14 @@ void InputDeviceHandler::init()
 
 bool InputDeviceHandler::setAt(Toplevel *toplevel)
 {
-    if (m_at == toplevel) {
+    if (m_at.at == toplevel) {
         return false;
     }
-    auto old = m_at;
-    m_at = toplevel;
+    auto old = m_at.at;
+    disconnect(m_at.surfaceCreatedConnection);
+    m_at.surfaceCreatedConnection = QMetaObject::Connection();
+
+    m_at.at = toplevel;
     emit atChanged(old, toplevel);
     return true;
 }
@@ -2281,7 +2284,19 @@ void InputDeviceHandler::setInternalWindow(QWindow *window)
 void InputDeviceHandler::updateFocus()
 {
     auto oldFocus = m_focus.focus;
-    m_focus.focus = m_at;
+
+    if (m_at.at && !m_at.at->surface()) {
+        // The surface has not yet been created (special XWayland case).
+        // Therefore listen for its creation.
+        if (!m_at.surfaceCreatedConnection) {
+            m_at.surfaceCreatedConnection = connect(m_at.at, &Toplevel::surfaceChanged,
+                                                    this, &InputDeviceHandler::update);
+        }
+        m_focus.focus = nullptr;
+    } else {
+        m_focus.focus = m_at.at;
+    }
+
     focusUpdate(oldFocus, m_focus.focus);
 }
 
@@ -2290,7 +2305,7 @@ bool InputDeviceHandler::updateDecoration()
     const auto oldDeco = m_focus.decoration;
     m_focus.decoration = nullptr;
 
-    auto *ac = qobject_cast<AbstractClient*>(m_at);
+    auto *ac = qobject_cast<AbstractClient*>(m_at.at);
     if (ac && ac->decoratedClient()) {
         const QRect clientRect = QRect(ac->clientPos(), ac->clientSize()).translated(ac->pos());
         if (!clientRect.contains(position().toPoint())) {
@@ -2358,7 +2373,7 @@ void InputDeviceHandler::update()
     }
     updateInternalWindow(nullptr);
 
-    if (m_focus.focus != m_at) {
+    if (m_focus.focus != m_at.at) {
         // focus change
         updateDecoration();
         updateFocus();
diff --git a/input.h b/input.h
index 588674d79e..fd1fbdfc21 100644
--- a/input.h
+++ b/input.h
@@ -389,7 +389,7 @@ public:
      * @return Toplevel* at device position.
      **/
     QPointer<Toplevel> at() const {
-        return m_at;
+        return m_at.at;
     }
     /**
      * @brief Toplevel currently having pointer input focus (this might
@@ -459,7 +459,11 @@ private:
 
     QWindow* findInternalWindow(const QPoint &pos) const;
 
-    QPointer<Toplevel> m_at;
+    struct {
+        QPointer<Toplevel> at;
+        QMetaObject::Connection surfaceCreatedConnection;
+    } m_at;
+
     struct {
         QPointer<Toplevel> focus;
         QPointer<Decoration::DecoratedClientImpl> decoration;