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/*
* 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.
*/
package android.webkit;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;
import android.webkit.DeviceMotionAndOrientationManager;
import java.lang.Runnable;
import java.util.List;
final class DeviceOrientationService implements SensorEventListener {
// The gravity vector expressed in the body frame.
private float[] mGravityVector;
// The geomagnetic vector expressed in the body frame.
private float[] mMagneticFieldVector;
private DeviceMotionAndOrientationManager mManager;
private boolean mIsRunning;
private Handler mHandler;
private SensorManager mSensorManager;
private Context mContext;
private Double mAlpha;
private Double mBeta;
private Double mGamma;
private boolean mHaveSentErrorEvent;
private static final double DELTA_DEGRESS = 1.0;
public DeviceOrientationService(DeviceMotionAndOrientationManager manager, Context context) {
mManager = manager;
assert(mManager != null);
mContext = context;
assert(mContext != null);
}
public void start() {
mIsRunning = true;
registerForSensors();
}
public void stop() {
mIsRunning = false;
unregisterFromSensors();
}
public void suspend() {
if (mIsRunning) {
unregisterFromSensors();
}
}
public void resume() {
if (mIsRunning) {
registerForSensors();
}
}
private void sendErrorEvent() {
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
// The spec requires that each listener receives the error event only once.
if (mHaveSentErrorEvent)
return;
mHaveSentErrorEvent = true;
mHandler.post(new Runnable() {
@Override
public void run() {
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
if (mIsRunning) {
// The special case of all nulls is used to signify a failure to get data.
mManager.onOrientationChange(null, null, null);
}
}
});
}
private void registerForSensors() {
if (mHandler == null) {
mHandler = new Handler();
}
if (!registerForAccelerometerSensor() || !registerForMagneticFieldSensor()) {
unregisterFromSensors();
sendErrorEvent();
}
}
private void getOrientationUsingGetRotationMatrix() {
if (mGravityVector == null || mMagneticFieldVector == null) {
return;
}
// Get the rotation matrix.
// The rotation matrix that transforms from the body frame to the earth frame.
float[] deviceRotationMatrix = new float[9];
if (!SensorManager.getRotationMatrix(
deviceRotationMatrix, null, mGravityVector, mMagneticFieldVector)) {
return;
}
// Convert rotation matrix to rotation angles.
// Assuming that the rotations are appied in the order listed at
// http://developer.android.com/reference/android/hardware/SensorEvent.html#values
// the rotations are applied about the same axes and in the same order as required by the
// API. The only conversions are sign changes as follows.
// The angles are in radians
float[] rotationAngles = new float[3];
SensorManager.getOrientation(deviceRotationMatrix, rotationAngles);
double alpha = Math.toDegrees(-rotationAngles[0]);
while (alpha < 0.0) { alpha += 360.0; } // [0, 360)
double beta = Math.toDegrees(-rotationAngles[1]);
while (beta < -180.0) { beta += 360.0; } // [-180, 180)
double gamma = Math.toDegrees(rotationAngles[2]);
while (gamma < -90.0) { gamma += 360.0; } // [-90, 90)
maybeSendChange(alpha, beta, gamma);
}
private SensorManager getSensorManager() {
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
if (mSensorManager == null) {
mSensorManager = (SensorManager) mContext.getSystemService(Context.SENSOR_SERVICE);
}
return mSensorManager;
}
private boolean registerForAccelerometerSensor() {
List<Sensor> sensors = getSensorManager().getSensorList(Sensor.TYPE_ACCELEROMETER);
if (sensors.isEmpty()) {
return false;
}
// TODO: Consider handling multiple sensors.
return getSensorManager().registerListener(
this, sensors.get(0), SensorManager.SENSOR_DELAY_FASTEST, mHandler);
}
private boolean registerForMagneticFieldSensor() {
List<Sensor> sensors = getSensorManager().getSensorList(Sensor.TYPE_MAGNETIC_FIELD);
if (sensors.isEmpty()) {
return false;
}
// TODO: Consider handling multiple sensors.
return getSensorManager().registerListener(
this, sensors.get(0), SensorManager.SENSOR_DELAY_FASTEST, mHandler);
}
private void unregisterFromSensors() {
getSensorManager().unregisterListener(this);
}
private void maybeSendChange(double alpha, double beta, double gamma) {
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
if (mAlpha == null || mBeta == null || mGamma == null
|| Math.abs(alpha - mAlpha) > DELTA_DEGRESS
|| Math.abs(beta - mBeta) > DELTA_DEGRESS
|| Math.abs(gamma - mGamma) > DELTA_DEGRESS) {
mAlpha = alpha;
mBeta = beta;
mGamma = gamma;
mManager.onOrientationChange(mAlpha, mBeta, mGamma);
// Now that we have successfully sent some data, reset whether we've sent an error.
mHaveSentErrorEvent = false;
}
}
/**
* SensorEventListener implementation.
* Callbacks happen on the thread on which we registered - the WebCore thread.
*/
@Override
public void onSensorChanged(SensorEvent event) {
assert(event.values.length == 3);
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
// We may get callbacks after the call to getSensorManager().unregisterListener() returns.
if (!mIsRunning) {
return;
}
switch (event.sensor.getType()) {
case Sensor.TYPE_ACCELEROMETER:
if (mGravityVector == null) {
mGravityVector = new float[3];
}
mGravityVector[0] = event.values[0];
mGravityVector[1] = event.values[1];
mGravityVector[2] = event.values[2];
getOrientationUsingGetRotationMatrix();
break;
case Sensor.TYPE_MAGNETIC_FIELD:
if (mMagneticFieldVector == null) {
mMagneticFieldVector = new float[3];
}
mMagneticFieldVector[0] = event.values[0];
mMagneticFieldVector[1] = event.values[1];
mMagneticFieldVector[2] = event.values[2];
getOrientationUsingGetRotationMatrix();
break;
default:
assert(false);
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
}
}
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