Detect change on the intersection of video and viewport.

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 21 matching lines @@
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptEventListener.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/HTMLNames.h"
 #include "core/css/MediaList.h"
 #include "core/dom/Attribute.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/ElementVisibilityObserver.h"
 #include "core/dom/Fullscreen.h"
+#include "core/dom/IntersectionGeometry.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/html/AutoplayUmaHelper.h"
 #include "core/html/HTMLMediaSource.h"
@@ skipping 2467 matching lines @@
   if (!m_seeking)
     scheduleTimeupdateEvent(true);
 
   if (!playbackRate())
     return;
 
   if (!m_paused && mediaControls())
     mediaControls()->playbackProgressed();
 
   cueTimeline().updateActiveCues(currentTime());
+
+  if (m_webMediaPlayer) {

[miu, 2016/11/21 21:07:03]

There's an early return from this method about 6-8 lines above. But we want this
to always execute. So, please move this up (perhaps to the very top of this
method?).

[xjz, 2016/11/21 23:58:42]

Done. Moved this to the very top of the method.

+    // Check whether the intersection with viewport has changed.
+    ExecutionContext* context = getExecutionContext();
+    DCHECK(context->isDocument());
+    Document& document = toDocument(*context);
+    IntersectionGeometry geometry(&document, this, Vector<Length>(), true);
+    geometry.computeGeometry();
+    WebRect intersectRect =
+        WebRect(geometry.intersectionRect().x().rawValue(),

[miu, 2016/11/21 21:07:04]

This translation between rectangle data types is a functional detail that
belongs in IntersectionGeometry more than it does here in HTMLMediaElement. Can
you change intersectionRect() and rootRect() to return a WebRect? If not, maybe
you could create two accessor methods in IntersectionGeometry:
intersectionWebRect() and rootWebRect()?

[xjz, 2016/11/21 23:58:42]

Done. Add accessor methods in IntersectionGeometry.

+                geometry.intersectionRect().y().rawValue(),
+                geometry.intersectionRect().width().rawValue(),
+                geometry.intersectionRect().height().rawValue());
+    if (m_currentViewportIntersection.intersectRect != intersectRect) {
+      m_currentViewportIntersection.intersectRect = intersectRect;
+      m_currentViewportIntersection.rootRect =
+          WebRect(geometry.rootRect().x().rawValue(),
+                  geometry.rootRect().y().rawValue(),
+                  geometry.rootRect().width().rawValue(),
+                  geometry.rootRect().height().rawValue());
+      m_webMediaPlayer->videoViewportIntersectionChanged(
+          m_currentViewportIntersection);
+    }
+  }
 }
 
 void HTMLMediaElement::scheduleTimeupdateEvent(bool periodicEvent) {
   // Per spec, consult current playback position to check for changing time.
   double mediaTime = currentPlaybackPosition();
   double now = WTF::currentTime();
 
   bool haveNotRecentlyFiredTimeupdate =
       (now - m_lastTimeUpdateEventWallTime) >= maxTimeupdateEventFrequency;
   bool mediaTimeHasProgressed = mediaTime != m_lastTimeUpdateEventMediaTime;
@@ skipping 1648 matching lines @@
 
 IntRect HTMLMediaElement::AutoplayHelperClientImpl::absoluteBoundingBoxRect()
     const {
   IntRect result;
   if (LayoutObject* object = m_element->layoutObject())
     result = object->absoluteBoundingBoxRect();
   return result;
 }
 
 }  // namespace blink