Create an App Widget in Android with Text-to-Speech (TTS)

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11. Create a Settings screen

Creating a Settings screen is easy with help of ADT.

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Go to File > New > Other... and select Android Object within Android folder in the wizard. Click Next and select Settings Activity in listed templates. Click Next, Next, and Finish.

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All the necessary code will get generated in the project. Let's take a look at the modifications we've done to the SettingsActivity class.

	public class SettingsActivity extends PreferenceActivity {
		
		public static String TTS_PREF = "tts_pref";
		public static String ALPHABET_PREF = "alphabet_pref";
		public static String INTERVAL_PREF = "interval_pref";
		public static String DEFAULT_INTERVAL = "60";
		public static String ALL_ALPHABET = "*";	
		
		private static final boolean ALWAYS_SIMPLE_PREFS = true;
		
		@Override
		protected void onCreate(Bundle savedInstanceState) {
			super.onCreate(savedInstanceState);
			setTitle(getString(R.string.title_activity_settings));
			setupActionBar();
		}
		
		@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
		private void setupActionBar() {
			if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
				getActionBar().setDisplayHomeAsUpEnabled(false);
				getActionBar().setDisplayUseLogoEnabled(true);
			}
			if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
				getActionBar().setHomeButtonEnabled(false);
			}
		}	
		
		@Override
		protected void onPostCreate(Bundle savedInstanceState) {
			super.onPostCreate(savedInstanceState);

			setupSimplePreferencesScreen();
		}

		private void setupSimplePreferencesScreen() {
			if (!isSimplePreferences(this)) {
				return;
			}

			// In the simplified UI, fragments are not used at all and we instead
			// use the older PreferenceActivity APIs.

			// Add 'general' preferences.
			addPreferencesFromResource(R.xml.pref_general);
			
			// Bind the summaries of EditText/List/Dialog/Ringtone preferences
			// to their values. When their values change, their summaries are
			// updated to reflect the new value, per the Android Design
			// guidelines.
			bindPreferenceSummaryToValue(findPreference(TTS_PREF));
			bindPreferenceSummaryToValue(findPreference(ALPHABET_PREF));
			bindPreferenceSummaryToValue(findPreference(INTERVAL_PREF));		
		}	

		@Override
		public boolean onIsMultiPane() {
			return isXLargeTablet(this) && !isSimplePreferences(this);
		}

		private static boolean isXLargeTablet(Context context) {
			return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
		}

		private static boolean isSimplePreferences(Context context) {
			return ALWAYS_SIMPLE_PREFS
					|| Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB
					|| !isXLargeTablet(context);
		}

		@Override
		@TargetApi(Build.VERSION_CODES.HONEYCOMB)
		public void onBuildHeaders(List<Header> target) {
			if (!isSimplePreferences(this)) {
				loadHeadersFromResource(R.xml.pref_headers, target);
			}
		}

		private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
			@Override
			public boolean onPreferenceChange(Preference preference, Object value) {
				String stringValue = value.toString();

				if (preference instanceof ListPreference) {
					// For list preferences, look up the correct display value in
					// the preference's 'entries' list.
					ListPreference listPreference = (ListPreference) preference;
					int index = listPreference.findIndexOfValue(stringValue);

					// Set the summary to reflect the new value.
					preference.setSummary(index >= 0 ? listPreference.getEntries()[index] : null);

				} else {
					// For all other preferences, set the summary to the value's
					// simple string representation.
					preference.setSummary(stringValue);
				}
				return true;
			}
		};

		private static void bindPreferenceSummaryToValue(Preference preference) {
			// Set the listener to watch for value changes.
			preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
			
			if (TTS_PREF.equals(preference.getKey())) return;

			// Trigger the listener immediately with the preference's
			// current value.
			sBindPreferenceSummaryToValueListener.onPreferenceChange(
					preference,
					PreferenceManager.getDefaultSharedPreferences(preference.getContext()).getString(preference.getKey(), ""));
		}
		
		//------------------------------------------------------------------------

		@TargetApi(Build.VERSION_CODES.HONEYCOMB)
		public static class GeneralPreferenceFragment extends PreferenceFragment {
			@Override
			public void onCreate(Bundle savedInstanceState) {
				super.onCreate(savedInstanceState);
				addPreferencesFromResource(R.xml.pref_general);

				// Bind the summaries of EditText/List/Dialog/Ringtone preferences
				// to their values. When their values change, their summaries are
				// updated to reflect the new value, per the Android Design
				// guidelines.
				bindPreferenceSummaryToValue(findPreference(TTS_PREF));
				bindPreferenceSummaryToValue(findPreference(ALPHABET_PREF));
				bindPreferenceSummaryToValue(findPreference(INTERVAL_PREF));
			}
		}	

	}
					

We have removed unnecessary preferences and have kept only General preferences for our simple requirement. There is a corresponding pref_general.xml file in res/xml directory that we've also modified.

	<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
		
		<Preference 
			android:summary="@string/app_desc" />    
		
		<ListPreference
			android:defaultValue="*"
			android:entries="@array/alphabets"
			android:entryValues="@array/alphabets"
			android:key="alphabet_pref"
			android:negativeButtonText="@null"
			android:positiveButtonText="@null"
			android:title="Show words beginning with" />    

		<ListPreference
			android:defaultValue="60"
			android:entries="@array/refresh_interval_titles"
			android:entryValues="@array/refresh_interval_values"
			android:key="interval_pref"
			android:negativeButtonText="@null"
			android:positiveButtonText="@null"
			android:title="Refresh interval" />
		
		<CheckBoxPreference
			android:defaultValue="false"
			android:key="tts_pref"
			android:summary="Listen to words and their meanings"
			android:title="Enable Text-to-speech" />    

	</PreferenceScreen>
						

Next, we will add code to detect TTS support before user can enable Text-to-Speech. We will use the code that we discussed in previous section.

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Modify SettingsActivity class as follows.

	private static final int TTS_CHECK_CODE = 101;
	
	private static WeakReference<Activity> weakActivity;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		//...
		weakActivity = new WeakReference<Activity>(this);
	}	
	
	private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
		@Override
		public boolean onPreferenceChange(Preference preference, Object value) {
			String stringValue = value.toString();

			if (TTS_PREF.equals(preference.getKey())){
				if ("true".equalsIgnoreCase(value.toString())) {
					Intent checkIntent = new Intent();
					checkIntent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
					
					Activity activity = weakActivity != null ? weakActivity.get() : null;
					if (activity != null) {
						activity.startActivityForResult(checkIntent, TTS_CHECK_CODE);
					}
					return false;
				}
				
			}
			
			//...
			
			return true;
		}
	};

	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
	    if (requestCode == TTS_CHECK_CODE) {
	        if (resultCode == TextToSpeech.Engine.CHECK_VOICE_DATA_PASS) {
	            // success, create the TTS instance
	        	CheckBoxPreference cbPreference = (CheckBoxPreference) findPreference(TTS_PREF);
	        	cbPreference.setChecked(true);
	        	
	        } else {
	        	Toast.makeText(this, getString(R.string.setup_tts), Toast.LENGTH_LONG).show();
	        	
	            // missing data, install it
	            Intent installIntent = new Intent();
	            installIntent.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
	            startActivity(installIntent);
	        }
	    }
	}	
					

Basically, we allow user to enable TTS only if its supported on the device, otherwise direct him to the Play Store.

27. What's next?

We've learned to create a simple but useful app widget in this tutorial. You can read more about creating sophisticated widgets from the official Android developers site. You might find the following resources useful.

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• Developing App Widgets
• App Widget Design Guidelines
• App Widget patterns

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