event_handler.h revision 68043e1e95eeb07d5cae7aca370b26518b0867d6 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef UI_EVENTS_EVENT_HANDLER_H_
6#define UI_EVENTS_EVENT_HANDLER_H_
7
8#include <stack>
9#include <vector>
10
11#include "base/basictypes.h"
12#include "ui/events/event_constants.h"
13#include "ui/events/events_export.h"
14
15namespace ui {
16
17class CancelModeEvent;
18class Event;
19class EventDispatcher;
20class EventTarget;
21class GestureEvent;
22class KeyEvent;
23class MouseEvent;
24class ScrollEvent;
25class TouchEvent;
26
27// Dispatches events to appropriate targets.  The default implementations of
28// all of the specific handlers (e.g. OnKeyEvent, OnMouseEvent) do nothing.
29class EVENTS_EXPORT EventHandler {
30 public:
31  EventHandler();
32  virtual ~EventHandler();
33
34  // This is called for all events. The default implementation routes the event
35  // to one of the event-specific callbacks (OnKeyEvent, OnMouseEvent etc.). If
36  // this is overridden, then normally, the override should chain into the
37  // default implementation for un-handled events.
38  virtual void OnEvent(Event* event);
39
40  virtual void OnKeyEvent(KeyEvent* event);
41
42  virtual void OnMouseEvent(MouseEvent* event);
43
44  virtual void OnScrollEvent(ScrollEvent* event);
45
46  virtual void OnTouchEvent(TouchEvent* event);
47
48  virtual void OnGestureEvent(GestureEvent* event);
49
50  virtual void OnCancelMode(CancelModeEvent* event);
51
52 private:
53  friend class EventDispatcher;
54
55  // EventDispatcher pushes itself on the top of this stack while dispatching
56  // events to this then pops itself off when done.
57  std::stack<EventDispatcher*> dispatchers_;
58
59  DISALLOW_COPY_AND_ASSIGN(EventHandler);
60};
61
62typedef std::vector<EventHandler*> EventHandlerList;
63
64}  // namespace ui
65
66#endif  // UI_EVENTS_EVENT_HANDLER_H_
67