Hook up the volume parameter to a slider preference dialog.

android/res/layout/seekbar_preference.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" >
+
+    <SeekBar
+        android:id="@+id/seekBar"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:padding="20dp" />
+
+</LinearLayout>

android/res/values/strings.xml

@@ -132,5 +132,6 @@
         <string name="speak">Speak</string>
         <string name="ssml">Load SSML Template</string>
         <string name="synthesis_demo">Enter text to speak:</string>
+        <string name="espeak_volume">Volume</string>
 
 </resources>

android/src/com/reecedunn/espeak/SeekBarPreference.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2013 Reece H. Dunn
+ *
+ * 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 com.reecedunn.espeak;
+
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.SharedPreferences;
+import android.preference.DialogPreference;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.SeekBar;
+
+public class SeekBarPreference extends DialogPreference
+{
+    private SeekBar mSeekBar;
+
+    private int mProgress = 0;
+    private int mMin = 0;
+    private int mMax = 100;
+
+    public void setProgress(int progress) {
+        mProgress = progress + mMin;
+        String text = Integer.toString(mProgress);
+        callChangeListener(text);
+    }
+
+    public int getProgress() {
+        return mProgress;
+    }
+
+    public void setMin(int min) {
+        mProgress -= mMin;
+        mMin =  min;
+        mProgress += mMin;
+        String text = Integer.toString(mProgress);
+        callChangeListener(text);
+    }
+
+    public int getMin() {
+        return mMin;
+    }
+
+    public void setMax(int max) {
+        mMax =  max;
+    }
+
+    public int getMax() {
+        return mMax;
+    }
+
+    public SeekBarPreference(Context context, AttributeSet attrs, int defStyle)
+    {
+        super(context, attrs, defStyle);
+        setDialogLayoutResource(R.layout.seekbar_preference);
+        setPositiveButtonText(android.R.string.ok);
+        setNegativeButtonText(android.R.string.cancel);
+    }
+
+    public SeekBarPreference(Context context, AttributeSet attrs)
+    {
+        this(context, attrs, 0);
+    }
+
+    public SeekBarPreference(Context context)
+    {
+        this(context, null);
+    }
+
+    @Override
+    protected View onCreateDialogView() {
+        View root = super.onCreateDialogView();
+        mSeekBar = (SeekBar)root.findViewById(R.id.seekBar);
+        return root;
+    }
+
+    @Override
+    protected void onBindDialogView(View view) {
+        mSeekBar.setMax(mMax - mMin);
+        mSeekBar.setProgress(mProgress + mMin);
+    }
+
+    @Override
+    public void onClick(DialogInterface dialog, int which) {
+        switch (which) {
+            case DialogInterface.BUTTON_POSITIVE:
+                mProgress = mSeekBar.getProgress() + mMin;
+                String text = Integer.toString(mProgress);
+                callChangeListener(text);
+                SharedPreferences.Editor editor = getSharedPreferences().edit();
+                editor.putString(getKey(), text);
+                editor.commit();
+                break;
+        }
+        super.onClick(dialog, which);
+    }
+}

android/src/com/reecedunn/espeak/TtsService.java

@@ -224,6 +224,7 @@ public class TtsService extends TextToSpeechService {
         mEngine.setVoice(mMatchingVoice, null, gender, SpeechSynthesis.AGE_ANY);
         mEngine.Rate.setValue(rate, request.getSpeechRate());
         mEngine.Pitch.setValue(pitch, request.getPitch());
+        mEngine.Volume.setValue(getPreferenceValue("espeak_volume", mEngine.Volume.getDefaultValue()));
         mEngine.synthesize(text, text.startsWith("<speak"));
     }
 

android/src/com/reecedunn/espeak/TtsSettingsActivity.java

@@ -17,6 +17,8 @@
 
 package com.reecedunn.espeak;
 
+import android.content.Context;
+import android.content.SharedPreferences;
 import android.os.Build;
 import android.os.Bundle;
 import android.preference.ListPreference;
@@ -25,6 +27,7 @@ import android.preference.Preference.OnPreferenceChangeListener;
 import android.preference.PreferenceActivity;
 import android.preference.PreferenceFragment;
 import android.preference.PreferenceGroup;
+import android.preference.PreferenceManager;
 
 public class TtsSettingsActivity extends PreferenceActivity {
     @Override
@@ -41,7 +44,7 @@ public class TtsSettingsActivity extends PreferenceActivity {
         else
         {
             addPreferencesFromResource(R.xml.preferences);
-            fixListSummaries(getPreferenceScreen());
+            createPreferences(TtsSettingsActivity.this, getPreferenceScreen());
         }
     }
 
@@ -51,16 +54,40 @@ public class TtsSettingsActivity extends PreferenceActivity {
             super.onCreate(savedInstanceState);
 
             addPreferencesFromResource(R.xml.preferences);
-            fixListSummaries(getPreferenceScreen());
+            createPreferences(getActivity(), getPreferenceScreen());
         }
     }
 
+    private static Preference createPreference(Context context, SpeechSynthesis.Parameter parameter, String key, int titleRes) {
+        final String title = context.getString(titleRes);
+
+        final SeekBarPreference pref = new SeekBarPreference(context);
+        pref.setTitle(title);
+        pref.setDialogTitle(title);
+        pref.setKey(key);
+        pref.setOnPreferenceChangeListener(mOnPreferenceChanged);
+        pref.setPersistent(true);
+
+        pref.setMin(parameter.getMinValue());
+        pref.setMax(parameter.getMaxValue());
+
+        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        final String prefString = prefs.getString(key, null);
+        if (prefString == null) {
+            pref.setProgress(parameter.getDefaultValue());
+        } else {
+            pref.setProgress(Integer.parseInt(prefString));
+        }
+
+        return pref;
+    }
+
     /**
      * Since the "%s" summary is currently broken, this sets the preference
      * change listener for all {@link ListPreference} views to fill in the
      * summary with the current entry value.
      */
-    private static void fixListSummaries(PreferenceGroup group) {
+    private static void createPreferences(Context context, PreferenceGroup group) {
         if (group == null) {
             return;
         }
@@ -71,34 +98,40 @@ public class TtsSettingsActivity extends PreferenceActivity {
             final Preference preference = group.getPreference(i);
 
             if (preference instanceof PreferenceGroup) {
-                fixListSummaries((PreferenceGroup) preference);
+                createPreferences(null, (PreferenceGroup) preference);
             } else if (preference instanceof ListPreference) {
-                preference.setOnPreferenceChangeListener(mPreferenceChangeListener);
+                preference.setOnPreferenceChangeListener(mOnPreferenceChanged);
             }
         }
+
+        if (context == null) {
+            return;
+        }
+
+        SpeechSynthesis engine = new SpeechSynthesis(context, null);
+
+        group.addPreference(createPreference(context, engine.Volume, "espeak_volume", R.string.espeak_volume));
     }
 
-    /**
-     * Listens for preference changes and updates the summary to reflect the
-     * current setting. This shouldn't be necessary, since preferences are
-     * supposed to automatically do this when the summary is set to "%s".
-     */
-    private static final OnPreferenceChangeListener mPreferenceChangeListener =
+    private static final OnPreferenceChangeListener mOnPreferenceChanged =
             new OnPreferenceChangeListener() {
                 @Override
                 public boolean onPreferenceChange(Preference preference, Object newValue) {
-                    if (preference instanceof ListPreference && newValue instanceof String) {
-                        final ListPreference listPreference = (ListPreference) preference;
-                        final int index = listPreference.findIndexOfValue((String) newValue);
-                        final CharSequence[] entries = listPreference.getEntries();
-
-                        if (index >= 0 && index < entries.length) {
-                            preference.setSummary(entries[index].toString().replaceAll("%", "%%"));
-                        } else {
-                            preference.setSummary("");
+                    if (newValue instanceof String) {
+                        String summary = "";
+                        if (preference instanceof ListPreference) {
+                            final ListPreference listPreference = (ListPreference) preference;
+                            final int index = listPreference.findIndexOfValue((String) newValue);
+                            final CharSequence[] entries = listPreference.getEntries();
+
+                            if (index >= 0 && index < entries.length) {
+                                summary = entries[index].toString();
+                            }
+                        } else if (preference instanceof SeekBarPreference) {
+                            summary = (String)newValue;
                         }
+                        preference.setSummary(summary.replaceAll("%", "%%"));
                     }
-
                     return true;
                 }
             };