Add default button to vibration/volume settings dialog

Change-Id: I7beb4517314efdefeb47d91b14a6b02c3075c19f
diff --git a/java/res/values/strings.xml b/java/res/values/strings.xml
index 5c54427..fd7aac4 100644
--- a/java/res/values/strings.xml
+++ b/java/res/values/strings.xml
@@ -376,4 +376,7 @@
     <string name="prefs_keypress_vibration_duration_settings">Keypress vibration duration settings</string>
     <!-- Title of the settings for keypress sound volume -->
     <string name="prefs_keypress_sound_volume_settings">Keypress sound volume settings</string>
+
+    <!-- Title of the button to revert to the default value of the device in the settings dialog [CHAR LIMIT=15] -->
+    <string name="button_default">Default</string>
 </resources>
diff --git a/java/src/com/android/inputmethod/latin/Settings.java b/java/src/com/android/inputmethod/latin/Settings.java
index f592a25..a720203 100644
--- a/java/src/com/android/inputmethod/latin/Settings.java
+++ b/java/src/com/android/inputmethod/latin/Settings.java
@@ -168,19 +168,21 @@
     public static float readKeypressSoundVolume(final SharedPreferences prefs,
             final Resources res) {
         final float volume = prefs.getFloat(PREF_KEYPRESS_SOUND_VOLUME, -1.0f);
-        if (volume >= 0) {
-            return volume;
-        }
+        return (volume >= 0) ? volume : readDefaultKeypressSoundVolume(res);
+    }
+
+    public static float readDefaultKeypressSoundVolume(final Resources res) {
         return Float.parseFloat(
                 ResourceUtils.getDeviceOverrideValue(res, R.array.keypress_volumes));
     }
 
-    public static int readVibrationDuration(final SharedPreferences prefs,
+    public static int readKeypressVibrationDuration(final SharedPreferences prefs,
             final Resources res) {
         final int ms = prefs.getInt(PREF_VIBRATION_DURATION_SETTINGS, -1);
-        if (ms >= 0) {
-            return ms;
-        }
+        return (ms >= 0) ? ms : readDefaultKeypressVibrationDuration(res);
+    }
+
+    public static int readDefaultKeypressVibrationDuration(final Resources res) {
         return Integer.parseInt(
                 ResourceUtils.getDeviceOverrideValue(res, R.array.keypress_vibration_durations));
     }
diff --git a/java/src/com/android/inputmethod/latin/SettingsFragment.java b/java/src/com/android/inputmethod/latin/SettingsFragment.java
index a4f0d99..6a43718 100644
--- a/java/src/com/android/inputmethod/latin/SettingsFragment.java
+++ b/java/src/com/android/inputmethod/latin/SettingsFragment.java
@@ -180,7 +180,7 @@
                     });
             mKeypressVibrationDurationSettingsPref.setSummary(
                     res.getString(R.string.settings_keypress_vibration_duration,
-                            Settings.readVibrationDuration(prefs, res)));
+                            Settings.readKeypressVibrationDuration(prefs, res)));
         }
 
         mKeypressSoundVolumeSettingsPref =
@@ -312,12 +312,24 @@
                 sp.edit().putInt(Settings.PREF_VIBRATION_DURATION_SETTINGS, value).apply();
             }
 
+            private void feedbackSettingsValue(final int value) {
+                AudioAndHapticFeedbackManager.getInstance().vibrate(value);
+            }
+
             @Override
             public void onPositiveButtonClick(final SeekBarDialog dialog) {
                 writePreference(sp, dialog.getValue());
             }
 
             @Override
+            public void onNeutralButtonClick(final SeekBarDialog dialog) {
+                final int defaultValue =
+                        Settings.readDefaultKeypressVibrationDuration(context.getResources());
+                dialog.setValue(defaultValue, false /* fromUser */);
+                writePreference(sp, defaultValue);
+            }
+
+            @Override
             public void onDismiss(final SeekBarDialog dialog) {
                 if (settingsPref != null) {
                     settingsPref.setSummary(dialog.getValueText());
@@ -326,13 +338,13 @@
 
             @Override
             public void onStopTrackingTouch(final SeekBarDialog dialog) {
-                final int ms = dialog.getValue();
-                AudioAndHapticFeedbackManager.getInstance().vibrate(ms);
+                feedbackSettingsValue(dialog.getValue());
             }
         };
-        final int currentMs = Settings.readVibrationDuration(sp, getResources());
+        final int currentMs = Settings.readKeypressVibrationDuration(sp, getResources());
         final SeekBarDialog.Builder builder = new SeekBarDialog.Builder(context);
         builder.setTitle(R.string.prefs_keypress_vibration_duration_settings)
+                .setNeutralButtonText(R.string.button_default)
                 .setListener(listener)
                 .setMaxValue(AudioAndHapticFeedbackManager.MAX_KEYPRESS_VIBRATION_DURATION)
                 .setValueFromat(R.string.settings_keypress_vibration_duration)
@@ -359,12 +371,24 @@
                 sp.edit().putFloat(Settings.PREF_KEYPRESS_SOUND_VOLUME, value).apply();
             }
 
+            private void feedbackSettingsValue(final float value) {
+                am.playSoundEffect(AudioManager.FX_KEYPRESS_STANDARD, value);
+            }
+
             @Override
             public void onPositiveButtonClick(final SeekBarDialog dialog) {
                 writePreference(sp, dialog.getValue() / PERCENT_FLOAT);
             }
 
             @Override
+            public void onNeutralButtonClick(final SeekBarDialog dialog) {
+                final float defaultValue =
+                        Settings.readDefaultKeypressSoundVolume(context.getResources());
+                dialog.setValue((int)(defaultValue * PERCENT_INT), false /* fromUser */);
+                writePreference(sp, defaultValue);
+            }
+
+            @Override
             public void onDismiss(final SeekBarDialog dialog) {
                 if (settingsPref != null) {
                     settingsPref.setSummary(dialog.getValueText());
@@ -373,13 +397,13 @@
 
             @Override
             public void onStopTrackingTouch(final SeekBarDialog dialog) {
-                final float volume = dialog.getValue() / PERCENT_FLOAT;
-                am.playSoundEffect(AudioManager.FX_KEYPRESS_STANDARD, volume);
+                feedbackSettingsValue(dialog.getValue() / PERCENT_FLOAT);
             }
         };
         final SeekBarDialog.Builder builder = new SeekBarDialog.Builder(context);
         final int currentVolumeInt = getCurrentKeyPressSoundVolumePercent(sp, getResources());
         builder.setTitle(R.string.prefs_keypress_sound_volume_settings)
+                .setNeutralButtonText(R.string.button_default)
                 .setListener(listener)
                 .setMaxValue(PERCENT_INT)
                 .setValue(currentVolumeInt)
diff --git a/java/src/com/android/inputmethod/latin/SettingsValues.java b/java/src/com/android/inputmethod/latin/SettingsValues.java
index fac85a8..0d3feaa 100644
--- a/java/src/com/android/inputmethod/latin/SettingsValues.java
+++ b/java/src/com/android/inputmethod/latin/SettingsValues.java
@@ -139,7 +139,7 @@
         mBigramPredictionEnabled = readBigramPredictionEnabled(prefs, res);
 
         // Compute other readable settings
-        mKeypressVibrationDuration = Settings.readVibrationDuration(prefs, res);
+        mKeypressVibrationDuration = Settings.readKeypressVibrationDuration(prefs, res);
         mKeypressSoundVolume = Settings.readKeypressSoundVolume(prefs, res);
         mKeyPreviewPopupDismissDelay = Settings.readKeyPreviewPopupDismissDelay(prefs, res);
         mAutoCorrectionThreshold = readAutoCorrectionThreshold(res,