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50 lines
2.0 KiB
C++
50 lines
2.0 KiB
C++
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef UI_EVENTS_EVENT_PROCESSOR_H_
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#define UI_EVENTS_EVENT_PROCESSOR_H_
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#include "ui/events/event_dispatcher.h"
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#include "ui/events/event_source.h"
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namespace ui {
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// EventProcessor receives an event from an EventSource and dispatches it to a
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// tree of EventTargets.
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class EVENTS_EXPORT EventProcessor : public EventDispatcherDelegate {
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public:
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~EventProcessor() override {}
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// Returns the root of the tree this event processor owns.
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virtual EventTarget* GetRootTarget() = 0;
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// Dispatches an event received from the EventSource to the tree of
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// EventTargets (whose root is returned by GetRootTarget()). The co-ordinate
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// space of the source must be the same as the root target, except that the
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// target may have a high-dpi scale applied.
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// TODO(tdanderson|sadrul): This is only virtual for testing purposes. It
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// should not be virtual at all.
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virtual EventDispatchDetails OnEventFromSource(Event* event)
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WARN_UNUSED_RESULT;
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protected:
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// Invoked at the start of processing, before an EventTargeter is used to
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// find the target of the event. If processing should not take place, marks
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// |event| as handled. Otherwise updates |event| so that the targeter can
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// operate correctly (e.g., it can be used to update the location of the
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// event when dispatching from an EventSource in high-DPI) and updates any
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// members in the event processor as necessary.
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virtual void OnEventProcessingStarted(Event* event);
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// Invoked when the processing of |event| has finished (i.e., when no further
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// dispatching of |event| will be performed by this EventProcessor). Note
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// that the last target to which |event| was dispatched may have been
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// destroyed.
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virtual void OnEventProcessingFinished(Event* event);
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};
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} // namespace ui
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#endif // UI_EVENTS_EVENT_PROCESSOR_H_
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