Merge remote-tracking branch 'origin/5.6' into 5.7

Change-Id: If6ba05867e7c98159e1b94ff71923e8b36bdbccb

5 files changed, 21 insertions, 7 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 3544382944..a4830130f1 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -281,6 +281,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
 #endif
 #ifndef QT_NO_OPENGL
       , renderToTextureReallyDirty(1)
+      , renderToTextureComposeActive(0)
 #endif
 #if defined(Q_OS_WIN)
       , noPaintOnScreen(0)
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index 838236536a..71691a4afa 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -750,6 +750,7 @@ public:
 #endif
 #ifndef QT_NO_OPENGL
     uint renderToTextureReallyDirty : 1;
+    uint renderToTextureComposeActive : 1;
 #endif
 
     // *************************** Platform specific ************************************
diff --git a/src/widgets/kernel/qwidgetbackingstore.cpp b/src/widgets/kernel/qwidgetbackingstore.cpp
index bb6f3316d6..03211b4e4c 100644
--- a/src/widgets/kernel/qwidgetbackingstore.cpp
+++ b/src/widgets/kernel/qwidgetbackingstore.cpp
@@ -67,6 +67,8 @@ QT_BEGIN_NAMESPACE
 
 extern QRegion qt_dirtyRegion(QWidget *);
 
+Q_GLOBAL_STATIC(QPlatformTextureList, qt_dummy_platformTextureList)
+
 /**
  * Flushes the contents of the \a backingStore into the screen area of \a widget.
  * \a tlwOffset is the position of the top level widget relative to the window surface.
@@ -109,6 +111,20 @@ void QWidgetBackingStore::qt_flush(QWidget *widget, const QRegion &region, QBack
         offset += widget->mapTo(tlw, QPoint());
 
 #ifndef QT_NO_OPENGL
+    const bool compositionWasActive = widget->d_func()->renderToTextureComposeActive;
+    if (!widgetTextures) {
+        widget->d_func()->renderToTextureComposeActive = false;
+        // Detect the case of falling back to the normal flush path when no
+        // render-to-texture widgets are visible anymore. We will force one
+        // last flush to go through the OpenGL-based composition to prevent
+        // artifacts. The next flush after this one will use the normal path.
+        if (compositionWasActive)
+            widgetTextures = qt_dummy_platformTextureList;
+    } else {
+        widget->d_func()->renderToTextureComposeActive = true;
+    }
+
+    // re-test since we may have been forced to this path via the dummy texture list above
     if (widgetTextures) {
         qt_window_private(tlw->windowHandle())->compositing = true;
         widget->window()->d_func()->sendComposeStatus(widget->window(), false);
@@ -984,8 +1000,6 @@ static void findAllTextureWidgetsRecursively(QWidget *tlw, QWidget *widget)
     }
 }
 
-Q_GLOBAL_STATIC(QPlatformTextureList, qt_dummy_platformTextureList)
-
 static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
 {
     foreach (QPlatformTextureList *tl, QWidgetPrivate::get(tlw)->topData()->widgetTextures) {
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index c14fd5a942..ed630913e7 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -2161,6 +2161,9 @@ bool QDockAreaLayoutInfo::updateTabBar() const
     if (oldCurrentId > 0 && currentTabId() != oldCurrentId)
         that->setCurrentTabId(oldCurrentId);
 
+    if (QDockWidgetGroupWindow *dwgw = qobject_cast<QDockWidgetGroupWindow *>(tabBar->parent()))
+        dwgw->adjustFlags();
+
     //returns if the tabbar is visible or not
     return ( (gap ? 1 : 0) + tabBar->count()) > 1;
 }
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 19444f8315..8229028dac 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -1392,8 +1392,6 @@ void QDockWidget::changeEvent(QEvent *event)
                 if (QDockAreaLayoutInfo *info = winLayout->layoutState.dockAreaLayout.info(this))
                     info->updateTabBar();
             }
-            if (QDockWidgetGroupWindow *p = qobject_cast<QDockWidgetGroupWindow *>(parent()))
-                p->adjustFlags();
         }
 #endif // QT_NO_TABBAR
         break;
@@ -1483,9 +1481,6 @@ bool QDockWidget::event(QEvent *event)
         }
         if (!isFloating() && layout != 0 && onTop)
             layout->raise(this);
-        if (QDockWidgetGroupWindow *p = qobject_cast<QDockWidgetGroupWindow *>(parent()))
-            p->adjustFlags();
-
         break;
     }
     case QEvent::WindowActivate: