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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_EVENT_REWRITER_H_
#define UI_EVENTS_EVENT_REWRITER_H_
#include "base/memory/scoped_ptr.h"
#include "ui/events/events_export.h"
namespace ui {
class Event;
// Return status of EventRewriter operations; see that class below.
enum EventRewriteStatus {
// Nothing was done; no rewritten event returned. Pass the original
// event to later rewriters, or send it to the EventProcessor if this
// was the final rewriter.
EVENT_REWRITE_CONTINUE,
// The event has been rewritten. Send the rewritten event to the
// EventProcessor instead of the original event (without sending
// either to any later rewriters).
EVENT_REWRITE_REWRITTEN,
// The event should be discarded, neither passing it to any later
// rewriters nor sending it to the EventProcessor.
EVENT_REWRITE_DISCARD,
// The event has been rewritten. As for EVENT_REWRITE_REWRITTEN,
// send the rewritten event to the EventProcessor instead of the
// original event (without sending either to any later rewriters).
// In addition the rewriter has one or more additional new events
// to be retrieved using |NextDispatchEvent()| and sent to the
// EventProcessor.
EVENT_REWRITE_DISPATCH_ANOTHER,
};
// EventRewriter provides a mechanism for Events to be rewritten
// before being dispatched from EventSource to EventProcessor.
class EVENTS_EXPORT EventRewriter {
public:
virtual ~EventRewriter() {}
// Potentially rewrites (replaces) an event, or requests it be discarded.
// or discards an event. If the rewriter wants to rewrite an event, and
// dispatch another event once the rewritten event is dispatched, it should
// return EVENT_REWRITE_DISPATCH_ANOTHER, and return the next event to
// dispatch from |NextDispatchEvent()|.
virtual EventRewriteStatus RewriteEvent(
const Event& event,
scoped_ptr<Event>* rewritten_event) = 0;
// Supplies an additional event to be dispatched. It is only valid to
// call this after the immediately previous call to |RewriteEvent()|
// or |NextDispatchEvent()| has returned EVENT_REWRITE_DISPATCH_ANOTHER.
// Should only return either EVENT_REWRITE_REWRITTEN or
// EVENT_REWRITE_DISPATCH_ANOTHER; otherwise the previous call should not
// have returned EVENT_REWRITE_DISPATCH_ANOTHER.
virtual EventRewriteStatus NextDispatchEvent(
const Event& last_event,
scoped_ptr<Event>* new_event) = 0;
};
} // namespace ui
#endif // UI_EVENTS_EVENT_REWRITER_H_
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