Don't always fully repaint on viewport resize

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 876 matching lines @@
 
     Document* document = m_frame->document();
     bool inSubtreeLayout = isSubtreeLayout();
     RenderObject* rootForThisLayout = inSubtreeLayout ? m_layoutSubtreeRoot : document->renderer();
     if (!rootForThisLayout) {
         // FIXME: Do we need to set m_size here?
         ASSERT_NOT_REACHED();
         return;
     }
 
-    bool shouldDoFullLayout = false;
     FontCachePurgePreventer fontCachePurgePreventer;
     RenderLayer* layer;
     {
         TemporaryChange<bool> changeSchedulingEnabled(m_layoutSchedulingEnabled, false);
 
         m_nestedLayoutCount++;
         if (!inSubtreeLayout) {
             Document* document = m_frame->document();
             Node* body = document->body();
             if (body && body->renderer()) {
                 if (isHTMLFrameSetElement(*body)) {
                     body->renderer()->setChildNeedsLayout();
                 } else if (isHTMLBodyElement(*body)) {
                     if (!m_firstLayout && m_size.height() != layoutSize().height() && body->renderer()->enclosingBox()->stretchesToViewport())
                         body->renderer()->setChildNeedsLayout();
                 }
             }
         }
         updateCounters();
         autoSizeIfEnabled();
 
         ScrollbarMode hMode;
         ScrollbarMode vMode;
         calculateScrollbarModesForLayoutAndSetViewportRenderer(hMode, vMode);
 
-        shouldDoFullLayout = !inSubtreeLayout && (m_firstLayout || toRenderView(rootForThisLayout)->document().printing());
-
         if (!inSubtreeLayout) {
             // Now set our scrollbar state for the layout.
             ScrollbarMode currentHMode = horizontalScrollbarMode();
             ScrollbarMode currentVMode = verticalScrollbarMode();
 
             if (m_firstLayout) {
                 setScrollbarsSuppressed(true);
 
+                m_doFullRepaint = true;
                 m_firstLayout = false;
                 m_firstLayoutCallbackPending = true;
                 m_lastViewportSize = layoutSize(IncludeScrollbars);
                 m_lastZoomFactor = rootForThisLayout->style()->zoom();
 
                 // Set the initial vMode to AlwaysOn if we're auto.
                 if (vMode == ScrollbarAuto)
                     setVerticalScrollbarMode(ScrollbarAlwaysOn); // This causes a vertical scrollbar to appear.
                 // Set the initial hMode to AlwaysOff if we're auto.
                 if (hMode == ScrollbarAuto)
                     setHorizontalScrollbarMode(ScrollbarAlwaysOff); // This causes a horizontal scrollbar to disappear.
 
                 setScrollbarModes(hMode, vMode);
                 setScrollbarsSuppressed(false, true);
             } else if (hMode != currentHMode || vMode != currentVMode) {
                 setScrollbarModes(hMode, vMode);
             }
 
             LayoutSize oldSize = m_size;
 
             m_size = LayoutSize(layoutSize().width(), layoutSize().height());
 
-            if (oldSize != m_size) {
-                shouldDoFullLayout = true;
-                if (!m_firstLayout) {
-                    RenderBox* rootRenderer = document->documentElement() ? document->documentElement()->renderBox() : 0;
-                    RenderBox* bodyRenderer = rootRenderer && document->body() ? document->body()->renderBox() : 0;
-                    if (bodyRenderer && bodyRenderer->stretchesToViewport())
-                        bodyRenderer->setChildNeedsLayout();
-                    else if (rootRenderer && rootRenderer->stretchesToViewport())
-                        rootRenderer->setChildNeedsLayout();
-                }
+            if (oldSize != m_size && !m_firstLayout) {
+                RenderBox* rootRenderer = document->documentElement() ? document->documentElement()->renderBox() : 0;
+                RenderBox* bodyRenderer = rootRenderer && document->body() ? document->body()->renderBox() : 0;
+                if (bodyRenderer && bodyRenderer->stretchesToViewport())
+                    bodyRenderer->setChildNeedsLayout();
+                else if (rootRenderer && rootRenderer->stretchesToViewport())
+                    rootRenderer->setChildNeedsLayout();
             }
+
+            // We need to set m_doFullRepaint before triggering layout as RenderObject::checkForRepaint
+            // checks the boolean to disable local repaints.
+            m_doFullRepaint |= renderView()->shouldDoFullRepaintForNextLayout();
         }
 
         layer = rootForThisLayout->enclosingLayer();
 
-        // We need to set m_doFullRepaint before triggering layout as RenderObject::checkForRepaint
-        // checks the boolean to disable local repaints.
-        m_doFullRepaint |= shouldDoFullLayout;
-
         performLayout(rootForThisLayout, inSubtreeLayout);
 
         m_layoutSubtreeRoot = 0;
     } // Reset m_layoutSchedulingEnabled to its previous value.
 
     if (!inSubtreeLayout && !toRenderView(rootForThisLayout)->document().printing())
         adjustViewSize();
 
     layer->updateLayerPositionsAfterLayout(renderView()->layer(), updateLayerPositionFlags(layer, inSubtreeLayout, m_doFullRepaint));
     renderView()->compositor()->setNeedsCompositingUpdate(CompositingUpdateAfterLayout);
@@ skipping 937 matching lines @@
 
     RenderView* renderView = this->renderView();
     return layoutPending()
         || (renderView && renderView->needsLayout())
         || isSubtreeLayout();
 }
 
 void FrameView::setNeedsLayout()
 {
     if (RenderView* renderView = this->renderView())
-        renderView->setNeedsLayoutAndFullRepaint();
+        renderView->setNeedsLayout();
 }
 
 bool FrameView::isTransparent() const
 {
     return m_isTransparent;
 }
 
 void FrameView::setTransparent(bool isTransparent)
 {
     m_isTransparent = isTransparent;
@@ skipping 1337 matching lines @@
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache()) {
         cache->remove(scrollbar);
         cache->handleScrollbarUpdate(this);
     }
 }
 
 } // namespace WebCore