Initial ResizeObserver implementation

third_party/WebKit/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.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "core/frame/FrameView.h"
 
+#include "bindings/core/v8/ScriptCallStack.h"

[szager1, 2016/05/23 19:49:10]

I don't think you use this.

[atotic1, 2016/05/25 00:15:52]

I am using it, through magic of templates. Won't compile without it.

 #include "core/HTMLNames.h"
 #include "core/MediaTypeNames.h"
 #include "core/css/FontFaceSet.h"
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/AXObjectCache.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/IntersectionObserverController.h"
 #include "core/editing/EditingUtilities.h"
 #include "core/editing/FrameSelection.h"
 #include "core/editing/RenderedPosition.h"
 #include "core/editing/markers/DocumentMarkerController.h"
+#include "core/events/ErrorEvent.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Location.h"
 #include "core/frame/PageScaleConstraintsSet.h"
 #include "core/frame/Settings.h"
 #include "core/frame/TopControls.h"
 #include "core/html/HTMLFrameElement.h"
 #include "core/html/HTMLPlugInElement.h"
@@ skipping 18 matching lines @@
 #include "core/layout/TracedLayoutObject.h"
 #include "core/layout/api/LayoutBoxModel.h"
 #include "core/layout/api/LayoutItem.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/layout/compositing/CompositedSelection.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "core/observer/ResizeObserverController.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/FocusController.h"
 #include "core/page/FrameTree.h"
 #include "core/page/Page.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/paint/FramePainter.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintPropertyTreeBuilder.h"
 #include "core/plugins/PluginView.h"
@@ skipping 2316 matching lines @@
 void FrameView::scheduleVisualUpdateForPaintInvalidationIfNeeded()
 {
     LocalFrame* localFrameRoot = frame().localFrameRoot();
     if (!localFrameRoot->view()->m_isUpdatingAllLifecyclePhases || lifecycle().state() >= DocumentLifecycle::PaintInvalidationClean) {
         // Schedule visual update to process the paint invalidation in the next cycle.
         localFrameRoot->scheduleVisualUpdateUnlessThrottled();
     }
     // Otherwise the paint invalidation will be handled in paint invalidation phase of this cycle.
 }
 
+void FrameView::notifyResizeObserver()
+{
+    if (!m_frame->document()->hasResizeObserverController())
+        return;
+
+    ResizeObserverController& resizeController = m_frame->document()->ensureResizeObserverController();
+
+    // Messy looping logic:
+    // Loop until :
+    // - no notifications were delivered, or
+    // - more than kRenderLoopLimit resizeObservations were processed
+    // DocumentLifecycle should be LayoutClean before and after processing all notifications.
+
+    size_t resizeNotifyCount = 0;
+    bool done = false;
+
+    while (!done) {

[szager1, 2016/05/23 19:49:10]

I think this loop might read better as:

do {
  resizeController.deliverObservations();
  if (state >= LayoutClean && !needsLayout())
    break;

  updateStyleAndLayoutIfNeededRecursive();

  if (++resizeNotifyCount > limit) {
    generate error;
    break;
  }

  resizeObserver.gatherObservations();
} while (resizeController.hasObservations());

ASSERT(!layoutView()->needsLayout());



Advantages:

- It clarifies that the exit condition for the loop is when there are no more
observations.
- The document is in a consistent state when the loop exits (hence the ASSERT).

[atotic1, 2016/05/25 00:15:52]

I reworked the loop into something more understandeable.

+
+        // This does not work because lifecycle does not roll back.
+        // if (lifecycle().state() < DocumentLifecycle::LayoutClean)
+
+        // This causes the bug too.
+        // if (m_frame->document()->needsLayoutTreeUpdate())
+        //    updateStyleAndLayoutIfNeededRecursive();
+
+        // FIXME(atotic) -- unsure if this is the right way to
+        // loop over layout pipeline.
+        if (lifecycle().state() < DocumentLifecycle::LayoutClean
+            || layoutView()->needsLayout())
+            updateStyleAndLayoutIfNeededRecursive();
+
+        resizeController.gatherObservations();
+        if (!resizeController.hasObservations()) {
+            // No resize entries delivered, we are done.
+            done = true;
+        } else {
+            resizeController.deliverObservations();
+            resizeNotifyCount++;
+            if (resizeNotifyCount == ResizeObserverController::kRenderLoopLimit) {

[szager1, 2016/05/23 19:49:10]

If you're going to generate an error, you should do it *before* gather/deliver,
and early-out.

[atotic1, 2016/05/25 00:15:52]

Acknowledged.

+                // report the error
+                ErrorEvent * error = ErrorEvent::create("ResizeObserver loop limit exceeded.", "", 0, 0, nullptr);
+                m_frame->document()->reportException(error, 0, nullptr, NotSharableCrossOrigin);
+                done = true;
+            }
+        }
+    }
+
+    if (layoutView()->needsLayout())
+        updateStyleAndLayoutIfNeededRecursive();
+}
+
 // TODO(leviw): We don't assert lifecycle information from documents in child PluginViews.
 void FrameView::updateLifecyclePhasesInternal(LifeCycleUpdateOption phases)
 {
     Optional<TemporaryChange<bool>> isUpdatingAllLifecyclePhasesScope;
     if (phases == AllPhases)
         isUpdatingAllLifecyclePhasesScope.emplace(m_isUpdatingAllLifecyclePhases, true);
 
     // This must be called from the root frame, since it recurses down, not up.
     // Otherwise the lifecycles of the frames might be out of sync.
     ASSERT(m_frame->isLocalRoot());
 
     if (shouldThrottleRendering()) {
         updateViewportIntersectionsForSubtree(std::min(phases, OnlyUpToCompositingCleanPlusScrolling));
         return;
     }
 
     updateStyleAndLayoutIfNeededRecursive();
+
+    notifyResizeObserver();

[szager1, 2016/05/23 19:49:10]

Maybe rename this to runUpdateNotifyLoop(), and remove the
updateStyleAndLayoutIfNeededRecursive() call just before this.

[atotic1, 2016/05/25 00:15:52]

I'd prefer not to rename it until it does something more than resize.
updateNotify does not convey much information.
If resizeObserver is undefined, it will not run the
updateStyleAndLayoutIfNeededRecursive()
Leaving it in for now.

This whole code segment needs a review by someone who understands the event
loop.

I do not understand the event cycle/layout enough to understand interaction
between
lifecycle().state(),  needsLayout(), and updateStyleAndLayoutIfNeededRecursive()

+
     ASSERT(lifecycle().state() >= DocumentLifecycle::LayoutClean);
 
     if (phases == OnlyUpToLayoutClean) {
         updateViewportIntersectionsForSubtree(phases);
         return;
     }
 
     if (LayoutViewItem view = layoutViewItem()) {
         {
             TRACE_EVENT1("devtools.timeline", "UpdateLayerTree", "data", InspectorUpdateLayerTreeEvent::data(m_frame.get()));
@@ skipping 1666 matching lines @@
     return m_subtreeThrottled || (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
 } // namespace blink