gecko-dev/dom/media/imagecapture/CaptureTask.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "CaptureTask.h"
#include "mozilla/dom/ImageCapture.h"
#include "mozilla/dom/ImageCaptureError.h"
#include "mozilla/dom/ImageEncoder.h"
#include "mozilla/dom/MediaStreamTrack.h"
#include "mozilla/dom/VideoStreamTrack.h"
#include "gfxUtils.h"
#include "nsThreadUtils.h"

namespace mozilla {

class CaptureTask::MediaStreamEventListener : public MediaStreamTrackListener
{
public:
  explicit MediaStreamEventListener(CaptureTask* aCaptureTask)
    : mCaptureTask(aCaptureTask) {};

  // MediaStreamListener methods.
  void NotifyEnded() override
  {
    if(!mCaptureTask->mImageGrabbedOrTrackEnd) {
      mCaptureTask->PostTrackEndEvent();
    }
  }

private:
  CaptureTask* mCaptureTask;
};

CaptureTask::CaptureTask(dom::ImageCapture* aImageCapture)
  : mImageCapture(aImageCapture)
  , mEventListener(new MediaStreamEventListener(this))
  , mImageGrabbedOrTrackEnd(false)
  , mPrincipalChanged(false)
{
}

nsresult
CaptureTask::TaskComplete(already_AddRefed<dom::Blob> aBlob, nsresult aRv)
{
  MOZ_ASSERT(NS_IsMainThread());

  DetachTrack();

  nsresult rv;
  RefPtr<dom::Blob> blob(aBlob);

  // We have to set the parent because the blob has been generated with a valid one.
  if (blob) {
    blob = dom::Blob::Create(mImageCapture->GetParentObject(), blob->Impl());
  }

  if (mPrincipalChanged) {
    aRv = NS_ERROR_DOM_SECURITY_ERR;
    IC_LOG("MediaStream principal should not change during TakePhoto().");
  }

  if (NS_SUCCEEDED(aRv)) {
    rv = mImageCapture->PostBlobEvent(blob);
  } else {
    rv = mImageCapture->PostErrorEvent(dom::ImageCaptureError::PHOTO_ERROR, aRv);
  }

  // Ensure ImageCapture dereference on main thread here because the TakePhoto()
  // sequences stopped here.
  mImageCapture = nullptr;

  return rv;
}

void
CaptureTask::AttachTrack()
{
  MOZ_ASSERT(NS_IsMainThread());

  dom::VideoStreamTrack* track = mImageCapture->GetVideoStreamTrack();
  track->AddPrincipalChangeObserver(this);
  track->AddListener(mEventListener.get());
  track->AddDirectListener(this);
}

void
CaptureTask::DetachTrack()
{
  MOZ_ASSERT(NS_IsMainThread());

  dom::VideoStreamTrack* track = mImageCapture->GetVideoStreamTrack();
  track->RemovePrincipalChangeObserver(this);
  track->RemoveListener(mEventListener.get());
  track->RemoveDirectListener(this);
}

void
CaptureTask::PrincipalChanged(dom::MediaStreamTrack* aMediaStreamTrack)
{
  MOZ_ASSERT(NS_IsMainThread());
  mPrincipalChanged = true;
}

void
CaptureTask::SetCurrentFrames(const VideoSegment& aSegment)
{
  if (mImageGrabbedOrTrackEnd) {
    return;
  }

  // Callback for encoding complete, it calls on main thread.
  class EncodeComplete : public dom::EncodeCompleteCallback
  {
  public:
    explicit EncodeComplete(CaptureTask* aTask) : mTask(aTask) {}

    nsresult ReceiveBlob(already_AddRefed<dom::Blob> aBlob) override
    {
      RefPtr<dom::Blob> blob(aBlob);
      mTask->TaskComplete(blob.forget(), NS_OK);
      mTask = nullptr;
      return NS_OK;
    }

  protected:
    RefPtr<CaptureTask> mTask;
  };

  for (VideoSegment::ConstChunkIterator iter(aSegment);
       !iter.IsEnded(); iter.Next()) {
    VideoChunk chunk = *iter;

    // Extract the first valid video frame.
    VideoFrame frame;
    if (!chunk.IsNull()) {
      RefPtr<layers::Image> image;
      if (chunk.mFrame.GetForceBlack()) {
        // Create a black image.
        image = VideoFrame::CreateBlackImage(chunk.mFrame.GetIntrinsicSize());
      } else {
        image = chunk.mFrame.GetImage();
      }
      if (!image) {
        MOZ_ASSERT(image);
        continue;
      }
      mImageGrabbedOrTrackEnd = true;

      // Encode image.
      nsresult rv;
      nsAutoString type(NS_LITERAL_STRING("image/jpeg"));
      nsAutoString options;
      rv = dom::ImageEncoder::ExtractDataFromLayersImageAsync(
                                type,
                                options,
                                false,
                                image,
                                new EncodeComplete(this));
      if (NS_FAILED(rv)) {
        PostTrackEndEvent();
      }
      return;
    }
  }
}

void
CaptureTask::PostTrackEndEvent()
{
  mImageGrabbedOrTrackEnd = true;

  // Got track end or finish event, stop the task.
  class TrackEndRunnable : public Runnable
  {
  public:
    explicit TrackEndRunnable(CaptureTask* aTask)
      : mozilla::Runnable("TrackEndRunnable")
      , mTask(aTask)
    {
    }

    NS_IMETHOD Run() override
    {
      mTask->TaskComplete(nullptr, NS_ERROR_FAILURE);
      mTask = nullptr;
      return NS_OK;
    }

  protected:
    RefPtr<CaptureTask> mTask;
  };

  IC_LOG("Got MediaStream track removed or finished event.");
  nsCOMPtr<nsIRunnable> event = new TrackEndRunnable(this);
  SystemGroup::Dispatch("CaptureTask::TaskComplete",
                        TaskCategory::Other,
                        event.forget());
}

} // namespace mozilla