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::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