Add infrastructure for partial layouts

Source/core/page/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 162 matching lines @@
     , m_isTrackingRepaints(false)
     , m_shouldUpdateWhileOffscreen(true)
     , m_deferSetNeedsLayouts(0)
     , m_setNeedsLayoutWasDeferred(false)
     , m_scrollCorner(0)
     , m_shouldAutoSize(false)
     , m_inAutoSize(false)
     , m_didRunAutosize(false)
     , m_hasSoftwareFilters(false)
     , m_visibleContentScaleFactor(1)
+    , m_partialLayout()
 {
     ASSERT(m_frame);
     init();
 
     Page* page = m_frame->page();
     if (!page)
         return;
 
     if (m_frame == page->mainFrame()) {
         ScrollableArea::setVerticalScrollElasticity(ScrollElasticityAllowed);
@@ skipping 77 matching lines @@
     m_trackedRepaintRects.clear();
     m_lastPaintTime = 0;
     m_paintBehavior = PaintBehaviorNormal;
     m_isPainting = false;
     m_visuallyNonEmptyCharacterCount = 0;
     m_visuallyNonEmptyPixelCount = 0;
     m_isVisuallyNonEmpty = false;
     m_firstVisuallyNonEmptyLayoutCallbackPending = true;
     m_maintainScrollPositionAnchor = 0;
     m_disableRepaints = 0;
+    m_partialLayout.reset();
 }
 
 void FrameView::removeFromAXObjectCache()
 {
     if (AXObjectCache* cache = axObjectCache())
         cache->remove(this);
 }
 
 void FrameView::resetScrollbars()
 {
@@ skipping 568 matching lines @@
     // the layout beats any sort of style recalc update that needs to occur.
     TemporaryChange<bool> changeDoingPreLayoutStyleUpdate(m_doingPreLayoutStyleUpdate, true);
     document->updateStyleIfNeeded();
 }
 
 void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLayout)
 {
     // performLayout is the actual guts of layout().
     // FIXME: The 300 other lines in layout() probably belong in other helper functions
     // so that a single human could understand what layout() is actually doing.
+    {
+        bool disableLayoutState = false;
+        if (inSubtreeLayout) {
+            RenderView* view = rootForThisLayout->view();
+            disableLayoutState = view->shouldDisableLayoutStateForSubtree(rootForThisLayout);
+            view->pushLayoutState(rootForThisLayout);
+        }
+        LayoutStateDisabler layoutStateDisabler(disableLayoutState ? rootForThisLayout->view() : 0);
 
-    bool disableLayoutState = false;
-    if (inSubtreeLayout) {
-        RenderView* view = rootForThisLayout->view();
-        disableLayoutState = view->shouldDisableLayoutStateForSubtree(rootForThisLayout);
-        view->pushLayoutState(rootForThisLayout);
+        m_inLayout = true;
+        beginDeferredRepaints();
+        forceLayoutParentViewIfNeeded();
+
+        // Text Autosizing requires two-pass layout which is incompatible with partial layout.
+        // If enabled, only do partial layout for the second layout.
+        // FIXME (crbug.com/256657): Do not do two layouts for text autosizing.
+        PartialLayoutDisabler partialLayoutDisabler(partialLayout(), m_frame->settings() && m_frame->settings()->textAutosizingEnabled());
+        rootForThisLayout->layout(); // THIS IS WHERE LAYOUT ACTUALLY HAPPENS.
     }
-    LayoutStateDisabler layoutStateDisabler(disableLayoutState ? rootForThisLayout->view() : 0);
-
-    m_inLayout = true;
-    beginDeferredRepaints();
-    forceLayoutParentViewIfNeeded();
-
-    rootForThisLayout->layout(); // THIS IS WHERE LAYOUT ACTUALLY HAPPENS.
 
     bool autosized = frame().document()->textAutosizer()->processSubtree(rootForThisLayout);
     if (autosized && rootForThisLayout->needsLayout()) {
         TRACE_EVENT0("webkit", "2nd layout due to Text Autosizing");
         rootForThisLayout->layout();
     }
 
     endDeferredRepaints();
     m_inLayout = false;
 
     if (inSubtreeLayout)
         rootForThisLayout->view()->popLayoutState(rootForThisLayout);
 }
 
 void FrameView::scheduleOrPerformPostLayoutTasks()
 {
     if (m_postLayoutTasksTimer.isActive()) {
         m_actionScheduler->resume();
         return;
     }
 
+    // Partial layouts should not happen with synchronous post layouts.
+    ASSERT(!(m_inSynchronousPostLayout && partialLayout().isStopping()));
+
     if (!m_inSynchronousPostLayout) {
         if (frame().document()->shouldDisplaySeamlesslyWithParent()) {
             if (RenderView* renderView = this->renderView())
                 renderView->updateWidgetPositions();
         } else {
             m_inSynchronousPostLayout = true;
             // Calls resumeScheduledEvents()
             performPostLayoutTasks();
             m_inSynchronousPostLayout = false;
         }
     }
 
     if (!m_postLayoutTasksTimer.isActive() && (needsLayout() || m_inSynchronousPostLayout || frame().document()->shouldDisplaySeamlesslyWithParent())) {
         // If we need layout or are already in a synchronous call to postLayoutTasks(),
         // defer widget updates and event dispatch until after we return. postLayoutTasks()
         // can make us need to update again, and we can get stuck in a nasty cycle unless
         // we call it through the timer here.
         m_postLayoutTasksTimer.startOneShot(0);
-        if (needsLayout()) {
+        if (!partialLayout().isStopping() && needsLayout()) {
             m_actionScheduler->pause();
             layout();
         }
     }
 }
 
 void FrameView::layout(bool allowSubtree)
 {
     // We should never layout a Document which is not in a Frame.
     ASSERT(m_frame);
     ASSERT(m_frame->view() == this);
     ASSERT(m_frame->page());
 
     if (m_inLayout)
         return;
 
+    ASSERT(!partialLayout().isStopping());
+
     TRACE_EVENT0("webkit", "FrameView::layout");
     TRACE_EVENT_SCOPED_SAMPLING_STATE("Blink", "Layout");
 
     // Protect the view from being deleted during layout (in recalcStyle)
     RefPtr<FrameView> protector(this);
 
     // Every scroll that happens during layout is programmatic.
     TemporaryChange<bool> changeInProgrammaticScroll(m_inProgrammaticScroll, true);
 
     m_layoutTimer.stop();
@@ skipping 21 matching lines @@
 
     Document* document = m_frame->document();
     bool inSubtreeLayout = m_layoutRoot;
     RenderObject* rootForThisLayout = inSubtreeLayout ? m_layoutRoot : document->renderer();
     if (!rootForThisLayout) {
         // FIXME: Do we need to set m_size here?
         ASSERT_NOT_REACHED();
         return;
     }
 
+    bool isPartialLayout = partialLayout().isPartialLayout();
+
     FontCachePurgePreventer fontCachePurgePreventer;
     RenderLayer* layer;
     {
         TemporaryChange<bool> changeSchedulingEnabled(m_layoutSchedulingEnabled, false);
 
         m_nestedLayoutCount++;
 
         updateCounters();
         autoSizeIfEnabled();
 
         ScrollbarMode hMode;
         ScrollbarMode vMode;
         calculateScrollbarModesForLayout(hMode, vMode);
 
-        m_doFullRepaint = !inSubtreeLayout && (m_firstLayout || toRenderView(rootForThisLayout)->printing());
+        m_doFullRepaint = !inSubtreeLayout && !isPartialLayout && (m_firstLayout || toRenderView(rootForThisLayout)->printing());
 
-        if (!inSubtreeLayout) {
+        if (!inSubtreeLayout && !isPartialLayout) {
             // Now set our scrollbar state for the layout.
             ScrollbarMode currentHMode = horizontalScrollbarMode();
             ScrollbarMode currentVMode = verticalScrollbarMode();
 
             if (m_firstLayout || (hMode != currentHMode || vMode != currentVMode)) {
                 if (m_firstLayout) {
                     setScrollbarsSuppressed(true);
 
                     m_firstLayout = false;
                     m_firstLayoutCallbackPending = true;
@@ skipping 26 matching lines @@
                         bodyRenderer->setChildNeedsLayout();
                     else if (rootRenderer && rootRenderer->stretchesToViewport())
                         rootRenderer->setChildNeedsLayout();
                 }
             }
         }
 
         layer = rootForThisLayout->enclosingLayer();
 
         m_actionScheduler->pause();
+
         performLayout(rootForThisLayout, inSubtreeLayout);
         m_layoutRoot = 0;
     } // Reset m_layoutSchedulingEnabled to its previous value.
 
     bool neededFullRepaint = m_doFullRepaint;
 
-    if (!inSubtreeLayout && !toRenderView(rootForThisLayout)->printing())
+    if (!inSubtreeLayout && !isPartialLayout && !toRenderView(rootForThisLayout)->printing())
         adjustViewSize();
 
     m_doFullRepaint = neededFullRepaint;
 
     // Now update the positions of all layers.
     beginDeferredRepaints();
     if (m_doFullRepaint) {
         // FIXME: This isn't really right, since the RenderView doesn't fully encompass
         // the visibleContentRect(). It just happens to work out most of the time,
         // since first layouts and printing don't have you scrolled anywhere.
         rootForThisLayout->view()->repaint();
     }
 
     layer->updateLayerPositionsAfterLayout(renderView()->layer(), updateLayerPositionFlags(layer, inSubtreeLayout, m_doFullRepaint));
 
     endDeferredRepaints();
 
     updateCompositingLayersAfterLayout();
 
     m_layoutCount++;
 
     if (AXObjectCache* cache = rootForThisLayout->document().existingAXObjectCache())
         cache->postNotification(rootForThisLayout, AXObjectCache::AXLayoutComplete, true);
     updateAnnotatedRegions();
 
-    ASSERT(!rootForThisLayout->needsLayout());
+    ASSERT(partialLayout().isStopping() || !rootForThisLayout->needsLayout());
 
     updateCanBlitOnScrollRecursively();
 
     if (document->hasListenerType(Document::OVERFLOWCHANGED_LISTENER))
         updateOverflowStatus(layoutWidth() < contentsWidth(), layoutHeight() < contentsHeight());
 
     // Resume scheduled events (FrameActionScheduler m_actionScheduler)
     // and ensure post layout tasks are executed or scheduled to be.
     scheduleOrPerformPostLayoutTasks();
 
     InspectorInstrumentation::didLayout(cookie, rootForThisLayout);
 
     m_nestedLayoutCount--;
     if (m_nestedLayoutCount)
         return;
 
+    if (partialLayout().isStopping())
+        return;
+
 #ifndef NDEBUG
     // Post-layout assert that nobody was re-marked as needing layout during layout.
     for (RenderObject* renderer = document->renderer(); renderer; renderer = renderer->nextInPreOrder())
         ASSERT_WITH_SECURITY_IMPLICATION(!renderer->needsLayout());
 #endif
 
     // FIXME: It should be not possible to remove the FrameView from the frame/page during layout
     // however m_inLayout is not set for most of this function, so none of our RELEASE_ASSERTS
     // in Frame/Page will fire. One of the post-layout tasks is disconnecting the Frame from
     // the page in fast/frames/crash-remove-iframe-during-object-beforeload-2.html
@@ skipping 2253 matching lines @@
 }
 
 AXObjectCache* FrameView::axObjectCache() const
 {
     if (frame().document())
         return frame().document()->existingAXObjectCache();
     return 0;
 }
 
 } // namespace WebCore