[Blink>Media] Add heuristic for dominant video detection for Android

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

Index: third_party/WebKit/Source/core/html/MediaCustomControlsFullscreenDetector.cpp
diff --git a/third_party/WebKit/Source/core/html/MediaCustomControlsFullscreenDetector.cpp b/third_party/WebKit/Source/core/html/MediaCustomControlsFullscreenDetector.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2c82edd0912895758b903fe160849176d4ace39d
--- /dev/null
+++ b/third_party/WebKit/Source/core/html/MediaCustomControlsFullscreenDetector.cpp
@@ -0,0 +1,129 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/html/MediaCustomControlsFullscreenDetector.h"
+
+#include "core/dom/DocumentFullscreen.h"
+#include "core/dom/TaskRunnerHelper.h"
+#include "core/events/Event.h"
+#include "core/html/HTMLVideoElement.h"
+#include "core/layout/IntersectionGeometry.h"
+
+namespace blink {
+
+namespace {
+
+constexpr double kCheckFullscreenIntervalSeconds = 1.0f;
+constexpr float kMostlyFillViewportThresholdOfOccupationProportion = 0.85f;
+constexpr float kMostlyFillViewportThresholdOfVisibleProportion = 0.75f;
+
+}  // anonymous namespace
+
+MediaCustomControlsFullscreenDetector::MediaCustomControlsFullscreenDetector(
+    HTMLVideoElement& video)
+    : EventListener(CPPEventListenerType),
+      m_videoElement(video),
+      m_checkViewportIntersectionTimer(
+          TaskRunnerHelper::get(TaskType::Unthrottled, &video.document()),
+          this,
+          &MediaCustomControlsFullscreenDetector::
+              onCheckViewportIntersectionTimerFired) {
+  videoElement().document().addEventListener(
+      EventTypeNames::webkitfullscreenchange, this, true);
+  videoElement().document().addEventListener(EventTypeNames::fullscreenchange,
+                                             this, true);
+}
+
+bool MediaCustomControlsFullscreenDetector::operator==(
+    const EventListener& other) const {
+  return this == &other;
+}
+
+void MediaCustomControlsFullscreenDetector::didMoveToNewDocument(
+    Document& oldDocument) {
+  oldDocument.removeEventListener(EventTypeNames::webkitfullscreenchange, this,
+                                  true);
+  oldDocument.removeEventListener(EventTypeNames::fullscreenchange, this, true);

[mlamouri (slow - plz ping), 2017/02/21 21:58:28]

We should call addEventListener on the new document, right?

Maybe this should be tested? :)

[Zhiqiang Zhang (Slow), 2017/02/22 12:29:18]

Done.

+}
+
+bool MediaCustomControlsFullscreenDetector::computeIsDominantVideo(
+    bool isVideoOrParentFullscreen,
+    const IntRect& targetRect,
+    const IntRect& rootRect,
+    const IntRect& intersectionRect) {
+  if (!isVideoOrParentFullscreen)
+    return false;

[mlamouri (slow - plz ping), 2017/02/21 21:58:28]

Can this happen? We should be fullscreen, right?

[Zhiqiang Zhang (Slow), 2017/02/22 12:29:18]

Done, removed this parameter as we should be in fullscreen when calling this
method.

+
+  const float xOccupationProportion =
+      1.0f * intersectionRect.width() / rootRect.width();
+  const float yOccupationProportion =
+      1.0f * intersectionRect.height() / rootRect.height();
+
+  // If the viewport is mostly occupied by the video, return true.
+  if (std::min(xOccupationProportion, yOccupationProportion) >=
+      kMostlyFillViewportThresholdOfOccupationProportion) {
+    return true;
+  }
+
+  // If neither of the dimensions of the viewport is mostly occupied by the
+  // video, return false.
+  if (std::max(xOccupationProportion, yOccupationProportion) <
+      kMostlyFillViewportThresholdOfOccupationProportion) {
+    return false;
+  }
+
+  // If the video is mostly visible in the indominant dimension, return true.
+  // Otherwise return false.
+  if (xOccupationProportion > yOccupationProportion) {
+    return targetRect.height() *
+               kMostlyFillViewportThresholdOfVisibleProportion <
+           intersectionRect.height();
+  }
+  return targetRect.width() * kMostlyFillViewportThresholdOfVisibleProportion <
+         intersectionRect.width();
+}
+
+void MediaCustomControlsFullscreenDetector::handleEvent(
+    ExecutionContext* context,
+    Event* event) {
+  DCHECK(event->type() == EventTypeNames::fullscreenchange ||
+         event->type() == EventTypeNames::webkitfullscreenchange);
+  if (!isVideoOrParentFullscreen()) {
+    if (videoElement().webMediaPlayer()) {
+      videoElement().webMediaPlayer()->becameDominantVisibleContentInFullscreen(
+          false);

[mlamouri (slow - plz ping), 2017/02/21 21:58:28]

We should probably cancel the timer too so we guarantee the callback will not be
called unless we are effectively fullscreen.

[Zhiqiang Zhang (Slow), 2017/02/22 12:29:18]

Done.

+    }
+    return;
+  }
+
+  m_checkViewportIntersectionTimer.startOneShot(kCheckFullscreenIntervalSeconds,
+                                                BLINK_FROM_HERE);
+}
+
+void MediaCustomControlsFullscreenDetector::
+    onCheckViewportIntersectionTimerFired(TimerBase*) {
+  IntersectionGeometry geometry(nullptr, videoElement(), Vector<Length>(),
+                                true);
+  geometry.computeGeometry();
+
+  bool isDominant = computeIsDominantVideo(
+      isVideoOrParentFullscreen(), geometry.targetIntRect(),
+      geometry.rootIntRect(), geometry.intersectionIntRect());
+
+  if (videoElement().webMediaPlayer()) {
+    videoElement().webMediaPlayer()->becameDominantVisibleContentInFullscreen(
+        isDominant);

[mlamouri (slow - plz ping), 2017/02/21 21:58:28]

What happens if the video goes fullscreen before playing or loading? Can we end
up with no webMediaPlayer? Should we listen to playing or loadedmetadata event
to guarantee that we properly notify the WMP?

[Zhiqiang Zhang (Slow), 2017/02/22 12:29:18]

Now I also listen to loadedmetadata. When any event is received, we check the
media element readyState, and early return if it's less thank HAVE_METADATA.
Yes, the trybots complained somehow.

+  }
+}
+
+bool MediaCustomControlsFullscreenDetector::isVideoOrParentFullscreen() {
+  return DocumentFullscreen::fullscreenElement(videoElement().document());
+}
+
+DEFINE_TRACE(MediaCustomControlsFullscreenDetector) {
+  EventListener::trace(visitor);
+  visitor->trace(m_videoElement);
+}
+
+}  // namespace blink