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MediaPlaybackDelayPolicy.h (3056B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
      5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef mozilla_dom_mediaplaybackdelaypolicy_h__
      8 #define mozilla_dom_mediaplaybackdelaypolicy_h__
      9 
     10 #include "AudioChannelAgent.h"
     11 #include "AudioChannelService.h"
     12 #include "mozilla/MozPromise.h"
     13 #include "mozilla/RefPtr.h"
     14 #include "nsISupportsImpl.h"
     15 
     16 typedef uint32_t SuspendTypes;
     17 
     18 namespace mozilla::dom {
     19 
     20 class HTMLMediaElement;
     21 /**
     22 * We usaually start AudioChannelAgent when media starts and stop it when media
     23 * stops. However, when we decide to delay media playback for unvisited tab, we
     24 * would start AudioChannelAgent even if media doesn't start in order to
     25 * register the agent to AudioChannelService, so that the service could notify
     26 * us when we are able to resume media playback. Therefore,
     27 * ResumeDelayedPlaybackAgent is used to handle this special use case of
     28 * AudioChannelAgent.
     29 * - Use `GetResumePromise()` to require resume-promise and then do follow-up
     30 *   resume behavior when promise is resolved.
     31 * - Use `UpdateAudibleState()` to update audible state only when media info
     32 *   changes. As having audio track or not is the only thing for us to decide
     33 *   whether we would show the delayed media playback icon on the tab bar.
     34 */
     35 class ResumeDelayedPlaybackAgent {
     36 public:
     37  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ResumeDelayedPlaybackAgent);
     38  ResumeDelayedPlaybackAgent() = default;
     39 
     40  using ResumePromise = MozPromise<bool, bool, true /* IsExclusive */>;
     41  RefPtr<ResumePromise> GetResumePromise();
     42  void UpdateAudibleState(const HTMLMediaElement* aElement, bool aIsAudible);
     43 
     44 private:
     45  friend class MediaPlaybackDelayPolicy;
     46 
     47  ~ResumeDelayedPlaybackAgent();
     48  bool InitDelegate(const HTMLMediaElement* aElement, bool aIsAudible);
     49 
     50  class ResumePlayDelegate final : public nsIAudioChannelAgentCallback {
     51   public:
     52    NS_DECL_ISUPPORTS
     53 
     54    ResumePlayDelegate() = default;
     55 
     56    bool Init(const HTMLMediaElement* aElement, bool aIsAudible);
     57    void UpdateAudibleState(const HTMLMediaElement* aElement, bool aIsAudible);
     58    RefPtr<ResumePromise> GetResumePromise();
     59    void Clear();
     60 
     61    NS_IMETHODIMP WindowVolumeChanged(float aVolume, bool aMuted) override;
     62    NS_IMETHODIMP WindowAudioCaptureChanged(bool aCapture) override;
     63    NS_IMETHODIMP WindowSuspendChanged(SuspendTypes aSuspend) override;
     64 
     65   private:
     66    virtual ~ResumePlayDelegate();
     67 
     68    MozPromiseHolder<ResumePromise> mPromise;
     69    RefPtr<AudioChannelAgent> mAudioChannelAgent;
     70  };
     71 
     72  RefPtr<ResumePlayDelegate> mDelegate;
     73 };
     74 
     75 class MediaPlaybackDelayPolicy {
     76 public:
     77  static bool ShouldDelayPlayback(const HTMLMediaElement* aElement);
     78  static RefPtr<ResumeDelayedPlaybackAgent> CreateResumeDelayedPlaybackAgent(
     79      const HTMLMediaElement* aElement, bool aIsAudible);
     80 };
     81 
     82 }  // namespace mozilla::dom
     83 
     84 #endif