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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 "ui/events/event_dispatcher.h"
#include "ui/events/event_source.h"
namespace ui {
// EventProcessor receives an event from an EventSource and dispatches it to a
// tree of EventTargets.
class EVENTS_EXPORT EventProcessor : public EventDispatcherDelegate {
public:
~EventProcessor() override {}
// Returns the root of the tree this event processor owns.
virtual EventTarget* GetRootTarget() = 0;
// Dispatches an event received from the EventSource to the tree of
// EventTargets (whose root is returned by GetRootTarget()). The co-ordinate
// space of the source must be the same as the root target, except that the
// target may have a high-dpi scale applied.
// TODO(tdanderson|sadrul): This is only virtual for testing purposes. It
// should not be virtual at all.
virtual EventDispatchDetails OnEventFromSource(Event* event)
WARN_UNUSED_RESULT;
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);
};
} // namespace ui
#endif // UI_EVENTS_EVENT_PROCESSOR_H_
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