Develop Reference

onfocuschanged never gets called for surfaceview (android)

In my android app i have activity containing a surfaceview. I want to start the surfaceview thread when the surfaceview/activity is visible to user. I have tried starting the thread in OnSurfaceCreated. That works but on some mobiles(samsung) The activity takes many seconds to become visible.The screen turns black when i resume activity. So i googled and found that when a view becomes visible onFocusChanged is called. I tried implementing OnFocusChanged in surfaceview but it is never called. below is my surfaceview class.
public class ImageSurface extends SurfaceView implements SurfaceHolder.Callback {
private DrawThread drawThread;
private SurfaceHolder sHolder;
private ImageHolder imageHolder;
Bitmap mybit;
Bitmap orgiBitmap;// ;)
int message;
Context context;
private String valMagField;
public ImageSurface(Context context, AttributeSet attrs) {
super(context, attrs);
this.context=context;
SurfaceHolder holder = getHolder();
holder.addCallback(this);
setFocusable(true);
clearFocus();
drawThread = new DrawThread(context);
}
public void setImageHolder(ImageHolder imageHolder){
this.imageHolder = imageHolder;
}
public void setBitmap(String filePath){
}
public void resume(){
drawThread.resumeThread();
}
#Override
public void onFocusChanged(boolean focus,int direction,Rect rect){
super.onFocusChanged(focus, direction, rect);
Log.d("in focus changed","onfocuschanged"+System.currentTimeMillis());
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
drawThread.setSurfaceSize(width, height);
resume();
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
long startTime, stopTime;
startTime = System.currentTimeMillis();
sHolder = holder;
drawThread.setRunning(true);
if(drawThread.getState()==Thread.State.NEW){
drawThread.start();
}
if(drawThread.getState()==Thread.State.TERMINATED){
drawThread = new DrawThread(context);
drawThread.setRunning(true);
drawThread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
drawThread.pauseThread();
}
class DrawThread extends Thread{
int value=0;
private Boolean drun;
int valSize =30;
Context context;
private int sHeight , sWidth;
int lastmessage;
boolean threadPaused= false;
public DrawThread(Context context){
drun = false;
this.context = context;
}
public void pauseThread(){
synchronized(this){
threadPaused = true;
this.notify();
}
}
public void resumeThread(){
synchronized(this){
threadPaused = false;
this.notify();
}
}
public void setRunning(Boolean run){
drun = run;
}
public boolean isRunning(){
return drun;
}
public void setSurfaceSize(int width , int height){
sWidth = width;
sHeight = height;
}
#Override
public void run(){
while(drun){
Canvas c = null;
//Log.d("yes","thread is running");
try{
synchronized(this){
if(threadPaused)
try {
this.wait();
} catch (InterruptedException e) {
Log.d("in wait of surface view thread","error"+e.toString());
}
}
c = sHolder.lockCanvas(null);
synchronized(sHolder){
updateCanvas(c);
}
}finally {
if(c!=null){
sHolder.unlockCanvasAndPost(c);
}
}
}
}
private void updateCanvas(Canvas canvas){
try{
if(imageHolder.dispBit!= null){
int x=(sWidth-imageHolder.dispBit.getWidth())/2,y=(sHeight-imageHolder.dispBit.getHeight())/2;
imageHolder.applyEffects();
if(canvas!=null)
canvas.drawBitmap(imageHolder.dispBit, x,y,null);
}
else if(imageHolder!=null)
imageHolder.setDisplaySize(sWidth, sHeight);
}catch(Exception e){
e.printStackTrace();
}
}
}
}

How can I bring to front an object in SurfaceView

Is there any way to get objects to foregorund in surfaceView.
for example:
canvas.drawBitmap(...);
canvas.drawText(...);
If I do that text appeared on bitmap. How can I reverse it without redrawing
Sorry for my English.

Canvas just encapsulates bitmap object and bitmap only saves colour of pixel at some position, it doesn't save separate layers. It's like to draw in MSPaint. So you can't change the Z-order of your primitives on canvas. However, why don't you just change the order of commands?

There is no method to bring elements front and back. You are trying to alter the Z-order of the elements here and this is not possible or there is no direct method in Android. All you can do is arrange them in the layout and enable and disable views so that it will give you the same effect.
You can use addView() or setVisibility(View.Visible) to bring bring elements back and front.

Please try to use bellow code.
//SurfaceView class
public class MainGamePanel extends SurfaceView implements
SurfaceHolder.Callback {
MainThread thread;
public MainGamePanel(Context context) {
super(context);
// TODO Auto-generated constructor stub
getHolder().addCallback(this);
setFocusable(true);
thread = new MainThread(getHolder(), this);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
Log.e("N", "Changed");
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
Log.e("N", "Created");
thread.setRunning(true);
thread.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
Log.e("N", "Destroyed");
boolean retry = true;
while (retry) {
try {
thread.join();
retry = false;
} catch (InterruptedException e) {
// try again shutting down the thread
}
}
}
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
if (event.getY() > getHeight() - 50) {
thread.setRunning(false);
((Activity) getContext()).finish();
} else {
Log.d("N", "Coords: x=" + event.getX() + ",y=" + event.getY());
}
}
return super.onTouchEvent(event);
}
}
//MainThread class
public class MainThread extends Thread {
// flag to hold game state
private boolean running;
private SurfaceHolder surfaceHolder;
private MainGamePanel gamePanel;
public void setRunning(boolean running) {
this.running = running;
}
public MainThread(SurfaceHolder surfaceHolder, MainGamePanel gamePanel) {
super();
this.surfaceHolder = surfaceHolder;
this.gamePanel = gamePanel;
}
#Override
public void run() {
long tickCount = 0L;
Log.d("N", "Starting game loop");
while (running) {
tickCount++;
// update game state
// render state to the screen
}
Log.d("N", "Game loop executed " + tickCount + " times");
}
}
//Main Activity
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MainGamePanel(this));
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}

Surfaceview ANR onResume

I'm working on a Android game using SurfaceView, the game works fine, so I want to pause it when the user hits HOME key but when getting back the SurfaceView disappears(black background Edit: sometimes the drawing appears) and buttons are inactive in both cases then I get ANR.
public class MainActivity extends Activity {
private Game game;
MainPanel mp;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
game = new Game();
LoadLevel();
Init();
setContentView(R.layout.main);//contains surfaceview and buttons
mp = (MainPanel) findViewById(R.id.SurfaceView01);
mp.Init(game,this);
Button btnTop = (Button) findViewById(R.id.buttonTop);
Button btnBottom = (Button) findViewById(R.id.buttonBottom);
Button btnLeft = (Button) findViewById(R.id.buttonLeft);
Button btnRight = (Button) findViewById(R.id.buttonRight);
btnTop.setOnClickListener...
}
private void Init() {
...
}
public void LoadLevel() {
...
}
#Override
protected void onResume() {
super.onResume();
Log.d("Tag","Resume");
}
#Override
protected void onPause() {
super.onPause();
Log.d("Tag","Pause");
}
}
public class MainPanel extends SurfaceView implements SurfaceHolder.Callback {
private MainThread thread;
private Game game;
private MainActivity act;
public MainPanel(Context context, AttributeSet attrs) {
super(context,attrs);
getHolder().addCallback(this);
}
public MainThread getThread() {
return thread;
}
public void Init(Game game, MainActivity act){
this.game = game;
this.act = act;
}
public void Move(int dir) {
...
}
public void update() {
...
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {}
#Override
public void surfaceCreated(SurfaceHolder holder) {
if (thread == null) {
thread = new MainThread(getHolder(), this);
thread.Start();
thread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
thread.Stop();
boolean retry = true;
while (retry) {
try {
thread.join();
retry = false;
} catch (InterruptedException e) {}
}
thread = null;
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.BLACK);
//drawing...
}
}
public class MainThread extends Thread {
private final static int MAX_FPS = 30;
private final static int MAX_FRAME_SKIPS = 3;
private final static int FRAME_PERIOD = 1000 / MAX_FPS;
private SurfaceHolder surfaceHolder;
private MainPanel gamePanel;
private boolean run = false;
private boolean start = false;
public MainThread(SurfaceHolder surfaceHolder, MainPanel gamePanel) {
super();
this.surfaceHolder = surfaceHolder;
this.gamePanel = gamePanel;
}
public void Start() {
this.run = true;
this.start = true;
}
public void Pause() {
this.start = false;
}
public void Resume() {
this.start = true;
}
public void Stop() {
this.run = false;
}
#Override
public void run() {
Canvas c = null;
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
while(run) {
while(start) {
try {
c = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
beginTime = System.currentTimeMillis();
framesSkipped = 0; // resetting the frames skipped
// update game state
gamePanel.update();
// render state to the screen draws the canvas on the panel
if(c!=null) gamePanel.onDraw(c);
// 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 update without rendering
gamePanel.update();
// add frame period to check if in next frame
sleepTime += FRAME_PERIOD;
framesSkipped++;
}
}
} finally {
if (c != null) surfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
}

Thx to this post why is my runnable giving ANR? I could solve the problem, I isolated the MainThread from the UI thread for further details check the best answer.

Refreshing canvas?

I try to display one from list of bitmaps during onDraw.
When i'm passing list to the canvas all are display and stay in their places.
When I pass one random bitmaps it's redrawing canvas all the time.
All works when i'm using public void drawEnemy(Canvas canvas) but not exactly like I want when using public void drawEn(Canvas canvas).
I want to display one random bitmap, then after a few seconds, delete it and display other bitmap. I think the problem is how I implemented onDrow() method. It's redrawing canvas all the time.
Activity:
public class NewGameActivity extends Activity{
NewGame newgame;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
// Landscape mode
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
// no title
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
// content Newgame.java
newgame = new NewGame(this);
setContentView(newgame);
}
Thread:
public class MainThread extends Thread{
private SurfaceHolder surfaceHolder;
private NewGame screen;
public MainThread(SurfaceHolder surfaceHolder, NewGame ekran) {
super();
this.surfaceHolder = surfaceHolder;
this.screen= screen;
}
private boolean running;
public void setRunning(boolean running) {
this.running = running;
}
#Override
public void run() {
Canvas canvas;
while (running) {
canvas = null;
try {
canvas = this.surfaceHolder.lockCanvas();
synchronized (surfaceHolder) {
this.screen.onDraw(canvas);
}
} finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
SurfaceView:
public class NewGame extends SurfaceView implements SurfaceHolder.Callback{
private MainThread thread;
private EnemyManager manager;
public NewGame(Context context) {
super(context);
getHolder().addCallback(this);
thread = new MainThread(getHolder(), this);
manager = new EnemyManager();
// TODO Auto-generated constructor stub
//adding enemy
Enemy e1 = new Enemy(BitmapFactory.decodeResource(getResources(), R.drawable.card), 1);
Enemy e2 = new Enemy(BitmapFactory.decodeResource(getResources(), R.drawable.horse), 2);
EnemyLocation l1 = new EnemyLocation(60, 180);
EnemyLocation l2 = new EnemyLocation(60, 50);
manager.AddEnemy(e1, l1);
manager.AddEnemy(e2, l2);
setFocusable(true);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.saloon), 0, 0, null);
manager.drawEn(canvas);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
thread.setRunning(true);
thread.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
thread.setRunning(false);
thread.stop();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
manager.handleActionDown((int)event.getX(), (int)event.getY());
}
return true;
}
}
EnemyManager:
public class EnemyManager {
private ArrayList<Enemy> enemyList;
private ArrayList<Enemy> suspects;
private Enemy cow;
private String message;
private int suspectID;
private Random rnd;
public String getMessage() {
return message;
}
public EnemyManager(){
enemyList = new ArrayList<Enemy>();
suspects = new ArrayList<Enemy>();
}
public void AddEnemy(Enemy enemy, EnemyLocation loc){
// set x,y enemy localization
enemy.setX(loc.getX());
enemy.setY(loc.getY());
enemyList.add(enemy);
}
public void clearEnemy() {
enemyList.clear();
}
// message if enemy touched
public void handleActionDown(int x, int y) {
for (Enemy enemy: enemyList) {
if (enemy.wasTouched(x, y)) {
message = enemy.getId();
return;
}
}
}
public void PrepareEnemy(){
suspectID = enemyList.get(rnd.nextInt(enemyList.size()+1)).getId();
suspects = new ArrayList<Enemy>();
suspects.add(getSuspectByID(suspectID));
}
private Enemy SingleEnemy(){
Double i = 1 + Math.random() * ((enemyList.size()-1)+1);
cow = getSuspectByID(i.intValue());
return cow;
}
private Enemy getSuspectByID(int suspectID) {
for (Enemy s: enemyList) {
if (s.getId() == suspectID) {
return s;
}
}
return null;
}
public void drawEn(Canvas canvas){
try {
Enemy k = SingleEnemy();
canvas.drawBitmap(cow.picture, cow.x, cow.y, null);
} catch (Exception e) {
// TODO: handle exception
}
}
// draw enemy
public void drawEnemy(Canvas canvas) {
try {
for (Enemy enemy: enemyList) {
canvas.drawBitmap(enemy.picture, enemy.x, enemy.y, null);
}
} catch (Exception e) {
// TODO: handle exception
}
}
}
das

As for as understand you are trying to do something like this (if it's not, please correct me):
This is rendering the canvas with all components:
Draw background
Draw enemy
To "refresh" the canvas you simply do something like this:
Draw background
Update
To pause the rendering you could do something like this:
int lastUpdateTime;
int delayTime = 2000; 2 seconds
if(System.currenttimeMillis() > lastUpdateTime + delayTime) {
// Finished waiting
}
You should only define lastUpdateTime when you want to wait and not in every iteration.
NB: Don't call Thread.sleep() in a rendering thread!

How can I change the picture that draws on the screen

This might seem like a silly qustion but how do you change the picture that draws on the screen.I have already been able to program a app were it draws a little icon where you touch the screen.So natually after I completed that I want to make it better by adding a option menu and the ability to change what icon you were being drown but when I ran the code the icon picture stayed the same.When I looked at it I found that when you click on any of the menu item it does do it's job and change the image id but when you go back to the main screen and try to create a new image it revertes back to the old image.I have no idea why it doesn't change because when I look at it everything make sense for it to change icon properly.If any one has any idea on what i am doing wrong or any suggestion on how to do this it would be greatly appreciate
Main
public class main extends Activity {
/** Called when the activity is first created. */
MenuItem item2;
int item3=R.drawable.ic_launcher;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FrameLayout sv = new FrameLayout(this);
LinearLayout ll = new LinearLayout(this);
Panel test = new Panel(this);
//ImageButton button = new ImageButton(this);
ll.setOrientation(LinearLayout.VERTICAL);
sv.addView(test);
//ll.addView(button);
sv.addView(ll);
setContentView(sv);
}
public boolean onCreateOptionsMenu(Menu menu) {
// TODO Auto-generated method stub
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// TODO Auto-generated method stub
Log.v("test", "item3 before is: "+item3);
item3=R.drawable.box;
Log.v("test", "item3 after is: "+item3);
return super.onOptionsItemSelected(item);
}
}
Panel
public class Panel extends SurfaceView implements SurfaceHolder.Callback {
private Bitmap image;
private ViewThread mThread;
private int x;
private int y;
private ArrayList<Element> mElements = new ArrayList<Element>();
public Panel(Context context) {
super(context );
image = BitmapFactory.decodeResource(getResources(),yantz.imageapp4.R.drawable.test);
getHolder().addCallback(this);
mThread = new ViewThread(this);
}
public void doDraw(Canvas canvas) {
canvas.drawColor(Color.CYAN);
canvas.drawBitmap(image, x, y, null);
synchronized (mElements){
for(Element element : mElements){
element.doDraw(canvas);
}
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
Log.v("test", "you have touched the sreen: ");
synchronized (mElements){
mElements.add(new Element(getResources(),(int) event.getX(),(int) event.getY()));
}
return super.onTouchEvent(event);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
if (!mThread.isAlive()) {
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
if (mThread.isAlive()) {
mThread.setRunning(false);
}
}
}
Elements
public class Element extends main{
private int mX;
private int mY;
int location ;
private Bitmap mBitmap;
public Element(Resources res, int x, int y) {
Log.v("element", "item3 before location is: "+item3);
location =item3;
mBitmap = BitmapFactory.decodeResource(res, location);
mX = x - mBitmap.getWidth() / 2;
mY = y - mBitmap.getHeight() / 2;
Log.v("element", "item3 before location is: "+item3);
}
public void doDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, mX, mY, null);
}
public void setlocation(int location2){
location=location2;
}
}
ViewThread
public class ViewThread extends Thread {
private Panel mPanel;
private SurfaceHolder mHolder;
private boolean mRun = false;
public ViewThread(Panel panel) {
mPanel = panel;
mHolder = mPanel.getHolder();
}
public void setRunning(boolean run) {
mRun = run;
}
#Override
public void run() {
Canvas canvas = null;
while (mRun) {
canvas = mHolder.lockCanvas();
if (canvas != null) {
mPanel.doDraw(canvas);
mHolder.unlockCanvasAndPost(canvas);
}
}
}
}

you can use
#Override
protected void onResume() {
super.onResume();
id="what ever you want";
//and set it to imagevIew;
}
if i have understood the uestion correctly,this happens because your activity pauses when it is not focused and resumes with default values.