[Remoting Host] Handle text event characters that are not presented on the keyboard

remoting/host/linux/x11_character_injector.h

+// Copyright 2016 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_HOST_LINUX_X11_CHARACTER_INJECTOR_H_
+#define REMOTING_HOST_LINUX_X11_CHARACTER_INJECTOR_H_
+
+#include <stdint.h>
+
+#include <queue>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/timer/timer.h"
+
+namespace remoting {
+
+class X11Keyboard;
+
+// This is a helper class for injecting unicode characters to XWindow server.
+// Characters will be queued up and sent when there is available resource.
+class X11CharacterInjector {
+ public:
+  explicit X11CharacterInjector(std::unique_ptr<X11Keyboard> keyboard);
+  ~X11CharacterInjector();
+
+  void Inject(uint32_t code_point);
+
+ private:
+  struct KeyInfo;
+  struct MapResult;
+
+  // Schedules a task to call DoInject after |delay| if no such task has been
+  // scheduled.
+  void Schedule(base::TimeDelta delay);
+  void DoInject();
+
+  // |code_point|: The Unicode code point for the character.
+  // If the returned result indicates success, caller can use the returned
+  // keycode and modifiers to simulate a key press that can generate the
+  // character.
+  //
+  // Note that the returned result will expire after some amount of time so do
+  // not store the result for later use.
+  MapResult MapCharacter(uint32_t code_point);
+
+  // Resets the expiration time of the KeyInfo in available_keycodes_[index]
+  // to now + the expire duration constant.
+  void ResetKeyInfoExpirationTime(base::TimeTicks now,
+                                  std::vector<KeyInfo>::iterator position);
+
+  std::unique_ptr<X11Keyboard> keyboard_;
+  std::queue<uint32_t> characters_queue_;
+  base::OneShotTimer injection_timer_;
+
+  // Sorted by ascending expiration time.
+  std::vector<KeyInfo> available_keycodes_;
+
+  base::ThreadChecker thread_checker_;
+  DISALLOW_COPY_AND_ASSIGN(X11CharacterInjector);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_LINUX_X11_CHARACTER_INJECTOR_H_