[Media controls] Add rotate-to-fullscreen gesture behind flag

third_party/WebKit/Source/modules/media_controls/MediaControlsRotateToFullscreenDelegate.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 "modules/media_controls/MediaControlsRotateToFullscreenDelegate.h"
+
+#include "core/dom/DocumentUserGestureToken.h"
+#include "core/dom/ElementVisibilityObserver.h"
+#include "core/dom/Fullscreen.h"
+#include "core/events/Event.h"
+#include "core/frame/LocalDOMWindow.h"
+#include "core/html/HTMLVideoElement.h"
+#include "core/page/ChromeClient.h"
+#include "modules/media_controls/MediaControlsImpl.h"
+#include "platform/UserGestureIndicator.h"
+#include "public/platform/WebScreenInfo.h"
+
+namespace blink {
+
+namespace {
+
+// Videos must be at least this big in both dimensions to qualify.
+constexpr unsigned kMinSize = 200;
+
+// At least this fraction of the video must be visible.
+constexpr float kVisibilityThreshold = 0.75;
+
+}  // anonymous namespace
+
+MediaControlsRotateToFullscreenDelegate::
+    MediaControlsRotateToFullscreenDelegate(HTMLVideoElement& video)
+    : EventListener(kCPPEventListenerType), video_element_(video) {}
+
+void MediaControlsRotateToFullscreenDelegate::Attach() {
+  DCHECK(video_element_->isConnected());
+
+  LocalDOMWindow* dom_window = video_element_->GetDocument().domWindow();
+  if (!dom_window)
+    return;
+
+  video_element_->addEventListener(EventTypeNames::play, this, true);
+  video_element_->addEventListener(EventTypeNames::pause, this, true);
+
+  // Listen to two different fullscreen events in order to make sure the new and
+  // old APIs are handled.
+  video_element_->addEventListener(EventTypeNames::webkitfullscreenchange, this,
+                                   true);
+  video_element_->GetDocument().addEventListener(
+      EventTypeNames::fullscreenchange, this, true);
+
+  current_screen_orientation_ = ComputeScreenOrientation();
+  // TODO(johnme): Check this is battery efficient (note that this doesn't need
+  // to receive events for 180 deg rotations).
+  dom_window->addEventListener(EventTypeNames::orientationchange, this, false);
+}
+
+void MediaControlsRotateToFullscreenDelegate::Detach() {
+  DCHECK(!video_element_->isConnected());
+
+  if (visibility_observer_) {
+    // TODO(johnme): Should I also call Stop in a prefinalizer?
+    visibility_observer_->Stop();
+    visibility_observer_ = nullptr;
+    is_visible_ = false;
+  }
+
+  video_element_->removeEventListener(EventTypeNames::play, this, true);
+  video_element_->removeEventListener(EventTypeNames::pause, this, true);
+
+  video_element_->removeEventListener(EventTypeNames::webkitfullscreenchange,
+                                      this, true);
+  video_element_->GetDocument().removeEventListener(
+      EventTypeNames::fullscreenchange, this, true);
+
+  LocalDOMWindow* dom_window = video_element_->GetDocument().domWindow();
+  if (!dom_window)
+    return;
+  dom_window->removeEventListener(EventTypeNames::orientationchange, this,
+                                  false);
+}
+
+bool MediaControlsRotateToFullscreenDelegate::operator==(
+    const EventListener& other) const {
+  return this == &other;
+}
+
+void MediaControlsRotateToFullscreenDelegate::handleEvent(
+    ExecutionContext* execution_context,
+    Event* event) {
+  if (event->type() == EventTypeNames::play ||
+      event->type() == EventTypeNames::pause ||
+      event->type() == EventTypeNames::fullscreenchange ||
+      event->type() == EventTypeNames::webkitfullscreenchange) {
+    OnStateChange();
+    return;
+  }
+  if (event->type() == EventTypeNames::orientationchange) {
+    OnScreenOrientationChange();
+    return;
+  }
+
+  NOTREACHED();
+}
+
+void MediaControlsRotateToFullscreenDelegate::OnStateChange() {
+  // TODO(johnme): Check this aggressive disabling doesn't lead to race
+  // conditions where we briefly don't know if the video is visible.
+  bool needs_visibility_observer =
+      !video_element_->paused() && !video_element_->IsFullscreen();
+  DVLOG(3) << __func__ << " " << !!visibility_observer_ << " -> "
+           << needs_visibility_observer;
+
+  if (needs_visibility_observer && !visibility_observer_) {
+    visibility_observer_ = new ElementVisibilityObserver(
+        video_element_,
+        WTF::Bind(&MediaControlsRotateToFullscreenDelegate::OnVisibilityChange,
+                  WrapWeakPersistent(this)));
+    visibility_observer_->Start(kVisibilityThreshold);
+  } else if (!needs_visibility_observer && visibility_observer_) {
+    visibility_observer_->Stop();
+    visibility_observer_ = nullptr;
+    is_visible_ = false;
+  }
+}
+
+void MediaControlsRotateToFullscreenDelegate::OnVisibilityChange(
+    bool is_visible) {
+  DVLOG(3) << __func__ << " " << is_visible_ << " -> " << is_visible;
+  is_visible_ = is_visible;
+}
+
+void MediaControlsRotateToFullscreenDelegate::OnScreenOrientationChange() {
+  SimpleOrientation previous_screen_orientation = current_screen_orientation_;
+  current_screen_orientation_ = ComputeScreenOrientation();
+  DVLOG(3) << __func__ << " " << static_cast<int>(previous_screen_orientation)
+           << " -> " << static_cast<int>(current_screen_orientation_);
+
+  // Only enable if native media controls are used.
+  if (!video_element_->ShouldShowControls())
+    return;
+
+  // Don't enter/exit fullscreen if some other element is fullscreen.
+  Element* fullscreen_element =
+      Fullscreen::CurrentFullScreenElementFrom(video_element_->GetDocument());
+  if (fullscreen_element && fullscreen_element != video_element_)
+    return;
+
+  // To enter fullscreen, video must be visible and playing.
+  // TODO(johnme): If orientation changes whilst this tab is in the background,
+  // we'll get an orientationchange event when this tab next becomes active.
+  // Check that those events don't trigger rotate-to-fullscreen.
+  if (!video_element_->IsFullscreen() &&
+      (!is_visible_ || video_element_->paused())) {
+    return;
+  }
+
+  // Ignore (unexpected) events where we have incomplete information.
+  if (previous_screen_orientation == SimpleOrientation::kUnknown ||
+      current_screen_orientation_ == SimpleOrientation::kUnknown) {
+    return;
+  }
+
+  // Ignore 180 degree rotations between PortraitPrimary and PortraitSecondary,
+  // or between LandscapePrimary and LandscapeSecondary.
+  if (previous_screen_orientation == current_screen_orientation_)
+    return;
+
+  SimpleOrientation video_orientation = ComputeVideoOrientation();
+
+  // Ignore videos that are square/small/etc.
+  if (video_orientation == SimpleOrientation::kUnknown)
+    return;
+
+  MediaControlsImpl& media_controls =
+      *static_cast<MediaControlsImpl*>(video_element_->GetMediaControls());
+
+  {
+    UserGestureIndicator gesture(
+        DocumentUserGestureToken::Create(&video_element_->GetDocument()));
+
+    bool should_be_fullscreen =
+        current_screen_orientation_ == video_orientation;
+    if (should_be_fullscreen && !video_element_->IsFullscreen())
+      media_controls.EnterFullscreen();
+    else if (!should_be_fullscreen && video_element_->IsFullscreen())
+      media_controls.ExitFullscreen();
+  }
+}
+
+MediaControlsRotateToFullscreenDelegate::SimpleOrientation
+MediaControlsRotateToFullscreenDelegate::ComputeVideoOrientation() const {
+  if (video_element_->getReadyState() == HTMLMediaElement::kHaveNothing)
+    return SimpleOrientation::kUnknown;
+
+  const unsigned width = video_element_->videoWidth();
+  const unsigned height = video_element_->videoHeight();
+
+  if (width < kMinSize || height < kMinSize)
+    return SimpleOrientation::kUnknown;  // Too small, ignore this video.
+
+  if (width >= height)
+    return SimpleOrientation::kLandscape;  // Includes square videos.
+  return SimpleOrientation::kPortrait;
+}
+
+MediaControlsRotateToFullscreenDelegate::SimpleOrientation
+MediaControlsRotateToFullscreenDelegate::ComputeScreenOrientation() const {
+  Frame* frame = video_element_->GetDocument().GetFrame();
+  if (!frame)
+    return SimpleOrientation::kUnknown;
+
+  switch (frame->GetChromeClient().GetScreenInfo().orientation_type) {
+    case kWebScreenOrientationPortraitPrimary:
+    case kWebScreenOrientationPortraitSecondary:
+      return SimpleOrientation::kPortrait;
+    case kWebScreenOrientationLandscapePrimary:
+    case kWebScreenOrientationLandscapeSecondary:
+      return SimpleOrientation::kLandscape;
+    case kWebScreenOrientationUndefined:
+      return SimpleOrientation::kUnknown;
+  }
+
+  NOTREACHED();
+  return SimpleOrientation::kUnknown;
+}
+
+DEFINE_TRACE(MediaControlsRotateToFullscreenDelegate) {
+  EventListener::Trace(visitor);
+  visitor->Trace(video_element_);
+  visitor->Trace(visibility_observer_);
+}
+
+}  // namespace blink