qt5-qtbase/qt5-qtbase-5.5-0000-add-function-for-qpa-plugins-to-explictly-destroy-qscreens.patch

commit 9b4fbe85d2e00c625c3d4abd975faf555000f685
Author: Giulio Camuffo <giuliocamuffo@gmail.com>
Date:   Sun Aug 31 16:16:53 2014 +0300

    Add a function for QPA plugins to explicitly destroy QScreens
    
    Previously QPlatformScreen was automatically deleting its QScreen
    in ~QPlatformScreen(). That means that we cannot use QScreen's
    methods when the screen is being removed, because doing so would
    call virtual methods of QPlatformScreen. By that point the
    QPlatformScreen subclass object does not exist anymore, and we
    call the default implementation instead of the subclassed one, or
    get a crash for the pure virtual methods. This happens for example
    when removing a screen which contains a QWindow with some QML item
    using QQuickScreenAttached.
    
    This patch adds a QPlatformIntegration::destroyScreen() function,
    which deletes the QScreen and later the QPlatformScreen.
    
    ~QPlatformScreen will still delete the QScreen if it was not deleted
    with destroyScreen(), so code not ported to the new approach
    will continue to work as before, with only a warning added.
    
    Task-number: QTBUG-41141
    Change-Id: Ie4a03dee08ceb4c3e94a81875411f6f723273fe1
    Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>
    Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index 39b031e..93b1359 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -429,7 +429,7 @@ QList<int> QPlatformIntegration::possibleKeys(const QKeyEvent *) const
   This adds the screen to QGuiApplication::screens(), and emits the
   QGuiApplication::screenAdded() signal.
 
-  The screen is automatically removed when the QPlatformScreen is destroyed.
+  The screen should be deleted by calling QPlatformIntegration::destroyScreen().
 */
 void QPlatformIntegration::screenAdded(QPlatformScreen *ps)
 {
@@ -439,6 +439,22 @@ void QPlatformIntegration::screenAdded(QPlatformScreen *ps)
     emit qGuiApp->screenAdded(screen);
 }
 
+/*!
+  Should be called by the implementation whenever a screen is removed.
+
+  This removes the screen from QGuiApplication::screens(), and deletes it.
+
+  Failing to call this and manually deleting the QPlatformScreen instead may
+  lead to a crash due to a pure virtual call.
+*/
+void QPlatformIntegration::destroyScreen(QPlatformScreen *screen)
+{
+    QGuiApplicationPrivate::screen_list.removeOne(screen->d_func()->screen);
+    delete screen->d_func()->screen;
+    screen->d_func()->screen = Q_NULLPTR;
+    delete screen;
+}
+
 QStringList QPlatformIntegration::themeNames() const
 {
     return QStringList();
diff --git a/src/gui/kernel/qplatformintegration.h b/src/gui/kernel/qplatformintegration.h
index d510240..9b7e2df 100644
--- a/src/gui/kernel/qplatformintegration.h
+++ b/src/gui/kernel/qplatformintegration.h
@@ -170,6 +170,7 @@ public:
 
 protected:
     void screenAdded(QPlatformScreen *screen);
+    void destroyScreen(QPlatformScreen *screen);
 };
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qplatformscreen.cpp b/src/gui/kernel/qplatformscreen.cpp
index 71710d1..fa6d785 100644
--- a/src/gui/kernel/qplatformscreen.cpp
+++ b/src/gui/kernel/qplatformscreen.cpp
@@ -52,9 +52,11 @@ QPlatformScreen::QPlatformScreen()
 QPlatformScreen::~QPlatformScreen()
 {
     Q_D(QPlatformScreen);
-
-    QGuiApplicationPrivate::screen_list.removeOne(d->screen);
-    delete d->screen;
+    if (d->screen) {
+        qWarning("Manually deleting a QPlatformScreen. Call QPlatformIntegration::destroyScreen instead.");
+        QGuiApplicationPrivate::screen_list.removeOne(d->screen);
+        delete d->screen;
+    }
 }
 
 /*!
diff --git a/src/plugins/platforms/cocoa/qcocoaintegration.mm b/src/plugins/platforms/cocoa/qcocoaintegration.mm
index 72bd096..180cb23 100644
--- a/src/plugins/platforms/cocoa/qcocoaintegration.mm
+++ b/src/plugins/platforms/cocoa/qcocoaintegration.mm
@@ -337,7 +337,7 @@ QCocoaIntegration::~QCocoaIntegration()
 
     // Delete screens in reverse order to avoid crash in case of multiple screens
     while (!mScreens.isEmpty()) {
-        delete mScreens.takeLast();
+        destroyScreen(mScreens.takeLast());
     }
 
     clearToolbars();
@@ -397,7 +397,7 @@ void QCocoaIntegration::updateScreens()
     // Now the leftovers in remainingScreens are no longer current, so we can delete them.
     foreach (QCocoaScreen* screen, remainingScreens) {
         mScreens.removeOne(screen);
-        delete screen;
+        destroyScreen(screen);
     }
     // All screens in mScreens are siblings, because we ignored the mirrors.
     foreach (QCocoaScreen* screen, mScreens)
diff --git a/src/plugins/platforms/ios/qiosintegration.mm b/src/plugins/platforms/ios/qiosintegration.mm
index 461f160..ff4b753 100644
--- a/src/plugins/platforms/ios/qiosintegration.mm
+++ b/src/plugins/platforms/ios/qiosintegration.mm
@@ -120,7 +120,7 @@ QIOSIntegration::~QIOSIntegration()
     m_inputContext = 0;
 
     foreach (QScreen *screen, QGuiApplication::screens())
-        delete screen->handle();
+        destroyScreen(screen->handle());
 
     delete m_platformServices;
     m_platformServices = 0;
diff --git a/src/plugins/platforms/kms/qkmsintegration.cpp b/src/plugins/platforms/kms/qkmsintegration.cpp
index d94d7d9..5ad58ba 100644
--- a/src/plugins/platforms/kms/qkmsintegration.cpp
+++ b/src/plugins/platforms/kms/qkmsintegration.cpp
@@ -74,7 +74,7 @@ QKmsIntegration::~QKmsIntegration()
         delete device;
     }
     foreach (QPlatformScreen *screen, m_screens) {
-        delete screen;
+        destroyScreen(screen);
     }
     delete m_fontDatabase;
     delete m_vtHandler;
diff --git a/src/plugins/platforms/linuxfb/qlinuxfbintegration.cpp b/src/plugins/platforms/linuxfb/qlinuxfbintegration.cpp
index 777da98..4e83656 100644
--- a/src/plugins/platforms/linuxfb/qlinuxfbintegration.cpp
+++ b/src/plugins/platforms/linuxfb/qlinuxfbintegration.cpp
@@ -57,7 +57,7 @@ QLinuxFbIntegration::QLinuxFbIntegration(const QStringList &paramList)
 
 QLinuxFbIntegration::~QLinuxFbIntegration()
 {
-    delete m_primaryScreen;
+    destroyScreen(m_primaryScreen);
 }
 
 void QLinuxFbIntegration::initialize()
diff --git a/src/plugins/platforms/minimalegl/qminimaleglintegration.cpp b/src/plugins/platforms/minimalegl/qminimaleglintegration.cpp
index 0b12e62..3fbed1e 100644
--- a/src/plugins/platforms/minimalegl/qminimaleglintegration.cpp
+++ b/src/plugins/platforms/minimalegl/qminimaleglintegration.cpp
@@ -60,7 +60,7 @@ QMinimalEglIntegration::QMinimalEglIntegration()
 
 QMinimalEglIntegration::~QMinimalEglIntegration()
 {
-    delete mScreen;
+    destroyScreen(mScreen);
 }
 
 bool QMinimalEglIntegration::hasCapability(QPlatformIntegration::Capability cap) const
diff --git a/src/plugins/platforms/openwfd/qopenwfdintegration.cpp b/src/plugins/platforms/openwfd/qopenwfdintegration.cpp
index 1e29fcc..26bdd14 100644
--- a/src/plugins/platforms/openwfd/qopenwfdintegration.cpp
+++ b/src/plugins/platforms/openwfd/qopenwfdintegration.cpp
@@ -133,3 +133,8 @@ void QOpenWFDIntegration::addScreen(QOpenWFDScreen *screen)
 {
     screenAdded(screen);
 }
+
+void QOpenWFDIntegration::destroyScreen(QOpenWFDScreen *screen)
+{
+    QPlatformIntegration::destroyScreen(screen);
+}
diff --git a/src/plugins/platforms/openwfd/qopenwfdintegration.h b/src/plugins/platforms/openwfd/qopenwfdintegration.h
index 6c086b7..9243205 100644
--- a/src/plugins/platforms/openwfd/qopenwfdintegration.h
+++ b/src/plugins/platforms/openwfd/qopenwfdintegration.h
@@ -63,6 +63,7 @@ public:
     QPlatformPrinterSupport *printerSupport() const;
 
     void addScreen(QOpenWFDScreen *screen);
+    void destroyScreen(QOpenWFDScreen *screen);
 private:
     QList<QPlatformScreen *> mScreens;
     QList<QOpenWFDDevice *>mDevices;
diff --git a/src/plugins/platforms/openwfd/qopenwfdport.cpp b/src/plugins/platforms/openwfd/qopenwfdport.cpp
index 0bdc6b2..b643644 100644
--- a/src/plugins/platforms/openwfd/qopenwfdport.cpp
+++ b/src/plugins/platforms/openwfd/qopenwfdport.cpp
@@ -140,7 +140,7 @@ void QOpenWFDPort::detach()
     mAttached = false;
     mOn = false;
 
-    delete mScreen;
+    mDevice->integration()->destroyScreen(mScreen);
 
     wfdDestroyPipeline(mDevice->handle(),mPipeline);
     mPipelineId = WFD_INVALID_PIPELINE_ID;
diff --git a/src/plugins/platforms/qnx/qqnxintegration.cpp b/src/plugins/platforms/qnx/qqnxintegration.cpp
index 34b79b6..d47da01 100644
--- a/src/plugins/platforms/qnx/qqnxintegration.cpp
+++ b/src/plugins/platforms/qnx/qqnxintegration.cpp
@@ -554,7 +554,7 @@ void QQnxIntegration::removeDisplay(QQnxScreen *screen)
     Q_CHECK_PTR(screen);
     Q_ASSERT(m_screens.contains(screen));
     m_screens.removeAll(screen);
-    screen->deleteLater();
+    destroyScreen(screen);
 }
 
 void QQnxIntegration::destroyDisplays()
diff --git a/src/plugins/platforms/windows/qwindowsintegration.h b/src/plugins/platforms/windows/qwindowsintegration.h
index d1617ea..7fb37bc 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.h
+++ b/src/plugins/platforms/windows/qwindowsintegration.h
@@ -94,6 +94,7 @@ public:
     static QWindowsIntegration *instance();
 
     inline void emitScreenAdded(QPlatformScreen *s) { screenAdded(s); }
+    inline void emitDestroyScreen(QPlatformScreen *s) { destroyScreen(s); }
 
     unsigned options() const;
 
diff --git a/src/plugins/platforms/windows/qwindowsscreen.cpp b/src/plugins/platforms/windows/qwindowsscreen.cpp
index fd57d9e..79219e3 100644
--- a/src/plugins/platforms/windows/qwindowsscreen.cpp
+++ b/src/plugins/platforms/windows/qwindowsscreen.cpp
@@ -462,7 +462,7 @@ void QWindowsScreenManager::removeScreen(int index)
         if (movedWindowCount)
             QWindowSystemInterface::flushWindowSystemEvents();
     }
-    delete m_screens.takeAt(index);
+    QWindowsIntegration::instance()->emitDestroyScreen(m_screens.takeAt(index));
 }
 
 /*!
@@ -497,4 +497,11 @@ bool QWindowsScreenManager::handleScreenChanges()
     return true;
 }
 
+void QWindowsScreenManager::clearScreens()
+{
+    // Delete screens in reverse order to avoid crash in case of multiple screens
+    while (!m_screens.isEmpty())
+        QWindowsIntegration::instance()->emitDestroyScreen(m_screens.takeLast());
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/windows/qwindowsscreen.h b/src/plugins/platforms/windows/qwindowsscreen.h
index aa14083..924912d 100644
--- a/src/plugins/platforms/windows/qwindowsscreen.h
+++ b/src/plugins/platforms/windows/qwindowsscreen.h
@@ -127,11 +127,7 @@ public:
 
     QWindowsScreenManager();
 
-    inline void clearScreens() {
-        // Delete screens in reverse order to avoid crash in case of multiple screens
-        while (!m_screens.isEmpty())
-            delete m_screens.takeLast();
-    }
+    void clearScreens();
 
     bool handleScreenChanges();
     bool handleDisplayChange(WPARAM wParam, LPARAM lParam);
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 5510c3b..ae59de5 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -279,11 +279,12 @@ void QXcbConnection::updateScreens()
         ++xcbScreenNumber;
     } // for each xcb screen
 
+    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
     // Now activeScreens is the complete set of screens which are active at this time.
     // Delete any existing screens which are not in activeScreens
     for (int i = m_screens.count() - 1; i >= 0; --i) {
         if (!activeScreens.contains(m_screens[i])) {
-            delete m_screens[i];
+            integration->destroyScreen(m_screens.at(i));
             m_screens.removeAt(i);
         }
     }
@@ -300,7 +301,7 @@ void QXcbConnection::updateScreens()
     // Now that they are in the right order, emit the added signals for new screens only
     foreach (QXcbScreen* screen, m_screens)
         if (newScreens.contains(screen))
-            ((QXcbIntegration*)QGuiApplicationPrivate::platformIntegration())->screenAdded(screen);
+            integration->screenAdded(screen);
 }
 
 QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGrabServer, const char *displayName)
@@ -431,9 +432,10 @@ QXcbConnection::~QXcbConnection()
 
     delete m_reader;
 
+    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
     // Delete screens in reverse order to avoid crash in case of multiple screens
     while (!m_screens.isEmpty())
-        delete m_screens.takeLast();
+        integration->destroyScreen(m_screens.takeLast());
 
 #ifdef XCB_USE_EGL
     if (m_has_egl)