How To Implement Gestures In Your Android Application

The project describes how to implement gestures for your application.

Underlying Algorithm:

Basic description of algorithm in step by step form:

1.) Create a Project GestureExample
2.) Insert following code in your main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"

   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   >
<TextView
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Try to draw the gesture"
   />
<android.gesture.GestureOverlayView
   android:id="@+id/gestures"
   android:layout_width="fill_parent"
   android:layout_height="0dip"
   android:layout_weight="1.0" />
</LinearLayout>

3.) Copy the gesture library from the SD card – e.g. by opening the Windows-> Show View -> Android File Explorer in Eclipse and save it somewhere for now. Now Create directory res/raw and put the downloaded gesture library “gesture” in there

4.) Run the application.

Steps to Create:

1.) Open Eclipse. Use the New Project Wizard and select Android Project Give the respective project name i.e. GestureExample.

2.) Enter following information:

Project name: GestureExample
Build Target: Android 2.3.3
Application name: GestureExample
Package name: org.example. GestureExample
Create Activity: GestureExample

On Clicking Finish GestureExample code structure is generated with the necessary Android Packages being imported along with GestureExample.java. GestureExample class will look like following:

package org.example.GestureExample;
import android.app.Activity;
import android.os.Bundle;
import java.util.ArrayList;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.gesture.GestureOverlayView.OnGesturePerformedListener;
import android.gesture.Prediction;
import android.util.Log;
import android.widget.Toast;

/**
 * A simple Activity listening for Gestures
 *
**/
public class GestureExample extends Activity {
        private GestureLibrary gLib;
        private static final String TAG = "com.android.gesture";

        @Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);

                gLib = GestureLibraries.fromRawResource(this, R.raw.gesture);
                if (!gLib.load()) {
                        Log.w(TAG, "could not load gesture library");
                        finish();
                }

                GestureOverlayView gestures = (GestureOverlayView)findViewById(R.id.gestures);
                gestures.addOnGesturePerformedListener(handleGestureListener);
        }

        /**
         * our gesture listener
         */
        private OnGesturePerformedListener handleGestureListener = newOnGesturePerformedListener() {
                @Override
                public void onGesturePerformed(GestureOverlayView gestureView,
                                Gesture gesture) {

                        ArrayList<Prediction> predictions =gLib.recognize(gesture);

                        // one prediction needed
                        if (predictions.size() > 0) {
                                Prediction prediction = predictions.get(0);
                                // checking prediction
                                if (prediction.score > 1.0) {
                                        // and action
                                        Toast.makeText(GestureExample.this, prediction.name,
                                                        Toast.LENGTH_SHORT).show();
                                }
                        }
                }
        };
}

Output – The final output