Develop Reference

Changing object speed

I have been creating this simple game for fun, and I have ran into to some troubles.
Setting new speed on an object falling down. As the score rises for the user, I woudl want to change the speed and increase it little by little. But what happens is that the current speed just adds with the speed I want to increase so it because more faster.
This is my Activity:
public void startTimer() {
timer = new Timer();
initializeTimerTask();
timer.schedule(timerTask, 100, 20);
}
public void stoptimertask() {
if (timer != null) {
timer.cancel();
timer = null;
}
}
public void initializeTimerTask() {
timerTask = new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
goDown();
}
});
}
};
}
public void goDown() {
frame = (FrameLayout) findViewById(R.id.frame);
frameHeight = frame.getHeight();
boxY = (int) txtWord.getY();
boxSizeY = txtWord.getHeight();
if(scoreCount >= 0)
{
boxY += 1;
}
if(scoreCount >= 5)
{
boxY += 2;
}
if(scoreCount >= 10)
{
boxY += 3;
}
txtWord.setY(boxY);
if (boxY > frameHeight - boxSizeY) {
boxY = frameHeight - boxSizeY;
stoptimertask();
displayGameOver();
}
}
Thanks in advance for any insight or help! :D

if(scoreCount >= 0 && scoreCount < 5)
{
boxY += 1;
}
if(scoreCount >= 5 && scoreCount < 10)
{
boxY += 2;
}
if(scoreCount >= 10)
{
boxY += 3;
}
Try this for the speed issue.

Handler postDelay() leading unexpected variable changes

I am working on a game and I am using postDelay() to make the animations smoother. A problem I am running into is that if I execute the method with postDelay() in it, the variables that the method operates on no longer gets changed in unexpected ways. This leads to weird behavior such as the bitmaps not drawing properly.
Here are the troublesome parts:
synchronized private void rotate(int dir) {
final int originalAngle = angle; //angle is the suspicious variable
final int steps = 4;
for (int i = 0; i != steps; i++) {
smoothAnimateRotate(i, steps, originalAngle, dir);
}
finishAnimateRotate(steps);
}
private void smoothAnimateRotate(final int i, final int steps, final int originalAngle, final int dir) {
handler.postDelayed(new Runnable() {
#Override
public void run() {
angle = originalAngle + dir*(90*(i+1))/steps;
rotateStep();
}
}, 100 * (i + 1));
}
private void rotateStep() {
angle = (angle+1800) % 360;
viewdx = (int) (Math.cos(radify(angle))*(1<<16));
viewdy = (int) (Math.sin(radify(angle))*(1<<16));
moveStep();
}
private void moveStep() {
notifyViewerRedraw() ;
try {
Thread.currentThread().sleep(25);
} catch (Exception e) { }
}
When rotate() is called very quickly, I think the variable angle somehow gets messed up. This doesn't happen when I call rotate() about one second apart, but if I do it very quickly, the angle, which is only suppose to be either 0, 90, 180, or 270 gets changed to 45 degrees or something else. I can't figure out why and debugging hasn't provided fruitful results. So how do I make sure angle does get modified in such unexpected manner?

I fixed it. I put a boolean called isRunning inside the Runnables and switched it on and off.
synchronized private void rotate(int dir) {
final int originalAngle = angle;
final int steps = 4;
if (!isRunning) {
for (int i = 0; i != steps; i++) {
smoothAnimateRotate(i, steps, originalAngle, dir);
}
finishAnimateRotate(steps);
}
}
private void smoothAnimateRotate(final int i, final int steps, final int originalAngle, final int dir) {
handler.postDelayed(new Runnable() {
#Override
public void run() {
isRunning = true;
angle = originalAngle + dir*(90*(i+1))/steps;
rotateStep();
}
}, 100 * (i + 1));
}
private void finishAnimateRotate(final int steps) {
handler.postDelayed(new Runnable() {
#Override
public void run() {
rotateFinish();
isRunning = false;
}
}, 100 * (steps + 1));
}

Android game in surfaceview lagg spikes

guys. I'm playing around with making my very first Android game, but stumbled into a problem. The framerate seems to have random lag spikes. If I comment the background(s) out the framerate gets much smoother. I've looked around SO and can't find anything to solve my problems. I have a feeling it has something to do with allocating a specific amount of time every time I draw, but I don't know how to properly implement such a feature. Any suggestions? Btw, tryed hardware ac, anti etc.
This is the class that starts the surfaceview :
package com.example.glassrunner;
Imports Here
public class Game extends Activity
{
MySurfaceView mySurfaceView;
public SoundPool spool;
private int soundID;
int length=0;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.setVolumeControlStream(AudioManager.STREAM_MUSIC);
mySurfaceView = new MySurfaceView(this);
setContentView(mySurfaceView);
}
#Override
protected void onResume()
{
// TODO Auto-generated method stub
super.onResume();
mySurfaceView.onResumeMySurfaceView();
}
#Override
protected void onPause()
{
// TODO Auto-generated method stub
super.onPause();
mySurfaceView.onPauseMySurfaceView();
}
#Override
protected void onDestroy()
{
super.onDestroy();
mySurfaceView = null;
}
}
This is the surfaceview class :
package com.example.glassrunner;
Imports here
public class MySurfaceView extends SurfaceView implements Runnable
{
public static boolean gameOver = false;
SurfaceHolder surfaceHolder;
Thread thread = null;
public Integer score=0;
public SoundPool spool;
private int soundID;
int length=0;
public static MediaPlayer mp;
volatile boolean running = false;
int Yposition = 450;
int Xposition = 50;
Paint textPaint;
long mLastTime;
Bitmap background;
Bitmap background2;
Bitmap lines;
Bitmap runSprite;
Bitmap box;
Paint bitmapPaint ;
Paint textPaint2;
Bitmap scaledBackground ;
Bitmap scaledBackground2 ;
Bitmap scaledLines ;
Bitmap scaledBox;
Canvas canvas;
Paint paint;
int SpX=0;
int SpY=0;
Bitmap[][] sprite;
/** Variables for the counter */
int frameSamplesCollected = 0;
int frameSampleTime = 0;
int fps = 0;
int speed = 5;
Toast GameOverToast;
Context context;
MediaPlayer mMediaPlayer;
public MySurfaceView(Context context)
{
super(context);
this.context = context;
// TODO Auto-generated constructor stub
surfaceHolder = getHolder();
surfaceHolder.setFormat(PixelFormat.RGB_565);
CharSequence text = "Game Over!";
int duration = Toast.LENGTH_SHORT;
GameOverToast = Toast.makeText(context, text, duration);
spool = new SoundPool(10, AudioManager.STREAM_MUSIC, 0);
soundID = spool.load(context, R.raw.jump, 1);
mp = MediaPlayer.create(context, R.raw.saturdaymorningfunk);
initialization();
}
public void initialization()
{
mp.setLooping(true);
mp.start();
Options options = new Options();
options.inSampleSize = 1/4;
options.inPreferredConfig = Bitmap.Config.RGB_565;
background=BitmapFactory.decodeResource(getResources(),R.drawable.background,options);
lines=BitmapFactory.decodeResource(getResources(),R.drawable.lines);// getting the png from drawable folder
background2=BitmapFactory.decodeResource(getResources(),R.drawable.background2,options);
runSprite=BitmapFactory.decodeResource(getResources(),R.drawable.runsprite);
box=BitmapFactory.decodeResource(getResources(),R.drawable.box);
bitmapPaint = new Paint(Paint.ANTI_ALIAS_FLAG); // tool for painting on the canvas
bitmapPaint.setAntiAlias(true);
bitmapPaint.setFilterBitmap(true);
textPaint = new Paint();
textPaint.setColor(Color.RED);
textPaint.setTextSize(32);
textPaint2 = new Paint();
textPaint2.setColor(Color.BLUE);
textPaint2.setTextSize(50);
scaledBackground = Bitmap.createScaledBitmap(background, 2560, 500, true);
scaledBackground2 = Bitmap.createScaledBitmap(background2, 2560, 400, true);
scaledLines = Bitmap.createScaledBitmap(lines, 2560, 30, true);
runSprite = Bitmap.createScaledBitmap(runSprite, 1400, 1000, true);
scaledBox = Bitmap.createScaledBitmap(box, 100, 100, true);
sprite = new Bitmap[4][7];
for(int row=0;row<=3;row++)
{
for(int col=0;col<=6;col++)
{
sprite[row][col] = Bitmap.createBitmap(runSprite, SpX, SpY, 200, 250);
SpX+=200;
}
SpX=0;
SpY+=250;
}
}
public void onResumeMySurfaceView()
{
mp.seekTo(length);
mp.start();
running = true;
thread = new Thread(this);
thread.start();
}
public void onPauseMySurfaceView()
{
mp.pause();
length=mp.getCurrentPosition();
boolean retry = true;
running = false;
while(retry){
try {
thread.join();
retry = false;
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void onDestroyMySurfaceView()
{
mp.stop();
running = false;
thread = null;
thread.stop();
}
private void fps()
{
long now = System.currentTimeMillis();
if (mLastTime != 0)
{
//Time difference between now and last time we were here
int time = (int) (now - mLastTime);
frameSampleTime += time;
frameSamplesCollected++;
//After 10 frames
if (frameSamplesCollected == 10)
{
//Update the fps variable
fps = (int) (10000 / frameSampleTime);
//Reset the sampletime + frames collected
frameSampleTime = 0;
frameSamplesCollected = 0;
}
}
mLastTime = now;
}
public boolean pressDown = false;
public long pressTime;
public boolean onTouchEvent(MotionEvent event)
{
if (event != null)
{
if (event.getAction() == MotionEvent.ACTION_DOWN)
{ if(Yposition == orgPos)
{
spool.play(soundID, 15, 15, 1, 0, 1f);
pressDown = true;
pressTime = System.currentTimeMillis();
}
}else if (event.getAction() == MotionEvent.ACTION_UP)
{
pressDown = false;
}
}
return true;
}
int x=0;
int y=100;
int x2=0;
int y2=20;
int row=0;
int col=0;
int limit = 100;
int orgPos = 450;
int Xbox = 1280;
int Ybox = 580;
Random r = new Random();
int RBox;
public static String Fscore;
boolean onTop = false;
long now;
long start;
long stop;
long time ;
int spritePosition = 0 ;
int spriteSize;
#Override
public void run()
{
while(running)
{
canvas = null;
if(surfaceHolder.getSurface().isValid())
{
canvas = surfaceHolder.lockCanvas();
fps(); // fps
// Update screen parameters
update();
draw();
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
public void update()
{
if(score<500)
{
speed = 7;
}
else if(score%500 == 0)
{
speed = 7 + (score / 500);
}
if(col==6)
{
row++;
col=0;
}
if(row==4)
{
row=0;
}
score++;
Fscore = score.toString();
if(x>-1280)
{
x-=speed;
}else if(x<=-1280)
{
x=0;
}
if(x2>-1280)
{
x2-=5;
}else if(x2<=-1280)
{
x2=-0;
}
RBox = r.nextInt(999)+1280;
if(Xbox > -100)
{
Xbox-=speed;
}else if(Xbox<=-100)
{
Xbox=RBox;
}
if( (Xposition + 200 == Xbox +40 )&&(Yposition + 250 > Ybox+20)||( Xposition+200<=Xbox+70)&&( Xposition+200>=Xbox+20)&&(Yposition + 250 > Ybox+30) ) // collision
{
GameOverToast.show();
running = false;
spool.release();
mp.release();
Looper.prepare();
Intent database = new Intent(context, MainHighscore.class);
database.putExtra("score", Fscore);
context.startActivity(database);
onDestroyMySurfaceView();
}
now = System.currentTimeMillis();
if(( now - pressTime) <= 600)
{
if(Yposition > limit)
{
Yposition -= 10;
}
}
onTop = false;
if((now - pressTime) >= 600 && (now - pressTime) <= 1200)
{
if(!(Yposition == orgPos))
{
if(Yposition+250 >= Ybox && Xposition+200>=Xbox+70 && Xposition <= Xbox+40)
{
onTop=true;
Yposition = 340;
}else
{
Yposition += 10;
}
}
}
if((now - pressTime) >= 1200)
{
if(Yposition < 450) Yposition +=10;
else Yposition = 450;
}
}
public void draw()
{
canvas.drawColor(Color.WHITE);
//canvas.drawBitmap(scaledBackground, x2,y2, bitmapPaint);
canvas.drawBitmap(scaledBackground2, x,y, bitmapPaint);
canvas.drawBitmap(scaledLines, x,650, bitmapPaint);
canvas.drawText(Fscore, 1050, 50, textPaint2);
canvas.drawText(fps + " fps", getWidth() / 2, getHeight() / 2, textPaint);
canvas.drawBitmap(sprite[row][col],Xposition,Yposition,bitmapPaint );
canvas.drawBitmap(scaledBox,Xbox,Ybox,bitmapPaint);
col++;
}
}

I think your problem might be actually the moving part. Your just drawing too much stuff, and the surfaceView is not meant for that.

How to make sprites in Android

I'm developing a game which includes sprites.
currently I'm loading a bitmap and using Rectangle to get the right frame from the bitmap.
the problem is loading bitmaps takes too much memory and I wont be able to load several sprites at the same time.
what are my alternatives for doing sprite in Android?

Try this one:
import org.cocos2d.layers.CCLayer;
public class GameLayer extends CCLayer{
CCSprite mSprite;
protected GameLayer() {
super();
CGSize winSize = CCDirector.sharedDirector().winSize();
mSprite = new CCSprite("image.png");
mSprite.setPosition(CGPoint.ccp(mSprite.getContentSize().width/2.0f, mSprite.getContentSize().height/2.0f));
addChild(mSprite);
}

/* It is Sprite class */
import android.graphics.*;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
public class Sprite {
int x;
private int y;
private boolean visibility = true;
private Bitmap sprite;
private int verticalFrame,horizontalFrame;
private int frameWidth,frameHeight;
private int sequence[] = new int[1];
private int maxFrame = 0;
private int currentFrame;
private int color;
private Rect src;
private Rect dest;
private int frameCount;
private Paint p = new Paint();
private int spInitX,spInitY;
private int rotate = 0;
private float currentRotateAngle = 0;
//private Graphics g;
public float velocityY;
public float velocityX;
public int height;
public Sprite(Bitmap sprite){
this.sprite = sprite;
this.frameWidth = sprite.getWidth();
this.frameHeight = sprite.getHeight();
setFrameCount();
}
public Sprite(Bitmap sprite,int frameWidth,int frameHeight){
this.sprite = sprite;
this.frameWidth = frameWidth;
this.frameHeight = frameHeight;
setFrameCount();
}
public void rotate(float angle){
currentRotateAngle = angle;
}
public void setImage(Bitmap bm,int frameWidth,int frameHeight){
this.sprite = bm;
this.frameWidth = frameWidth;
this.frameHeight = frameHeight;
}
public Bitmap getBitmap(){
return sprite;
}
public void paint(Canvas canvas){
dest.offsetTo(getX(), getY());
// g.drawImage(sprite, x, y,src.left,src.top,frameWidth,frameHeight);
canvas.drawBitmap(sprite, src, dest, null);
}
public int getMaxFrame(){
return maxFrame;
}
public int getFrameSequenceLength(){
return sequence.length;
}
public void setFrameSequence(int seq[]){
sequence = seq;
}
public void previousFrame(){
if(sequence.length > 1){
if(frameCount > 0){
setFrame(sequence[frameCount]);
frameCount--;
}else{
frameCount = sequence.length - 1;
setFrame(sequence[frameCount]);
}
}else{
setFrame(frameCount);
if(frameCount > 0){
frameCount++;
}else{
frameCount = maxFrame - 1;
}
}
}
public void setPixel(int x,int y){
spInitX = x;
spInitY = y;
}
public void nextFrame(){
if(sequence.length > 1){
if(frameCount < sequence.length){
setFrame(sequence[frameCount]);
frameCount++;
}else{
frameCount = 0;
setFrame(sequence[frameCount]);
}
}else{
setFrame(frameCount);
if(frameCount < maxFrame){
frameCount++;
}else{
frameCount = 0;
}
}
}
public int getFrame(){
return currentFrame;
}
public void setPosition(int x,int y){
this.x = x;
this.y = y;
}
public void setFrameCount(){
verticalFrame = sprite.getHeight() / frameHeight;
horizontalFrame = sprite.getWidth() / frameWidth;
src = new Rect(0,0,frameWidth,frameHeight);
dest = new Rect(0,0,frameWidth,frameHeight);
maxFrame = verticalFrame * horizontalFrame;
}
public void setFrame(int frame){
if(frame < maxFrame){
currentFrame = frame;
}
int hf = currentFrame % horizontalFrame;
int vf = currentFrame / horizontalFrame;
src.left = hf * frameWidth;
src.right = src.left + frameWidth;
src.top = vf * frameHeight;
src.bottom = src.top + frameHeight;
}
public boolean collidesWith(Sprite sp,boolean cl){
int maxHGap = (getWidth() + sp.getWidth())/2;
int maxVGap = (getHeight() + sp.getHeight())/2;
int x = getX() + getWidth()/2;
int y = getY() + getHeight()/2;
int x1 = sp.getX() + sp.getWidth()/2;
int y1 = sp.getY() + sp.getHeight()/2;
if(Math.abs(x - x1) < maxHGap && Math.abs(y - y1) < maxVGap){
return true;
}
return false;
}
public void setVisible(boolean v){
visibility = v;
}
public final boolean isVisible(){
return visibility;
}
public int getX(){
return x;
}
public int getY(){
return y;
}
public void setX(int x) {
this.x = x;
}
public void setY(int y) {
this.y = y;
}
public void move(int moveX,int moveY){
setX(getX()+moveX);
setY(getY()+moveY);
//this.y+=y;
//this.x+=x;
}
public final int getWidth(){
return frameWidth;
}
public final int getHeight(){
return frameHeight;
}
public void setEventY(int i) {
// TODO Auto-generated method stub
}
public int getEventY() {
// TODO Auto-generated method stub
return 0;
}
}
/*Create Main Thread Class Also */
import java.text.DecimalFormat;
import android.graphics.Canvas;
import android.util.Log;
import android.view.SurfaceHolder;
public class MainThread extends Thread {
boolean isPaused;
private static final String TAG = MainThread.class.getSimpleName();
// desired fps
private final static int MAX_FPS = 50;
// maximum number of frames to be skipped
private final static int MAX_FRAME_SKIPS = 5;
// the frame period
private final static int FRAME_PERIOD = 1000 / MAX_FPS;
/* Stuff for stats */
private DecimalFormat df = new DecimalFormat("0.##"); // 2 dp
// we'll be reading the stats every second
private final static int STAT_INTERVAL = 1000; // ms
// the average will be calculated by storing
// the last n FPSs
private final static int FPS_HISTORY_NR = 10;
// last time the status was stored
private long lastStatusStore = 0;
// the status time counter
private long statusIntervalTimer = 0l;
// number of frames skipped since the game started
private long totalFramesSkipped = 0l;
// number of frames skipped in a store cycle (1 sec)
private long framesSkippedPerStatCycle = 0l;
// number of rendered frames in an interval
private int frameCountPerStatCycle = 0;
private long totalFrameCount = 0l;
// the last FPS values
private double fpsStore[];
// the number of times the stat has been read
private long statsCount = 0;
// the average FPS since the game started
private double averageFps = 0.0;
// Surface holder that can access the physical surface
private SurfaceHolder surfaceHolder;
// The actual view that handles inputs
// and draws to the surface
private GameView gv;
// flag to hold game state
private boolean running;
public void setRunning(boolean running) {
this.running = running;
}
public MainThread(SurfaceHolder surfaceHolder, GameView gv) {
super();
this.surfaceHolder = surfaceHolder;
this.gv = gv;
}
public MainThread(Setting setting) {
// TODO Auto-generated constructor stub
}
public void setPause(int i) {
synchronized (gv.getHolder()) {
if (i == 0) {
isPaused = false;
}
if (i == 1) {
isPaused = true;
}
}
}
#Override
public void run() {
Canvas canvas;
Log.d(TAG, "Starting game loop");
initTimingElements();
long beginTime; // the time when the cycle begun
long timeDiff; // the time it took for the cycle to execute
int sleepTime; // ms to sleep (<0 if we're behind)
int framesSkipped; // number of frames being skipped
sleepTime = 0;
while (running) {
canvas = null;
// try locking the canvas for exclusive pixel editing
// in the surface
try {
canvas = this.surfaceHolder.lockCanvas();
synchronized (surfaceHolder) {
beginTime = System.currentTimeMillis();
framesSkipped = 0; // resetting the frames skipped
// update game state
this.gv.update();
// render state to the screen
// draws the canvas on the panel
this.gv.render(canvas);
// calculate how long did the cycle take
timeDiff = System.currentTimeMillis() - beginTime;
// calculate sleep time
sleepTime = (int) (FRAME_PERIOD - timeDiff);
if (sleepTime > 0) {
// if sleepTime > 0 we're OK
try {
// send the thread to sleep for a short period
// very useful for battery saving
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
}
}
while (sleepTime < 0 && framesSkipped < MAX_FRAME_SKIPS) {
// we need to catch up
this.gv.update(); // update without rendering
sleepTime += FRAME_PERIOD; // add frame period to check
// if in next frame
framesSkipped++;
}
if (framesSkipped > 0) {
Log.d(TAG, "Skipped:" + framesSkipped);
}
// for statistics
framesSkippedPerStatCycle += framesSkipped;
// calling the routine to store the gathered statistics
storeStats();
}
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} finally {
// in case of an exception the surface is not left in
// an inconsistent state
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
} // end finally
}
}
private void storeStats() {
frameCountPerStatCycle++;
totalFrameCount++;
// assuming that the sleep works each call to storeStats
// happens at 1000/FPS so we just add it up
// statusIntervalTimer += FRAME_PERIOD;
// check the actual time
statusIntervalTimer += (System.currentTimeMillis() - statusIntervalTimer);
if (statusIntervalTimer >= lastStatusStore + STAT_INTERVAL) {
// calculate the actual frames pers status check interval
double actualFps = (double) (frameCountPerStatCycle / (STAT_INTERVAL / 1000));
// stores the latest fps in the array
fpsStore[(int) statsCount % FPS_HISTORY_NR] = actualFps;
// increase the number of times statistics was calculated
statsCount++;
double totalFps = 0.0;
// sum up the stored fps values
for (int i = 0; i < FPS_HISTORY_NR; i++) {
totalFps += fpsStore[i];
}
// obtain the average
if (statsCount < FPS_HISTORY_NR) {
// in case of the first 10 triggers
averageFps = totalFps / statsCount;
} else {
averageFps = totalFps / FPS_HISTORY_NR;
}
// saving the number of total frames skipped
totalFramesSkipped += framesSkippedPerStatCycle;
// resetting the counters after a status record (1 sec)
framesSkippedPerStatCycle = 0;
statusIntervalTimer = 0;
frameCountPerStatCycle = 0;
statusIntervalTimer = System.currentTimeMillis();
lastStatusStore = statusIntervalTimer;
// Log.d(TAG, "Average FPS:" + df.format(averageFps));
gv.setAvgFps("FPS: " + df.format(averageFps));
}
}
private void initTimingElements() {
// initialise timing elements
fpsStore = new double[FPS_HISTORY_NR];
for (int i = 0; i < FPS_HISTORY_NR; i++) {
fpsStore[i] = 0.0;
}
Log.d(TAG + ".initTimingElements()",
"Timing elements for stats initialised");
}
}

Lower or fade sound in android

I'm making a simple trivia game, and running a looping ~1 min mp3 file when the user arrives at the main menu. The sound is set to stop when user clicks any of the buttons on the menu (i.e. Play Game).
My problem is that when the sound stops, its kind of a jarring cut off. Rather than do .pause() or .stop(), is there a way to make the sound slowly fade out after a button is pressed?
Thanks

EDIT (3/13/13): Updated with new QA'd code
This is my entire handler class for Android MediaPlayer. Look at the play() and pause() functions. Both contain the ability to either fade or not. The updateVolume() function was the key to let the sound increase/decrease linearly.
public class MusicHandler
{
private MediaPlayer mediaPlayer;
private Context context;
private int iVolume;
private final static int INT_VOLUME_MAX = 100;
private final static int INT_VOLUME_MIN = 0;
private final static float FLOAT_VOLUME_MAX = 1;
private final static float FLOAT_VOLUME_MIN = 0;
public MusicHandler(Context context)
{
this.context = context;
}
public void load(String path, boolean looping)
{
mediaPlayer = MediaPlayer.create(context, Uri.fromFile(new File(path)));
mediaPlayer.setLooping(looping);
}
public void load(int address, boolean looping)
{
mediaPlayer = MediaPlayer.create(context, address);
mediaPlayer.setLooping(looping);
}
public void play(int fadeDuration)
{
//Set current volume, depending on fade or not
if (fadeDuration > 0)
iVolume = INT_VOLUME_MIN;
else
iVolume = INT_VOLUME_MAX;
updateVolume(0);
//Play music
if(!mediaPlayer.isPlaying()) mediaPlayer.start();
//Start increasing volume in increments
if(fadeDuration > 0)
{
final Timer timer = new Timer(true);
TimerTask timerTask = new TimerTask()
{
#Override
public void run()
{
updateVolume(1);
if (iVolume == INT_VOLUME_MAX)
{
timer.cancel();
timer.purge();
}
}
};
// calculate delay, cannot be zero, set to 1 if zero
int delay = fadeDuration/INT_VOLUME_MAX;
if (delay == 0) delay = 1;
timer.schedule(timerTask, delay, delay);
}
}
public void pause(int fadeDuration)
{
//Set current volume, depending on fade or not
if (fadeDuration > 0)
iVolume = INT_VOLUME_MAX;
else
iVolume = INT_VOLUME_MIN;
updateVolume(0);
//Start increasing volume in increments
if(fadeDuration > 0)
{
final Timer timer = new Timer(true);
TimerTask timerTask = new TimerTask()
{
#Override
public void run()
{
updateVolume(-1);
if (iVolume == INT_VOLUME_MIN)
{
//Pause music
if (mediaPlayer.isPlaying()) mediaPlayer.pause();
timer.cancel();
timer.purge();
}
}
};
// calculate delay, cannot be zero, set to 1 if zero
int delay = fadeDuration/INT_VOLUME_MAX;
if (delay == 0) delay = 1;
timer.schedule(timerTask, delay, delay);
}
}
private void updateVolume(int change)
{
//increment or decrement depending on type of fade
iVolume = iVolume + change;
//ensure iVolume within boundaries
if (iVolume < INT_VOLUME_MIN)
iVolume = INT_VOLUME_MIN;
else if (iVolume > INT_VOLUME_MAX)
iVolume = INT_VOLUME_MAX;
//convert to float value
float fVolume = 1 - ((float) Math.log(INT_VOLUME_MAX - iVolume) / (float) Math.log(INT_VOLUME_MAX));
//ensure fVolume within boundaries
if (fVolume < FLOAT_VOLUME_MIN)
fVolume = FLOAT_VOLUME_MIN;
else if (fVolume > FLOAT_VOLUME_MAX)
fVolume = FLOAT_VOLUME_MAX;
mediaPlayer.setVolume(fVolume, fVolume);
}
}

https://stackoverflow.com/a/29246026/922514
private static void crossFade() {
MediaPlayerManager.fadeOut(currentPlayer, 2000);
MediaPlayerManager.fadeIn(auxPlayer, 2000);
currentPlayer = auxPlayer;
auxPlayer = null;
}
public static void fadeOut(final MediaPlayer _player, final int duration) {
final float deviceVolume = getDeviceVolume();
final Handler h = new Handler();
h.postDelayed(new Runnable() {
private float time = duration;
private float volume = 0.0f;
#Override
public void run() {
if (!_player.isPlaying())
_player.start();
// can call h again after work!
time -= 100;
volume = (deviceVolume * time) / duration;
_player.setVolume(volume, volume);
if (time > 0)
h.postDelayed(this, 100);
else {
_player.stop();
_player.release();
}
}
}, 100); // 1 second delay (takes millis)
}
public static void fadeIn(final MediaPlayer _player, final int duration) {
final float deviceVolume = getDeviceVolume();
final Handler h = new Handler();
h.postDelayed(new Runnable() {
private float time = 0.0f;
private float volume = 0.0f;
#Override
public void run() {
if (!_player.isPlaying())
_player.start();
// can call h again after work!
time += 100;
volume = (deviceVolume * time) / duration;
_player.setVolume(volume, volume);
if (time < duration)
h.postDelayed(this, 100);
}
}, 100); // 1 second delay (takes millis)
}
public static float getDeviceVolume() {
int volumeLevel = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
return (float) volumeLevel / maxVolume;
}

You can use AudioManager:
public static final int STEP_DOWN = 5; // how far each step goes down
// later on, and in a backgroud thread like an AsyncTask
AudioManager am = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
int targetVol = 0; // or whatever you wanted.
int currentVol = am.getStreamVolume(AudioManager.STREAM_MUSIC);
while(currentVol > targetVol)
{
am.setStreamVolume(AudioManager.STREAM_MUSIC, currentVol - STEP_DOWN, 0);
currentVol = am.getStreamVolume(AudioManager.STREAM_MUSIC);
thread.sleep(100);
}
You probably also want to record the original volume they had media set to, and reset it to that after you fade out to mute and stop your music.
That code may not be exact, I don't currently have access to any way of testing it, but I hope it leads you in the right direction....