SpeechRecognitionUtil.java

/*
 * Copyright 2011 Greg Milette and Adam Stroud
 * 
 * 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 root.gast.speech;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.speech.RecognitionListener;
import android.speech.RecognizerIntent;
import android.speech.SpeechRecognizer;

/**
 * A utility class to perform common speech recognition functions
 * @author Greg Milette <<a href="mailto:gregorym@gmail.com">gregorym@gmail.com</a>>
 */
public class SpeechRecognitionUtil
{
    private static final String TAG = "SpeechRecognitionUtil";

    //Note: Google seems to send back these values
    //use at your own risk
    public static final String UNSUPPORTED_GOOGLE_RESULTS_CONFIDENCE = "com.google.android.voicesearch.UNSUPPORTED_PARTIAL_RESULTS_CONFIDENCE";
    public static final String UNSUPPORTED_GOOGLE_RESULTS = "com.google.android.voicesearch.UNSUPPORTED_PARTIAL_RESULTS";

    /**
     * checks if the device supports speech recognition 
     * at all
     */
    public static boolean isSpeechAvailable(Context context)
    {
        PackageManager pm = context.getPackageManager();
        List<ResolveInfo> activities = pm.queryIntentActivities(
                new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);

        boolean available = true;
        if (activities.size() == 0) 
        {
            available = false;
        }
        return available;
        //also works, but it is checking something slightly different
        //it checks for the recognizer service. so we use the above check
        //instead since it directly answers the question of whether or not
        //the app can service the intent the app will send
//      return SpeechRecognizer.isRecognitionAvailable(context);
    }

    /**
     * collects language details and returns result to andThen
     */
    public static void getLanguageDetails(Context context,
            OnLanguageDetailsListener andThen)
    {
        Intent detailsIntent = new Intent(
                RecognizerIntent.ACTION_GET_LANGUAGE_DETAILS);
        LanguageDetailsChecker checker = new LanguageDetailsChecker(andThen);
        context.sendOrderedBroadcast(detailsIntent, null, checker, null,
                Activity.RESULT_OK, null, null);
        //also works
    //  Intent detailsIntent = RecognizerIntent.getVoiceDetailsIntent(this);
    }
    
    public static List<String> getHeardFromDirect(Bundle bundle)
    {
        List<String> results = new ArrayList<String>();
        if ((bundle != null)
                && bundle.containsKey(SpeechRecognizer.RESULTS_RECOGNITION))
        {
            results =
                bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
        }
        return results;
    }

    public static float[] getConfidenceFromDirect(Bundle bundle)
    {
        float [] scores = null;
        if ((bundle != null)
                && bundle.containsKey(SpeechRecognizer.RESULTS_RECOGNITION))
        {
            scores =
                bundle.getFloatArray(SpeechRecognizer.CONFIDENCE_SCORES);
        }
        return scores;
    }

    public static List<String> getHeardFromDirectPartial(Bundle bundle)
    {
        List<String> results = new ArrayList<String>();
        if (bundle.containsKey(UNSUPPORTED_GOOGLE_RESULTS))
        {
            String [] resultsArray =
                bundle.getStringArray(UNSUPPORTED_GOOGLE_RESULTS);
            results = Arrays.asList(resultsArray);
        }
        else
        {
            return getHeardFromDirect(bundle);
        }
        return results;
    }

    public static float[] getConfidenceFromDirectPartial(Bundle bundle)
    {
        float[] scores = null;

        if (bundle
                .containsKey(UNSUPPORTED_GOOGLE_RESULTS_CONFIDENCE))
        {
            scores =
                    bundle.getFloatArray(UNSUPPORTED_GOOGLE_RESULTS_CONFIDENCE);
        }
        else
        {
            scores = getConfidenceFromDirect(bundle);
        }

        return scores;
    }

    public static void recognizeSpeechDirectly(Context context, 
            Intent recognizerIntent, RecognitionListener listener,
            SpeechRecognizer recognizer)
    {
        //need to have a calling package for it to work
        if (!recognizerIntent.hasExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE))
        {
            recognizerIntent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, "com.dummy");
        }
        
        recognizer.setRecognitionListener(listener);
        recognizer.startListening(recognizerIntent);
    }

    public static String diagnoseErrorCode(int errorCode)
    {
        String message;
        switch (errorCode)
        {
            case SpeechRecognizer.ERROR_AUDIO:
                message = "Audio recording error";
                break;
            case SpeechRecognizer.ERROR_CLIENT:
                message = "Client side error";
                break;
            case SpeechRecognizer.ERROR_INSUFFICIENT_PERMISSIONS:
                message = "Insufficient permissions";
                break;
            case SpeechRecognizer.ERROR_NETWORK:
                message = "Network error";
                break;
            case SpeechRecognizer.ERROR_NETWORK_TIMEOUT:
                message = "Network timeout";
                break;
            case SpeechRecognizer.ERROR_NO_MATCH:
                message = "No match";
                break;
            case SpeechRecognizer.ERROR_RECOGNIZER_BUSY:
                message = "RecognitionService busy";
                break;
            case SpeechRecognizer.ERROR_SERVER:
                message = "error from server";
                break;
            case SpeechRecognizer.ERROR_SPEECH_TIMEOUT:
                message = "No speech input";
                break;
            default:
                message = "Didn't understand, please try again.";
                break;
        }
        return message;
    }
}