Copy the (early prototype of) remoting in Chrome into the public tree....

remoting/client/decoder.h

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef REMOTING_CLIENT_DECODER_H_
+#define REMOTING_CLIENT_DECODER_H_
+
+#include <vector>
+
+#include "base/callback.h"
+#include "base/scoped_ptr.h"
+#include "gfx/rect.h"
+#include "media/base/video_frame.h"
+#include "remoting/base/protocol/chromotocol.pb.h"
+
+namespace remoting {
+
+// Defines the behavior of a decoder for decoding images received from the
+// host.
+//
+// Sequence of actions with a decoder is as follows:
+//
+// 1. BeginDecode(VideoFrame)
+// 2. PartialDecode(HostMessage)
+//    ...
+// 3. EndDecode()
+//
+// The decoder will reply with:
+// 1. PartialDecodeDone(VideoFrame, UpdatedRects)
+//    ...
+// 2. DecodeDone(VideoFrame)
+//
+// The format of VideoFrame is a contract between the object that creates the
+// decoder (most likely the renderer) and the decoder.
+class Decoder {
+ public:
+  typedef std::vector<gfx::Rect> UpdatedRects;
+  typedef Callback2<scoped_refptr<media::VideoFrame>, UpdatedRects>::Type
+      PartialDecodeDoneCallback;
+  typedef Callback1<scoped_refptr<media::VideoFrame> >::Type
+      DecodeDoneCallback;
+
+  Decoder(PartialDecodeDoneCallback* partial_decode_done_callback,
+          DecodeDoneCallback* decode_done_callback)
+      : partial_decode_done_(partial_decode_done_callback),
+        decode_done_(decode_done_callback) {
+  }
+
+  virtual ~Decoder() {
+  }
+
+  // Tell the decoder to use |frame| as a target to write the decoded image
+  // for the coming update stream.
+  // Return true if the decoder can writes output to |frame| and accept
+  // the codec format.
+  // TODO(hclam): Provide more information when calling this function.
+  virtual bool BeginDecode(scoped_refptr<media::VideoFrame> frame) = 0;
+
+  // Give a HostMessage that contains the update stream packet that contains
+  // the encoded data to the decoder.
+  // The decoder will own |message| and is responsible for deleting it.
+  // If the decoder has written something into |frame|,
+  // |partial_decode_done_| is called with |frame| and updated regions.
+  // Return true if the decoder can accept |message| and decode it.
+  virtual bool PartialDecode(chromotocol_pb::HostMessage* message) = 0;
+
+  // Notify the decoder that we have received the last update stream packet.
+  // If the decoding of the update stream has completed |decode_done_| is
+  // called with |frame|.
+  // If the update stream is not received fully and this method is called the
+  // decoder should also call |decode_done_| as soon as possible.
+  virtual void EndDecode() = 0;
+
+ protected:
+  PartialDecodeDoneCallback* partial_decode_done() {
+    return partial_decode_done_.get();
+  }
+
+  DecodeDoneCallback* decode_done() {
+    return decode_done_.get();
+  }
+
+ private:
+  scoped_ptr<PartialDecodeDoneCallback> partial_decode_done_;
+  scoped_ptr<DecodeDoneCallback> decode_done_;
+
+  DISALLOW_COPY_AND_ASSIGN(Decoder);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_CLIENT_DECODER_H_