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replicant-frameworks_native/libs/ui/Input.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

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//
// Copyright 2010 The Android Open Source Project
//
// Provides a pipe-based transport for native events in the NDK.
//
#define LOG_TAG "Input"
//#define LOG_NDEBUG 0
// Log debug messages about keymap probing.
#define DEBUG_PROBE 0
// Log debug messages about velocity tracking.
#define DEBUG_VELOCITY 0
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <ui/Input.h>
#include <math.h>
#ifdef HAVE_ANDROID_OS
#include <binder/Parcel.h>
#include "SkPoint.h"
#include "SkMatrix.h"
#include "SkScalar.h"
#endif
namespace android {
static const char* CONFIGURATION_FILE_DIR[] = {
"idc/",
"keylayout/",
"keychars/",
};
static const char* CONFIGURATION_FILE_EXTENSION[] = {
".idc",
".kl",
".kcm",
};
static bool isValidNameChar(char ch) {
return isascii(ch) && (isdigit(ch) || isalpha(ch) || ch == '-' || ch == '_');
}
static void appendInputDeviceConfigurationFileRelativePath(String8& path,
const String8& name, InputDeviceConfigurationFileType type) {
path.append(CONFIGURATION_FILE_DIR[type]);
for (size_t i = 0; i < name.length(); i++) {
char ch = name[i];
if (!isValidNameChar(ch)) {
ch = '_';
}
path.append(&ch, 1);
}
path.append(CONFIGURATION_FILE_EXTENSION[type]);
}
String8 getInputDeviceConfigurationFilePathByDeviceIdentifier(
const InputDeviceIdentifier& deviceIdentifier,
InputDeviceConfigurationFileType type) {
if (deviceIdentifier.vendor !=0 && deviceIdentifier.product != 0) {
if (deviceIdentifier.version != 0) {
// Try vendor product version.
String8 versionPath(getInputDeviceConfigurationFilePathByName(
String8::format("Vendor_%04x_Product_%04x_Version_%04x",
deviceIdentifier.vendor, deviceIdentifier.product,
deviceIdentifier.version),
type));
if (!versionPath.isEmpty()) {
return versionPath;
}
}
// Try vendor product.
String8 productPath(getInputDeviceConfigurationFilePathByName(
String8::format("Vendor_%04x_Product_%04x",
deviceIdentifier.vendor, deviceIdentifier.product),
type));
if (!productPath.isEmpty()) {
return productPath;
}
}
// Try device name.
return getInputDeviceConfigurationFilePathByName(deviceIdentifier.name, type);
}
String8 getInputDeviceConfigurationFilePathByName(
const String8& name, InputDeviceConfigurationFileType type) {
// Search system repository.
String8 path;
path.setTo(getenv("ANDROID_ROOT"));
path.append("/usr/");
appendInputDeviceConfigurationFileRelativePath(path, name, type);
#if DEBUG_PROBE
LOGD("Probing for system provided input device configuration file: path='%s'", path.string());
#endif
if (!access(path.string(), R_OK)) {
#if DEBUG_PROBE
LOGD("Found");
#endif
return path;
}
// Search user repository.
// TODO Should only look here if not in safe mode.
path.setTo(getenv("ANDROID_DATA"));
path.append("/system/devices/");
appendInputDeviceConfigurationFileRelativePath(path, name, type);
#if DEBUG_PROBE
LOGD("Probing for system user input device configuration file: path='%s'", path.string());
#endif
if (!access(path.string(), R_OK)) {
#if DEBUG_PROBE
LOGD("Found");
#endif
return path;
}
// Not found.
#if DEBUG_PROBE
LOGD("Probe failed to find input device configuration file: name='%s', type=%d",
name.string(), type);
#endif
return String8();
}
// --- InputEvent ---
void InputEvent::initialize(int32_t deviceId, int32_t source) {
mDeviceId = deviceId;
mSource = source;
}
void InputEvent::initialize(const InputEvent& from) {
mDeviceId = from.mDeviceId;
mSource = from.mSource;
}
// --- KeyEvent ---
bool KeyEvent::hasDefaultAction(int32_t keyCode) {
switch (keyCode) {
case AKEYCODE_HOME:
case AKEYCODE_BACK:
case AKEYCODE_CALL:
case AKEYCODE_ENDCALL:
case AKEYCODE_VOLUME_UP:
case AKEYCODE_VOLUME_DOWN:
case AKEYCODE_VOLUME_MUTE:
case AKEYCODE_POWER:
case AKEYCODE_CAMERA:
case AKEYCODE_HEADSETHOOK:
case AKEYCODE_MENU:
case AKEYCODE_NOTIFICATION:
case AKEYCODE_FOCUS:
case AKEYCODE_SEARCH:
case AKEYCODE_MEDIA_PLAY:
case AKEYCODE_MEDIA_PAUSE:
case AKEYCODE_MEDIA_PLAY_PAUSE:
case AKEYCODE_MEDIA_STOP:
case AKEYCODE_MEDIA_NEXT:
case AKEYCODE_MEDIA_PREVIOUS:
case AKEYCODE_MEDIA_REWIND:
case AKEYCODE_MEDIA_RECORD:
case AKEYCODE_MEDIA_FAST_FORWARD:
case AKEYCODE_MUTE:
return true;
}
return false;
}
bool KeyEvent::hasDefaultAction() const {
return hasDefaultAction(getKeyCode());
}
bool KeyEvent::isSystemKey(int32_t keyCode) {
switch (keyCode) {
case AKEYCODE_MENU:
case AKEYCODE_SOFT_RIGHT:
case AKEYCODE_HOME:
case AKEYCODE_BACK:
case AKEYCODE_CALL:
case AKEYCODE_ENDCALL:
case AKEYCODE_VOLUME_UP:
case AKEYCODE_VOLUME_DOWN:
case AKEYCODE_VOLUME_MUTE:
case AKEYCODE_MUTE:
case AKEYCODE_POWER:
case AKEYCODE_HEADSETHOOK:
case AKEYCODE_MEDIA_PLAY:
case AKEYCODE_MEDIA_PAUSE:
case AKEYCODE_MEDIA_PLAY_PAUSE:
case AKEYCODE_MEDIA_STOP:
case AKEYCODE_MEDIA_NEXT:
case AKEYCODE_MEDIA_PREVIOUS:
case AKEYCODE_MEDIA_REWIND:
case AKEYCODE_MEDIA_RECORD:
case AKEYCODE_MEDIA_FAST_FORWARD:
case AKEYCODE_CAMERA:
case AKEYCODE_FOCUS:
case AKEYCODE_SEARCH:
return true;
}
return false;
}
bool KeyEvent::isSystemKey() const {
return isSystemKey(getKeyCode());
}
void KeyEvent::initialize(
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) {
InputEvent::initialize(deviceId, source);
mAction = action;
mFlags = flags;
mKeyCode = keyCode;
mScanCode = scanCode;
mMetaState = metaState;
mRepeatCount = repeatCount;
mDownTime = downTime;
mEventTime = eventTime;
}
void KeyEvent::initialize(const KeyEvent& from) {
InputEvent::initialize(from);
mAction = from.mAction;
mFlags = from.mFlags;
mKeyCode = from.mKeyCode;
mScanCode = from.mScanCode;
mMetaState = from.mMetaState;
mRepeatCount = from.mRepeatCount;
mDownTime = from.mDownTime;
mEventTime = from.mEventTime;
}
// --- PointerCoords ---
float PointerCoords::getAxisValue(int32_t axis) const {
if (axis < 0 || axis > 63) {
return 0;
}
uint64_t axisBit = 1LL << axis;
if (!(bits & axisBit)) {
return 0;
}
uint32_t index = __builtin_popcountll(bits & (axisBit - 1LL));
return values[index];
}
status_t PointerCoords::setAxisValue(int32_t axis, float value) {
if (axis < 0 || axis > 63) {
return NAME_NOT_FOUND;
}
uint64_t axisBit = 1LL << axis;
uint32_t index = __builtin_popcountll(bits & (axisBit - 1LL));
if (!(bits & axisBit)) {
uint32_t count = __builtin_popcountll(bits);
if (count >= MAX_AXES) {
tooManyAxes(axis);
return NO_MEMORY;
}
bits |= axisBit;
for (uint32_t i = count; i > index; i--) {
values[i] = values[i - 1];
}
}
values[index] = value;
return OK;
}
float* PointerCoords::editAxisValue(int32_t axis) {
if (axis < 0 || axis > 63) {
return NULL;
}
uint64_t axisBit = 1LL << axis;
if (!(bits & axisBit)) {
return NULL;
}
uint32_t index = __builtin_popcountll(bits & (axisBit - 1LL));
return &values[index];
}
#ifdef HAVE_ANDROID_OS
status_t PointerCoords::readFromParcel(Parcel* parcel) {
bits = parcel->readInt64();
uint32_t count = __builtin_popcountll(bits);
if (count > MAX_AXES) {
return BAD_VALUE;
}
for (uint32_t i = 0; i < count; i++) {
values[i] = parcel->readInt32();
}
return OK;
}
status_t PointerCoords::writeToParcel(Parcel* parcel) const {
parcel->writeInt64(bits);
uint32_t count = __builtin_popcountll(bits);
for (uint32_t i = 0; i < count; i++) {
parcel->writeInt32(values[i]);
}
return OK;
}
#endif
void PointerCoords::tooManyAxes(int axis) {
LOGW("Could not set value for axis %d because the PointerCoords structure is full and "
"cannot contain more than %d axis values.", axis, int(MAX_AXES));
}
bool PointerCoords::operator==(const PointerCoords& other) const {
if (bits != other.bits) {
return false;
}
uint32_t count = __builtin_popcountll(bits);
for (uint32_t i = 0; i < count; i++) {
if (values[i] != other.values[i]) {
return false;
}
}
return true;
}
void PointerCoords::copyFrom(const PointerCoords& other) {
bits = other.bits;
uint32_t count = __builtin_popcountll(bits);
for (uint32_t i = 0; i < count; i++) {
values[i] = other.values[i];
}
}
// --- MotionEvent ---
void MotionEvent::initialize(
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) {
InputEvent::initialize(deviceId, source);
mAction = action;
mFlags = flags;
mEdgeFlags = edgeFlags;
mMetaState = metaState;
mXOffset = xOffset;
mYOffset = yOffset;
mXPrecision = xPrecision;
mYPrecision = yPrecision;
mDownTime = downTime;
mPointerIds.clear();
mPointerIds.appendArray(pointerIds, pointerCount);
mSampleEventTimes.clear();
mSamplePointerCoords.clear();
addSample(eventTime, pointerCoords);
}
void MotionEvent::copyFrom(const MotionEvent* other, bool keepHistory) {
InputEvent::initialize(other->mDeviceId, other->mSource);
mAction = other->mAction;
mFlags = other->mFlags;
mEdgeFlags = other->mEdgeFlags;
mMetaState = other->mMetaState;
mXOffset = other->mXOffset;
mYOffset = other->mYOffset;
mXPrecision = other->mXPrecision;
mYPrecision = other->mYPrecision;
mDownTime = other->mDownTime;
mPointerIds = other->mPointerIds;
if (keepHistory) {
mSampleEventTimes = other->mSampleEventTimes;
mSamplePointerCoords = other->mSamplePointerCoords;
} else {
mSampleEventTimes.clear();
mSampleEventTimes.push(other->getEventTime());
mSamplePointerCoords.clear();
size_t pointerCount = other->getPointerCount();
size_t historySize = other->getHistorySize();
mSamplePointerCoords.appendArray(other->mSamplePointerCoords.array()
+ (historySize * pointerCount), pointerCount);
}
}
void MotionEvent::addSample(
int64_t eventTime,
const PointerCoords* pointerCoords) {
mSampleEventTimes.push(eventTime);
mSamplePointerCoords.appendArray(pointerCoords, getPointerCount());
}
const PointerCoords* MotionEvent::getRawPointerCoords(size_t pointerIndex) const {
return &mSamplePointerCoords[getHistorySize() * getPointerCount() + pointerIndex];
}
float MotionEvent::getRawAxisValue(int32_t axis, size_t pointerIndex) const {
return getRawPointerCoords(pointerIndex)->getAxisValue(axis);
}
float MotionEvent::getAxisValue(int32_t axis, size_t pointerIndex) const {
float value = getRawPointerCoords(pointerIndex)->getAxisValue(axis);
switch (axis) {
case AMOTION_EVENT_AXIS_X:
value += mXOffset;
break;
case AMOTION_EVENT_AXIS_Y:
value += mYOffset;
break;
}
return value;
}
const PointerCoords* MotionEvent::getHistoricalRawPointerCoords(
size_t pointerIndex, size_t historicalIndex) const {
return &mSamplePointerCoords[historicalIndex * getPointerCount() + pointerIndex];
}
float MotionEvent::getHistoricalRawAxisValue(int32_t axis, size_t pointerIndex,
size_t historicalIndex) const {
return getHistoricalRawPointerCoords(pointerIndex, historicalIndex)->getAxisValue(axis);
}
float MotionEvent::getHistoricalAxisValue(int32_t axis, size_t pointerIndex,
size_t historicalIndex) const {
float value = getHistoricalRawPointerCoords(pointerIndex, historicalIndex)->getAxisValue(axis);
switch (axis) {
case AMOTION_EVENT_AXIS_X:
value += mXOffset;
break;
case AMOTION_EVENT_AXIS_Y:
value += mYOffset;
break;
}
return value;
}
void MotionEvent::offsetLocation(float xOffset, float yOffset) {
mXOffset += xOffset;
mYOffset += yOffset;
}
static inline void scaleAxisValue(PointerCoords& c, int axis, float scaleFactor) {
float* value = c.editAxisValue(axis);
if (value) {
*value *= scaleFactor;
}
}
void MotionEvent::scale(float scaleFactor) {
mXOffset *= scaleFactor;
mYOffset *= scaleFactor;
mXPrecision *= scaleFactor;
mYPrecision *= scaleFactor;
size_t numSamples = mSamplePointerCoords.size();
for (size_t i = 0; i < numSamples; i++) {
PointerCoords& c = mSamplePointerCoords.editItemAt(i);
// No need to scale pressure or size since they are normalized.
// No need to scale orientation since it is meaningless to do so.
scaleAxisValue(c, AMOTION_EVENT_AXIS_X, scaleFactor);
scaleAxisValue(c, AMOTION_EVENT_AXIS_Y, scaleFactor);
scaleAxisValue(c, AMOTION_EVENT_AXIS_TOUCH_MAJOR, scaleFactor);
scaleAxisValue(c, AMOTION_EVENT_AXIS_TOUCH_MINOR, scaleFactor);
scaleAxisValue(c, AMOTION_EVENT_AXIS_TOOL_MAJOR, scaleFactor);
scaleAxisValue(c, AMOTION_EVENT_AXIS_TOOL_MINOR, scaleFactor);
}
}
#ifdef HAVE_ANDROID_OS
static inline float transformAngle(const SkMatrix* matrix, float angleRadians) {
// Construct and transform a vector oriented at the specified clockwise angle from vertical.
// Coordinate system: down is increasing Y, right is increasing X.
SkPoint vector;
vector.fX = SkFloatToScalar(sinf(angleRadians));
vector.fY = SkFloatToScalar(-cosf(angleRadians));
matrix->mapVectors(& vector, 1);
// Derive the transformed vector's clockwise angle from vertical.
float result = atan2f(SkScalarToFloat(vector.fX), SkScalarToFloat(-vector.fY));
if (result < - M_PI_2) {
result += M_PI;
} else if (result > M_PI_2) {
result -= M_PI;
}
return result;
}
void MotionEvent::transform(const SkMatrix* matrix) {
float oldXOffset = mXOffset;
float oldYOffset = mYOffset;
// The tricky part of this implementation is to preserve the value of
// rawX and rawY. So we apply the transformation to the first point
// then derive an appropriate new X/Y offset that will preserve rawX and rawY.
SkPoint point;
float rawX = getRawX(0);
float rawY = getRawY(0);
matrix->mapXY(SkFloatToScalar(rawX + oldXOffset), SkFloatToScalar(rawY + oldYOffset),
& point);
float newX = SkScalarToFloat(point.fX);
float newY = SkScalarToFloat(point.fY);
float newXOffset = newX - rawX;
float newYOffset = newY - rawY;
mXOffset = newXOffset;
mYOffset = newYOffset;
// Apply the transformation to all samples.
size_t numSamples = mSamplePointerCoords.size();
for (size_t i = 0; i < numSamples; i++) {
PointerCoords& c = mSamplePointerCoords.editItemAt(i);
float* xPtr = c.editAxisValue(AMOTION_EVENT_AXIS_X);
float* yPtr = c.editAxisValue(AMOTION_EVENT_AXIS_Y);
if (xPtr && yPtr) {
float x = *xPtr + oldXOffset;
float y = *yPtr + oldYOffset;
matrix->mapXY(SkFloatToScalar(x), SkFloatToScalar(y), & point);
*xPtr = SkScalarToFloat(point.fX) - newXOffset;
*yPtr = SkScalarToFloat(point.fY) - newYOffset;
}
float* orientationPtr = c.editAxisValue(AMOTION_EVENT_AXIS_ORIENTATION);
if (orientationPtr) {
*orientationPtr = transformAngle(matrix, *orientationPtr);
}
}
}
status_t MotionEvent::readFromParcel(Parcel* parcel) {
size_t pointerCount = parcel->readInt32();
size_t sampleCount = parcel->readInt32();
if (pointerCount == 0 || pointerCount > MAX_POINTERS || sampleCount == 0) {
return BAD_VALUE;
}
mDeviceId = parcel->readInt32();
mSource = parcel->readInt32();
mAction = parcel->readInt32();
mFlags = parcel->readInt32();
mEdgeFlags = parcel->readInt32();
mMetaState = parcel->readInt32();
mXOffset = parcel->readFloat();
mYOffset = parcel->readFloat();
mXPrecision = parcel->readFloat();
mYPrecision = parcel->readFloat();
mDownTime = parcel->readInt64();
mPointerIds.clear();
mPointerIds.setCapacity(pointerCount);
mSampleEventTimes.clear();
mSampleEventTimes.setCapacity(sampleCount);
mSamplePointerCoords.clear();
mSamplePointerCoords.setCapacity(sampleCount * pointerCount);
for (size_t i = 0; i < pointerCount; i++) {
mPointerIds.push(parcel->readInt32());
}
while (sampleCount-- > 0) {
mSampleEventTimes.push(parcel->readInt64());
for (size_t i = 0; i < pointerCount; i++) {
mSamplePointerCoords.push();
status_t status = mSamplePointerCoords.editTop().readFromParcel(parcel);
if (status) {
return status;
}
}
}
return OK;
}
status_t MotionEvent::writeToParcel(Parcel* parcel) const {
size_t pointerCount = mPointerIds.size();
size_t sampleCount = mSampleEventTimes.size();
parcel->writeInt32(pointerCount);
parcel->writeInt32(sampleCount);
parcel->writeInt32(mDeviceId);
parcel->writeInt32(mSource);
parcel->writeInt32(mAction);
parcel->writeInt32(mFlags);
parcel->writeInt32(mEdgeFlags);
parcel->writeInt32(mMetaState);
parcel->writeFloat(mXOffset);
parcel->writeFloat(mYOffset);
parcel->writeFloat(mXPrecision);
parcel->writeFloat(mYPrecision);
parcel->writeInt64(mDownTime);
for (size_t i = 0; i < pointerCount; i++) {
parcel->writeInt32(mPointerIds.itemAt(i));
}
const PointerCoords* pc = mSamplePointerCoords.array();
for (size_t h = 0; h < sampleCount; h++) {
parcel->writeInt64(mSampleEventTimes.itemAt(h));
for (size_t i = 0; i < pointerCount; i++) {
status_t status = (pc++)->writeToParcel(parcel);
if (status) {
return status;
}
}
}
return OK;
}
#endif
bool MotionEvent::isTouchEvent(int32_t source, int32_t action) {
if (source & AINPUT_SOURCE_CLASS_POINTER) {
// Specifically excludes HOVER_MOVE and SCROLL.
switch (action & AMOTION_EVENT_ACTION_MASK) {
case AMOTION_EVENT_ACTION_DOWN:
case AMOTION_EVENT_ACTION_MOVE:
case AMOTION_EVENT_ACTION_UP:
case AMOTION_EVENT_ACTION_POINTER_DOWN:
case AMOTION_EVENT_ACTION_POINTER_UP:
case AMOTION_EVENT_ACTION_CANCEL:
case AMOTION_EVENT_ACTION_OUTSIDE:
return true;
}
}
return false;
}
// --- VelocityTracker ---
VelocityTracker::VelocityTracker() {
clear();
}
void VelocityTracker::clear() {
mIndex = 0;
mMovements[0].idBits.clear();
}
void VelocityTracker::addMovement(nsecs_t eventTime, BitSet32 idBits, const Position* positions) {
if (++mIndex == HISTORY_SIZE) {
mIndex = 0;
}
Movement& movement = mMovements[mIndex];
movement.eventTime = eventTime;
movement.idBits = idBits;
uint32_t count = idBits.count();
for (uint32_t i = 0; i < count; i++) {
movement.positions[i] = positions[i];
}
#if DEBUG_VELOCITY
LOGD("VelocityTracker: addMovement eventTime=%lld, idBits=0x%08x", eventTime, idBits.value);
for (BitSet32 iterBits(idBits); !iterBits.isEmpty(); ) {
uint32_t id = iterBits.firstMarkedBit();
uint32_t index = idBits.getIndexOfBit(id);
iterBits.clearBit(id);
float vx, vy;
bool available = getVelocity(id, &vx, &vy);
if (available) {
LOGD(" %d: position (%0.3f, %0.3f), velocity (%0.3f, %0.3f), speed %0.3f",
id, positions[index].x, positions[index].y, vx, vy, sqrtf(vx * vx + vy * vy));
} else {
assert(vx == 0 && vy == 0);
LOGD(" %d: position (%0.3f, %0.3f), velocity not available",
id, positions[index].x, positions[index].y);
}
}
#endif
}
bool VelocityTracker::getVelocity(uint32_t id, float* outVx, float* outVy) const {
const Movement& newestMovement = mMovements[mIndex];
if (newestMovement.idBits.hasBit(id)) {
// Find the oldest sample that contains the pointer and that is not older than MAX_AGE.
nsecs_t minTime = newestMovement.eventTime - MAX_AGE;
uint32_t oldestIndex = mIndex;
uint32_t numTouches = 1;
do {
uint32_t nextOldestIndex = (oldestIndex == 0 ? HISTORY_SIZE : oldestIndex) - 1;
const Movement& nextOldestMovement = mMovements[nextOldestIndex];
if (!nextOldestMovement.idBits.hasBit(id)
|| nextOldestMovement.eventTime < minTime) {
break;
}
oldestIndex = nextOldestIndex;
} while (++numTouches < HISTORY_SIZE);
// If we have a lot of samples, skip the last received sample since it is
// probably pretty noisy compared to the sum of all of the traces already acquired.
//
// NOTE: This condition exists in the android.view.VelocityTracker and imposes a
// bias against the most recent data.
if (numTouches > 3) {
numTouches -= 1;
}
// Calculate an exponentially weighted moving average of the velocity at different
// points in time measured relative to the oldest samples. This is essentially
// an IIR filter.
//
// One problem with this algorithm is that the sample data may be poorly conditioned.
// Sometimes samples arrive very close together in time which can cause us to
// overestimate the velocity at that time point. Most samples might be measured
// 16ms apart but some consecutive samples could be only 0.5sm apart due to
// the way they are reported by the hardware or driver (sometimes in bursts or with
// significant jitter). The instantaneous velocity for those samples 0.5ms apart will
// be calculated to be 32 times what it should have been.
// To work around this effect, we impose a minimum duration on the samples.
//
// FIXME: Samples close together in time can have an disproportionately large
// impact on the result because all samples are equally weighted. The average should
// instead take the time factor into account.
//
// FIXME: The minimum duration condition does not exist in
// android.view.VelocityTracker yet. It is less important there because sample times
// are truncated to the millisecond so back to back samples will often appear to be
// zero milliseconds apart and will be ignored if they are the oldest ones.
float accumVx = 0;
float accumVy = 0;
uint32_t index = oldestIndex;
uint32_t samplesUsed = 0;
const Movement& oldestMovement = mMovements[oldestIndex];
const Position& oldestPosition =
oldestMovement.positions[oldestMovement.idBits.getIndexOfBit(id)];
while (numTouches-- > 1) {
if (++index == HISTORY_SIZE) {
index = 0;
}
const Movement& movement = mMovements[index];
nsecs_t duration = movement.eventTime - oldestMovement.eventTime;
if (duration > MIN_DURATION) {
const Position& position = movement.positions[movement.idBits.getIndexOfBit(id)];
float scale = 1000000000.0f / duration; // one over time delta in seconds
float vx = (position.x - oldestPosition.x) * scale;
float vy = (position.y - oldestPosition.y) * scale;
accumVx = accumVx == 0 ? vx : (accumVx + vx) * 0.5f;
accumVy = accumVy == 0 ? vy : (accumVy + vy) * 0.5f;
samplesUsed += 1;
}
}
// Make sure we used at least one sample.
if (samplesUsed != 0) {
*outVx = accumVx;
*outVy = accumVy;
return true;
}
}
// No data available for this pointer.
*outVx = 0;
*outVy = 0;
return false;
}
// --- InputDeviceInfo ---
InputDeviceInfo::InputDeviceInfo() {
initialize(-1, String8("uninitialized device info"));
}
InputDeviceInfo::InputDeviceInfo(const InputDeviceInfo& other) :
mId(other.mId), mName(other.mName), mSources(other.mSources),
mKeyboardType(other.mKeyboardType),
mMotionRanges(other.mMotionRanges) {
}
InputDeviceInfo::~InputDeviceInfo() {
}
void InputDeviceInfo::initialize(int32_t id, const String8& name) {
mId = id;
mName = name;
mSources = 0;
mKeyboardType = AINPUT_KEYBOARD_TYPE_NONE;
mMotionRanges.clear();
}
const InputDeviceInfo::MotionRange* InputDeviceInfo::getMotionRange(
int32_t axis, uint32_t source) const {
size_t numRanges = mMotionRanges.size();
for (size_t i = 0; i < numRanges; i++) {
const MotionRange& range = mMotionRanges.itemAt(i);
if (range.axis == axis && range.source == source) {
return &range;
}
}
return NULL;
}
void InputDeviceInfo::addSource(uint32_t source) {
mSources |= source;
}
void InputDeviceInfo::addMotionRange(int32_t axis, uint32_t source, float min, float max,
float flat, float fuzz) {
MotionRange range = { axis, source, min, max, flat, fuzz };
mMotionRanges.add(range);
}
void InputDeviceInfo::addMotionRange(const MotionRange& range) {
mMotionRanges.add(range);
}
} // namespace android
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