include/input/InputTransport.h - android_frameworks_native - Gitiles

 /*
  * Copyright (C) 2010 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef _LIBINPUT_INPUT_TRANSPORT_H
 #define _LIBINPUT_INPUT_TRANSPORT_H

 #pragma GCC system_header

 /**
  * Native input transport.
  *
  * The InputChannel provides a mechanism for exchanging InputMessage structures across processes.
  *
  * The InputPublisher and InputConsumer each handle one end-point of an input channel.
  * The InputPublisher is used by the input dispatcher to send events to the application.
  * The InputConsumer is used by the application to receive events from the input dispatcher.
  */

 #include <string>

 #include <android-base/chrono_utils.h>

 #include <binder/IBinder.h>
 #include <input/Input.h>
 #include <input/LatencyStatistics.h>
 #include <utils/BitSet.h>
 #include <utils/Errors.h>
 #include <utils/RefBase.h>
 #include <utils/Timers.h>
 #include <utils/Vector.h>

 #include <android-base/unique_fd.h>

 namespace android {
 class Parcel;

 /*
  * Intermediate representation used to send input events and related signals.
  *
  * Note that this structure is used for IPCs so its layout must be identical
  * on 64 and 32 bit processes. This is tested in StructLayout_test.cpp.
  *
  * Since the struct must be aligned to an 8-byte boundary, there could be uninitialized bytes
  * in-between the defined fields. This padding data should be explicitly accounted for by adding
  * "empty" fields into the struct. This data is memset to zero before sending the struct across
  * the socket. Adding the explicit fields ensures that the memset is not optimized away by the
  * compiler. When a new field is added to the struct, the corresponding change
  * in StructLayout_test should be made.
  */
 struct InputMessage {
     enum {
         TYPE_KEY = 1,
         TYPE_MOTION = 2,
         TYPE_FINISHED = 3,
     };

     struct Header {
         uint32_t type;
         // We don't need this field in order to align the body below but we
         // leave it here because InputMessage::size() and other functions
         // compute the size of this structure as sizeof(Header) + sizeof(Body).
         uint32_t padding;
     } header;

     // Body *must* be 8 byte aligned.
     union Body {
         struct Key {
             uint32_t seq;
             uint32_t empty1;
             nsecs_t eventTime __attribute__((aligned(8)));
             int32_t deviceId;
             int32_t source;
             int32_t displayId;
             int32_t action;
             int32_t flags;
             int32_t keyCode;
             int32_t scanCode;
             int32_t metaState;
             int32_t repeatCount;
             uint32_t empty2;
             nsecs_t downTime __attribute__((aligned(8)));

             inline size_t size() const {
                 return sizeof(Key);
             }
         } key;

         struct Motion {
             uint32_t seq;
             uint32_t empty1;
             nsecs_t eventTime __attribute__((aligned(8)));
             int32_t deviceId;
             int32_t source;
             int32_t displayId;
             int32_t action;
             int32_t actionButton;
             int32_t flags;
             int32_t metaState;
             int32_t buttonState;
             MotionClassification classification; // base type: uint8_t
             uint8_t empty2[3];
             int32_t edgeFlags;
             nsecs_t downTime __attribute__((aligned(8)));
             float xOffset;
             float yOffset;
             float xPrecision;
             float yPrecision;
             float xCursorPosition;
             float yCursorPosition;
             uint32_t pointerCount;
             uint32_t empty3;
             // Note that PointerCoords requires 8 byte alignment.
             struct Pointer {
                 PointerProperties properties;
                 PointerCoords coords;
             } pointers[MAX_POINTERS];

             int32_t getActionId() const {
                 uint32_t index = (action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK)
                         >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
                 return pointers[index].properties.id;
             }

             inline size_t size() const {
                 return sizeof(Motion) - sizeof(Pointer) * MAX_POINTERS
                         + sizeof(Pointer) * pointerCount;
             }
         } motion;

         struct Finished {
             uint32_t seq;
             bool handled;

             inline size_t size() const {
                 return sizeof(Finished);
             }
         } finished;
     } __attribute__((aligned(8))) body;

     bool isValid(size_t actualSize) const;
     size_t size() const;
     void getSanitizedCopy(InputMessage* msg) const;
 };

 /*
  * An input channel consists of a local unix domain socket used to send and receive
  * input messages across processes.  Each channel has a descriptive name for debugging purposes.
  *
  * Each endpoint has its own InputChannel object that specifies its file descriptor.
  *
  * The input channel is closed when all references to it are released.
  */
 class InputChannel : public RefBase {
 protected:
     virtual ~InputChannel();

 public:
     static sp<InputChannel> create(const std::string& name, android::base::unique_fd fd);

     /* Creates a pair of input channels.
      *
      * Returns OK on success.
      */
     static status_t openInputChannelPair(const std::string& name,
             sp<InputChannel>& outServerChannel, sp<InputChannel>& outClientChannel);

     inline std::string getName() const { return mName; }
     inline int getFd() const { return mFd.get(); }

     /* Sends a message to the other endpoint.
      *
      * If the channel is full then the message is guaranteed not to have been sent at all.
      * Try again after the consumer has sent a finished signal indicating that it has
      * consumed some of the pending messages from the channel.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if the channel is full.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Other errors probably indicate that the channel is broken.
      */
     status_t sendMessage(const InputMessage* msg);

     /* Receives a message sent by the other endpoint.
      *
      * If there is no message present, try again after poll() indicates that the fd
      * is readable.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if there is no message present.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Other errors probably indicate that the channel is broken.
      */
     status_t receiveMessage(InputMessage* msg);

     /* Returns a new object that has a duplicate of this channel's fd. */
     sp<InputChannel> dup() const;

     status_t write(Parcel& out) const;
     static sp<InputChannel> read(const Parcel& from);

     sp<IBinder> getToken() const;
     void setToken(const sp<IBinder>& token);

 private:
     InputChannel(const std::string& name, android::base::unique_fd fd);
     std::string mName;
     android::base::unique_fd mFd;

     sp<IBinder> mToken = nullptr;
 };

 /*
  * Publishes input events to an input channel.
  */
 class InputPublisher {
 public:
     /* Creates a publisher associated with an input channel. */
     explicit InputPublisher(const sp<InputChannel>& channel);

     /* Destroys the publisher and releases its input channel. */
     ~InputPublisher();

     /* Gets the underlying input channel. */
     inline sp<InputChannel> getChannel() { return mChannel; }

     /* Publishes a key event to the input channel.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if the channel is full.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Returns BAD_VALUE if seq is 0.
      * Other errors probably indicate that the channel is broken.
      */
     status_t publishKeyEvent(
             uint32_t seq,
             int32_t deviceId,
             int32_t source,
             int32_t displayId,
             int32_t action,
             int32_t flags,
             int32_t keyCode,
             int32_t scanCode,
             int32_t metaState,
             int32_t repeatCount,
             nsecs_t downTime,
             nsecs_t eventTime);

     /* Publishes a motion event to the input channel.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if the channel is full.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Returns BAD_VALUE if seq is 0 or if pointerCount is less than 1 or greater than MAX_POINTERS.
      * Other errors probably indicate that the channel is broken.
      */
     status_t publishMotionEvent(uint32_t seq, int32_t deviceId, int32_t source, int32_t displayId,
                                 int32_t action, int32_t actionButton, int32_t flags,
                                 int32_t edgeFlags, int32_t metaState, int32_t buttonState,
                                 MotionClassification classification, float xOffset, float yOffset,
                                 float xPrecision, float yPrecision, float xCursorPosition,
                                 float yCursorPosition, nsecs_t downTime, nsecs_t eventTime,
                                 uint32_t pointerCount, const PointerProperties* pointerProperties,
                                 const PointerCoords* pointerCoords);

     /* Receives the finished signal from the consumer in reply to the original dispatch signal.
      * If a signal was received, returns the message sequence number,
      * and whether the consumer handled the message.
      *
      * The returned sequence number is never 0 unless the operation failed.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if there is no signal present.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Other errors probably indicate that the channel is broken.
      */
     status_t receiveFinishedSignal(uint32_t* outSeq, bool* outHandled);

 private:
     static constexpr std::chrono::duration TOUCH_STATS_REPORT_PERIOD = 5min;

     sp<InputChannel> mChannel;
     LatencyStatistics mTouchStatistics{TOUCH_STATS_REPORT_PERIOD};

     void reportTouchEventForStatistics(nsecs_t evdevTime);
 };

 /*
  * Consumes input events from an input channel.
  */
 class InputConsumer {
 public:
     /* Creates a consumer associated with an input channel. */
     explicit InputConsumer(const sp<InputChannel>& channel);

     /* Destroys the consumer and releases its input channel. */
     ~InputConsumer();

     /* Gets the underlying input channel. */
     inline sp<InputChannel> getChannel() { return mChannel; }

     /* Consumes an input event from the input channel and copies its contents into
      * an InputEvent object created using the specified factory.
      *
      * Tries to combine a series of move events into larger batches whenever possible.
      *
      * If consumeBatches is false, then defers consuming pending batched events if it
      * is possible for additional samples to be added to them later.  Call hasPendingBatch()
      * to determine whether a pending batch is available to be consumed.
      *
      * If consumeBatches is true, then events are still batched but they are consumed
      * immediately as soon as the input channel is exhausted.
      *
      * The frameTime parameter specifies the time when the current display frame started
      * rendering in the CLOCK_MONOTONIC time base, or -1 if unknown.
      *
      * The returned sequence number is never 0 unless the operation failed.
      *
      * Returns OK on success.
      * Returns WOULD_BLOCK if there is no event present.
      * Returns DEAD_OBJECT if the channel's peer has been closed.
      * Returns NO_MEMORY if the event could not be created.
      * Other errors probably indicate that the channel is broken.
      */
     status_t consume(InputEventFactoryInterface* factory, bool consumeBatches,
             nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent);

     /* Sends a finished signal to the publisher to inform it that the message
      * with the specified sequence number has finished being process and whether
      * the message was handled by the consumer.
      *
      * Returns OK on success.
      * Returns BAD_VALUE if seq is 0.
      * Other errors probably indicate that the channel is broken.
      */
     status_t sendFinishedSignal(uint32_t seq, bool handled);

     /* Returns true if there is a deferred event waiting.
      *
      * Should be called after calling consume() to determine whether the consumer
      * has a deferred event to be processed.  Deferred events are somewhat special in
      * that they have already been removed from the input channel.  If the input channel
      * becomes empty, the client may need to do extra work to ensure that it processes
      * the deferred event despite the fact that the input channel's file descriptor
      * is not readable.
      *
      * One option is simply to call consume() in a loop until it returns WOULD_BLOCK.
      * This guarantees that all deferred events will be processed.
      *
      * Alternately, the caller can call hasDeferredEvent() to determine whether there is
      * a deferred event waiting and then ensure that its event loop wakes up at least
      * one more time to consume the deferred event.
      */
     bool hasDeferredEvent() const;

     /* Returns true if there is a pending batch.
      *
      * Should be called after calling consume() with consumeBatches == false to determine
      * whether consume() should be called again later on with consumeBatches == true.
      */
     bool hasPendingBatch() const;

 private:
     // True if touch resampling is enabled.
     const bool mResampleTouch;

     // The input channel.
     sp<InputChannel> mChannel;

     // The current input message.
     InputMessage mMsg;

     // True if mMsg contains a valid input message that was deferred from the previous
     // call to consume and that still needs to be handled.
     bool mMsgDeferred;

     // Batched motion events per device and source.
     struct Batch {
         Vector<InputMessage> samples;
     };
     Vector<Batch> mBatches;

     // Touch state per device and source, only for sources of class pointer.
     struct History {
         nsecs_t eventTime;
         BitSet32 idBits;
         int32_t idToIndex[MAX_POINTER_ID + 1];
         PointerCoords pointers[MAX_POINTERS];

         void initializeFrom(const InputMessage& msg) {
             eventTime = msg.body.motion.eventTime;
             idBits.clear();
             for (uint32_t i = 0; i < msg.body.motion.pointerCount; i++) {
                 uint32_t id = msg.body.motion.pointers[i].properties.id;
                 idBits.markBit(id);
                 idToIndex[id] = i;
                 pointers[i].copyFrom(msg.body.motion.pointers[i].coords);
             }
         }

         void initializeFrom(const History& other) {
             eventTime = other.eventTime;
             idBits = other.idBits; // temporary copy
             for (size_t i = 0; i < other.idBits.count(); i++) {
                 uint32_t id = idBits.clearFirstMarkedBit();
                 int32_t index = other.idToIndex[id];
                 idToIndex[id] = index;
                 pointers[index].copyFrom(other.pointers[index]);
             }
             idBits = other.idBits; // final copy
         }

         const PointerCoords& getPointerById(uint32_t id) const {
             return pointers[idToIndex[id]];
         }

         bool hasPointerId(uint32_t id) const {
             return idBits.hasBit(id);
         }
     };
     struct TouchState {
         int32_t deviceId;
         int32_t source;
         size_t historyCurrent;
         size_t historySize;
         History history[2];
         History lastResample;

         void initialize(int32_t deviceId, int32_t source) {
             this->deviceId = deviceId;
             this->source = source;
             historyCurrent = 0;
             historySize = 0;
             lastResample.eventTime = 0;
             lastResample.idBits.clear();
         }

         void addHistory(const InputMessage& msg) {
             historyCurrent ^= 1;
             if (historySize < 2) {
                 historySize += 1;
             }
             history[historyCurrent].initializeFrom(msg);
         }

         const History* getHistory(size_t index) const {
             return &history[(historyCurrent + index) & 1];
         }

         bool recentCoordinatesAreIdentical(uint32_t id) const {
             // Return true if the two most recently received "raw" coordinates are identical
             if (historySize < 2) {
                 return false;
             }
             if (!getHistory(0)->hasPointerId(id) || !getHistory(1)->hasPointerId(id)) {
                 return false;
             }
             float currentX = getHistory(0)->getPointerById(id).getX();
             float currentY = getHistory(0)->getPointerById(id).getY();
             float previousX = getHistory(1)->getPointerById(id).getX();
             float previousY = getHistory(1)->getPointerById(id).getY();
             if (currentX == previousX && currentY == previousY) {
                 return true;
             }
             return false;
         }
     };
     Vector<TouchState> mTouchStates;

     // Chain of batched sequence numbers.  When multiple input messages are combined into
     // a batch, we append a record here that associates the last sequence number in the
     // batch with the previous one.  When the finished signal is sent, we traverse the
     // chain to individually finish all input messages that were part of the batch.
     struct SeqChain {
         uint32_t seq;   // sequence number of batched input message
         uint32_t chain; // sequence number of previous batched input message
     };
     Vector<SeqChain> mSeqChains;

     status_t consumeBatch(InputEventFactoryInterface* factory,
             nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent);
     status_t consumeSamples(InputEventFactoryInterface* factory,
             Batch& batch, size_t count, uint32_t* outSeq, InputEvent** outEvent);

     void updateTouchState(InputMessage& msg);
     void resampleTouchState(nsecs_t frameTime, MotionEvent* event,
             const InputMessage *next);

     ssize_t findBatch(int32_t deviceId, int32_t source) const;
     ssize_t findTouchState(int32_t deviceId, int32_t source) const;

     status_t sendUnchainedFinishedSignal(uint32_t seq, bool handled);

     static void rewriteMessage(TouchState& state, InputMessage& msg);
     static void initializeKeyEvent(KeyEvent* event, const InputMessage* msg);
     static void initializeMotionEvent(MotionEvent* event, const InputMessage* msg);
     static void addSample(MotionEvent* event, const InputMessage* msg);
     static bool canAddSample(const Batch& batch, const InputMessage* msg);
     static ssize_t findSampleNoLaterThan(const Batch& batch, nsecs_t time);
     static bool shouldResampleTool(int32_t toolType);

     static bool isTouchResamplingEnabled();
 };

 } // namespace android

 #endif // _LIBINPUT_INPUT_TRANSPORT_H
	/*
	* Copyright (C) 2010 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef _LIBINPUT_INPUT_TRANSPORT_H
	#define _LIBINPUT_INPUT_TRANSPORT_H

	#pragma GCC system_header

	/**
	* Native input transport.
	*
	* The InputChannel provides a mechanism for exchanging InputMessage structures across processes.
	*
	* The InputPublisher and InputConsumer each handle one end-point of an input channel.
	* The InputPublisher is used by the input dispatcher to send events to the application.
	* The InputConsumer is used by the application to receive events from the input dispatcher.
	*/

	#include <string>

	#include <android-base/chrono_utils.h>

	#include <binder/IBinder.h>
	#include <input/Input.h>
	#include <input/LatencyStatistics.h>
	#include <utils/BitSet.h>
	#include <utils/Errors.h>
	#include <utils/RefBase.h>
	#include <utils/Timers.h>
	#include <utils/Vector.h>

	#include <android-base/unique_fd.h>

	namespace android {
	class Parcel;

	/*
	* Intermediate representation used to send input events and related signals.
	*
	* Note that this structure is used for IPCs so its layout must be identical
	* on 64 and 32 bit processes. This is tested in StructLayout_test.cpp.
	*
	* Since the struct must be aligned to an 8-byte boundary, there could be uninitialized bytes
	* in-between the defined fields. This padding data should be explicitly accounted for by adding
	* "empty" fields into the struct. This data is memset to zero before sending the struct across
	* the socket. Adding the explicit fields ensures that the memset is not optimized away by the
	* compiler. When a new field is added to the struct, the corresponding change
	* in StructLayout_test should be made.
	*/
	struct InputMessage {
	enum {
	TYPE_KEY = 1,
	TYPE_MOTION = 2,
	TYPE_FINISHED = 3,
	};

	struct Header {
	uint32_t type;
	// We don't need this field in order to align the body below but we
	// leave it here because InputMessage::size() and other functions
	// compute the size of this structure as sizeof(Header) + sizeof(Body).
	uint32_t padding;
	} header;

	// Body must be 8 byte aligned.
	union Body {
	struct Key {
	uint32_t seq;
	uint32_t empty1;
	nsecs_t eventTime __attribute__((aligned(8)));
	int32_t deviceId;
	int32_t source;
	int32_t displayId;
	int32_t action;
	int32_t flags;
	int32_t keyCode;
	int32_t scanCode;
	int32_t metaState;
	int32_t repeatCount;
	uint32_t empty2;
	nsecs_t downTime __attribute__((aligned(8)));

	inline size_t size() const {
	return sizeof(Key);
	}
	} key;

	struct Motion {
	uint32_t seq;
	uint32_t empty1;
	nsecs_t eventTime __attribute__((aligned(8)));
	int32_t deviceId;
	int32_t source;
	int32_t displayId;
	int32_t action;
	int32_t actionButton;
	int32_t flags;
	int32_t metaState;
	int32_t buttonState;
	MotionClassification classification; // base type: uint8_t
	uint8_t empty2[3];
	int32_t edgeFlags;
	nsecs_t downTime __attribute__((aligned(8)));
	float xOffset;
	float yOffset;
	float xPrecision;
	float yPrecision;
	float xCursorPosition;
	float yCursorPosition;
	uint32_t pointerCount;
	uint32_t empty3;
	// Note that PointerCoords requires 8 byte alignment.
	struct Pointer {
	PointerProperties properties;
	PointerCoords coords;
	} pointers[MAX_POINTERS];

	int32_t getActionId() const {
	uint32_t index = (action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK)
	>> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
	return pointers[index].properties.id;
	}

	inline size_t size() const {
	return sizeof(Motion) - sizeof(Pointer) * MAX_POINTERS
	+ sizeof(Pointer) * pointerCount;
	}
	} motion;

	struct Finished {
	uint32_t seq;
	bool handled;

	inline size_t size() const {
	return sizeof(Finished);
	}
	} finished;
	} __attribute__((aligned(8))) body;

	bool isValid(size_t actualSize) const;
	size_t size() const;
	void getSanitizedCopy(InputMessage* msg) const;
	};

	/*
	* An input channel consists of a local unix domain socket used to send and receive
	* input messages across processes. Each channel has a descriptive name for debugging purposes.
	*
	* Each endpoint has its own InputChannel object that specifies its file descriptor.
	*
	* The input channel is closed when all references to it are released.
	*/
	class InputChannel : public RefBase {
	protected:
	virtual ~InputChannel();

	public:
	static sp<InputChannel> create(const std::string& name, android::base::unique_fd fd);

	/* Creates a pair of input channels.
	*
	* Returns OK on success.
	*/
	static status_t openInputChannelPair(const std::string& name,
	sp<InputChannel>& outServerChannel, sp<InputChannel>& outClientChannel);

	inline std::string getName() const { return mName; }
	inline int getFd() const { return mFd.get(); }

	/* Sends a message to the other endpoint.
	*
	* If the channel is full then the message is guaranteed not to have been sent at all.
	* Try again after the consumer has sent a finished signal indicating that it has
	* consumed some of the pending messages from the channel.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if the channel is full.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t sendMessage(const InputMessage* msg);

	/* Receives a message sent by the other endpoint.
	*
	* If there is no message present, try again after poll() indicates that the fd
	* is readable.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if there is no message present.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t receiveMessage(InputMessage* msg);

	/* Returns a new object that has a duplicate of this channel's fd. */
	sp<InputChannel> dup() const;

	status_t write(Parcel& out) const;
	static sp<InputChannel> read(const Parcel& from);

	sp<IBinder> getToken() const;
	void setToken(const sp<IBinder>& token);

	private:
	InputChannel(const std::string& name, android::base::unique_fd fd);
	std::string mName;
	android::base::unique_fd mFd;

	sp<IBinder> mToken = nullptr;
	};

	/*
	* Publishes input events to an input channel.
	*/
	class InputPublisher {
	public:
	/* Creates a publisher associated with an input channel. */
	explicit InputPublisher(const sp<InputChannel>& channel);

	/* Destroys the publisher and releases its input channel. */
	~InputPublisher();

	/* Gets the underlying input channel. */
	inline sp<InputChannel> getChannel() { return mChannel; }

	/* Publishes a key event to the input channel.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if the channel is full.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Returns BAD_VALUE if seq is 0.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t publishKeyEvent(
	uint32_t seq,
	int32_t deviceId,
	int32_t source,
	int32_t displayId,
	int32_t action,
	int32_t flags,
	int32_t keyCode,
	int32_t scanCode,
	int32_t metaState,
	int32_t repeatCount,
	nsecs_t downTime,
	nsecs_t eventTime);

	/* Publishes a motion event to the input channel.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if the channel is full.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Returns BAD_VALUE if seq is 0 or if pointerCount is less than 1 or greater than MAX_POINTERS.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t publishMotionEvent(uint32_t seq, int32_t deviceId, int32_t source, int32_t displayId,
	int32_t action, int32_t actionButton, int32_t flags,
	int32_t edgeFlags, int32_t metaState, int32_t buttonState,
	MotionClassification classification, float xOffset, float yOffset,
	float xPrecision, float yPrecision, float xCursorPosition,
	float yCursorPosition, nsecs_t downTime, nsecs_t eventTime,
	uint32_t pointerCount, const PointerProperties* pointerProperties,
	const PointerCoords* pointerCoords);

	/* Receives the finished signal from the consumer in reply to the original dispatch signal.
	* If a signal was received, returns the message sequence number,
	* and whether the consumer handled the message.
	*
	* The returned sequence number is never 0 unless the operation failed.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if there is no signal present.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t receiveFinishedSignal(uint32_t* outSeq, bool* outHandled);

	private:
	static constexpr std::chrono::duration TOUCH_STATS_REPORT_PERIOD = 5min;

	sp<InputChannel> mChannel;
	LatencyStatistics mTouchStatistics{TOUCH_STATS_REPORT_PERIOD};

	void reportTouchEventForStatistics(nsecs_t evdevTime);
	};

	/*
	* Consumes input events from an input channel.
	*/
	class InputConsumer {
	public:
	/* Creates a consumer associated with an input channel. */
	explicit InputConsumer(const sp<InputChannel>& channel);

	/* Destroys the consumer and releases its input channel. */
	~InputConsumer();

	/* Gets the underlying input channel. */
	inline sp<InputChannel> getChannel() { return mChannel; }

	/* Consumes an input event from the input channel and copies its contents into
	* an InputEvent object created using the specified factory.
	*
	* Tries to combine a series of move events into larger batches whenever possible.
	*
	* If consumeBatches is false, then defers consuming pending batched events if it
	* is possible for additional samples to be added to them later. Call hasPendingBatch()
	* to determine whether a pending batch is available to be consumed.
	*
	* If consumeBatches is true, then events are still batched but they are consumed
	* immediately as soon as the input channel is exhausted.
	*
	* The frameTime parameter specifies the time when the current display frame started
	* rendering in the CLOCK_MONOTONIC time base, or -1 if unknown.
	*
	* The returned sequence number is never 0 unless the operation failed.
	*
	* Returns OK on success.
	* Returns WOULD_BLOCK if there is no event present.
	* Returns DEAD_OBJECT if the channel's peer has been closed.
	* Returns NO_MEMORY if the event could not be created.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t consume(InputEventFactoryInterface* factory, bool consumeBatches,
	nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent);

	/* Sends a finished signal to the publisher to inform it that the message
	* with the specified sequence number has finished being process and whether
	* the message was handled by the consumer.
	*
	* Returns OK on success.
	* Returns BAD_VALUE if seq is 0.
	* Other errors probably indicate that the channel is broken.
	*/
	status_t sendFinishedSignal(uint32_t seq, bool handled);

	/* Returns true if there is a deferred event waiting.
	*
	* Should be called after calling consume() to determine whether the consumer
	* has a deferred event to be processed. Deferred events are somewhat special in
	* that they have already been removed from the input channel. If the input channel
	* becomes empty, the client may need to do extra work to ensure that it processes
	* the deferred event despite the fact that the input channel's file descriptor
	* is not readable.
	*
	* One option is simply to call consume() in a loop until it returns WOULD_BLOCK.
	* This guarantees that all deferred events will be processed.
	*
	* Alternately, the caller can call hasDeferredEvent() to determine whether there is
	* a deferred event waiting and then ensure that its event loop wakes up at least
	* one more time to consume the deferred event.
	*/
	bool hasDeferredEvent() const;

	/* Returns true if there is a pending batch.
	*
	* Should be called after calling consume() with consumeBatches == false to determine
	* whether consume() should be called again later on with consumeBatches == true.
	*/
	bool hasPendingBatch() const;

	private:
	// True if touch resampling is enabled.
	const bool mResampleTouch;

	// The input channel.
	sp<InputChannel> mChannel;

	// The current input message.
	InputMessage mMsg;

	// True if mMsg contains a valid input message that was deferred from the previous
	// call to consume and that still needs to be handled.
	bool mMsgDeferred;

	// Batched motion events per device and source.
	struct Batch {
	Vector<InputMessage> samples;
	};
	Vector<Batch> mBatches;

	// Touch state per device and source, only for sources of class pointer.
	struct History {
	nsecs_t eventTime;
	BitSet32 idBits;
	int32_t idToIndex[MAX_POINTER_ID + 1];
	PointerCoords pointers[MAX_POINTERS];

	void initializeFrom(const InputMessage& msg) {
	eventTime = msg.body.motion.eventTime;
	idBits.clear();
	for (uint32_t i = 0; i < msg.body.motion.pointerCount; i++) {
	uint32_t id = msg.body.motion.pointers[i].properties.id;
	idBits.markBit(id);
	idToIndex[id] = i;
	pointers[i].copyFrom(msg.body.motion.pointers[i].coords);
	}
	}

	void initializeFrom(const History& other) {
	eventTime = other.eventTime;
	idBits = other.idBits; // temporary copy
	for (size_t i = 0; i < other.idBits.count(); i++) {
	uint32_t id = idBits.clearFirstMarkedBit();
	int32_t index = other.idToIndex[id];
	idToIndex[id] = index;
	pointers[index].copyFrom(other.pointers[index]);
	}
	idBits = other.idBits; // final copy
	}

	const PointerCoords& getPointerById(uint32_t id) const {
	return pointers[idToIndex[id]];
	}

	bool hasPointerId(uint32_t id) const {
	return idBits.hasBit(id);
	}
	};
	struct TouchState {
	int32_t deviceId;
	int32_t source;
	size_t historyCurrent;
	size_t historySize;
	History history[2];
	History lastResample;

	void initialize(int32_t deviceId, int32_t source) {
	this->deviceId = deviceId;
	this->source = source;
	historyCurrent = 0;
	historySize = 0;
	lastResample.eventTime = 0;
	lastResample.idBits.clear();
	}

	void addHistory(const InputMessage& msg) {
	historyCurrent ^= 1;
	if (historySize < 2) {
	historySize += 1;
	}
	history[historyCurrent].initializeFrom(msg);
	}

	const History* getHistory(size_t index) const {
	return &history[(historyCurrent + index) & 1];
	}

	bool recentCoordinatesAreIdentical(uint32_t id) const {
	// Return true if the two most recently received "raw" coordinates are identical
	if (historySize < 2) {
	return false;
	}
	if (!getHistory(0)->hasPointerId(id) \|\| !getHistory(1)->hasPointerId(id)) {
	return false;
	}
	float currentX = getHistory(0)->getPointerById(id).getX();
	float currentY = getHistory(0)->getPointerById(id).getY();
	float previousX = getHistory(1)->getPointerById(id).getX();
	float previousY = getHistory(1)->getPointerById(id).getY();
	if (currentX == previousX && currentY == previousY) {
	return true;
	}
	return false;
	}
	};
	Vector<TouchState> mTouchStates;

	// Chain of batched sequence numbers. When multiple input messages are combined into
	// a batch, we append a record here that associates the last sequence number in the
	// batch with the previous one. When the finished signal is sent, we traverse the
	// chain to individually finish all input messages that were part of the batch.
	struct SeqChain {
	uint32_t seq; // sequence number of batched input message
	uint32_t chain; // sequence number of previous batched input message
	};
	Vector<SeqChain> mSeqChains;

	status_t consumeBatch(InputEventFactoryInterface* factory,
	nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent);
	status_t consumeSamples(InputEventFactoryInterface* factory,
	Batch& batch, size_t count, uint32_t* outSeq, InputEvent** outEvent);

	void updateTouchState(InputMessage& msg);
	void resampleTouchState(nsecs_t frameTime, MotionEvent* event,
	const InputMessage *next);

	ssize_t findBatch(int32_t deviceId, int32_t source) const;
	ssize_t findTouchState(int32_t deviceId, int32_t source) const;

	status_t sendUnchainedFinishedSignal(uint32_t seq, bool handled);

	static void rewriteMessage(TouchState& state, InputMessage& msg);
	static void initializeKeyEvent(KeyEvent* event, const InputMessage* msg);
	static void initializeMotionEvent(MotionEvent* event, const InputMessage* msg);
	static void addSample(MotionEvent* event, const InputMessage* msg);
	static bool canAddSample(const Batch& batch, const InputMessage* msg);
	static ssize_t findSampleNoLaterThan(const Batch& batch, nsecs_t time);
	static bool shouldResampleTool(int32_t toolType);

	static bool isTouchResamplingEnabled();
	};

	} // namespace android

	#endif // _LIBINPUT_INPUT_TRANSPORT_H