ui/base/events/event_target.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_TARGET_H_
   6 #define UI_BASE_EVENTS_EVENT_TARGET_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "ui/base/events/event_handler.h"
  11 #include "ui/base/ui_export.h"
  12
  13 namespace ui {
  14
  15 class EventDispatcher;
  16
  17 class UI_EXPORT EventTarget : public EventHandler {
  18  public:
  19   typedef std::vector<EventTarget*> EventTargets;
  20
  21   class TestApi {
  22    public:
  23     explicit TestApi(EventTarget* target) : target_(target) {}
  24
  25     const EventHandlerList& pre_target_handlers() {
  26       return target_->pre_target_list_;
  27     }
  28
  29    private:
  30     TestApi();
  31     EventTarget* target_;
  32
  33     DISALLOW_COPY_AND_ASSIGN(TestApi);
  34   };
  35
  36   class DispatcherApi {
  37    public:
  38     explicit DispatcherApi(EventTarget* target) : target_(target) {}
  39
  40     const EventHandlerList& pre_target_list() const {
  41       return target_->pre_target_list_;
  42     }
  43
  44    private:
  45     DispatcherApi();
  46     EventTarget* target_;
  47
  48     DISALLOW_COPY_AND_ASSIGN(DispatcherApi);
  49   };
  50
  51   EventTarget();
  52   virtual ~EventTarget();
  53
  54   virtual bool CanAcceptEvent(const ui::Event& event) = 0;
  55   virtual EventTarget* GetParentTarget() = 0;
  56
  57   // Adds a handler to receive events before the target. The handler must be
  58   // explicitly removed from the target before the handler is destroyed. The
  59   // EventTarget does not take ownership of the handler.
  60   void AddPreTargetHandler(EventHandler* handler);
  61   void RemovePreTargetHandler(EventHandler* handler);
  62
  63   // Adds a handler to receive events after the target. The handler must be
  64   // explicitly removed from the target before the handler is destroyed. The
  65   // EventTarget does not take ownership of the handler.
  66   void AddPostTargetHandler(EventHandler* handler);
  67   void RemovePostTargetHandler(EventHandler* handler);
  68
  69  protected:
  70   void set_target_handler(EventHandler* handler) {
  71     target_handler_ = handler;
  72   }
  73
  74   // Overridden from EventHandler:
  75   virtual void OnEvent(Event* event) OVERRIDE;
  76   virtual void OnKeyEvent(KeyEvent* event) OVERRIDE;
  77   virtual void OnMouseEvent(MouseEvent* event) OVERRIDE;
  78   virtual void OnScrollEvent(ScrollEvent* event) OVERRIDE;
  79   virtual void OnTouchEvent(TouchEvent* event) OVERRIDE;
  80   virtual void OnGestureEvent(GestureEvent* event) OVERRIDE;
  81
  82  private:
  83   friend class EventDispatcher;
  84
  85   // Returns the list of handlers that should receive the event before the
  86   // target. The handlers from the outermost target are first in the list, and
  87   // the handlers on |this| are the last in the list.
  88   void GetPreTargetHandlers(EventHandlerList* list);
  89
  90   // Returns the list of handlers that should receive the event after the
  91   // target. The handlers from the outermost target are last in the list, and
  92   // the handlers on |this| are the first in the list.
  93   void GetPostTargetHandlers(EventHandlerList* list);
  94
  95   EventHandlerList pre_target_list_;
  96   EventHandlerList post_target_list_;
  97   EventHandler* target_handler_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(EventTarget);
 100 };
 101
 102 }  // namespace ui
 103
 104 #endif  // UI_BASE_EVENTS_EVENT_TARGET_H_