/TalkBack/src/com/google/android/marvin/talkback/TalkBackPreferencesActivity.java

  1/*
  2 * Copyright 2010 Google Inc.
  3 *
  4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  5 * use this file except in compliance with the License. You may obtain a copy of
  6 * the License at
  7 *
  8 * http://www.apache.org/licenses/LICENSE-2.0
  9 *
 10 * Unless required by applicable law or agreed to in writing, software
 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 13 * License for the specific language governing permissions and limitations under
 14 * the License.
 15 */
 16
 17package com.google.android.marvin.talkback;
 18
 19import android.hardware.Sensor;
 20import android.hardware.SensorManager;
 21import android.os.Build;
 22import android.os.Bundle;
 23import android.os.Vibrator;
 24import android.preference.CheckBoxPreference;
 25import android.preference.ListPreference;
 26import android.preference.Preference;
 27import android.preference.Preference.OnPreferenceChangeListener;
 28import android.preference.PreferenceActivity;
 29import android.preference.PreferenceGroup;
 30
 31/**
 32 * Activity used to set TalkBack's service preferences. This activity is loaded
 33 * when the TalkBackService is first connected to and allows the user to select
 34 * a font zoom size.
 35 * 
 36 * @author alanv@google.com (Alan Viverette)
 37 */
 38public class TalkBackPreferencesActivity extends PreferenceActivity {
 39    /**
 40     * Loads the preferences from the XML preference definition and defines an
 41     * onPreferenceChangeListener for the font zoom size that restarts the
 42     * TalkBack service.
 43     */
 44    @Override
 45    public void onCreate(Bundle savedInstanceState) {
 46        super.onCreate(savedInstanceState);
 47
 48        addPreferencesFromResource(R.xml.preferences);
 49
 50        fixListSummaries(getPreferenceScreen());
 51
 52        checkVibrationSupport();
 53        checkProximitySupport();
 54        checkDeveloperSupport();
 55    }
 56
 57    /**
 58     * Since the "%s" summary is currently broken, this sets the preference
 59     * change listener for all {@link ListPreference} views to fill in the
 60     * summary with the current entry value.
 61     */
 62    private void fixListSummaries(PreferenceGroup group) {
 63        if (group == null) {
 64            return;
 65        }
 66
 67        final int count = group.getPreferenceCount();
 68
 69        for (int i = 0; i < count; i++) {
 70            final Preference preference = group.getPreference(i);
 71
 72            if (preference instanceof PreferenceGroup) {
 73                fixListSummaries((PreferenceGroup) preference);
 74            } else if (preference instanceof ListPreference) {
 75                preference.setOnPreferenceChangeListener(mPreferenceChangeListener);
 76            }
 77        }
 78    }
 79
 80    /**
 81     * Ensure that the vibration setting does not appear on devices without a
 82     * vibrator.
 83     */
 84    private void checkVibrationSupport() {
 85        final Vibrator vibrator = (Vibrator) getSystemService(VIBRATOR_SERVICE);
 86        final PreferenceGroup category =
 87                (PreferenceGroup) findPreferenceByResId(R.string.pref_category_feedback_key);
 88        final CheckBoxPreference prefVibration =
 89                (CheckBoxPreference) findPreferenceByResId(R.string.pref_vibration_key);
 90        final Preference prefVibrationPatterns =
 91                findPreferenceByResId(R.string.pref_vibration_patterns_key);
 92
 93        if (vibrator == null || !vibrator.hasVibrator()) {
 94            prefVibration.setChecked(false);
 95            category.removePreference(prefVibrationPatterns);
 96            category.removePreference(prefVibration);
 97        }
 98    }
 99
100    /**
101     * Ensure that the proximity sensor setting does not appear on devices
102     * without a proximity sensor.
103     */
104    private void checkProximitySupport() {
105        final SensorManager manager = (SensorManager) getSystemService(SENSOR_SERVICE);
106        final Sensor proximity = manager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
107        final PreferenceGroup category =
108                (PreferenceGroup) findPreferenceByResId(R.string.pref_category_when_to_speak_key);
109        final CheckBoxPreference prefProximity =
110                (CheckBoxPreference) findPreferenceByResId(R.string.pref_proximity_key);
111
112        if (proximity == null) {
113            prefProximity.setChecked(false);
114            category.removePreference(prefProximity);
115        }
116    }
117
118    /**
119     * Ensure that the developer settings category only appears on debug and
120     * engineering builds.
121     */
122    private void checkDeveloperSupport() {
123        final boolean isDebugBuild = Build.TYPE.contains("debug") || Build.TYPE.contains("eng");
124        final Preference developer = findPreferenceByResId(R.string.pref_category_developer_key);
125
126        if (!isDebugBuild) {
127            getPreferenceScreen().removePreference(developer);
128        }
129    }
130
131    /**
132     * Returns the preference associated with the specified resource identifier.
133     * 
134     * @param resId A string resource identifier.
135     * @return The preference associated with the specified resource identifier.
136     */
137    private Preference findPreferenceByResId(int resId) {
138        return findPreference(getString(resId));
139    }
140
141    /**
142     * Listens for preference changes and updates the summary to reflect the
143     * current setting. This shouldn't be necessary, since preferences are
144     * supposed to automatically do this when the summary is set to "%s".
145     */
146    private final OnPreferenceChangeListener mPreferenceChangeListener =
147            new OnPreferenceChangeListener() {
148                @Override
149                public boolean onPreferenceChange(Preference preference, Object newValue) {
150                    if (preference instanceof ListPreference && newValue instanceof String) {
151                        final ListPreference listPreference = (ListPreference) preference;
152                        final int index = listPreference.findIndexOfValue((String) newValue);
153                        final CharSequence[] entries = listPreference.getEntries();
154
155                        if (index >= 0 && index < entries.length) {
156                            preference.setSummary(entries[index].toString().replaceAll("%", "%%"));
157                        } else {
158                            preference.setSummary("");
159                        }
160                    }
161
162                    return true;
163                }
164            };
165}