ui/base/events/event_handler.h

   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_BASE_EVENTS_EVENT_HANDLER_H_
   6 #define UI_BASE_EVENTS_EVENT_HANDLER_H_
   7
   8 #include <stack>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "ui/base/events/event_constants.h"
  13 #include "ui/base/ui_export.h"
  14
  15 namespace ui {
  16
  17 class CancelModeEvent;
  18 class Event;
  19 class EventDispatcher;
  20 class EventTarget;
  21 class GestureEvent;
  22 class KeyEvent;
  23 class MouseEvent;
  24 class ScrollEvent;
  25 class TouchEvent;
  26
  27 // Dispatches events to appropriate targets.  The default implementations of
  28 // all of the specific handlers (e.g. OnKeyEvent, OnMouseEvent) do nothing.
  29 class UI_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
  62 typedef std::vector<EventHandler*> EventHandlerList;
  63
  64 }  // namespace ui
  65
  66 #endif  // UI_BASE_EVENTS_EVENT_HANDLER_H_