The Tor Browser: comparison widget/gonk/ProcessOrientation.cpp

--1:000000000000
+:7a598d67b519
+/*
+* Copyright (c) 2013, Linux Foundation. All rights reserved
+*
+* Copyright (C) 2008 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.
+*/
+#include "base/basictypes.h"
+#include "mozilla/Hal.h"
+#include "nsIScreen.h"
+#include "nsIScreenManager.h"
+#include "OrientationObserver.h"
+#include "ProcessOrientation.h"
+#include "mozilla/HalSensor.h"
+#include "math.h"
+#include "limits.h"
+#include "android/log.h"
+#if 0
+#define LOGD(args...)  __android_log_print(ANDROID_LOG_DEBUG, "ProcessOrientation" , ## args)
+#else
+#define LOGD(args...)
+#endif
+namespace mozilla {
+// We work with all angles in degrees in this class.
+#define RADIANS_TO_DEGREES (180/M_PI)
+// Number of nanoseconds per millisecond.
+#define NANOS_PER_MS 1000000
+// Indices into SensorEvent.values for the accelerometer sensor.
+#define ACCELEROMETER_DATA_X 0
+#define ACCELEROMETER_DATA_Y 1
+#define ACCELEROMETER_DATA_Z 2
+// The minimum amount of time that a predicted rotation must be stable before
+// it is accepted as a valid rotation proposal. This value can be quite small
+// because the low-pass filter already suppresses most of the noise so we're
+// really just looking for quick confirmation that the last few samples are in
+// agreement as to the desired orientation.
+#define PROPOSAL_SETTLE_TIME_NANOS (40*NANOS_PER_MS)
+// The minimum amount of time that must have elapsed since the device last
+// exited the flat state (time since it was picked up) before the proposed
+// rotation can change.
+#define PROPOSAL_MIN_TIME_SINCE_FLAT_ENDED_NANOS (500*NANOS_PER_MS)
+// The minimum amount of time that must have elapsed since the device stopped
+// swinging (time since device appeared to be in the process of being put down
+// or put away into a pocket) before the proposed rotation can change.
+#define PROPOSAL_MIN_TIME_SINCE_SWING_ENDED_NANOS (300*NANOS_PER_MS)
+// The minimum amount of time that must have elapsed since the device stopped
+// undergoing external acceleration before the proposed rotation can change.
+#define PROPOSAL_MIN_TIME_SINCE_ACCELERATION_ENDED_NANOS (500*NANOS_PER_MS)
+// If the tilt angle remains greater than the specified angle for a minimum of
+// the specified time, then the device is deemed to be lying flat
+// (just chillin' on a table).
+#define FLAT_ANGLE 75
+#define FLAT_TIME_NANOS (1000*NANOS_PER_MS)
+// If the tilt angle has increased by at least delta degrees within the
+// specified amount of time, then the device is deemed to be swinging away
+// from the user down towards flat (tilt = 90).
+#define SWING_AWAY_ANGLE_DELTA 20
+#define SWING_TIME_NANOS (300*NANOS_PER_MS)
+// The maximum sample inter-arrival time in milliseconds. If the acceleration
+// samples are further apart than this amount in time, we reset the state of
+// the low-pass filter and orientation properties.  This helps to handle
+// boundary conditions when the device is turned on, wakes from suspend or
+// there is a significant gap in samples.
+#define MAX_FILTER_DELTA_TIME_NANOS (1000*NANOS_PER_MS)
+// The acceleration filter time constant.
+//
+// This time constant is used to tune the acceleration filter such that
+// impulses and vibrational noise (think car dock) is suppressed before we try
+// to calculate the tilt and orientation angles.
+//
+// The filter time constant is related to the filter cutoff frequency, which
+// is the frequency at which signals are attenuated by 3dB (half the passband
+// power). Each successive octave beyond this frequency is attenuated by an
+// additional 6dB.
+//
+// Given a time constant t in seconds, the filter cutoff frequency Fc in Hertz
+// is given by Fc = 1 / (2pi * t).
+//
+// The higher the time constant, the lower the cutoff frequency, so more noise
+// will be suppressed.
+//
+// Filtering adds latency proportional the time constant (inversely
+// proportional to the cutoff frequency) so we don't want to make the time
+// constant too large or we can lose responsiveness.  Likewise we don't want
+// to make it too small or we do a poor job suppressing acceleration spikes.
+// Empirically, 100ms seems to be too small and 500ms is too large. Android
+// default is 200.
+#define FILTER_TIME_CONSTANT_MS 200.0f
+// State for orientation detection. Thresholds for minimum and maximum
+// allowable deviation from gravity.
+//
+// If the device is undergoing external acceleration (being bumped, in a car
+// that is turning around a corner or a plane taking off) then the magnitude
+// may be substantially more or less than gravity.  This can skew our
+// orientation detection by making us think that up is pointed in a different
+// direction.
+//
+// Conversely, if the device is in freefall, then there will be no gravity to
+// measure at all.  This is problematic because we cannot detect the orientation
+// without gravity to tell us which way is up. A magnitude near 0 produces
+// singularities in the tilt and orientation calculations.
+//
+// In both cases, we postpone choosing an orientation.
+//
+// However, we need to tolerate some acceleration because the angular momentum
+// of turning the device can skew the observed acceleration for a short period
+// of time.
+#define NEAR_ZERO_MAGNITUDE 1 // m/s^2
+#define ACCELERATION_TOLERANCE 4 // m/s^2
+#define STANDARD_GRAVITY 9.80665f
+#define MIN_ACCELERATION_MAGNITUDE (STANDARD_GRAVITY-ACCELERATION_TOLERANCE)
+#define MAX_ACCELERATION_MAGNITUDE (STANDARD_GRAVITY+ACCELERATION_TOLERANCE)
+// Maximum absolute tilt angle at which to consider orientation data. Beyond
+// this (i.e. when screen is facing the sky or ground), we completely ignore
+// orientation data.
+#define MAX_TILT 75
+// The gap angle in degrees between adjacent orientation angles for
+// hysteresis.This creates a "dead zone" between the current orientation and a
+// proposed adjacent orientation. No orientation proposal is made when the
+// orientation angle is within the gap between the current orientation and the
+// adjacent orientation.
+#define ADJACENT_ORIENTATION_ANGLE_GAP 45
+const int
+ProcessOrientation::tiltTolerance[][4] = {
+{-25, 70}, // ROTATION_0
+{-25, 65}, // ROTATION_90
+{-25, 60}, // ROTATION_180
+{-25, 65}  // ROTATION_270
+};
+int
+ProcessOrientation::GetProposedRotation()
+{
+return mProposedRotation;
+}
+int
+ProcessOrientation::OnSensorChanged(const SensorData& event,
+int deviceCurrentRotation)
+{
+// The vector given in the SensorEvent points straight up (towards the sky)
+// under ideal conditions (the phone is not accelerating). I'll call this up
+// vector elsewhere.
+const InfallibleTArray<float>& values = event.values();
+float x = values[ACCELEROMETER_DATA_X];
+float y = values[ACCELEROMETER_DATA_Y];
+float z = values[ACCELEROMETER_DATA_Z];
+LOGD
+("ProcessOrientation: Raw acceleration vector: x = %f, y = %f, z = %f,"
+"magnitude = %f\n", x, y, z, sqrt(x * x + y * y + z * z));
+// Apply a low-pass filter to the acceleration up vector in cartesian space.
+// Reset the orientation listener state if the samples are too far apart in
+// time or when we see values of (0, 0, 0) which indicates that we polled the
+// accelerometer too soon after turning it on and we don't have any data yet.
+const long now = event.timestamp();
+const long then = mLastFilteredTimestampNanos;
+const float timeDeltaMS = (now - then) * 0.000001f;
+bool skipSample = false;
+if (now < then
+|| now > then + MAX_FILTER_DELTA_TIME_NANOS
+|| (x == 0 && y == 0 && z == 0)) {
+LOGD
+("ProcessOrientation: Resetting orientation listener.");
+Reset();
+skipSample = true;
+} else {
+const float alpha = timeDeltaMS / (FILTER_TIME_CONSTANT_MS + timeDeltaMS);
+x = alpha * (x - mLastFilteredX) + mLastFilteredX;
+y = alpha * (y - mLastFilteredY) + mLastFilteredY;
+z = alpha * (z - mLastFilteredZ) + mLastFilteredZ;
+LOGD
+("ProcessOrientation: Filtered acceleration vector: x=%f, y=%f, z=%f,"
+"magnitude=%f", z, y, z, sqrt(x * x + y * y + z * z));
+skipSample = false;
+}
+mLastFilteredTimestampNanos = now;
+mLastFilteredX = x;
+mLastFilteredY = y;
+mLastFilteredZ = z;
+bool isAccelerating = false;
+bool isFlat = false;
+bool isSwinging = false;
+if (skipSample) {
+return -1;
+}
+// Calculate the magnitude of the acceleration vector.
+const float magnitude = sqrt(x * x + y * y + z * z);
+if (magnitude < NEAR_ZERO_MAGNITUDE) {
+LOGD
+("ProcessOrientation: Ignoring sensor data, magnitude too close to"
+" zero.");
+ClearPredictedRotation();
+} else {
+// Determine whether the device appears to be undergoing external
+// acceleration.
+if (this->IsAccelerating(magnitude)) {
+isAccelerating = true;
+mAccelerationTimestampNanos = now;
+}
+// Calculate the tilt angle. This is the angle between the up vector and
+// the x-y plane (the plane of the screen) in a range of [-90, 90]
+// degrees.
+//   -90 degrees: screen horizontal and facing the ground (overhead)
+//     0 degrees: screen vertical
+//    90 degrees: screen horizontal and facing the sky (on table)
+const int tiltAngle =
+static_cast<int>(roundf(asin(z / magnitude) * RADIANS_TO_DEGREES));
+AddTiltHistoryEntry(now, tiltAngle);
+// Determine whether the device appears to be flat or swinging.
+if (this->IsFlat(now)) {
+isFlat = true;
+mFlatTimestampNanos = now;
+}
+if (this->IsSwinging(now, tiltAngle)) {
+isSwinging = true;
+mSwingTimestampNanos = now;
+}
+// If the tilt angle is too close to horizontal then we cannot determine
+// the orientation angle of the screen.
+if (abs(tiltAngle) > MAX_TILT) {
+LOGD
+("ProcessOrientation: Ignoring sensor data, tilt angle too high:"
+" tiltAngle=%d", tiltAngle);
+ClearPredictedRotation();
+} else {
+// Calculate the orientation angle.
+// This is the angle between the x-y projection of the up vector onto
+// the +y-axis, increasing clockwise in a range of [0, 360] degrees.
+int orientationAngle =
+static_cast<int>(roundf(-atan2f(-x, y) * RADIANS_TO_DEGREES));
+if (orientationAngle < 0) {
+// atan2 returns [-180, 180]; normalize to [0, 360]
+orientationAngle += 360;
+}
+// Find the nearest rotation.
+int nearestRotation = (orientationAngle + 45) / 90;
+if (nearestRotation == 4) {
+nearestRotation = 0;
+}
+// Determine the predicted orientation.
+if (IsTiltAngleAcceptable(nearestRotation, tiltAngle)
+&&
+IsOrientationAngleAcceptable
+(nearestRotation, orientationAngle, deviceCurrentRotation)) {
+UpdatePredictedRotation(now, nearestRotation);
+LOGD
+("ProcessOrientation: Predicted: tiltAngle=%d, orientationAngle=%d,"
+" predictedRotation=%d, predictedRotationAgeMS=%f",
+tiltAngle,
+orientationAngle,
+mPredictedRotation,
+((now - mPredictedRotationTimestampNanos) * 0.000001f));
+} else {
+LOGD
+("ProcessOrientation: Ignoring sensor data, no predicted rotation:"
+" tiltAngle=%d, orientationAngle=%d",
+tiltAngle,
+orientationAngle);
+ClearPredictedRotation();
+}
+}
+}
+// Determine new proposed rotation.
+const int oldProposedRotation = mProposedRotation;
+if (mPredictedRotation < 0 || IsPredictedRotationAcceptable(now)) {
+mProposedRotation = mPredictedRotation;
+}
+// Write final statistics about where we are in the orientation detection
+// process.
+LOGD
+("ProcessOrientation: Result: oldProposedRotation=%d,currentRotation=%d, "
+"proposedRotation=%d, predictedRotation=%d, timeDeltaMS=%f, "
+"isAccelerating=%d, isFlat=%d, isSwinging=%d, timeUntilSettledMS=%f, "
+"timeUntilAccelerationDelayExpiredMS=%f, timeUntilFlatDelayExpiredMS=%f, "
+"timeUntilSwingDelayExpiredMS=%f",
+oldProposedRotation,
+deviceCurrentRotation, mProposedRotation,
+mPredictedRotation, timeDeltaMS, isAccelerating, isFlat,
+isSwinging, RemainingMS(now,
+mPredictedRotationTimestampNanos +
+PROPOSAL_SETTLE_TIME_NANOS),
+RemainingMS(now,
+mAccelerationTimestampNanos +
+PROPOSAL_MIN_TIME_SINCE_ACCELERATION_ENDED_NANOS),
+RemainingMS(now,
+mFlatTimestampNanos +
+PROPOSAL_MIN_TIME_SINCE_FLAT_ENDED_NANOS),
+RemainingMS(now,
+mSwingTimestampNanos +
+PROPOSAL_MIN_TIME_SINCE_SWING_ENDED_NANOS));
+// Tell the listener.
+if (mProposedRotation != oldProposedRotation && mProposedRotation >= 0) {
+LOGD
+("ProcessOrientation: Proposed rotation changed!  proposedRotation=%d, "
+"oldProposedRotation=%d",
+mProposedRotation,
+oldProposedRotation);
+return mProposedRotation;
+}
+// Don't rotate screen
+return -1;
+}
+bool
+ProcessOrientation::IsTiltAngleAcceptable(int rotation, int tiltAngle)
+{
+return (tiltAngle >= tiltTolerance[rotation][0]
+&& tiltAngle <= tiltTolerance[rotation][1]);
+}
+bool
+ProcessOrientation::IsOrientationAngleAcceptable(int rotation,
+int orientationAngle,
+int currentRotation)
+{
+// If there is no current rotation, then there is no gap.
+// The gap is used only to introduce hysteresis among advertised orientation
+// changes to avoid flapping.
+if (currentRotation < 0) {
+return true;
+}
+// If the specified rotation is the same or is counter-clockwise adjacent
+// to the current rotation, then we set a lower bound on the orientation
+// angle. For example, if currentRotation is ROTATION_0 and proposed is
+// ROTATION_90, then we want to check orientationAngle > 45 + GAP / 2.
+if (rotation == currentRotation || rotation == (currentRotation + 1) % 4) {
+int lowerBound = rotation * 90 - 45 + ADJACENT_ORIENTATION_ANGLE_GAP / 2;
+if (rotation == 0) {
+if (orientationAngle >= 315 && orientationAngle < lowerBound + 360) {
+return false;
+}
+} else {
+if (orientationAngle < lowerBound) {
+return false;
+}
+}
+}
+// If the specified rotation is the same or is clockwise adjacent, then we
+// set an upper bound on the orientation angle. For example, if
+// currentRotation is ROTATION_0 and rotation is ROTATION_270, then we want
+// to check orientationAngle < 315 - GAP / 2.
+if (rotation == currentRotation || rotation == (currentRotation + 3) % 4) {
+int upperBound = rotation * 90 + 45 - ADJACENT_ORIENTATION_ANGLE_GAP / 2;
+if (rotation == 0) {
+if (orientationAngle <= 45 && orientationAngle > upperBound) {
+return false;
+}
+} else {
+if (orientationAngle > upperBound) {
+return false;
+}
+}
+}
+return true;
+}
+bool
+ProcessOrientation::IsPredictedRotationAcceptable(long now)
+{
+// The predicted rotation must have settled long enough.
+if (now < mPredictedRotationTimestampNanos + PROPOSAL_SETTLE_TIME_NANOS) {
+return false;
+}
+// The last flat state (time since picked up) must have been sufficiently long
+// ago.
+if (now < mFlatTimestampNanos + PROPOSAL_MIN_TIME_SINCE_FLAT_ENDED_NANOS) {
+return false;
+}
+// The last swing state (time since last movement to put down) must have been
+// sufficiently long ago.
+if (now < mSwingTimestampNanos + PROPOSAL_MIN_TIME_SINCE_SWING_ENDED_NANOS) {
+return false;
+}
+// The last acceleration state must have been sufficiently long ago.
+if (now < mAccelerationTimestampNanos
++ PROPOSAL_MIN_TIME_SINCE_ACCELERATION_ENDED_NANOS) {
+return false;
+}
+// Looks good!
+return true;
+}
+int
+ProcessOrientation::Reset()
+{
+mLastFilteredTimestampNanos = LONG_MIN;
+mProposedRotation = -1;
+mFlatTimestampNanos = LONG_MIN;
+mSwingTimestampNanos = LONG_MIN;
+mAccelerationTimestampNanos = LONG_MIN;
+ClearPredictedRotation();
+ClearTiltHistory();
+return -1;
+}
+void
+ProcessOrientation::ClearPredictedRotation()
+{
+mPredictedRotation = -1;
+mPredictedRotationTimestampNanos = LONG_MIN;
+}
+void
+ProcessOrientation::UpdatePredictedRotation(long now, int rotation)
+{
+if (mPredictedRotation != rotation) {
+mPredictedRotation = rotation;
+mPredictedRotationTimestampNanos = now;
+}
+}
+bool
+ProcessOrientation::IsAccelerating(float magnitude)
+{
+return magnitude < MIN_ACCELERATION_MAGNITUDE
+|| magnitude > MAX_ACCELERATION_MAGNITUDE;
+}
+void
+ProcessOrientation::ClearTiltHistory()
+{
+mTiltHistory.history[0].timestampNanos = LONG_MIN;
+mTiltHistory.index = 1;
+}
+void
+ProcessOrientation::AddTiltHistoryEntry(long now, float tilt)
+{
+mTiltHistory.history[mTiltHistory.index].tiltAngle = tilt;
+mTiltHistory.history[mTiltHistory.index].timestampNanos = now;
+mTiltHistory.index = (mTiltHistory.index + 1) % TILT_HISTORY_SIZE;
+mTiltHistory.history[mTiltHistory.index].timestampNanos = LONG_MIN;
+}
+bool
+ProcessOrientation::IsFlat(long now)
+{
+for (int i = mTiltHistory.index; (i = NextTiltHistoryIndex(i)) >= 0;) {
+if (mTiltHistory.history[i].tiltAngle < FLAT_ANGLE) {
+break;
+}
+if (mTiltHistory.history[i].timestampNanos + FLAT_TIME_NANOS <= now) {
+// Tilt has remained greater than FLAT_TILT_ANGLE for FLAT_TIME_NANOS.
+return true;
+}
+}
+return false;
+}
+bool
+ProcessOrientation::IsSwinging(long now, float tilt)
+{
+for (int i = mTiltHistory.index; (i = NextTiltHistoryIndex(i)) >= 0;) {
+if (mTiltHistory.history[i].timestampNanos + SWING_TIME_NANOS < now) {
+break;
+}
+if (mTiltHistory.history[i].tiltAngle + SWING_AWAY_ANGLE_DELTA <= tilt) {
+// Tilted away by SWING_AWAY_ANGLE_DELTA within SWING_TIME_NANOS.
+return true;
+}
+}
+return false;
+}
+int
+ProcessOrientation::NextTiltHistoryIndex(int index)
+{
+index = (index == 0 ? TILT_HISTORY_SIZE : index) - 1;
+return mTiltHistory.history[index].timestampNanos != LONG_MIN ? index : -1;
+}
+float
+ProcessOrientation::RemainingMS(long now, long until)
+{
+return now >= until ? 0 : (until - now) * 0.000001f;
+}
+} // namespace mozilla

The Tor Browser / file comparison

comparison: widget/gonk/ProcessOrientation.cpp

widget/gonk/ProcessOrientation.cpp