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// Copyright 2013 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_PROCESSOR_H_
#define UI_EVENTS_EVENT_PROCESSOR_H_
#include "base/memory/weak_ptr.h"
#include "ui/events/event_dispatcher.h"
#include "ui/events/event_sink.h"
#include "ui/events/event_source.h"
namespace ui {
class EventTargeter;
// EventProcessor inherits EventSink to receive an event from an EventSource
// and dispatches it to a tree of EventTargets.
class EVENTS_EXPORT EventProcessor : public EventDispatcherDelegate,
public EventSink {
public:
EventProcessor();
~EventProcessor() override;
// EventSink overrides:
EventDispatchDetails OnEventFromSource(Event* event) override;
// Returns the initial target for the event. A value of null means use the
// root and default targeter to find the target. This pass may process the
// event.
virtual EventTarget* GetInitialEventTarget(Event* event) = 0;
// Returns the EventTarget with the right EventTargeter that we should use for
// dispatching this |event|.
virtual EventTarget* GetRootForEvent(Event* event) = 0;
// If the root target returned by GetRootForEvent() does not have a
// targeter set, then the default targeter is used to find the target.
virtual EventTargeter* GetDefaultEventTargeter() = 0;
protected:
// Invoked at the start of processing, before an EventTargeter is used to
// find the target of the event. If processing should not take place, marks
// |event| as handled. Otherwise updates |event| so that the targeter can
// operate correctly (e.g., it can be used to update the location of the
// event when dispatching from an EventSource in high-DPI) and updates any
// members in the event processor as necessary.
virtual void OnEventProcessingStarted(Event* event);
// Invoked when the processing of |event| has finished (i.e., when no further
// dispatching of |event| will be performed by this EventProcessor). Note
// that the last target to which |event| was dispatched may have been
// destroyed.
virtual void OnEventProcessingFinished(Event* event);
private:
base::WeakPtrFactory<EventProcessor> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(EventProcessor);
};
} // namespace ui
#endif // UI_EVENTS_EVENT_PROCESSOR_H_
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