Moving Encoder and Decoder to remoting/base

Putting Encder and Decoder together so we can have test that tests both
of them.

TEST=remoting_unittests

Review URL: http://codereview.chromium.org/2840036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@53427 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 114 insertions, 0 deletions

diff --git a/remoting/base/decoder.h b/remoting/base/decoder.h
new file mode 100644
index 0000000..1df477d
--- /dev/null
+++ b/remoting/base/decoder.h
@@ -0,0 +1,114 @@
+// 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_BASE_DECODER_H_
+#define REMOTING_BASE_DECODER_H_
+
+#include <vector>
+
+#include "base/task.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 {
+
+// TODO(hclam): Merge this with the one in remoting/host/encoder.h.
+typedef std::vector<gfx::Rect> UpdatedRects;
+
+// Defines the behavior of a decoder for decoding images received from the
+// host.
+//
+// Sequence of actions with a decoder is as follows:
+//
+// 1. BeginDecode(PartialDecodeDone, DecodeDone, 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:
+
+  virtual ~Decoder() {
+  }
+
+  // Tell the decoder to use |frame| as a target to write the decoded image
+  // for the coming update stream.
+  // If decode is partially done and |frame| can be read, |partial_decode_done|
+  // is called and |update_rects| contains the updated regions.
+  // If decode is completed |decode_done| is called.
+  // 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,
+                           UpdatedRects* updated_rects,
+                           Task* partial_decode_done,
+                           Task* decode_done) = 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.
+  //
+  // HostMessage returned by this method will contain a
+  // UpdateStreamPacketMessage.
+  // This message will contain either:
+  // 1. UpdateStreamBeginRect
+  // 2. UpdateStreamRectData
+  // 3. UpdateStreamEndRect
+  //
+  // See remoting/base/protocol/chromotocol.proto for more information about
+  // these messages.
+  virtual bool PartialDecode(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:
+  // Every decoder will have two internal states because there are three
+  // kinds of messages send to PartialDecode().
+  //
+  // Here's a state diagram:
+  //
+  //                UpdateStreamBeginRect       UpdateStreamRectData
+  //                    ..............              ............
+  //                   .              .            .            .
+  //                  .                v          .              .
+  // kWaitingForBeginRect         kWaitingForRectData            .
+  //                  ^                .          ^              .
+  //                   .              .            .            .
+  //                    ..............              ............
+  //                    UpdateStreaEndRect
+  enum State {
+    // In this state the decoder is waiting for UpdateStreamBeginRect.
+    // After receiving UpdateStreaBeginRect, the encoder will transit to
+    // to kWaitingForRectData state.
+    kWaitingForBeginRect,
+
+    // In this state the decoder is waiting for UpdateStreamRectData.
+    // The decode remains in this state if UpdateStreamRectData is received.
+    // The decoder will transit to kWaitingForBeginRect if UpdateStreamEndRect
+    // is received.
+    kWaitingForRectData,
+  };
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_BASE_DECODER_H_