Android Open Source - maps-app-android Compass

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Apache License - 2.0 TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by...

Java Source Code

/* Copyright 1995-2014 Esri
 */*from w  w  w .  j  ava2 s.c  o m*/
 * 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.
 *
 * For additional information, contact:
 * Environmental Systems Research Institute, Inc.
 * Attn: Contracts Dept
 * 380 New York Street
 * Redlands, California, USA 92373
 *
 * email: contracts@esri.com
 *
 */

package com.esri.android.mapsapp.tools;

import com.esri.android.map.MapView;
import com.esri.android.mapsapp.R;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.view.View;

/**
 * The implementation of compass. There are two modes of operation for rotating
 * the compass, one is using device motion sensors and latter using the pinch
 * listeners.
 * 
 */
public class Compass extends View implements SensorEventListener {

  float mAngle = 0;
  Paint mPaint;
  Bitmap mBitmap;
  Matrix mMatrix;
  MapView mMapView;

  // Handles the sensors
  public SensorManager sensorManager;

  // Sensors for accelerometer and magnetometer
  public Sensor gsensor;
  public Sensor msensor;

  // Used for orientation of the compass
  private float[] mGravity = new float[3];
  private float[] mGeomagnetic = new float[3];

  // The angle of rotation of the compass
  private float azimuth = 0f;

  // To send and receive notification from the sensors.
  public SensorEventListener sensorEventListener;
  
  int width;

  public Compass(Context context) {
    super(context);

    mPaint = new Paint();
    mMatrix = new Matrix();
    
    mBitmap = BitmapFactory.decodeResource(getResources(),
        R.drawable.ic_compass);
        
    sensorManager = (SensorManager) context
        .getSystemService(Context.SENSOR_SERVICE);
    gsensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    msensor = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
  }

  public void start() {
    // A copy of instance which is used to restart the sensors
    sensorEventListener = this;

    // Enable the sensors
    sensorManager.registerListener(this, gsensor,
        SensorManager.SENSOR_DELAY_GAME);
    sensorManager.registerListener(this, msensor,
        SensorManager.SENSOR_DELAY_GAME);
  }

  public void stop() {
    // Disable the sensors
    sensorManager.unregisterListener(this);
  }

  /**
   * Updates the angle, in degrees, at which the compass is draw within this
   * view.
   */
  public void setRotationAngle(double angle) {
    // Save the new rotation angle.
    mAngle = (float) angle;

    // Force the compass to re-paint itself.
    postInvalidate();
  }

  /** Draws the compass image at the current angle of rotation on the canvas. */
  @Override
  protected void onDraw(Canvas canvas) {

    // Reset the matrix to default values.
    mMatrix.reset();

    // Pass the current rotation angle to the matrix. The center of rotation
    // is set to be the center of the bitmap.
    mMatrix.postRotate(-this.mAngle, mBitmap.getHeight() / 2,
        mBitmap.getWidth() / 2);

    // Use the matrix to draw the bitmap image of the compass.
    canvas.drawBitmap(mBitmap, mMatrix, mPaint);

    super.onDraw(canvas);

  }

  public void onSensorChanged(SensorEvent event) {
    final float alpha = 0.97f;

    synchronized (this) {
      if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {

        mGravity[0] = alpha * mGravity[0] + (1 - alpha)
            * event.values[0];
        mGravity[1] = alpha * mGravity[1] + (1 - alpha)
            * event.values[1];
        mGravity[2] = alpha * mGravity[2] + (1 - alpha)
            * event.values[2];
      }

      if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {

        mGeomagnetic[0] = alpha * mGeomagnetic[0] + (1 - alpha)
            * event.values[0];
        mGeomagnetic[1] = alpha * mGeomagnetic[1] + (1 - alpha)
            * event.values[1];
        mGeomagnetic[2] = alpha * mGeomagnetic[2] + (1 - alpha)
            * event.values[2];

      }

      float R[] = new float[9];
      float I[] = new float[9];
      boolean success = SensorManager.getRotationMatrix(R, I, mGravity,
          mGeomagnetic);

      if (success) {
        float orientation[] = new float[3];
        SensorManager.getOrientation(R, orientation);
        azimuth = (float) Math.toDegrees(orientation[0]); // orientation
        azimuth = (azimuth + 360) % 360;

        setRotationAngle(-azimuth);
      }
    }
  }

  public void onAccuracyChanged(Sensor sensor, int accuracy) {
  }
}

Java Source Code List

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