dom/media/MediaPlaybackDelayPolicy.h

   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 {
  19 namespace dom {
  20
  21 class HTMLMediaElement;
  22 /**
  23  * We usaually start AudioChannelAgent when media starts and stop it when media
  24  * stops. However, when we decide to delay media playback for unvisited tab, we
  25  * would start AudioChannelAgent even if media doesn't start in order to
  26  * register the agent to AudioChannelService, so that the service could notify
  27  * us when we are able to resume media playback. Therefore,
  28  * ResumeDelayedPlaybackAgent is used to handle this special use case of
  29  * AudioChannelAgent.
  30  * - Use `GetResumePromise()` to require resume-promise and then do follow-up
  31  *   resume behavior when promise is resolved.
  32  * - Use `UpdateAudibleState()` to update audible state only when media info
  33  *   changes. As having audio track or not is the only thing for us to decide
  34  *   whether we would show the delayed media playback icon on the tab bar.
  35  */
  36 class ResumeDelayedPlaybackAgent {
  37  public:
  38   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ResumeDelayedPlaybackAgent);
  39   ResumeDelayedPlaybackAgent() = default;
  40
  41   using ResumePromise = MozPromise<bool, bool, true /* IsExclusive */>;
  42   RefPtr<ResumePromise> GetResumePromise();
  43   void UpdateAudibleState(const HTMLMediaElement* aElement, bool aIsAudible);
  44
  45  private:
  46   friend class MediaPlaybackDelayPolicy;
  47
  48   ~ResumeDelayedPlaybackAgent();
  49   bool InitDelegate(const HTMLMediaElement* aElement, bool aIsAudible);
  50
  51   class ResumePlayDelegate final : public nsIAudioChannelAgentCallback {
  52    public:
  53     NS_DECL_ISUPPORTS
  54
  55     ResumePlayDelegate() = default;
  56
  57     bool Init(const HTMLMediaElement* aElement, bool aIsAudible);
  58     void UpdateAudibleState(const HTMLMediaElement* aElement, bool aIsAudible);
  59     RefPtr<ResumePromise> GetResumePromise();
  60     void Clear();
  61
  62     NS_IMETHODIMP WindowVolumeChanged(float aVolume, bool aMuted) override;
  63     NS_IMETHODIMP WindowAudioCaptureChanged(bool aCapture) override;
  64     NS_IMETHODIMP WindowSuspendChanged(SuspendTypes aSuspend) override;
  65
  66    private:
  67     virtual ~ResumePlayDelegate();
  68
  69     MozPromiseHolder<ResumePromise> mPromise;
  70     RefPtr<AudioChannelAgent> mAudioChannelAgent;
  71   };
  72
  73   RefPtr<ResumePlayDelegate> mDelegate;
  74 };
  75
  76 class MediaPlaybackDelayPolicy {
  77  public:
  78   static bool ShouldDelayPlayback(const HTMLMediaElement* aElement);
  79   static RefPtr<ResumeDelayedPlaybackAgent> CreateResumeDelayedPlaybackAgent(
  80       const HTMLMediaElement* aElement, bool aIsAudible);
  81 };
  82
  83 }  // namespace dom
  84 }  // namespace mozilla
  85
  86 #endif