tor-browser

The Tor Browser
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CaptureTask.h (3252B)

      1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
      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
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef CAPTURETASK_H
      8 #define CAPTURETASK_H
      9 
     10 #include "MediaTrackGraph.h"
     11 #include "MediaTrackListener.h"
     12 #include "PrincipalChangeObserver.h"
     13 
     14 namespace mozilla {
     15 
     16 namespace dom {
     17 class BlobImpl;
     18 class ImageCapture;
     19 class MediaStreamTrack;
     20 }  // namespace dom
     21 
     22 /**
     23 * CaptureTask retrieves image from MediaTrack and encodes the image to jpeg in
     24 * ImageEncoder. The whole procedures start at AttachTrack(), it will add this
     25 * class into MediaTrack and retrieves an image in MediaTrackGraph thread.
     26 * Once the image is retrieved, it will be sent to ImageEncoder and the encoded
     27 * blob will be sent out via encoder callback in main thread.
     28 *
     29 * CaptureTask holds a reference of ImageCapture to ensure ImageCapture won't be
     30 * released during the period of the capturing process described above.
     31 */
     32 class CaptureTask : public DirectMediaTrackListener,
     33                    public dom::PrincipalChangeObserver<dom::MediaStreamTrack> {
     34 public:
     35  class MediaTrackEventListener;
     36 
     37  // DirectMediaTrackListener methods
     38  void NotifyRealtimeTrackData(MediaTrackGraph* aGraph, TrackTime aTrackOffset,
     39                               const MediaSegment& aMedia) override;
     40 
     41  // PrincipalChangeObserver<MediaStreamTrack> methods
     42  void PrincipalChanged(dom::MediaStreamTrack* aMediaStreamTrack) override;
     43 
     44  // CaptureTask methods.
     45 
     46  // It is called when aBlob is ready to post back to script in company with
     47  // aRv == NS_OK. If aRv is not NS_OK, it will post an error event to script.
     48  //
     49  // Note:
     50  //   this function should be called on main thread.
     51  nsresult TaskComplete(already_AddRefed<dom::BlobImpl> aBlobImpl,
     52                        nsresult aRv);
     53 
     54  // Add listeners into MediaStreamTrack and PrincipalChangeObserver.
     55  // It should be on main thread only.
     56  void AttachTrack();
     57 
     58  // Remove listeners from MediaStreamTrack and PrincipalChangeObserver.
     59  // It should be on main thread only.
     60  void DetachTrack();
     61 
     62  // CaptureTask should be created on main thread.
     63  explicit CaptureTask(dom::ImageCapture* aImageCapture);
     64 
     65 protected:
     66  virtual ~CaptureTask() = default;
     67 
     68  // Post a runnable on main thread to end this task and call TaskComplete to
     69  // post error event to script. It is called off-main-thread.
     70  void PostTrackEndEvent();
     71 
     72  // The ImageCapture associates with this task. This reference count should not
     73  // change in this class unless it clears this reference after a blob or error
     74  // event to script.
     75  RefPtr<dom::ImageCapture> mImageCapture;
     76 
     77  RefPtr<MediaTrackEventListener> mEventListener;
     78 
     79  // True when an image is retrieved from the video track, or MediaTrackGraph
     80  // sends a track finish, end, or removed event. Any thread.
     81  Atomic<bool> mImageGrabbedOrTrackEnd;
     82 
     83  // True after MediaStreamTrack principal changes while waiting for a photo
     84  // to finish and we should raise a security error.
     85  bool mPrincipalChanged;
     86 };
     87 
     88 }  // namespace mozilla
     89 
     90 #endif  // CAPTURETASK_H