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// Copyright 2014 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_PLATFORM_PLATFORM_EVENT_SOURCE_H_
#define UI_EVENTS_PLATFORM_PLATFORM_EVENT_SOURCE_H_
#include <stdint.h>
#include <map>
#include <vector>
#include "base/auto_reset.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "ui/events/events_export.h"
#include "ui/events/platform/platform_event_types.h"
namespace ui {
class Event;
class PlatformEventDispatcher;
class PlatformEventObserver;
class ScopedEventDispatcher;
namespace test {
class PlatformEventSourceTestAPI;
}
// PlatformEventSource receives events from a source and dispatches the events
// to the appropriate dispatchers.
class EVENTS_EXPORT PlatformEventSource {
public:
virtual ~PlatformEventSource();
static PlatformEventSource* GetInstance();
// Adds a dispatcher to the dispatcher list. If a dispatcher is added during
// dispatching an event, then the newly added dispatcher also receives that
// event.
void AddPlatformEventDispatcher(PlatformEventDispatcher* dispatcher);
// Removes a dispatcher from the dispatcher list. Dispatchers can safely be
// removed from the dispatcher list during an event is being dispatched,
// without affecting the dispatch of the event to other existing dispatchers.
void RemovePlatformEventDispatcher(PlatformEventDispatcher* dispatcher);
// Installs a PlatformEventDispatcher that receives all the events. The
// dispatcher can process the event, or request that the default dispatchers
// be invoked by setting |POST_DISPATCH_PERFORM_DEFAULT| flag from the
// |DispatchEvent()| override.
// The returned |ScopedEventDispatcher| object is a handler for the overridden
// dispatcher. When this handler is destroyed, it removes the overridden
// dispatcher, and restores the previous override-dispatcher (or NULL if there
// wasn't any).
scoped_ptr<ScopedEventDispatcher> OverrideDispatcher(
PlatformEventDispatcher* dispatcher);
// Called to indicate that the source should stop dispatching the current
// stream of events and wait until the next iteration of the message-loop to
// dispatch the rest of the events.
virtual void StopCurrentEventStream();
void AddPlatformEventObserver(PlatformEventObserver* observer);
void RemovePlatformEventObserver(PlatformEventObserver* observer);
static scoped_ptr<PlatformEventSource> CreateDefault();
protected:
PlatformEventSource();
// Dispatches |platform_event| to the dispatchers. If there is an override
// dispatcher installed using |OverrideDispatcher()|, then that dispatcher
// receives the event first. |POST_DISPATCH_QUIT_LOOP| flag is set in the
// returned value if the event-source should stop dispatching events at the
// current message-loop iteration.
virtual uint32_t DispatchEvent(PlatformEvent platform_event);
private:
friend class ScopedEventDispatcher;
friend class test::PlatformEventSourceTestAPI;
static PlatformEventSource* instance_;
// This is invoked when the list of dispatchers changes (i.e. a new dispatcher
// is added, or a dispatcher is removed).
virtual void OnDispatcherListChanged();
void OnOverriddenDispatcherRestored();
// Use an base::ObserverList<> instead of an std::vector<> to store the list
// of
// dispatchers, so that adding/removing dispatchers during an event dispatch
// is well-defined.
typedef base::ObserverList<PlatformEventDispatcher>
PlatformEventDispatcherList;
PlatformEventDispatcherList dispatchers_;
PlatformEventDispatcher* overridden_dispatcher_;
// Used to keep track of whether the current override-dispatcher has been
// reset and a previous override-dispatcher has been restored.
bool overridden_dispatcher_restored_;
base::ObserverList<PlatformEventObserver> observers_;
DISALLOW_COPY_AND_ASSIGN(PlatformEventSource);
};
} // namespace ui
#endif // UI_EVENTS_PLATFORM_PLATFORM_EVENT_SOURCE_H_
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