1 files changed, 132 insertions, 0 deletions
diff --git a/dom/media/CanvasCaptureMediaStream.h b/dom/media/CanvasCaptureMediaStream.h
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+++ b/dom/media/CanvasCaptureMediaStream.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
+/* 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/. */
+
+#ifndef mozilla_dom_CanvasCaptureMediaStream_h_
+#define mozilla_dom_CanvasCaptureMediaStream_h_
+
+#include "DOMMediaStream.h"
+#include "mozilla/dom/HTMLCanvasElement.h"
+#include "PrincipalHandle.h"
+
+class nsIPrincipal;
+
+namespace mozilla {
+class DOMMediaStream;
+class SourceMediaTrack;
+
+namespace layers {
+class Image;
+}  // namespace layers
+
+namespace dom {
+class CanvasCaptureMediaStream;
+class HTMLCanvasElement;
+class OutputStreamFrameListener;
+
+/*
+ * The CanvasCaptureMediaStream is a MediaStream subclass that provides a video
+ * track containing frames from a canvas. See an architectural overview below.
+ *
+ * ----------------------------------------------------------------------------
+ *     === Main Thread ===              __________________________
+ *                                     |                          |
+ *                                     | CanvasCaptureMediaStream |
+ *                                     |__________________________|
+ *                                                  |
+ *                                                  | RequestFrame()
+ *                                                  v
+ *                                       ________________________
+ *  ________   FrameCaptureRequested?   |                        |
+ * |        | ------------------------> |   OutputStreamDriver   |
+ * | Canvas |  SetFrameCapture()        | (FrameCaptureListener) |
+ * |________| ------------------------> |________________________|
+ *                                                  |
+ *                                                  | SetImage() -
+ *                                                  | AppendToTrack()
+ *                                                  |
+ *                                                  v
+ *                                      __________________________
+ *                                     |                          |
+ *                                     |  MTG / SourceMediaTrack  |
+ *                                     |__________________________|
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Base class for drivers of the output stream.
+ * It is up to each sub class to implement the NewFrame() callback of
+ * FrameCaptureListener.
+ */
+class OutputStreamDriver : public FrameCaptureListener {
+ public:
+  OutputStreamDriver(SourceMediaTrack* aSourceStream,
+                     const PrincipalHandle& aPrincipalHandle);
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(OutputStreamDriver);
+
+  /*
+   * Called from js' requestFrame() when it wants the next painted frame to be
+   * explicitly captured.
+   */
+  virtual void RequestFrameCapture() = 0;
+
+  /*
+   * Sub classes can SetImage() to update the image being appended to the
+   * output stream. It will be appended on the next NotifyPull from MTG.
+   */
+  void SetImage(RefPtr<layers::Image>&& aImage, const TimeStamp& aTime);
+
+  /*
+   * Ends the track in mSourceStream when we know there won't be any more images
+   * requested for it.
+   */
+  void EndTrack();
+
+  const RefPtr<SourceMediaTrack> mSourceStream;
+  const PrincipalHandle mPrincipalHandle;
+
+ protected:
+  virtual ~OutputStreamDriver();
+};
+
+class CanvasCaptureMediaStream : public DOMMediaStream {
+ public:
+  CanvasCaptureMediaStream(nsPIDOMWindowInner* aWindow,
+                           HTMLCanvasElement* aCanvas);
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(CanvasCaptureMediaStream,
+                                           DOMMediaStream)
+
+  nsresult Init(const dom::Optional<double>& aFPS, nsIPrincipal* aPrincipal);
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  // WebIDL
+  HTMLCanvasElement* Canvas() const { return mCanvas; }
+  void RequestFrame();
+
+  dom::FrameCaptureListener* FrameCaptureListener();
+
+  /**
+   * Stops capturing for this stream at mCanvas.
+   */
+  void StopCapture();
+
+  SourceMediaTrack* GetSourceStream() const;
+
+ protected:
+  ~CanvasCaptureMediaStream();
+
+ private:
+  RefPtr<HTMLCanvasElement> mCanvas;
+  RefPtr<OutputStreamDriver> mOutputStreamDriver;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif /* mozilla_dom_CanvasCaptureMediaStream_h_ */