Android example source code file (VolumePreference.java)

This example Android source code file (VolumePreference.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, audiomanager, basesavedstate, contentobserver, dialog, handler, media, os, override, parcelable, photo, savedstate, seekbar, seekbarvolumizer, sound, uri, video, view, volumepreference, volumestore

The VolumePreference.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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 android.preference;

import android.app.Dialog;
import android.content.Context;
import android.content.res.TypedArray;
import android.database.ContentObserver;
import android.media.AudioManager;
import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Handler;
import android.os.Parcel;
import android.os.Parcelable;
import android.provider.Settings;
import android.provider.Settings.System;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.view.View;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

/**
 * @hide
 */
public class VolumePreference extends SeekBarPreference implements 
        PreferenceManager.OnActivityStopListener, View.OnKeyListener {

    private static final String TAG = "VolumePreference";
    
    private int mStreamType;

    /** May be null if the dialog isn't visible. */
    private SeekBarVolumizer mSeekBarVolumizer;
    
    public VolumePreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        
        TypedArray a = context.obtainStyledAttributes(attrs,
                com.android.internal.R.styleable.VolumePreference, 0, 0);
        mStreamType = a.getInt(android.R.styleable.VolumePreference_streamType, 0);
        a.recycle();        
    }

    public void setStreamType(int streamType) {
        mStreamType = streamType;
    }

    @Override
    protected void onBindDialogView(View view) {
        super.onBindDialogView(view);
    
        final SeekBar seekBar = (SeekBar) view.findViewById(com.android.internal.R.id.seekbar);
        mSeekBarVolumizer = new SeekBarVolumizer(getContext(), seekBar, mStreamType);

        getPreferenceManager().registerOnActivityStopListener(this);

        // grab focus and key events so that pressing the volume buttons in the
        // dialog doesn't also show the normal volume adjust toast.
        view.setOnKeyListener(this);
        view.setFocusableInTouchMode(true);
        view.requestFocus();
    }

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        // If key arrives immediately after the activity has been cleaned up.
        if (mSeekBarVolumizer == null) return true;
        boolean isdown = (event.getAction() == KeyEvent.ACTION_DOWN);
        switch (keyCode) {
            case KeyEvent.KEYCODE_VOLUME_DOWN:
                if (isdown) {
                    mSeekBarVolumizer.changeVolumeBy(-1);
                }
                return true;
            case KeyEvent.KEYCODE_VOLUME_UP:
                if (isdown) {
                    mSeekBarVolumizer.changeVolumeBy(1);
                }
                return true;
            default:
                return false;
        }
    }

    @Override
    protected void onDialogClosed(boolean positiveResult) {
        super.onDialogClosed(positiveResult);
        
        if (!positiveResult && mSeekBarVolumizer != null) {
            mSeekBarVolumizer.revertVolume();
        }

        cleanup();
    }

    public void onActivityStop() {
        cleanup();
    }

    /**
     * Do clean up.  This can be called multiple times!
     */
    private void cleanup() {
       getPreferenceManager().unregisterOnActivityStopListener(this);

       if (mSeekBarVolumizer != null) {
           Dialog dialog = getDialog();
           if (dialog != null && dialog.isShowing()) {
               View view = dialog.getWindow().getDecorView()
                       .findViewById(com.android.internal.R.id.seekbar);
               if (view != null) view.setOnKeyListener(null);
               // Stopped while dialog was showing, revert changes
               mSeekBarVolumizer.revertVolume();
           }
           mSeekBarVolumizer.stop();
           mSeekBarVolumizer = null;
       }

    }

    protected void onSampleStarting(SeekBarVolumizer volumizer) {
        if (mSeekBarVolumizer != null && volumizer != mSeekBarVolumizer) {
            mSeekBarVolumizer.stopSample();
        }
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        final Parcelable superState = super.onSaveInstanceState();
        if (isPersistent()) {
            // No need to save instance state since it's persistent
            return superState;
        }

        final SavedState myState = new SavedState(superState);
        if (mSeekBarVolumizer != null) {
            mSeekBarVolumizer.onSaveInstanceState(myState.getVolumeStore());
        }
        return myState;
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (state == null || !state.getClass().equals(SavedState.class)) {
            // Didn't save state for us in onSaveInstanceState
            super.onRestoreInstanceState(state);
            return;
        }

        SavedState myState = (SavedState) state;
        super.onRestoreInstanceState(myState.getSuperState());
        if (mSeekBarVolumizer != null) {
            mSeekBarVolumizer.onRestoreInstanceState(myState.getVolumeStore());
        }
    }

    public static class VolumeStore {
        public int volume = -1;
        public int originalVolume = -1;
    }

    private static class SavedState extends BaseSavedState {
        VolumeStore mVolumeStore = new VolumeStore();

        public SavedState(Parcel source) {
            super(source);
            mVolumeStore.volume = source.readInt();
            mVolumeStore.originalVolume = source.readInt();
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeInt(mVolumeStore.volume);
            dest.writeInt(mVolumeStore.originalVolume);
        }

        VolumeStore getVolumeStore() {
            return mVolumeStore;
        }

        public SavedState(Parcelable superState) {
            super(superState);
        }

        public static final Parcelable.Creator<SavedState> CREATOR =
                new Parcelable.Creator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

    /**
     * Turns a {@link SeekBar} into a volume control.
     */
    public class SeekBarVolumizer implements OnSeekBarChangeListener, Runnable {

        private Context mContext;
        private Handler mHandler = new Handler();
    
        private AudioManager mAudioManager;
        private int mStreamType;
        private int mOriginalStreamVolume; 
        private Ringtone mRingtone;
    
        private int mLastProgress = -1;
        private SeekBar mSeekBar;
        
        private ContentObserver mVolumeObserver = new ContentObserver(mHandler) {
            @Override
            public void onChange(boolean selfChange) {
                super.onChange(selfChange);
                if (mSeekBar != null) {
                    int volume = System.getInt(mContext.getContentResolver(),
                            System.VOLUME_SETTINGS[mStreamType], -1);
                    // Works around an atomicity problem with volume updates
                    // TODO: Fix the actual issue, probably in AudioService
                    if (volume >= 0) {
                        mSeekBar.setProgress(volume);
                    }
                }
            }
        };

        public SeekBarVolumizer(Context context, SeekBar seekBar, int streamType) {
            mContext = context;
            mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
            mStreamType = streamType;
            mSeekBar = seekBar;
            
            initSeekBar(seekBar);
        }

        private void initSeekBar(SeekBar seekBar) {
            seekBar.setMax(mAudioManager.getStreamMaxVolume(mStreamType));
            mOriginalStreamVolume = mAudioManager.getStreamVolume(mStreamType);
            seekBar.setProgress(mOriginalStreamVolume);
            seekBar.setOnSeekBarChangeListener(this);
            
            mContext.getContentResolver().registerContentObserver(
                    System.getUriFor(System.VOLUME_SETTINGS[mStreamType]),
                    false, mVolumeObserver);
    
            Uri defaultUri = null;
            if (mStreamType == AudioManager.STREAM_RING) {
                defaultUri = Settings.System.DEFAULT_RINGTONE_URI;
            } else if (mStreamType == AudioManager.STREAM_NOTIFICATION) {
                defaultUri = Settings.System.DEFAULT_NOTIFICATION_URI;
            } else {
                defaultUri = Settings.System.DEFAULT_ALARM_ALERT_URI;
            }

            mRingtone = RingtoneManager.getRingtone(mContext, defaultUri);
            if (mRingtone != null) {
                mRingtone.setStreamType(mStreamType);
            }
        }
        
        public void stop() {
            stopSample();
            mContext.getContentResolver().unregisterContentObserver(mVolumeObserver);
            mSeekBar.setOnSeekBarChangeListener(null);
        }
        
        public void revertVolume() {
            mAudioManager.setStreamVolume(mStreamType, mOriginalStreamVolume, 0);
        }
        
        public void onProgressChanged(SeekBar seekBar, int progress,
                boolean fromTouch) {
            if (!fromTouch) {
                return;
            }
    
            postSetVolume(progress);
        }

        void postSetVolume(int progress) {
            // Do the volume changing separately to give responsive UI
            mLastProgress = progress;
            mHandler.removeCallbacks(this);
            mHandler.post(this);
        }
    
        public void onStartTrackingTouch(SeekBar seekBar) {
        }

        public void onStopTrackingTouch(SeekBar seekBar) {
            if (mRingtone != null && !mRingtone.isPlaying()) {
                sample();
            }
        }
        
        public void run() {
            mAudioManager.setStreamVolume(mStreamType, mLastProgress, 0);
        }
        
        private void sample() {
            onSampleStarting(this);
            mRingtone.play();
        }
    
        public void stopSample() {
            if (mRingtone != null) {
                mRingtone.stop();
            }
        }

        public SeekBar getSeekBar() {
            return mSeekBar;
        }
        
        public void changeVolumeBy(int amount) {
            mSeekBar.incrementProgressBy(amount);
            if (mRingtone != null && !mRingtone.isPlaying()) {
                sample();
            }
            postSetVolume(mSeekBar.getProgress());
        }

        public void onSaveInstanceState(VolumeStore volumeStore) {
            if (mLastProgress >= 0) {
                volumeStore.volume = mLastProgress;
                volumeStore.originalVolume = mOriginalStreamVolume;
            }
        }

        public void onRestoreInstanceState(VolumeStore volumeStore) {
            if (volumeStore.volume != -1) {
                mOriginalStreamVolume = volumeStore.originalVolume;
                mLastProgress = volumeStore.volume;
                postSetVolume(mLastProgress);
            }
        }
    }
}