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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 CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_
#define CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "content/common/content_export.h"
#include "content/common/input/input_event_disposition.h"
namespace content {
class BrowserInputEvent;
class EventPacketAck;
class InputQueueClient;
// |InputQueue| handles browser input event batching and response.
// Event packets are assembled into sequential event packets. A flush entails
// delivery and dispatch of a single event packet, and continues until the
// packet is ack'ed and all its events have been dispatched to the renderer.
class CONTENT_EXPORT InputQueue {
public:
// The |client| should outlive the InputQueue.
InputQueue(InputQueueClient* client);
virtual ~InputQueue();
// If a flush is in progress, |event| will be dispatched in the next flush.
// If no flush is in progress, a flush will be requested if necessary.
// |event| is assumed to be both non-NULL and valid.
void QueueEvent(scoped_ptr<BrowserInputEvent> event);
// Initiates the flush of the pending event packet to |client_|, if necessary.
// This should only be called in response to |client_->SetNeedsFlush()|.
void BeginFlush();
// Called by the owner upon EventPacket responses from the sender target. This
// will dispatch event acks for events with a corresponding |ack_handler|.
enum AckResult {
ACK_OK, // |acked_packet| was processed successfully.
ACK_UNEXPECTED, // |acked_packet| was unexpected; no flush was in-progress.
ACK_INVALID, // |acked_packet| contains invalid data.
ACK_SHUTDOWN // |acked_packet| processing triggered queue shutdown.
};
AckResult OnEventPacketAck(int64 packet_id,
const InputEventDispositions& dispositions);
// Total number of evenst in the queue, both being flushed and pending flush.
size_t QueuedEventCount() const;
protected:
friend class InputQueueTest;
// Delivers |in_flush_packet_| to the client.
void DeliverInFlushPacket();
// Requests a flush via |client_| if the necessary request has not been made.
void RequestFlushIfNecessary();
// True when |in_flush_packet_| is non-empty.
bool FlushInProgress() const;
private:
InputQueueClient* client_;
// Used to assign unique, non-zero ID's to each delivered EventPacket.
int64 next_packet_id_;
// Avoid spamming the client with redundant flush requests.
bool flush_requested_;
class BrowserEventPacket;
scoped_ptr<BrowserEventPacket> in_flush_packet_;
scoped_ptr<BrowserEventPacket> pending_flush_packet_;
DISALLOW_COPY_AND_ASSIGN(InputQueue);
};
} // namespace content
#endif // CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_
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