blob: c7a7dec712de609ff1d21da5cbdd91745f02ac58 [file] [log] [blame]
// Copyright (c) 2012 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 UI_EVENTS_EVENT_DISPATCHER_H_
#define UI_EVENTS_EVENT_DISPATCHER_H_
#include "base/auto_reset.h"
#include "ui/events/event.h"
#include "ui/events/event_constants.h"
#include "ui/events/event_target.h"
#include "ui/events/events_export.h"
namespace ui {
class EventDispatcher;
struct EventDispatchDetails {
EventDispatchDetails()
: dispatcher_destroyed(false),
target_destroyed(false) {}
bool dispatcher_destroyed;
bool target_destroyed;
};
class EVENTS_EXPORT EventDispatcherDelegate {
public:
EventDispatcherDelegate();
virtual ~EventDispatcherDelegate();
// Returns whether an event can still be dispatched to a target. (e.g. during
// event dispatch, one of the handlers may have destroyed the target, in which
// case the event can no longer be dispatched to the target).
virtual bool CanDispatchToTarget(EventTarget* target) = 0;
// Returns the event being dispatched (or NULL if no event is being
// dispatched).
Event* current_event();
protected:
// Dispatches the event to the target. Returns true if the delegate is still
// alive after dispatching event, and false if the delegate was destroyed
// during the event dispatch.
EventDispatchDetails DispatchEvent(EventTarget* target, Event* event)
WARN_UNUSED_RESULT;
private:
EventDispatcher* dispatcher_;
DISALLOW_COPY_AND_ASSIGN(EventDispatcherDelegate);
};
// Dispatches events to appropriate targets.
class EVENTS_EXPORT EventDispatcher {
public:
explicit EventDispatcher(EventDispatcherDelegate* delegate);
virtual ~EventDispatcher();
void ProcessEvent(EventTarget* target, Event* event);
const Event* current_event() const { return current_event_; }
Event* current_event() { return current_event_; }
bool delegate_destroyed() const { return !delegate_; }
const EventDispatchDetails& details() const { return details_; }
void OnHandlerDestroyed(EventHandler* handler);
void OnDispatcherDelegateDestroyed();
private:
void DispatchEventToEventHandlers(EventHandlerList* list, Event* event);
// Dispatches an event, and makes sure it sets ER_CONSUMED on the
// event-handling result if the dispatcher itself has been destroyed during
// dispatching the event to the event handler.
void DispatchEvent(EventHandler* handler, Event* event);
EventDispatcherDelegate* delegate_;
Event* current_event_;
EventHandlerList handler_list_;
EventDispatchDetails details_;
DISALLOW_COPY_AND_ASSIGN(EventDispatcher);
};
} // namespace ui
#endif // UI_EVENTS_EVENT_DISPATCHER_H_