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noloman on 02/23/13

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Last Edited at 02/23/13 02:47am

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Shake event listener

/ Published in: Java

Shake event listener

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package com.xs2theworld.apptown.hardware;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

/**
 * Listener that detects shake gesture.
 */
public class ShakeEventListener implements SensorEventListener {

/** Minimum movement force to consider. */
	private static final int MIN_FORCE = 10;

/**
	 * Minimum times in a shake gesture that the direction of movement needs to
	 * change.
	 */
	private static final int MIN_DIRECTION_CHANGE = 3;

/** Maximum pause between movements. */
	private static final int MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE = 200;

/** Maximum allowed time for shake gesture. */
	private static final int MAX_TOTAL_DURATION_OF_SHAKE = 400;

/** Time when the gesture started. */
	private long mFirstDirectionChangeTime = 0;

/** Time when the last movement started. */
	private long mLastDirectionChangeTime;

/** How many movements are considered so far. */
	private int mDirectionChangeCount = 0;

/** The last x position. */
	private float lastX = 0;

/** The last y position. */
	private float lastY = 0;

/** The last z position. */
	private float lastZ = 0;

/** OnShakeListener that is called when shake is detected. */
	private OnShakeListener mShakeListener;

/**
	 * Interface for shake gesture.
	 */
	public interface OnShakeListener {

/**
		 * Called when shake gesture is detected.
		 */
		void onShake();
	}

public void setOnShakeListener(OnShakeListener listener) {
		mShakeListener = listener;
	}

@Override
	public void onSensorChanged(SensorEvent se) {
		// get sensor data
		float x = se.values[SensorManager.DATA_X];
		float y = se.values[SensorManager.DATA_Y];
		float z = se.values[SensorManager.DATA_Z];

// calculate movement
		float totalMovement = Math.abs(x + y + z - lastX - lastY - lastZ);

if (totalMovement > MIN_FORCE) {

// get time
			long now = System.currentTimeMillis();

// store first movement time
			if (mFirstDirectionChangeTime == 0) {
				mFirstDirectionChangeTime = now;
				mLastDirectionChangeTime = now;
			}

// check if the last movement was not long ago
			long lastChangeWasAgo = now - mLastDirectionChangeTime;
			if (lastChangeWasAgo < MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE) {

// store movement data
				mLastDirectionChangeTime = now;
				mDirectionChangeCount++;

// store last sensor data
				lastX = x;
				lastY = y;
				lastZ = z;

// check how many movements are so far
				if (mDirectionChangeCount >= MIN_DIRECTION_CHANGE) {

// check total duration
					long totalDuration = now - mFirstDirectionChangeTime;
					if (totalDuration < MAX_TOTAL_DURATION_OF_SHAKE) {
						mShakeListener.onShake();
						resetShakeParameters();
					}
				}

} else {
				resetShakeParameters();
			}
		}
	}

/**
	 * Resets the shake parameters to their default values.
	 */
	private void resetShakeParameters() {
		mFirstDirectionChangeTime = 0;
		mDirectionChangeCount = 0;
		mLastDirectionChangeTime = 0;
		lastX = 0;
		lastY = 0;
		lastZ = 0;
	}

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

}

In our activity:

private SensorManager mSensorManager;

private ShakeEventListener mSensorListener;

in our onCreate():

mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    mSensorListener = new ShakeEventListener();

mSensorListener.setOnShakeListener(new ShakeEventListener.OnShakeListener() {

public void onShake() {
        Toast.makeText(KPBActivityImpl.this, "Shake!", Toast.LENGTH_SHORT).show();
      }
    });

Then:

@Override
  protected void onResume() {
    super.onResume();
    mSensorManager.registerListener(mSensorListener,
        mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
        SensorManager.SENSOR_DELAY_UI);
  }

@Override
  protected void onPause() {
    mSensorManager.unregisterListener(mSensorListener);
    super.onStop();
  }

URL: http://stackoverflow.com/a/5117254/257948

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