Since version 1.6 Android offers a library for recognition and handling of new gestures using a touch display. With the gesture builder it is possible to capture new gestures in the emulator. Gestures can be integrated into an activity like that.

GestureLibrary gLib = GestureLibraries.fromRawResource(this, R.raw.spells);
if (!gLib.load()) {
  finish();
}

  • Furthermore we need a gesture overlay in the UI:

     <android.gesture.GestureOverlayView
    android:id="@+id/gestures"
    android:layout_width="fill_parent"
    android:layout_height="0dip"
    android:layout_weight="1.0" />

  • In the next step we implement an event handler for the gesture (Source: http://developer.android.com/resources/articles/gestures.html):

    GestureOverlayView gestures = (GestureOverlayView) findViewById(R.id.gestures);
gestures.addOnGesturePerformedListener(this);

public void onGesturePerformed(GestureOverlayView overlay, Gesture gesture) {
 ArrayList<prediction> predictions = mLibrary.recognize(gesture);

   if (predictions.size() > 0) {
     Prediction prediction = predictions.get(0);
     if (prediction.score > 1.0) {
       Toast.makeText(this, prediction.name, Toast.LENGTH_SHORT).show();
     }
   }
 }

Update : In Android 2.2 there is a new class GestureUtils providing some new methods for feature extraction, geometric transformation and gesture similarity comparison – for more information take a look at the class docs.

Update : I have written a tutorial for creating a sample app recognizing getures – take a look here.

More information