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/*
* 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.
*/
package android.view;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.Log;
/**
* Helper class for receiving notifications from the SensorManager when
* the orientation of the device has changed.
*/
public abstract class OrientationEventListener {
private static final String TAG = "OrientationEventListener";
private static final boolean DEBUG = false;
private static final boolean localLOGV = false;
private int mOrientation = ORIENTATION_UNKNOWN;
private SensorManager mSensorManager;
private boolean mEnabled = false;
private int mRate;
private Sensor mSensor;
private SensorEventListener mSensorEventListener;
private OrientationListener mOldListener;
/**
* Returned from onOrientationChanged when the device orientation cannot be determined
* (typically when the device is in a close to flat position).
*
* @see #onOrientationChanged
*/
public static final int ORIENTATION_UNKNOWN = -1;
/**
* Creates a new OrientationEventListener.
*
* @param context for the OrientationEventListener.
*/
public OrientationEventListener(Context context) {
this(context, SensorManager.SENSOR_DELAY_NORMAL);
}
/**
* Creates a new OrientationEventListener.
*
* @param context for the OrientationEventListener.
* @param rate at which sensor events are processed (see also
* {@link android.hardware.SensorManager SensorManager}). Use the default
* value of {@link android.hardware.SensorManager#SENSOR_DELAY_NORMAL
* SENSOR_DELAY_NORMAL} for simple screen orientation change detection.
*/
public OrientationEventListener(Context context, int rate) {
mSensorManager = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);
mRate = rate;
mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
if (mSensor != null) {
// Create listener only if sensors do exist
mSensorEventListener = new SensorEventListenerImpl();
}
}
void registerListener(OrientationListener lis) {
mOldListener = lis;
}
/**
* Enables the OrientationEventListener so it will monitor the sensor and call
* {@link #onOrientationChanged} when the device orientation changes.
*/
public void enable() {
if (mSensor == null) {
Log.w(TAG, "Cannot detect sensors. Not enabled");
return;
}
if (mEnabled == false) {
if (localLOGV) Log.d(TAG, "OrientationEventListener enabled");
mSensorManager.registerListener(mSensorEventListener, mSensor, mRate);
mEnabled = true;
}
}
/**
* Disables the OrientationEventListener.
*/
public void disable() {
if (mSensor == null) {
Log.w(TAG, "Cannot detect sensors. Invalid disable");
return;
}
if (mEnabled == true) {
if (localLOGV) Log.d(TAG, "OrientationEventListener disabled");
mSensorManager.unregisterListener(mSensorEventListener);
mEnabled = false;
}
}
class SensorEventListenerImpl implements SensorEventListener {
private static final int _DATA_X = 0;
private static final int _DATA_Y = 1;
private static final int _DATA_Z = 2;
public void onSensorChanged(SensorEvent event) {
float[] values = event.values;
int orientation = ORIENTATION_UNKNOWN;
float X = -values[_DATA_X];
float Y = -values[_DATA_Y];
float Z = -values[_DATA_Z];
float magnitude = X*X + Y*Y;
// Don't trust the angle if the magnitude is small compared to the y value
if (magnitude * 4 >= Z*Z) {
float OneEightyOverPi = 57.29577957855f;
float angle = (float)Math.atan2(-Y, X) * OneEightyOverPi;
orientation = 90 - (int)Math.round(angle);
// normalize to 0 - 359 range
while (orientation >= 360) {
orientation -= 360;
}
while (orientation < 0) {
orientation += 360;
}
}
if (mOldListener != null) {
mOldListener.onSensorChanged(Sensor.TYPE_ACCELEROMETER, event.values);
}
if (orientation != mOrientation) {
mOrientation = orientation;
onOrientationChanged(orientation);
}
}
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
}
/*
* Returns true if sensor is enabled and false otherwise
*/
public boolean canDetectOrientation() {
return mSensor != null;
}
/**
* Called when the orientation of the device has changed.
* orientation parameter is in degrees, ranging from 0 to 359.
* orientation is 0 degrees when the device is oriented in its natural position,
* 90 degrees when its left side is at the top, 180 degrees when it is upside down,
* and 270 degrees when its right side is to the top.
* {@link #ORIENTATION_UNKNOWN} is returned when the device is close to flat
* and the orientation cannot be determined.
*
* @param orientation The new orientation of the device.
*
* @see #ORIENTATION_UNKNOWN
*/
abstract public void onOrientationChanged(int orientation);
}
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