Merge remote-tracking branch 'origin/5.11' into dev

Change-Id: I0120f804522c0c652e9537b6e9fe08189f071ed2

6 files changed, 109 insertions, 104 deletions

diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index 369405c7cd..b41a883e80 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -2386,7 +2386,7 @@ inline T qVariantToHelper(const QVariant::Private &d, const HandlersManager &han
     \l QMetaType::QVariantList of a type that can be converted to QString;
     otherwise returns an empty list.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QStringList QVariant::toStringList() const
 {
@@ -2394,14 +2394,19 @@ QStringList QVariant::toStringList() const
 }
 
 /*!
-    Returns the variant as a QString if the variant has userType() \l
-    QMetaType::QString, \l QMetaType::Bool, \l QMetaType::QByteArray,
+    Returns the variant as a QString if the variant has a userType()
+    including, but not limited to:
+
+    \l QMetaType::QString, \l QMetaType::Bool, \l QMetaType::QByteArray,
     \l QMetaType::QChar, \l QMetaType::QDate, \l QMetaType::QDateTime,
     \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong,
     \l QMetaType::QStringList, \l QMetaType::QTime, \l QMetaType::UInt, or
-    \l QMetaType::ULongLong; otherwise returns an empty string.
+    \l QMetaType::ULongLong.
+
+    Calling QVariant::toString() on an unsupported variant returns an empty
+    string.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QString QVariant::toString() const
 {
@@ -2412,7 +2417,7 @@ QString QVariant::toString() const
     Returns the variant as a QMap<QString, QVariant> if the variant
     has type() \l QMetaType::QVariantMap; otherwise returns an empty map.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QVariantMap QVariant::toMap() const
 {
@@ -2423,7 +2428,7 @@ QVariantMap QVariant::toMap() const
     Returns the variant as a QHash<QString, QVariant> if the variant
     has type() \l QMetaType::QVariantHash; otherwise returns an empty map.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QVariantHash QVariant::toHash() const
 {
@@ -2440,7 +2445,7 @@ QVariantHash QVariant::toHash() const
     If the type() is \l QMetaType::QString, an invalid date will be returned if
     the string cannot be parsed as a Qt::ISODate format date.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QDate QVariant::toDate() const
 {
@@ -2457,7 +2462,7 @@ QDate QVariant::toDate() const
     If the type() is \l QMetaType::QString, an invalid time will be returned if
     the string cannot be parsed as a Qt::ISODate format time.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QTime QVariant::toTime() const
 {
@@ -2474,7 +2479,7 @@ QTime QVariant::toTime() const
     If the type() is \l QMetaType::QString, an invalid date/time will be
     returned if the string cannot be parsed as a Qt::ISODate format date/time.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QDateTime QVariant::toDateTime() const
 {
@@ -2488,7 +2493,7 @@ QDateTime QVariant::toDateTime() const
     Returns the variant as a QEasingCurve if the variant has userType()
     \l QMetaType::QEasingCurve; otherwise returns a default easing curve.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 #ifndef QT_BOOTSTRAPPED
 QEasingCurve QVariant::toEasingCurve() const
@@ -2504,7 +2509,7 @@ QEasingCurve QVariant::toEasingCurve() const
     \l QMetaType::QByteArray or \l QMetaType::QString (converted using
     QString::fromUtf8()); otherwise returns an empty byte array.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QByteArray QVariant::toByteArray() const
 {
@@ -2519,7 +2524,7 @@ QByteArray QVariant::toByteArray() const
     \l QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null
     QPoint.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QPoint QVariant::toPoint() const
 {
@@ -2532,7 +2537,7 @@ QPoint QVariant::toPoint() const
     Returns the variant as a QRect if the variant has userType()
     \l QMetaType::QRect; otherwise returns an invalid QRect.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QRect QVariant::toRect() const
 {
@@ -2545,7 +2550,7 @@ QRect QVariant::toRect() const
     Returns the variant as a QSize if the variant has userType()
     \l QMetaType::QSize; otherwise returns an invalid QSize.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QSize QVariant::toSize() const
 {
@@ -2558,7 +2563,7 @@ QSize QVariant::toSize() const
     Returns the variant as a QSizeF if the variant has userType() \l
     QMetaType::QSizeF; otherwise returns an invalid QSizeF.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QSizeF QVariant::toSizeF() const
 {
@@ -2572,7 +2577,7 @@ QSizeF QVariant::toSizeF() const
     \l QMetaType::QRect or \l QMetaType::QRectF; otherwise returns an invalid
     QRectF.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QRectF QVariant::toRectF() const
 {
@@ -2585,7 +2590,7 @@ QRectF QVariant::toRectF() const
     Returns the variant as a QLineF if the variant has userType()
     \l QMetaType::QLineF; otherwise returns an invalid QLineF.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QLineF QVariant::toLineF() const
 {
@@ -2598,7 +2603,7 @@ QLineF QVariant::toLineF() const
     Returns the variant as a QLine if the variant has userType()
     \l QMetaType::QLine; otherwise returns an invalid QLine.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QLine QVariant::toLine() const
 {
@@ -2612,7 +2617,7 @@ QLine QVariant::toLine() const
     QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null
     QPointF.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QPointF QVariant::toPointF() const
 {
@@ -2628,7 +2633,7 @@ QPointF QVariant::toPointF() const
     Returns the variant as a QUrl if the variant has userType()
     \l QMetaType::QUrl; otherwise returns an invalid QUrl.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QUrl QVariant::toUrl() const
 {
@@ -2642,7 +2647,7 @@ QUrl QVariant::toUrl() const
     Returns the variant as a QLocale if the variant has userType()
     \l QMetaType::QLocale; otherwise returns an invalid QLocale.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QLocale QVariant::toLocale() const
 {
@@ -2656,7 +2661,7 @@ QLocale QVariant::toLocale() const
     Returns the variant as a QRegExp if the variant has userType()
     \l QMetaType::QRegExp; otherwise returns an empty QRegExp.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 #ifndef QT_NO_REGEXP
 QRegExp QVariant::toRegExp() const
@@ -2673,7 +2678,7 @@ QRegExp QVariant::toRegExp() const
     Returns the variant as a QRegularExpression if the variant has userType() \l
     QRegularExpression; otherwise returns an empty QRegularExpression.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QRegularExpression QVariant::toRegularExpression() const
 {
@@ -2688,7 +2693,7 @@ QRegularExpression QVariant::toRegularExpression() const
     Returns the variant as a QModelIndex if the variant has userType() \l
     QModelIndex; otherwise returns a default constructed QModelIndex.
 
-    \sa canConvert(), convert(), toPersistentModelIndex()
+    \sa canConvert(int targetTypeId), convert(), toPersistentModelIndex()
 */
 QModelIndex QVariant::toModelIndex() const
 {
@@ -2701,7 +2706,7 @@ QModelIndex QVariant::toModelIndex() const
     Returns the variant as a QPersistentModelIndex if the variant has userType() \l
     QPersistentModelIndex; otherwise returns a default constructed QPersistentModelIndex.
 
-    \sa canConvert(), convert(), toModelIndex()
+    \sa canConvert(int targetTypeId), convert(), toModelIndex()
 */
 QPersistentModelIndex QVariant::toPersistentModelIndex() const
 {
@@ -2717,7 +2722,7 @@ QPersistentModelIndex QVariant::toPersistentModelIndex() const
     \l QMetaType::QUuid, \l QMetaType::QByteArray or \l QMetaType::QString;
     otherwise returns a default-constructed QUuid.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QUuid QVariant::toUuid() const
 {
@@ -2730,7 +2735,7 @@ QUuid QVariant::toUuid() const
     Returns the variant as a QJsonValue if the variant has userType() \l
     QJsonValue; otherwise returns a default constructed QJsonValue.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QJsonValue QVariant::toJsonValue() const
 {
@@ -2743,7 +2748,7 @@ QJsonValue QVariant::toJsonValue() const
     Returns the variant as a QJsonObject if the variant has userType() \l
     QJsonObject; otherwise returns a default constructed QJsonObject.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QJsonObject QVariant::toJsonObject() const
 {
@@ -2756,7 +2761,7 @@ QJsonObject QVariant::toJsonObject() const
     Returns the variant as a QJsonArray if the variant has userType() \l
     QJsonArray; otherwise returns a default constructed QJsonArray.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QJsonArray QVariant::toJsonArray() const
 {
@@ -2769,7 +2774,7 @@ QJsonArray QVariant::toJsonArray() const
     Returns the variant as a QJsonDocument if the variant has userType() \l
     QJsonDocument; otherwise returns a default constructed QJsonDocument.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QJsonDocument QVariant::toJsonDocument() const
 {
@@ -2784,7 +2789,7 @@ QJsonDocument QVariant::toJsonDocument() const
     \l QMetaType::QChar, \l QMetaType::Int, or \l QMetaType::UInt; otherwise
     returns an invalid QChar.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QChar QVariant::toChar() const
 {
@@ -2795,7 +2800,7 @@ QChar QVariant::toChar() const
     Returns the variant as a QBitArray if the variant has userType()
     \l QMetaType::QBitArray; otherwise returns an empty bit array.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QBitArray QVariant::toBitArray() const
 {
@@ -2838,7 +2843,7 @@ inline T qNumVariantToHelper(const QVariant::Private &d,
     will not be reflected in \a ok. A simple workaround is to use
     QString::toInt().
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 int QVariant::toInt(bool *ok) const
 {
@@ -2860,7 +2865,7 @@ int QVariant::toInt(bool *ok) const
     overflow will not be reflected in \a ok. A simple workaround is to use
     QString::toUInt().
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 uint QVariant::toUInt(bool *ok) const
 {
@@ -2877,7 +2882,7 @@ uint QVariant::toUInt(bool *ok) const
     If \a ok is non-null: \c{*}\c{ok} is set to true if the value could be
     converted to an int; otherwise \c{*}\c{ok} is set to false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 qlonglong QVariant::toLongLong(bool *ok) const
 {
@@ -2894,7 +2899,7 @@ qlonglong QVariant::toLongLong(bool *ok) const
     If \a ok is non-null: \c{*}\a{ok} is set to true if the value could be
     converted to an int; otherwise \c{*}\a{ok} is set to false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 qulonglong QVariant::toULongLong(bool *ok) const
 {
@@ -2911,7 +2916,7 @@ qulonglong QVariant::toULongLong(bool *ok) const
     \l QMetaType::QByteArray and its lower-case content is not one of the
     following: empty, "0" or "false"; otherwise returns \c false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 bool QVariant::toBool() const
 {
@@ -2934,7 +2939,7 @@ bool QVariant::toBool() const
     If \a ok is non-null: \c{*}\a{ok} is set to true if the value could be
     converted to a double; otherwise \c{*}\a{ok} is set to false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 double QVariant::toDouble(bool *ok) const
 {
@@ -2953,7 +2958,7 @@ double QVariant::toDouble(bool *ok) const
     If \a ok is non-null: \c{*}\a{ok} is set to true if the value could be
     converted to a double; otherwise \c{*}\a{ok} is set to false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 float QVariant::toFloat(bool *ok) const
 {
@@ -2972,7 +2977,7 @@ float QVariant::toFloat(bool *ok) const
     If \a ok is non-null: \c{*}\a{ok} is set to true if the value could be
     converted to a double; otherwise \c{*}\a{ok} is set to false.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 qreal QVariant::toReal(bool *ok) const
 {
@@ -2984,7 +2989,7 @@ qreal QVariant::toReal(bool *ok) const
     \l QMetaType::QVariantList or \l QMetaType::QStringList; otherwise returns
     an empty list.
 
-    \sa canConvert(), convert()
+    \sa canConvert(int targetTypeId), convert()
 */
 QVariantList QVariant::toList() const
 {
@@ -3366,7 +3371,7 @@ bool QVariant::canConvert(int targetTypeId) const
     failed a previous conversion will always fail, changing the type, remaining null,
     and returning \c false.
 
-    \sa canConvert(), clear()
+    \sa canConvert(int targetTypeId), clear()
 */
 
 bool QVariant::convert(int targetTypeId)
diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp
index 9a5505bd1e..f418ac1205 100644
--- a/src/corelib/thread/qsemaphore.cpp
+++ b/src/corelib/thread/qsemaphore.cpp
@@ -291,10 +291,14 @@ public:
 QSemaphore::QSemaphore(int n)
 {
     Q_ASSERT_X(n >= 0, "QSemaphore", "parameter 'n' must be non-negative");
-    if (futexAvailable())
-        u.store(n);
-    else
+    if (futexAvailable()) {
+        quintptr nn = unsigned(n);
+        if (futexHasWaiterCount)
+            nn |= quint64(nn) << 32;    // token count replicated in high word
+        u.store(nn);
+    } else {
         d = new QSemaphorePrivate(n);
+    }
 }
 
 /*!
diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index 404a722e29..a4e5130937 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -2889,7 +2889,7 @@ Q_GUI_EXPORT QStringList qt_sort_families_by_writing_system(QChar::Script script
         uint order = i;
         if (testFamily == nullptr
               || (testFamily->writingSystems[writingSystem] & QtFontFamily::Supported) == 0) {
-            order |= 1 << 31;
+            order |= 1u << 31;
         }
 
         supported.insert(order, family);
diff --git a/src/network/ssl/qsslsocket_winrt.cpp b/src/network/ssl/qsslsocket_winrt.cpp
index ff9dccc734..53a8a8b61b 100644
--- a/src/network/ssl/qsslsocket_winrt.cpp
+++ b/src/network/ssl/qsslsocket_winrt.cpp
@@ -236,9 +236,9 @@ void QSslSocketBackendPrivate::startClientEncryption()
     switch (q->protocol()) {
     case QSsl::AnyProtocol:
     case QSsl::SslV3:
+    case QSsl::TlsV1SslV3:
         protectionLevel = SocketProtectionLevel_Ssl; // Only use this value if weak cipher support is required
         break;
-    case QSsl::TlsV1SslV3:
     case QSsl::TlsV1_0:
         protectionLevel = SocketProtectionLevel_Tls10;
         break;
diff --git a/src/plugins/platforms/xcb/qxcbbackingstore.cpp b/src/plugins/platforms/xcb/qxcbbackingstore.cpp
index 70d1757af4..659d1c53cb 100644
--- a/src/plugins/platforms/xcb/qxcbbackingstore.cpp
+++ b/src/plugins/platforms/xcb/qxcbbackingstore.cpp
@@ -70,11 +70,13 @@
 
 QT_BEGIN_NAMESPACE
 
-class QXcbShmImage : public QXcbObject
+class QXcbBackingStore;
+
+class QXcbBackingStoreImage : public QXcbObject
 {
 public:
-    QXcbShmImage(QXcbScreen *connection, const QSize &size, uint depth, QImage::Format format);
-    ~QXcbShmImage() { destroy(true); }
+    QXcbBackingStoreImage(QXcbBackingStore *backingStore, const QSize &size);
+    ~QXcbBackingStoreImage() { destroy(true); }
 
     void resize(const QSize &size);
 
@@ -105,25 +107,24 @@ private:
     void flushPixmap(const QRegion &region, bool fullRegion = false);
     void setClip(const QRegion &region);
 
-    xcb_window_t m_screen_root;
-
     xcb_shm_segment_info_t m_shm_info;
-    size_t m_segmentSize;
+    QXcbBackingStore *m_backingStore = nullptr;
+    size_t m_segmentSize = 0;
 
-    xcb_image_t *m_xcb_image;
+    xcb_image_t *m_xcb_image = nullptr;
 
     QImage m_qimage;
-    QPlatformGraphicsBuffer *m_graphics_buffer;
+    QPlatformGraphicsBuffer *m_graphics_buffer = nullptr;
 
-    xcb_gcontext_t m_gc;
-    xcb_drawable_t m_gc_drawable;
+    xcb_gcontext_t m_gc = 0;
+    xcb_drawable_t m_gc_drawable = 0;
 
     // When using shared memory these variables are used only for server-side scrolling.
     // When not using shared memory, we maintain a server-side pixmap with the backing
     // store as well as repainted content not yet flushed to the pixmap. We only flush
     // the regions we need and only when these are marked dirty. This way we can just
     // do a server-side copy on expose instead of sending the pixels every time
-    xcb_pixmap_t m_xcb_pixmap;
+    xcb_pixmap_t m_xcb_pixmap = 0;
     QRegion m_pendingFlush;
 
     // This is the scrolled region which is stored in server-side pixmap
@@ -136,16 +137,15 @@ private:
     // as a pixmap region to server
     QByteArray m_flushBuffer;
 
-    bool m_hasAlpha;
-    bool m_clientSideScroll;
+    bool m_hasAlpha = false;
+    bool m_clientSideScroll = false;
 };
 
-class QXcbShmGraphicsBuffer : public QPlatformGraphicsBuffer
+class QXcbGraphicsBuffer : public QPlatformGraphicsBuffer
 {
 public:
-    QXcbShmGraphicsBuffer(QImage *image)
+    QXcbGraphicsBuffer(QImage *image)
         : QPlatformGraphicsBuffer(image->size(), QImage::toPixelFormat(image->format()))
-        , m_access_lock(QPlatformGraphicsBuffer::None)
         , m_image(image)
     { }
 
@@ -165,9 +165,10 @@ public:
     int bytesPerLine() const override { return m_image->bytesPerLine(); }
 
     Origin origin() const override { return QPlatformGraphicsBuffer::OriginTopLeft; }
+
 private:
-    AccessTypes m_access_lock;
-    QImage *m_image;
+    AccessTypes m_access_lock = QPlatformGraphicsBuffer::None;
+    QImage *m_image = nullptr;
 };
 
 static inline size_t imageDataSize(const xcb_image_t *image)
@@ -175,28 +176,25 @@ static inline size_t imageDataSize(const xcb_image_t *image)
     return static_cast<size_t>(image->stride) * image->height;
 }
 
-QXcbShmImage::QXcbShmImage(QXcbScreen *screen, const QSize &size, uint depth, QImage::Format format)
-    : QXcbObject(screen->connection())
-    , m_screen_root(screen->screen()->root)
-    , m_segmentSize(0)
-    , m_graphics_buffer(nullptr)
-    , m_gc(0)
-    , m_gc_drawable(0)
-    , m_xcb_pixmap(0)
-    , m_clientSideScroll(false)
-{
-    const xcb_format_t *fmt = connection()->formatForDepth(depth);
+QXcbBackingStoreImage::QXcbBackingStoreImage(QXcbBackingStore *backingStore, const QSize &size)
+    : QXcbObject(backingStore->connection())
+    , m_backingStore(backingStore)
+{
+    QXcbWindow *window = static_cast<QXcbWindow *>(backingStore->window()->handle());
+    const xcb_format_t *fmt = connection()->formatForDepth(window->depth());
     Q_ASSERT(fmt);
 
+    memset(&m_shm_info, 0, sizeof m_shm_info);
+
+    QImage::Format format = window->imageFormat();
     m_hasAlpha = QImage::toPixelFormat(format).alphaUsage() == QPixelFormat::UsesAlpha;
     if (!m_hasAlpha)
-        format = qt_maybeAlphaVersionWithSameDepth(format);
-
-    memset(&m_shm_info, 0, sizeof m_shm_info);
-    create(size, fmt, format);
+        create(size, fmt, qt_maybeAlphaVersionWithSameDepth(format));
+    else
+        create(size, fmt, format);
 }
 
-void QXcbShmImage::resize(const QSize &size)
+void QXcbBackingStoreImage::resize(const QSize &size)
 {
     xcb_format_t fmt;
     fmt.depth = m_xcb_image->depth;
@@ -207,7 +205,7 @@ void QXcbShmImage::resize(const QSize &size)
     create(size, &fmt, m_qimage.format());
 }
 
-void QXcbShmImage::create(const QSize &size, const xcb_format_t *fmt, QImage::Format format)
+void QXcbBackingStoreImage::create(const QSize &size, const xcb_format_t *fmt, QImage::Format format)
 {
     m_xcb_image = xcb_image_create(size.width(), size.height(),
                                    XCB_IMAGE_FORMAT_Z_PIXMAP,
@@ -232,17 +230,18 @@ void QXcbShmImage::create(const QSize &size, const xcb_format_t *fmt, QImage::Fo
     m_xcb_image->data = m_shm_info.shmaddr ? m_shm_info.shmaddr : (uint8_t *)malloc(segmentSize);
 
     m_qimage = QImage( (uchar*) m_xcb_image->data, m_xcb_image->width, m_xcb_image->height, m_xcb_image->stride, format);
-    m_graphics_buffer = new QXcbShmGraphicsBuffer(&m_qimage);
+    m_graphics_buffer = new QXcbGraphicsBuffer(&m_qimage);
 
     m_xcb_pixmap = xcb_generate_id(xcb_connection());
+    auto xcbScreen = static_cast<QXcbScreen *>(m_backingStore->window()->screen()->handle());
     xcb_create_pixmap(xcb_connection(),
                       m_xcb_image->depth,
                       m_xcb_pixmap,
-                      m_screen_root,
+                      xcbScreen->root(),
                       m_xcb_image->width, m_xcb_image->height);
 }
 
-void QXcbShmImage::destroy(bool destroyShm)
+void QXcbBackingStoreImage::destroy(bool destroyShm)
 {
     if (m_xcb_image->data) {
         if (m_shm_info.shmaddr) {
@@ -268,7 +267,7 @@ void QXcbShmImage::destroy(bool destroyShm)
     m_xcb_pixmap = 0;
 }
 
-void QXcbShmImage::flushScrolledRegion(bool clientSideScroll)
+void QXcbBackingStoreImage::flushScrolledRegion(bool clientSideScroll)
 {
     if (m_clientSideScroll == clientSideScroll)
        return;
@@ -316,7 +315,7 @@ void QXcbShmImage::flushScrolledRegion(bool clientSideScroll)
     }
 }
 
-void QXcbShmImage::createShmSegment(size_t segmentSize)
+void QXcbBackingStoreImage::createShmSegment(size_t segmentSize)
 {
     Q_ASSERT(connection()->hasShm());
     Q_ASSERT(m_segmentSize == 0);
@@ -400,7 +399,7 @@ void QXcbShmImage::createShmSegment(size_t segmentSize)
     }
 }
 
-void QXcbShmImage::destroyShmSegment(size_t segmentSize)
+void QXcbBackingStoreImage::destroyShmSegment(size_t segmentSize)
 {
 #ifndef XCB_USE_SHM_FD
     Q_UNUSED(segmentSize)
@@ -433,7 +432,7 @@ void QXcbShmImage::destroyShmSegment(size_t segmentSize)
 
 extern void qt_scrollRectInImage(QImage &img, const QRect &rect, const QPoint &offset);
 
-bool QXcbShmImage::scroll(const QRegion &area, int dx, int dy)
+bool QXcbBackingStoreImage::scroll(const QRegion &area, int dx, int dy)
 {
     const QRect bounds(QPoint(), size());
     const QRegion scrollArea(area & bounds);
@@ -477,7 +476,7 @@ bool QXcbShmImage::scroll(const QRegion &area, int dx, int dy)
     return true;
 }
 
-void QXcbShmImage::ensureGC(xcb_drawable_t dst)
+void QXcbBackingStoreImage::ensureGC(xcb_drawable_t dst)
 {
     if (m_gc_drawable != dst) {
         if (m_gc)
@@ -557,7 +556,7 @@ static inline quint32 round_up_scanline(quint32 base, quint32 pad)
     return (base + pad - 1) & -pad;
 }
 
-void QXcbShmImage::shmPutImage(xcb_drawable_t drawable, const QRegion &region, const QPoint &offset)
+void QXcbBackingStoreImage::shmPutImage(xcb_drawable_t drawable, const QRegion &region, const QPoint &offset)
 {
     for (const QRect &rect : region) {
         const QPoint source = rect.translated(offset).topLeft();
@@ -578,7 +577,7 @@ void QXcbShmImage::shmPutImage(xcb_drawable_t drawable, const QRegion &region, c
     m_dirtyShm |= region.translated(offset);
 }
 
-void QXcbShmImage::flushPixmap(const QRegion &region, bool fullRegion)
+void QXcbBackingStoreImage::flushPixmap(const QRegion &region, bool fullRegion)
 {
     if (!fullRegion) {
         auto actualRegion = m_pendingFlush.intersected(region);
@@ -647,7 +646,7 @@ void QXcbShmImage::flushPixmap(const QRegion &region, bool fullRegion)
     }
 }
 
-void QXcbShmImage::setClip(const QRegion &region)
+void QXcbBackingStoreImage::setClip(const QRegion &region)
 {
     if (region.isEmpty()) {
         static const uint32_t mask = XCB_GC_CLIP_MASK;
@@ -663,7 +662,7 @@ void QXcbShmImage::setClip(const QRegion &region)
     }
 }
 
-void QXcbShmImage::put(xcb_drawable_t dst, const QRegion &region, const QPoint &offset)
+void QXcbBackingStoreImage::put(xcb_drawable_t dst, const QRegion &region, const QPoint &offset)
 {
     Q_ASSERT(!m_clientSideScroll);
 
@@ -704,7 +703,7 @@ void QXcbShmImage::put(xcb_drawable_t dst, const QRegion &region, const QPoint &
     setClip(QRegion());
 }
 
-void QXcbShmImage::preparePaint(const QRegion &region)
+void QXcbBackingStoreImage::preparePaint(const QRegion &region)
 {
     if (hasShm()) {
         // to prevent X from reading from the image region while we're writing to it
@@ -719,7 +718,6 @@ void QXcbShmImage::preparePaint(const QRegion &region)
 
 QXcbBackingStore::QXcbBackingStore(QWindow *window)
     : QPlatformBackingStore(window)
-    , m_image(0)
 {
     QXcbScreen *screen = static_cast<QXcbScreen *>(window->screen()->handle());
     setConnection(screen->connection());
@@ -856,12 +854,10 @@ void QXcbBackingStore::resize(const QSize &size, const QRegion &)
     }
     QXcbWindow* win = static_cast<QXcbWindow *>(pw);
 
-    if (m_image) {
+    if (m_image)
         m_image->resize(size);
-    } else {
-        QXcbScreen *screen = static_cast<QXcbScreen *>(window()->screen()->handle());
-        m_image = new QXcbShmImage(screen, size, win->depth(), win->imageFormat());
-    }
+    else
+        m_image = new QXcbBackingStoreImage(this, size);
 
     // Slow path for bgr888 VNC: Create an additional image, paint into that and
     // swap R and B while copying to m_image after each paint.
diff --git a/src/plugins/platforms/xcb/qxcbbackingstore.h b/src/plugins/platforms/xcb/qxcbbackingstore.h
index 2e8fbfb7fa..747626c213 100644
--- a/src/plugins/platforms/xcb/qxcbbackingstore.h
+++ b/src/plugins/platforms/xcb/qxcbbackingstore.h
@@ -49,7 +49,7 @@
 
 QT_BEGIN_NAMESPACE
 
-class QXcbShmImage;
+class QXcbBackingStoreImage;
 
 class QXcbBackingStore : public QXcbObject, public QPlatformBackingStore
 {
@@ -75,7 +75,7 @@ public:
     void endPaint() override;
 
 private:
-    QXcbShmImage *m_image;
+    QXcbBackingStoreImage *m_image = nullptr;
     QStack<QRegion> m_paintRegions;
     QImage m_rgbImage;
 };