keyboard_handler_base.h

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// Copyright 2013 The Flutter 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 FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HANDLER_BASE_H_
#define FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HANDLER_BASE_H_
 
#include <string>
 
namespace flutter {
 
// Interface for classes that handles keyboard input events.
//
// Keyboard handlers are added to |FlutterWindowsView| in a chain.
// When a key event arrives, |KeyboardHook| is called on each handler
// until the first one that returns true. Then the proper text hooks
// are called on each handler.
class KeyboardHandlerBase {
 public:
  using KeyEventCallback = std::function<void(bool)>;
 
  virtual ~KeyboardHandlerBase() = default;
 
  // A function for hooking into keyboard input.
  virtual void KeyboardHook(int key,
                            int scancode,
                            int action,
                            char32_t character,
                            bool extended,
                            bool was_down,
                            KeyEventCallback callback) = 0;
 
  // If needed, synthesize modifier keys events by comparing the
  // given modifiers state to the known pressing state..
  virtual void SyncModifiersIfNeeded(int modifiers_state) = 0;
 
  // Returns the keyboard pressed state.
  //
  // Returns the keyboard pressed state. The map contains one entry per
  // pressed keys, mapping from the logical key to the physical key.
  virtual std::map<uint64_t, uint64_t> GetPressedState() = 0;
};
 
}  // namespace flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HANDLER_BASE_H_