replicant-frameworks_native/libs/ui/InputTransport.cpp
Jeff Brown fa773aa745 Use touch pad gestures to manipulate the pointer.
1. Single finger tap performs a click.
2. Single finger movement moves the pointer (hovers).
3. Button press plus movement performs click or drag.
   While dragging, the pointer follows the finger that is moving
   fastest.  This is important if there are additional fingers
   down on the touch pad for the purpose of applying force
   to an integrated button underneath.
4. Two fingers near each other moving in the same direction
   are coalesced as a swipe gesture under the pointer.
5. Two or more fingers moving in arbitrary directions are
   transformed into touches in the vicinity of the pointer.
   This makes scale/zoom and rotate gestures possible.

Added a native VelocityTracker implementation to enable intelligent
switching of the active pointer during drags.

Change-Id: I5ada57e7f2bdb9b0a791843eb354a8c706b365dc
2011-03-14 14:12:03 -07:00

715 lines
24 KiB
C++

//
// Copyright 2010 The Android Open Source Project
//
// Provides a shared memory transport for input events.
//
#define LOG_TAG "InputTransport"
//#define LOG_NDEBUG 0
// Log debug messages about channel signalling (send signal, receive signal)
#define DEBUG_CHANNEL_SIGNALS 0
// Log debug messages whenever InputChannel objects are created/destroyed
#define DEBUG_CHANNEL_LIFECYCLE 0
// Log debug messages about transport actions (initialize, reset, publish, ...)
#define DEBUG_TRANSPORT_ACTIONS 0
#include <cutils/ashmem.h>
#include <cutils/log.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <ui/InputTransport.h>
#include <unistd.h>
namespace android {
// Must be at least sizeof(InputMessage) + sufficient space for pointer data
static const int DEFAULT_MESSAGE_BUFFER_SIZE = 16384;
// Signal sent by the producer to the consumer to inform it that a new message is
// available to be consumed in the shared memory buffer.
static const char INPUT_SIGNAL_DISPATCH = 'D';
// Signal sent by the consumer to the producer to inform it that it has finished
// consuming the most recent message and it handled it.
static const char INPUT_SIGNAL_FINISHED_HANDLED = 'f';
// Signal sent by the consumer to the producer to inform it that it has finished
// consuming the most recent message but it did not handle it.
static const char INPUT_SIGNAL_FINISHED_UNHANDLED = 'u';
// --- InputChannel ---
InputChannel::InputChannel(const String8& name, int32_t ashmemFd, int32_t receivePipeFd,
int32_t sendPipeFd) :
mName(name), mAshmemFd(ashmemFd), mReceivePipeFd(receivePipeFd), mSendPipeFd(sendPipeFd) {
#if DEBUG_CHANNEL_LIFECYCLE
LOGD("Input channel constructed: name='%s', ashmemFd=%d, receivePipeFd=%d, sendPipeFd=%d",
mName.string(), ashmemFd, receivePipeFd, sendPipeFd);
#endif
int result = fcntl(mReceivePipeFd, F_SETFL, O_NONBLOCK);
LOG_ALWAYS_FATAL_IF(result != 0, "channel '%s' ~ Could not make receive pipe "
"non-blocking. errno=%d", mName.string(), errno);
result = fcntl(mSendPipeFd, F_SETFL, O_NONBLOCK);
LOG_ALWAYS_FATAL_IF(result != 0, "channel '%s' ~ Could not make send pipe "
"non-blocking. errno=%d", mName.string(), errno);
}
InputChannel::~InputChannel() {
#if DEBUG_CHANNEL_LIFECYCLE
LOGD("Input channel destroyed: name='%s', ashmemFd=%d, receivePipeFd=%d, sendPipeFd=%d",
mName.string(), mAshmemFd, mReceivePipeFd, mSendPipeFd);
#endif
::close(mAshmemFd);
::close(mReceivePipeFd);
::close(mSendPipeFd);
}
status_t InputChannel::openInputChannelPair(const String8& name,
sp<InputChannel>& outServerChannel, sp<InputChannel>& outClientChannel) {
status_t result;
int serverAshmemFd = ashmem_create_region(name.string(), DEFAULT_MESSAGE_BUFFER_SIZE);
if (serverAshmemFd < 0) {
result = -errno;
LOGE("channel '%s' ~ Could not create shared memory region. errno=%d",
name.string(), errno);
} else {
result = ashmem_set_prot_region(serverAshmemFd, PROT_READ | PROT_WRITE);
if (result < 0) {
LOGE("channel '%s' ~ Error %d trying to set protection of ashmem fd %d.",
name.string(), result, serverAshmemFd);
} else {
// Dup the file descriptor because the server and client input channel objects that
// are returned may have different lifetimes but they share the same shared memory region.
int clientAshmemFd;
clientAshmemFd = dup(serverAshmemFd);
if (clientAshmemFd < 0) {
result = -errno;
LOGE("channel '%s' ~ Could not dup() shared memory region fd. errno=%d",
name.string(), errno);
} else {
int forward[2];
if (pipe(forward)) {
result = -errno;
LOGE("channel '%s' ~ Could not create forward pipe. errno=%d",
name.string(), errno);
} else {
int reverse[2];
if (pipe(reverse)) {
result = -errno;
LOGE("channel '%s' ~ Could not create reverse pipe. errno=%d",
name.string(), errno);
} else {
String8 serverChannelName = name;
serverChannelName.append(" (server)");
outServerChannel = new InputChannel(serverChannelName,
serverAshmemFd, reverse[0], forward[1]);
String8 clientChannelName = name;
clientChannelName.append(" (client)");
outClientChannel = new InputChannel(clientChannelName,
clientAshmemFd, forward[0], reverse[1]);
return OK;
}
::close(forward[0]);
::close(forward[1]);
}
::close(clientAshmemFd);
}
}
::close(serverAshmemFd);
}
outServerChannel.clear();
outClientChannel.clear();
return result;
}
status_t InputChannel::sendSignal(char signal) {
ssize_t nWrite;
do {
nWrite = ::write(mSendPipeFd, & signal, 1);
} while (nWrite == -1 && errno == EINTR);
if (nWrite == 1) {
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ sent signal '%c'", mName.string(), signal);
#endif
return OK;
}
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ error sending signal '%c', errno=%d", mName.string(), signal, errno);
#endif
return -errno;
}
status_t InputChannel::receiveSignal(char* outSignal) {
ssize_t nRead;
do {
nRead = ::read(mReceivePipeFd, outSignal, 1);
} while (nRead == -1 && errno == EINTR);
if (nRead == 1) {
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ received signal '%c'", mName.string(), *outSignal);
#endif
return OK;
}
if (nRead == 0) { // check for EOF
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ receive signal failed because peer was closed", mName.string());
#endif
return DEAD_OBJECT;
}
if (errno == EAGAIN) {
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ receive signal failed because no signal available", mName.string());
#endif
return WOULD_BLOCK;
}
#if DEBUG_CHANNEL_SIGNALS
LOGD("channel '%s' ~ receive signal failed, errno=%d", mName.string(), errno);
#endif
return -errno;
}
// --- InputPublisher ---
InputPublisher::InputPublisher(const sp<InputChannel>& channel) :
mChannel(channel), mSharedMessage(NULL),
mPinned(false), mSemaphoreInitialized(false), mWasDispatched(false),
mMotionEventSampleDataTail(NULL) {
}
InputPublisher::~InputPublisher() {
reset();
if (mSharedMessage) {
munmap(mSharedMessage, mAshmemSize);
}
}
status_t InputPublisher::initialize() {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ initialize",
mChannel->getName().string());
#endif
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_get_size_region(ashmemFd);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d getting size of ashmem fd %d.",
mChannel->getName().string(), result, ashmemFd);
return UNKNOWN_ERROR;
}
mAshmemSize = (size_t) result;
mSharedMessage = static_cast<InputMessage*>(mmap(NULL, mAshmemSize,
PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0));
if (! mSharedMessage) {
LOGE("channel '%s' publisher ~ mmap failed on ashmem fd %d.",
mChannel->getName().string(), ashmemFd);
return NO_MEMORY;
}
mPinned = true;
mSharedMessage->consumed = false;
return reset();
}
status_t InputPublisher::reset() {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ reset",
mChannel->getName().string());
#endif
if (mPinned) {
// Destroy the semaphore since we are about to unpin the memory region that contains it.
int result;
if (mSemaphoreInitialized) {
if (mSharedMessage->consumed) {
result = sem_post(& mSharedMessage->semaphore);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d in sem_post.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
}
result = sem_destroy(& mSharedMessage->semaphore);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d in sem_destroy.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
mSemaphoreInitialized = false;
}
// Unpin the region since we no longer care about its contents.
int ashmemFd = mChannel->getAshmemFd();
result = ashmem_unpin_region(ashmemFd, 0, 0);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d unpinning ashmem fd %d.",
mChannel->getName().string(), result, ashmemFd);
return UNKNOWN_ERROR;
}
mPinned = false;
}
mMotionEventSampleDataTail = NULL;
mWasDispatched = false;
return OK;
}
status_t InputPublisher::publishInputEvent(
int32_t type,
int32_t deviceId,
int32_t source) {
if (mPinned) {
LOGE("channel '%s' publisher ~ Attempted to publish a new event but publisher has "
"not yet been reset.", mChannel->getName().string());
return INVALID_OPERATION;
}
// Pin the region.
// We do not check for ASHMEM_NOT_PURGED because we don't care about the previous
// contents of the buffer so it does not matter whether it was purged in the meantime.
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_pin_region(ashmemFd, 0, 0);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d pinning ashmem fd %d.",
mChannel->getName().string(), result, ashmemFd);
return UNKNOWN_ERROR;
}
mPinned = true;
result = sem_init(& mSharedMessage->semaphore, 1, 1);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d in sem_init.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
mSemaphoreInitialized = true;
mSharedMessage->consumed = false;
mSharedMessage->type = type;
mSharedMessage->deviceId = deviceId;
mSharedMessage->source = source;
return OK;
}
status_t InputPublisher::publishKeyEvent(
int32_t deviceId,
int32_t source,
int32_t action,
int32_t flags,
int32_t keyCode,
int32_t scanCode,
int32_t metaState,
int32_t repeatCount,
nsecs_t downTime,
nsecs_t eventTime) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ publishKeyEvent: deviceId=%d, source=0x%x, "
"action=0x%x, flags=0x%x, keyCode=%d, scanCode=%d, metaState=0x%x, repeatCount=%d,"
"downTime=%lld, eventTime=%lld",
mChannel->getName().string(),
deviceId, source, action, flags, keyCode, scanCode, metaState, repeatCount,
downTime, eventTime);
#endif
status_t result = publishInputEvent(AINPUT_EVENT_TYPE_KEY, deviceId, source);
if (result < 0) {
return result;
}
mSharedMessage->key.action = action;
mSharedMessage->key.flags = flags;
mSharedMessage->key.keyCode = keyCode;
mSharedMessage->key.scanCode = scanCode;
mSharedMessage->key.metaState = metaState;
mSharedMessage->key.repeatCount = repeatCount;
mSharedMessage->key.downTime = downTime;
mSharedMessage->key.eventTime = eventTime;
return OK;
}
status_t InputPublisher::publishMotionEvent(
int32_t deviceId,
int32_t source,
int32_t action,
int32_t flags,
int32_t edgeFlags,
int32_t metaState,
float xOffset,
float yOffset,
float xPrecision,
float yPrecision,
nsecs_t downTime,
nsecs_t eventTime,
size_t pointerCount,
const int32_t* pointerIds,
const PointerCoords* pointerCoords) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ publishMotionEvent: deviceId=%d, source=0x%x, "
"action=0x%x, flags=0x%x, edgeFlags=0x%x, metaState=0x%x, xOffset=%f, yOffset=%f, "
"xPrecision=%f, yPrecision=%f, downTime=%lld, eventTime=%lld, "
"pointerCount=%d",
mChannel->getName().string(),
deviceId, source, action, flags, edgeFlags, metaState, xOffset, yOffset,
xPrecision, yPrecision, downTime, eventTime, pointerCount);
#endif
if (pointerCount > MAX_POINTERS || pointerCount < 1) {
LOGE("channel '%s' publisher ~ Invalid number of pointers provided: %d.",
mChannel->getName().string(), pointerCount);
return BAD_VALUE;
}
status_t result = publishInputEvent(AINPUT_EVENT_TYPE_MOTION, deviceId, source);
if (result < 0) {
return result;
}
mSharedMessage->motion.action = action;
mSharedMessage->motion.flags = flags;
mSharedMessage->motion.edgeFlags = edgeFlags;
mSharedMessage->motion.metaState = metaState;
mSharedMessage->motion.xOffset = xOffset;
mSharedMessage->motion.yOffset = yOffset;
mSharedMessage->motion.xPrecision = xPrecision;
mSharedMessage->motion.yPrecision = yPrecision;
mSharedMessage->motion.downTime = downTime;
mSharedMessage->motion.pointerCount = pointerCount;
mSharedMessage->motion.sampleCount = 1;
mSharedMessage->motion.sampleData[0].eventTime = eventTime;
for (size_t i = 0; i < pointerCount; i++) {
mSharedMessage->motion.pointerIds[i] = pointerIds[i];
mSharedMessage->motion.sampleData[0].coords[i].copyFrom(pointerCoords[i]);
}
// Cache essential information about the motion event to ensure that a malicious consumer
// cannot confuse the publisher by modifying the contents of the shared memory buffer while
// it is being updated.
if (action == AMOTION_EVENT_ACTION_MOVE
|| action == AMOTION_EVENT_ACTION_HOVER_MOVE) {
mMotionEventPointerCount = pointerCount;
mMotionEventSampleDataStride = InputMessage::sampleDataStride(pointerCount);
mMotionEventSampleDataTail = InputMessage::sampleDataPtrIncrement(
mSharedMessage->motion.sampleData, mMotionEventSampleDataStride);
} else {
mMotionEventSampleDataTail = NULL;
}
return OK;
}
status_t InputPublisher::appendMotionSample(
nsecs_t eventTime,
const PointerCoords* pointerCoords) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ appendMotionSample: eventTime=%lld",
mChannel->getName().string(), eventTime);
#endif
if (! mPinned || ! mMotionEventSampleDataTail) {
LOGE("channel '%s' publisher ~ Cannot append motion sample because there is no current "
"AMOTION_EVENT_ACTION_MOVE event.", mChannel->getName().string());
return INVALID_OPERATION;
}
InputMessage::SampleData* newTail = InputMessage::sampleDataPtrIncrement(
mMotionEventSampleDataTail, mMotionEventSampleDataStride);
size_t newBytesUsed = reinterpret_cast<char*>(newTail) -
reinterpret_cast<char*>(mSharedMessage);
if (newBytesUsed > mAshmemSize) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ Cannot append motion sample because the shared memory "
"buffer is full. Buffer size: %d bytes, pointers: %d, samples: %d",
mChannel->getName().string(),
mAshmemSize, mMotionEventPointerCount, mSharedMessage->motion.sampleCount);
#endif
return NO_MEMORY;
}
int result;
if (mWasDispatched) {
result = sem_trywait(& mSharedMessage->semaphore);
if (result < 0) {
if (errno == EAGAIN) {
// Only possible source of contention is the consumer having consumed (or being in the
// process of consuming) the message and left the semaphore count at 0.
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ Cannot append motion sample because the message has "
"already been consumed.", mChannel->getName().string());
#endif
return FAILED_TRANSACTION;
} else {
LOGE("channel '%s' publisher ~ Error %d in sem_trywait.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
}
}
mMotionEventSampleDataTail->eventTime = eventTime;
for (size_t i = 0; i < mMotionEventPointerCount; i++) {
mMotionEventSampleDataTail->coords[i].copyFrom(pointerCoords[i]);
}
mMotionEventSampleDataTail = newTail;
mSharedMessage->motion.sampleCount += 1;
if (mWasDispatched) {
result = sem_post(& mSharedMessage->semaphore);
if (result < 0) {
LOGE("channel '%s' publisher ~ Error %d in sem_post.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
}
return OK;
}
status_t InputPublisher::sendDispatchSignal() {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ sendDispatchSignal",
mChannel->getName().string());
#endif
mWasDispatched = true;
return mChannel->sendSignal(INPUT_SIGNAL_DISPATCH);
}
status_t InputPublisher::receiveFinishedSignal(bool* outHandled) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' publisher ~ receiveFinishedSignal",
mChannel->getName().string());
#endif
char signal;
status_t result = mChannel->receiveSignal(& signal);
if (result) {
*outHandled = false;
return result;
}
if (signal == INPUT_SIGNAL_FINISHED_HANDLED) {
*outHandled = true;
} else if (signal == INPUT_SIGNAL_FINISHED_UNHANDLED) {
*outHandled = false;
} else {
LOGE("channel '%s' publisher ~ Received unexpected signal '%c' from consumer",
mChannel->getName().string(), signal);
return UNKNOWN_ERROR;
}
return OK;
}
// --- InputConsumer ---
InputConsumer::InputConsumer(const sp<InputChannel>& channel) :
mChannel(channel), mSharedMessage(NULL) {
}
InputConsumer::~InputConsumer() {
if (mSharedMessage) {
munmap(mSharedMessage, mAshmemSize);
}
}
status_t InputConsumer::initialize() {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' consumer ~ initialize",
mChannel->getName().string());
#endif
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_get_size_region(ashmemFd);
if (result < 0) {
LOGE("channel '%s' consumer ~ Error %d getting size of ashmem fd %d.",
mChannel->getName().string(), result, ashmemFd);
return UNKNOWN_ERROR;
}
mAshmemSize = (size_t) result;
mSharedMessage = static_cast<InputMessage*>(mmap(NULL, mAshmemSize,
PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0));
if (! mSharedMessage) {
LOGE("channel '%s' consumer ~ mmap failed on ashmem fd %d.",
mChannel->getName().string(), ashmemFd);
return NO_MEMORY;
}
return OK;
}
status_t InputConsumer::consume(InputEventFactoryInterface* factory, InputEvent** outEvent) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' consumer ~ consume",
mChannel->getName().string());
#endif
*outEvent = NULL;
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_pin_region(ashmemFd, 0, 0);
if (result != ASHMEM_NOT_PURGED) {
if (result == ASHMEM_WAS_PURGED) {
LOGE("channel '%s' consumer ~ Error %d pinning ashmem fd %d because it was purged "
"which probably indicates that the publisher and consumer are out of sync.",
mChannel->getName().string(), result, ashmemFd);
return INVALID_OPERATION;
}
LOGE("channel '%s' consumer ~ Error %d pinning ashmem fd %d.",
mChannel->getName().string(), result, ashmemFd);
return UNKNOWN_ERROR;
}
if (mSharedMessage->consumed) {
LOGE("channel '%s' consumer ~ The current message has already been consumed.",
mChannel->getName().string());
return INVALID_OPERATION;
}
// Acquire but *never release* the semaphore. Contention on the semaphore is used to signal
// to the publisher that the message has been consumed (or is in the process of being
// consumed). Eventually the publisher will reinitialize the semaphore for the next message.
result = sem_wait(& mSharedMessage->semaphore);
if (result < 0) {
LOGE("channel '%s' consumer ~ Error %d in sem_wait.",
mChannel->getName().string(), errno);
return UNKNOWN_ERROR;
}
mSharedMessage->consumed = true;
switch (mSharedMessage->type) {
case AINPUT_EVENT_TYPE_KEY: {
KeyEvent* keyEvent = factory->createKeyEvent();
if (! keyEvent) return NO_MEMORY;
populateKeyEvent(keyEvent);
*outEvent = keyEvent;
break;
}
case AINPUT_EVENT_TYPE_MOTION: {
MotionEvent* motionEvent = factory->createMotionEvent();
if (! motionEvent) return NO_MEMORY;
populateMotionEvent(motionEvent);
*outEvent = motionEvent;
break;
}
default:
LOGE("channel '%s' consumer ~ Received message of unknown type %d",
mChannel->getName().string(), mSharedMessage->type);
return UNKNOWN_ERROR;
}
return OK;
}
status_t InputConsumer::sendFinishedSignal(bool handled) {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' consumer ~ sendFinishedSignal: handled=%d",
mChannel->getName().string(), handled);
#endif
return mChannel->sendSignal(handled
? INPUT_SIGNAL_FINISHED_HANDLED
: INPUT_SIGNAL_FINISHED_UNHANDLED);
}
status_t InputConsumer::receiveDispatchSignal() {
#if DEBUG_TRANSPORT_ACTIONS
LOGD("channel '%s' consumer ~ receiveDispatchSignal",
mChannel->getName().string());
#endif
char signal;
status_t result = mChannel->receiveSignal(& signal);
if (result) {
return result;
}
if (signal != INPUT_SIGNAL_DISPATCH) {
LOGE("channel '%s' consumer ~ Received unexpected signal '%c' from publisher",
mChannel->getName().string(), signal);
return UNKNOWN_ERROR;
}
return OK;
}
void InputConsumer::populateKeyEvent(KeyEvent* keyEvent) const {
keyEvent->initialize(
mSharedMessage->deviceId,
mSharedMessage->source,
mSharedMessage->key.action,
mSharedMessage->key.flags,
mSharedMessage->key.keyCode,
mSharedMessage->key.scanCode,
mSharedMessage->key.metaState,
mSharedMessage->key.repeatCount,
mSharedMessage->key.downTime,
mSharedMessage->key.eventTime);
}
void InputConsumer::populateMotionEvent(MotionEvent* motionEvent) const {
motionEvent->initialize(
mSharedMessage->deviceId,
mSharedMessage->source,
mSharedMessage->motion.action,
mSharedMessage->motion.flags,
mSharedMessage->motion.edgeFlags,
mSharedMessage->motion.metaState,
mSharedMessage->motion.xOffset,
mSharedMessage->motion.yOffset,
mSharedMessage->motion.xPrecision,
mSharedMessage->motion.yPrecision,
mSharedMessage->motion.downTime,
mSharedMessage->motion.sampleData[0].eventTime,
mSharedMessage->motion.pointerCount,
mSharedMessage->motion.pointerIds,
mSharedMessage->motion.sampleData[0].coords);
size_t sampleCount = mSharedMessage->motion.sampleCount;
if (sampleCount > 1) {
InputMessage::SampleData* sampleData = mSharedMessage->motion.sampleData;
size_t sampleDataStride = InputMessage::sampleDataStride(
mSharedMessage->motion.pointerCount);
while (--sampleCount > 0) {
sampleData = InputMessage::sampleDataPtrIncrement(sampleData, sampleDataStride);
motionEvent->addSample(sampleData->eventTime, sampleData->coords);
}
}
}
} // namespace android