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

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

+// 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/Fullscreen.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().addEventListener(EventTypeNames::DOMNodeInsertedIntoDocument,
+                                  this, false);
+  videoElement().addEventListener(EventTypeNames::DOMNodeRemovedFromDocument,
+                                  this, false);
+
+  videoElement().addEventListener(EventTypeNames::loadedmetadata, this, true);
+}
+
+bool MediaCustomControlsFullscreenDetector::operator==(
+    const EventListener& other) const {
+  return this == &other;
+}
+
+void MediaCustomControlsFullscreenDetector::attach() {
+  videoElement().document().addEventListener(
+      EventTypeNames::webkitfullscreenchange, this, true);
+  videoElement().document().addEventListener(EventTypeNames::fullscreenchange,
+                                             this, true);
+}
+
+void MediaCustomControlsFullscreenDetector::detach() {
+  videoElement().document().removeEventListener(
+      EventTypeNames::webkitfullscreenchange, this, true);
+  videoElement().document().removeEventListener(
+      EventTypeNames::fullscreenchange, this, true);
+}
+
+bool MediaCustomControlsFullscreenDetector::computeIsDominantVideoForTests(
+    const IntRect& targetRect,
+    const IntRect& rootRect,
+    const IntRect& intersectionRect) {
+  if (targetRect.isEmpty() || rootRect.isEmpty())
+    return false;
+
+  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) {
+  if (event->type() == EventTypeNames::DOMNodeInsertedIntoDocument) {
+    attach();
+  } else if (event->type() == EventTypeNames::DOMNodeRemovedFromDocument) {
+    detach();
+  }

[mlamouri (slow - plz ping), 2017/03/02 14:23:36]

What about:
if (event->type() == ...) {
  attach();
  return;
}
if (event-type() == ...) {
  detach();
  return;
}

DCHECK(... event must be one of the expected ones ...);

[mlamouri (slow - plz ping), 2017/03/02 14:27:18]

Zhiqiang told me how wrong I was. Second time today :)

[Zhiqiang Zhang (Slow), 2017/03/02 14:33:42]

Added DCHECK() and comments explaining why

+
+  // Video is not loaded yet.
+  if (videoElement().getReadyState() < HTMLMediaElement::kHaveMetadata)
+    return;
+
+  if (!videoElement().isConnected() || !isVideoOrParentFullscreen()) {
+    m_checkViewportIntersectionTimer.stop();
+
+    if (videoElement().webMediaPlayer())
+      videoElement().webMediaPlayer()->setIsEffectivelyFullscreen(false);
+
+    return;
+  }
+
+  m_checkViewportIntersectionTimer.startOneShot(kCheckFullscreenIntervalSeconds,
+                                                BLINK_FROM_HERE);
+}
+
+void MediaCustomControlsFullscreenDetector::
+    onCheckViewportIntersectionTimerFired(TimerBase*) {
+  DCHECK(isVideoOrParentFullscreen());
+  IntersectionGeometry geometry(nullptr, videoElement(), Vector<Length>(),
+                                true);
+  geometry.computeGeometry();
+
+  bool isDominant = computeIsDominantVideoForTests(
+      geometry.targetIntRect(), geometry.rootIntRect(),
+      geometry.intersectionIntRect());
+
+  if (videoElement().webMediaPlayer())
+    videoElement().webMediaPlayer()->setIsEffectivelyFullscreen(isDominant);
+}
+
+bool MediaCustomControlsFullscreenDetector::isVideoOrParentFullscreen() {
+  Element* fullscreenElement =
+      Fullscreen::currentFullScreenElementFrom(videoElement().document());
+  if (!fullscreenElement)
+    return false;
+
+  return fullscreenElement->contains(&videoElement());
+}
+
+DEFINE_TRACE(MediaCustomControlsFullscreenDetector) {
+  EventListener::trace(visitor);
+  visitor->trace(m_videoElement);
+}
+
+}  // namespace blink