[Chromoting] Add a filter that will stop the host sending unnecessary clipboard events to the clien…

remoting/protocol/clipboard_echo_filter.h

+// Copyright (c) 2012 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_PROTOCOL_CLIPBOARD_ECHO_FILTER_H_
+#define REMOTING_PROTOCOL_CLIPBOARD_ECHO_FILTER_H_
+
+#include <map>
+#include <string>
+
+#include "base/compiler_specific.h"
+#include "remoting/protocol/clipboard_stub.h"
+
+namespace remoting {
+namespace protocol {
+
+// ClipboardEchoFilter stops the host sending a clipboard item to the
+// client, if that item was the latest item received from the client.
+class ClipboardEchoFilter {
+ public:
+  ClipboardEchoFilter();
+  ~ClipboardEchoFilter();
+
+  // Sets the ClipboardStub that sends events to the client.
+  void set_client_stub(ClipboardStub* client_stub);
+
+  // Sets the ClipboardStub that sends events to the host.
+  void set_host_stub(ClipboardStub* host_stub);
+
+  // Gets the ClipboardStub that sends events through this filter and on to the
+  // client.
+  ClipboardStub* client_filter();
+
+  // Gets the ClipboardStub that sends events through this filter and on to the
+  // host.
+  ClipboardStub* host_filter();
+
+ private:
+  class ClientFilter : public ClipboardStub {
+   public:
+    ClientFilter(ClipboardEchoFilter* filter);
+    virtual void InjectClipboardEvent(const ClipboardEvent& event) OVERRIDE;
+
+   private:
+    ClipboardEchoFilter* filter_;
+  };
+
+  class HostFilter : public ClipboardStub {
+   public:
+    HostFilter(ClipboardEchoFilter* filter);
+    virtual void InjectClipboardEvent(const ClipboardEvent& event) OVERRIDE;
+
+   private:
+    ClipboardEchoFilter* filter_;
+  };
+
+  void InjectClipboardEventToHost(const ClipboardEvent& event);
+  void InjectClipboardEventToClient(const ClipboardEvent& event);
+
+  ClipboardStub* host_stub_;
+  ClipboardStub* client_stub_;
+  ClientFilter client_filter_;
+  HostFilter host_filter_;
+
+  // The latest item received from the client.
+  std::string client_latest_mime_type_;
+  std::string client_latest_data_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClipboardEchoFilter);
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_CLIPBOARD_ECHO_FILTER_H_