GUI: batch framebuffer update notifications

src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp

@@ -27,6 +27,7 @@
 
 /* Qt includes: */
 #include <QImage>
+#include <QList>
 #include <QRegion>
 #include <QPainter>
 #include <QPaintEvent>
@@ -77,8 +78,8 @@ class ATL_NO_VTABLE UIFrameBufferPrivate : public QObject,
 
     /** Notifies listener about guest-screen resolution changes. */
     void sigNotifyChange(int iWidth, int iHeight);
-    /** Notifies listener about guest-screen updates. */
-    void sigNotifyUpdate(int iX, int iY, int iWidth, int iHeight);
+    /** Notifies listener that one or more guest-screen updates are pending. */
+    void sigNotifyUpdatePending();
     /** Notifies listener about guest-screen visible-region changes. */
     void sigSetVisibleRegion(QRegion region);
 
@@ -262,6 +263,8 @@ class ATL_NO_VTABLE UIFrameBufferPrivate : public QObject,
 
 protected slots:
 
+    /** Handles coalesced guest-screen updates. */
+    void sltHandlePendingNotifyUpdate();
     /** Handles guest requests to change mouse pointer shape or position. */
     void sltMousePointerShapeOrPositionChange();
 
@@ -274,6 +277,8 @@ protected slots:
 
     /** Updates coordinate-system: */
     void updateCoordinateSystem();
+    /** Queues a guest-screen update rectangle for asynchronous GUI-thread processing. */
+    void queueNotifyUpdate(ULONG uX, ULONG uY, ULONG uWidth, ULONG uHeight);
 
     /** Default paint routine. */
     void paintDefault(QPaintEvent *pEvent);
@@ -312,6 +317,10 @@ protected slots:
     CDisplaySourceBitmap m_pendingSourceBitmap;
     /** Holds whether there is a pending source bitmap which must be applied. */
     bool m_fPendingSourceBitmap;
+    /** Holds pending guest-screen update rectangles. */
+    QList<QRect> m_pendingUpdateRectangles;
+    /** Holds whether a pending-update flush has already been queued. */
+    bool m_fNotifyUpdatePending;
 
     /** Holds machine-view this frame-buffer is bounded to. */
     UIMachineView *m_pMachineView;
@@ -391,6 +400,7 @@ UIFrameBufferPrivate::UIFrameBufferPrivate()
     : m_uScreenId(0)
     , m_iWidth(0), m_iHeight(0)
     , m_fPendingSourceBitmap(false)
+    , m_fNotifyUpdatePending(false)
     , m_pMachineView(NULL)
     , m_iWinId(0)
     , m_fUpdatesAllowed(false)
@@ -695,7 +705,7 @@ STDMETHODIMP UIFrameBufferPrivate::NotifyUpdate(ULONG uX, ULONG uY, ULONG uWidth
     LogRel3(("GUI: UIFrameBufferPrivate::NotifyUpdate: Origin=%lux%lu, Size=%lux%lu, Sending to async-handler\n",
              (unsigned long)uX, (unsigned long)uY,
              (unsigned long)uWidth, (unsigned long)uHeight));
-    emit sigNotifyUpdate(uX, uY, uWidth, uHeight);
+    queueNotifyUpdate(uX, uY, uWidth, uHeight);
 
     /* Unlock access to frame-buffer: */
     unlock();
@@ -748,7 +758,7 @@ STDMETHODIMP UIFrameBufferPrivate::NotifyUpdateImage(ULONG uX, ULONG uY,
         LogRel3(("GUI: UIFrameBufferPrivate::NotifyUpdateImage: Origin=%lux%lu, Size=%lux%lu, Sending to async-handler\n",
                  (unsigned long)uX, (unsigned long)uY,
                  (unsigned long)uWidth, (unsigned long)uHeight));
-        emit sigNotifyUpdate(uX, uY, uWidth, uHeight);
+        queueNotifyUpdate(uX, uY, uWidth, uHeight);
     }
 
     /* Unlock access to frame-buffer: */
@@ -1221,8 +1231,8 @@ void UIFrameBufferPrivate::prepareConnections()
     connect(this, &UIFrameBufferPrivate::sigNotifyChange,
             m_pMachineView, &UIMachineView::sltHandleNotifyChange,
             Qt::QueuedConnection);
-    connect(this, &UIFrameBufferPrivate::sigNotifyUpdate,
-            m_pMachineView, &UIMachineView::sltHandleNotifyUpdate,
+    connect(this, &UIFrameBufferPrivate::sigNotifyUpdatePending,
+            this, &UIFrameBufferPrivate::sltHandlePendingNotifyUpdate,
             Qt::QueuedConnection);
     connect(this, &UIFrameBufferPrivate::sigSetVisibleRegion,
             m_pMachineView, &UIMachineView::sltHandleSetVisibleRegion,
@@ -1240,8 +1250,8 @@ void UIFrameBufferPrivate::cleanupConnections()
     /* Detach EMT connections: */
     disconnect(this, &UIFrameBufferPrivate::sigNotifyChange,
                m_pMachineView, &UIMachineView::sltHandleNotifyChange);
-    disconnect(this, &UIFrameBufferPrivate::sigNotifyUpdate,
-               m_pMachineView, &UIMachineView::sltHandleNotifyUpdate);
+    disconnect(this, &UIFrameBufferPrivate::sigNotifyUpdatePending,
+               this, &UIFrameBufferPrivate::sltHandlePendingNotifyUpdate);
     disconnect(this, &UIFrameBufferPrivate::sigSetVisibleRegion,
                m_pMachineView, &UIMachineView::sltHandleSetVisibleRegion);
 
@@ -1266,6 +1276,63 @@ void UIFrameBufferPrivate::updateCoordinateSystem()
         m_transform = m_transform.scale(1.0 / devicePixelRatio(), 1.0 / devicePixelRatio());
 }
 
+void UIFrameBufferPrivate::queueNotifyUpdate(ULONG uX, ULONG uY, ULONG uWidth, ULONG uHeight)
+{
+    const QRect rect((int)uX, (int)uY, (int)uWidth, (int)uHeight);
+    if (rect.isEmpty())
+        return;
+
+    m_pendingUpdateRectangles << rect;
+    if (!m_fNotifyUpdatePending)
+    {
+        m_fNotifyUpdatePending = true;
+        emit sigNotifyUpdatePending();
+    }
+}
+
+void UIFrameBufferPrivate::sltHandlePendingNotifyUpdate()
+{
+    if (!m_pMachineView)
+    {
+        lock();
+        m_pendingUpdateRectangles.clear();
+        m_fNotifyUpdatePending = false;
+        unlock();
+        return;
+    }
+
+    lock();
+
+    if (   m_fUnused
+        || m_pendingUpdateRectangles.isEmpty())
+    {
+        m_pendingUpdateRectangles.clear();
+        m_fNotifyUpdatePending = false;
+        unlock();
+        return;
+    }
+
+    const int cMaxUpdateRectanglesPerPass = 8;
+    QList<QRect> updateRectangles;
+    updateRectangles.reserve(cMaxUpdateRectanglesPerPass);
+    /* Keep the batch deliberately small.  Large Retina update bursts are cheaper
+     * as a few bounded viewport updates than as one huge Qt backing-store flush. */
+    while (   updateRectangles.size() < cMaxUpdateRectanglesPerPass
+           && !m_pendingUpdateRectangles.isEmpty())
+        updateRectangles << m_pendingUpdateRectangles.takeFirst();
+
+    const bool fHasMoreUpdates = !m_pendingUpdateRectangles.isEmpty();
+    m_fNotifyUpdatePending = fHasMoreUpdates;
+
+    unlock();
+
+    for (QList<QRect>::const_iterator it = updateRectangles.begin(); it != updateRectangles.end(); ++it)
+        m_pMachineView->sltHandleNotifyUpdate(it->x(), it->y(), it->width(), it->height());
+
+    if (fHasMoreUpdates)
+        emit sigNotifyUpdatePending();
+}
+
 void UIFrameBufferPrivate::paintDefault(QPaintEvent *pEvent)
 {
     /* Make sure cached image is valid: */

src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp

@@ -763,13 +763,23 @@ void UIMachineView::sltHandleNotifyChange(int iWidth, int iHeight)
 }
 
 void UIMachineView::sltHandleNotifyUpdate(int iX, int iY, int iWidth, int iHeight)
+{
+    /* Prepare corresponding viewport part: */
+    const QRect rect = viewportRectangleForGuestUpdate(QRect(iX, iY, iWidth, iHeight));
+    if (rect.isEmpty())
+        return;
+
+    /* Update corresponding viewport part: */
+    viewport()->update(rect);
+}
+
+QRect UIMachineView::viewportRectangleForGuestUpdate(const QRect &guestRect)
 {
     /* Sanity check: */
     if (!frameBuffer())
-        return;
+        return QRect();
 
-    /* Prepare corresponding viewport part: */
-    QRect rect(iX, iY, iWidth, iHeight);
+    QRect rect = guestRect;
 
     /* Take the scaling into account: */
     const double dScaleFactor = frameBuffer()->scaleFactor();
@@ -804,11 +814,7 @@ void UIMachineView::sltHandleNotifyUpdate(int iX, int iY, int iWidth, int iHeigh
 
     /* Limit the resulting part by the viewport rectangle: */
     rect &= viewport()->rect();
-    if (rect.isEmpty())
-        return;
-
-    /* Update corresponding viewport part: */
-    viewport()->update(rect);
+    return rect;
 }
 
 void UIMachineView::sltHandleSetVisibleRegion(QRegion region)
@@ -1253,8 +1259,12 @@ void UIMachineView::prepareViewport()
     /* Prepare viewport: */
     AssertPtrReturnVoid(viewport());
     {
-        /* Enable manual painting: */
+        /* The framebuffer paints the requested update itself; avoid widget-level
+         * background fills and let Qt preserve static contents where possible. */
+        viewport()->setAutoFillBackground(false);
         viewport()->setAttribute(Qt::WA_OpaquePaintEvent);
+        viewport()->setAttribute(Qt::WA_NoSystemBackground);
+        viewport()->setAttribute(Qt::WA_StaticContents);
         /* Enable multi-touch support: */
         viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
     }

src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.h

@@ -381,6 +381,8 @@ protected slots:
     QSize scaledForward(QSize size) const;
     /** Scales passed size backward. */
     QSize scaledBackward(QSize size) const;
+    /** Converts a guest dirty rectangle to a viewport dirty rectangle. */
+    QRect viewportRectangleForGuestUpdate(const QRect &rect);
 
     /** Updates mouse pointer @a pixmap, @a iXHot and @a iYHot according to scaling attributes. */
     void updateMousePointerPixmapScaling(QPixmap &pixmap, int &iXHot, int &iYHot);