/*
 * 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.
/**
 * 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
/**
     * 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.
Params:
context – for the OrientationEventListener./**
     * Creates a new OrientationEventListener.
     * 
     * @param context for the OrientationEventListener.
     */
    public OrientationEventListener(Context context) {
        this(context, SensorManager.SENSOR_DELAY_NORMAL);
    }
    
    
Creates a new OrientationEventListener.
Params:
context – for the OrientationEventListener.
rate – at which sensor events are processed (see also SensorManager). Use the default value of 
SENSOR_DELAY_NORMAL for simple screen orientation change detection./**
     * 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 onOrientationChanged when the device orientation changes. /**
     * 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.
/**
     * 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. ORIENTATION_UNKNOWN is returned when the device is close to flat and the orientation cannot be determined. 
Params:
orientation – The new orientation of the device.
 @see #ORIENTATION_UNKNOWN/**
     * 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);
}