1 files changed, 11 insertions, 10 deletions

diff --git a/Source/WebKit2/UIProcess/qt/QtViewportHandler.cpp b/Source/WebKit2/UIProcess/qt/QtViewportHandler.cpp
index a1f56d189..faff331be 100644
--- a/Source/WebKit2/UIProcess/qt/QtViewportHandler.cpp
+++ b/Source/WebKit2/UIProcess/qt/QtViewportHandler.cpp
@@ -171,6 +171,14 @@ QtViewportHandler::QtViewportHandler(WebKit::WebPageProxy* proxy, QQuickWebView*
     m_scaleAnimation->setDuration(kScaleAnimationDurationMillis);
     m_scaleAnimation->setEasingCurve(QEasingCurve::OutCubic);
 
+    // Initializing Viewport Raw Attributes to avoid random negative scale factors
+    // if there is a race condition between the first layout and setting the viewport attributes for the first time.
+    m_rawAttributes.devicePixelRatio = m_devicePixelRatio;
+    m_rawAttributes.initialScale = 1;
+    m_rawAttributes.minimumScale = m_minimumScale;
+    m_rawAttributes.maximumScale = m_maximumScale;
+    m_rawAttributes.userScalable = m_allowsUserScaling;
+
     connect(m_viewportItem, SIGNAL(movementStarted()), SLOT(flickMoveStarted()), Qt::DirectConnection);
     connect(m_viewportItem, SIGNAL(movementEnded()), SLOT(flickMoveEnded()), Qt::DirectConnection);
 
@@ -694,13 +702,10 @@ void QtViewportHandler::pinchGestureCancelled()
     m_scaleUpdateDeferrer.clear();
 }
 
-QRect QtViewportHandler::visibleContentsRect() const
+QRectF QtViewportHandler::visibleContentsRect() const
 {
     const QRectF visibleRect(m_viewportItem->boundingRect().intersected(m_pageItem->boundingRect()));
-
-    // We avoid using toAlignedRect() because it produces inconsistent width and height.
-    QRectF mappedRect(m_viewportItem->mapRectToWebContent(visibleRect));
-    return QRect(floor(mappedRect.x()), floor(mappedRect.y()), floor(mappedRect.width()), floor(mappedRect.height()));
+    return m_viewportItem->mapRectToWebContent(visibleRect);
 }
 
 void QtViewportHandler::informVisibleContentChange(const QPointF& trajectoryVector)
@@ -709,17 +714,13 @@ void QtViewportHandler::informVisibleContentChange(const QPointF& trajectoryVect
     if (!drawingArea)
         return;
 
-    if (m_lastVisibleContentsRect == visibleContentsRect())
-        return;
-
     qreal scale = m_pageItem->contentsScale();
 
     if (scale != m_lastCommittedScale)
         emit m_viewportItem->experimental()->test()->contentsScaleCommitted();
     m_lastCommittedScale = scale;
-    m_lastVisibleContentsRect = visibleContentsRect();
 
-    drawingArea->setVisibleContentsRect(visibleContentsRect(), scale, trajectoryVector, m_viewportItem->contentPos());
+    drawingArea->setVisibleContentsRect(visibleContentsRect(), scale, trajectoryVector);
 
     // Ensure that updatePaintNode is always called before painting.
     m_pageItem->update();