Develop Reference

Unable to get screen width & height in surface holder in android?

i am new to android and stuck with getting screen size. Here is my code,
package com.piyush.droidz;
import android.app.Activity;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import com.piyush.droidz.model.boy;
public class MainGamePanel extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = MainGamePanel.class.getSimpleName();
private GameThread td;
private boy b1;
private int s_width;
private int s_height;
public MainGamePanel(Context context) {
super(context);
getHolder().addCallback(this);
Log.d(TAG, "Screen width=" + s_width);
b1 = new boy(BitmapFactory.decodeResource(getResources(), R.drawable.boy), 50, 50);
td = new GameThread(getHolder(), this);
setFocusable(true);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
s_width = getHolder().getSurfaceFrame().width();
Log.d(TAG, "Present Screen width=" + s_width);
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
td.setRunning(true);
td.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
td.setRunning(false);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
b1.handleActionDown((int)event.getX(), (int)event.getY());
if (event.getY()>getHeight()-50) {
td.setRunning(false);
((Activity) getContext()).finish();
}
else {
Log.d(TAG, "Coordinates: X="+event.getX()+", Y="+event.getY());
}
}
if (event.getAction()==MotionEvent.ACTION_MOVE) {
if (b1.isTouched()) {
b1.setX((int)event.getX());
b1.setY((int)event.getY());
}
}
if (event.getAction()==MotionEvent.ACTION_UP) {
b1.setTouched(false);
}
return true;
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.parseColor("#ff0000"));
b1.draw(canvas);
}
}
in the first log-tag it shows 0 where as in the second log-tag it shows exact width of emulator. I have tried initializing the "s_width" with getHolder().getSurfaceFrame().width() even before the constructor but still "s_width" is 0. Also tried WindowManagerand getwindowManager() but it is not recognized by IDE in this class. Here is my Activity class,
package com.piyush.droidz;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class DroidzActivity extends Activity {
MainGamePanel mgp;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mgp = new MainGamePanel(this);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(mgp);
}
}
please help!

Have you tried?
DisplayMetrics metrics = new DisplayMetrics();
WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
windowManager.getDefaultDisplay().getMetrics(metrics);
You need to use context for getting the WindowManager. please see the documentation
http://developer.android.com/reference/android/view/WindowManager.html
Preferably the above should be done inside the constructor
public MainGamePanel(Context context) {}
Hope it helps. :)

How to clear canvas in a surface view?

I am developing an Android Digital signature app in which user can sign and i have to save this file as image.i am using SurfaceView for drawing. DigitalSignatureActivity has two Buttons Save,Clear.
1.Save Button to save file as image
2.Clear Button to clear surface.
But i am unable to clear the surface.i tried drawingSurface.setBackgroundColor(Color.BLACK); still previous sign is retained and canvas.drawColor(Color.BLACK); has no effect and
i am able to save file but its not storing signature perfectly(Some contents are missing) please help.
My code is:
DigitalSignatureActivity.java
package com.pop.digitalsign;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.os.Environment;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;
public class DigitalSignatureActivity extends Activity implements
View.OnTouchListener {
private DrawingSurface drawingSurface;
private DrawingPath currentDrawingPath;
private Paint currentPaint;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setCurrentPaint();
drawingSurface = (DrawingSurface) findViewById(R.id.drawingSurface);
drawingSurface.setOnTouchListener(this);
}
private void setCurrentPaint() {
currentPaint = new Paint();
currentPaint.setDither(true);
currentPaint.setColor(Color.WHITE);
currentPaint.setStyle(Paint.Style.STROKE);
currentPaint.setStrokeJoin(Paint.Join.ROUND);
currentPaint.setStrokeCap(Paint.Cap.ROUND);
currentPaint.setStrokeWidth(2);
}
public boolean onTouch(View view, MotionEvent motionEvent) {
if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
drawingSurface.setBackgroundColor(0);
currentDrawingPath = new DrawingPath();
currentDrawingPath.paint = currentPaint;
currentDrawingPath.path = new Path();
currentDrawingPath.path.moveTo(motionEvent.getX(),
motionEvent.getY());
currentDrawingPath.path.lineTo(motionEvent.getX(),
motionEvent.getY());
} else if (motionEvent.getAction() == MotionEvent.ACTION_MOVE) {
currentDrawingPath.path.lineTo(motionEvent.getX(),motionEvent.getY());
drawingSurface.addDrawingPath(currentDrawingPath);
} else if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
currentDrawingPath.path.lineTo(motionEvent.getX(),motionEvent.getY());
}
return true;
}
//To save file as Image
public void saveDrawing(View v) throws IOException {
File mediaStorageDir = new File(
Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MySignatures");
Bitmap nBitmap = drawingSurface.getBitmap();
try {
if (!mediaStorageDir.exists()) {
mediaStorageDir.mkdirs();
}
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
File mediaFile = new File(mediaStorageDir.getPath()
+ File.separator + "SIGN_" + timeStamp + ".png");
FileOutputStream out = new FileOutputStream(mediaFile);
nBitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
out.flush();
out.close();
Toast.makeText(this, "Signature saved to " + mediaFile,
Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Not saved",
Toast.LENGTH_SHORT).show();
}
}
//To clear Surface
public void clearScreen(View v) {
//drawingSurface.setBackgroundColor(Color.BLACK);
drawingSurface.clear();
}
}
DrawingSurface.java
package com.pop.digitalsign;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class DrawingSurface extends SurfaceView implements SurfaceHolder.Callback {
private Boolean _run;
protected DrawThread thread;
private Bitmap mBitmap;
Canvas canvas;
private CommandManager commandManager;
public DrawingSurface(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
commandManager = new CommandManager();
thread = new DrawThread(getHolder());
}
class DrawThread extends Thread{
public SurfaceHolder mSurfaceHolder;
public DrawThread(SurfaceHolder surfaceHolder){
mSurfaceHolder = surfaceHolder;
}
public DrawThread() {
// TODO Auto-generated constructor stub
}
public void setRunning(boolean run) {
_run = run;
}
#Override
public void run() {
canvas = null;
while (_run){
try{
canvas = mSurfaceHolder.lockCanvas(null);
//canvas.drawColor(Color.WHITE);
if(mBitmap == null){
mBitmap = Bitmap.createBitmap (1, 1, Bitmap.Config.ARGB_8888);;
}
final Canvas c = new Canvas (mBitmap);
c.drawColor(0, PorterDuff.Mode.CLEAR);
commandManager.executeAll(c);
canvas.drawBitmap (mBitmap, 0, 0,null);
} finally {
if(canvas!=null){
mSurfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
public void addDrawingPath (DrawingPath drawingPath){
commandManager.addCommand(drawingPath);
}
public void clear(){
//Here i want to clear surface
canvas.drawColor(Color.BLACK);//it has no effect
}
public boolean hasMoreUndo(){
return commandManager.hasMoreUndo();
}
public Bitmap getBitmap(){
return mBitmap;
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
mBitmap = Bitmap.createBitmap (width, height, Bitmap.Config.ARGB_8888);;
}
public void surfaceCreated(SurfaceHolder holder) {
thread.setRunning(true);
thread.start();
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
thread.setRunning(false);
while (retry) {
try {
thread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
}
CommandManager.java
package com.pop.digitalsign;
import android.graphics.Canvas;
import java.util.Iterator;
import java.util.List;
import java.util.Collections;
import java.util.ArrayList;
public class CommandManager {
private List<DrawingPath> currentStack;
public CommandManager(){
currentStack = Collections.synchronizedList(new ArrayList<DrawingPath>());
}
public void addCommand(DrawingPath command){
currentStack.add(command);
}
public void undo (){
final int length = currentStackLength();
if ( length > 0) {
final DrawingPath undoCommand = currentStack.get( length - 1 );
currentStack.remove( length - 1 );
undoCommand.undo();
}
}
public int currentStackLength(){
final int length = currentStack.toArray().length;
return length;
}
public void executeAll( Canvas canvas){
if( currentStack != null ){
synchronized( currentStack ) {
final Iterator<?> i = currentStack.iterator();
while ( i.hasNext() ){
final DrawingPath drawingPath = (DrawingPath) i.next();
drawingPath.draw( canvas );
}
}
}
}
public boolean hasMoreUndo(){
return currentStack.toArray().length > 0;
}
}
DrawingPath.java
package com.pop.digitalsign;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
public class DrawingPath {
public Path path;
public Paint paint;
public void draw(Canvas canvas) {
canvas.drawPath( path, paint );
}
public void undo() {
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#android:color/white" >
<com.pop.digitalsign.DrawingSurface
android:id="#+id/drawingSurface"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:gravity="center" >
<Button
android:id="#+id/saveBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="saveDrawing"
android:text="#string/save" />
<Button
android:id="#+id/clearBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="clearScreen"
android:text="#string/clear" />
</LinearLayout>
</RelativeLayout>

the best suggestion i have is to use this
if (surfaceHolder.getSurface().isValid()) {
Canvas c = surfaceHolder.lockCanvas();
if (first >= 0) {
c.drawARGB(255, 255, 255, 255);
first--;
}
The value of first is 2 you can use what every name you want.
The reason is that the canvas is double buffered so you need to clear both screen by painting it white.
This stops the flickering

canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)

In DrawingSurface add this method
public void resetCanvas(){ commandManager.clearAllPath(); }
and call this method, when you need to action for clear..
objectNameofDrawingSurefaceClass.resetCanvas();
add the code in CommandManager
public void clearAllPath(){currentStack.clear(); }
ok..

cant create Region while drawing on android canvas

I have this code
package com.cerbertek;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Region;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class PlayGameView extends SurfaceView implements SurfaceHolder.Callback {
private CanvasThread canvasthread;
private Context mContext;
private Region firstRec;
private ArrayList<Region> regions;
private class CanvasThread extends Thread {
private SurfaceHolder _holder;
private boolean _run = false;
public CanvasThread(SurfaceHolder surfaceHolder) {
_holder = surfaceHolder;
}
public void setRunning(boolean run) {
_run = run;
}
#Override
public void run() {
Canvas c;
while (_run) {
c = null;
try {
c = _holder.lockCanvas(null);
synchronized (_holder) {
onDraw(c);
}
} finally {
if (c != null) {
_holder.unlockCanvasAndPost(c);
}
}
}
}
}
public PlayGameView (Context context, AttributeSet attrs) {
super(context, attrs);
SurfaceHolder holder = getHolder();
holder.addCallback(this);
canvasthread = new CanvasThread(getHolder());
setFocusable(true);
}
#Override
public void onDraw(Canvas canvas) {
Paint paint = new Paint ();
Bitmap wrench = BitmapFactory.decodeResource(getResources(), R.drawable.wrench);
canvas.drawColor(Color .BLACK);
for(int i = 0; i < 4; i++) {
for(int j = 0; j < 4; j++) {
int left = canvas.getWidth()/2 - wrench.getWidth()*2 + j*wrench.getWidth();
int top = 0 + i*wrench.getHeight();
canvas.drawBitmap(wrench, left, top, null);
Log.d(i + " " + j, left+ " " + top);
Region reg = new Region(left, top, left + wrench.getWidth(), top + wrench.getHeight());
regions.add(reg);
}
}
}
public ArrayList<Region> getRegions() {
return regions;
}
#Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
}
#Override
public void surfaceCreated(SurfaceHolder arg0) {
canvasthread.setRunning(true);
canvasthread.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder arg0) {
boolean retry = true;
canvasthread.setRunning(false);
while (retry) {
try {
canvasthread.join();
retry = false;
} catch (InterruptedException e) {
// we will try it again and again...
}
}
}
}
in onDraw() method I want to create a Region and add it to ArrayList, that returning by getRegions() method.
But it now works!
I saw first image and then NullPoiterExeption on regions.add(reg); line.
Please hlp me

In the constructor put:
regions = new ArrayList<Region>();
You were forgetting to initialize it.

How to make SurfaceView with transparent background?

I have simple layout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/RelativeLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/backgroundtimer"
android:orientation="vertical" >
<TextView
android:id="#+id/TextView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="#string/hello" />
<com.fmech.zenclock.surface.ZenClockSurface
android:id="#+id/zenClockSurface1"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"/>
</RelativeLayout>
And a have ZenClockSurface class
package com.fmech.zenclock.surface;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class ZenClockSurface extends SurfaceView implements SurfaceHolder.Callback{
private DrawClock drawClock;
public ZenClockSurface(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context) {
super(context);
this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context, AttributeSet attrs) {
super(context, attrs);
this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
getHolder().addCallback(this);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
//this.getHolder().setFormat(PixelFormat.TRANSPARENT);
drawClock = new DrawClock(getHolder(), getResources());
drawClock.setRunning(true);
drawClock.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
// завершаем работу потока
drawClock.setRunning(false);
while (retry) {
try {
drawClock.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
class DrawClock extends Thread{
private boolean runFlag = false;
private SurfaceHolder surfaceHolder;
private Bitmap picture;
private Matrix matrix;
private long prevTime;
private Paint painter;
public DrawClock(SurfaceHolder surfaceHolder, Resources resources){
this.surfaceHolder = surfaceHolder;
this.surfaceHolder.setFormat(PixelFormat.TRANSLUCENT);
picture = BitmapFactory.decodeResource(resources, R.drawable.ic_launcher);
matrix = new Matrix();
this.painter=new Paint();
this.painter.setStyle(Paint.Style.FILL);
}
public void setRunning(boolean run) {
runFlag = run;
}
#Override
public void run() {
Canvas canvas;
while (runFlag) {
matrix.preRotate(1.0f, picture.getWidth() / 2, picture.getHeight() / 2);
canvas = null;
try {
//surfaceHolder.getSurface().setAlpha(0.5f);
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
canvas.drawColor(Color.TRANSPARENT);
canvas.drawBitmap(picture, matrix, this.painter);
}
}
finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
}
And code of activity
package com.fmech.zenclock.surface;
import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
public class ZenClockSurfaceActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFormat(PixelFormat.TRANSLUCENT);
setContentView(R.layout.main);
}
}
I want what background color of android picture was tranparent but i get black background.
I have background on RelativeLayout with some picture bu SurfaceView rotate Android icon with no transparent.
How i can do transparent?

Yeah, i did it i solve problem
Activity code
package com.fmech.zenclock.surface;
import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class ZenClockSurfaceActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ZenClockSurface sfvTrack = (ZenClockSurface)findViewById(R.id.zenClockSurface1);
sfvTrack.setZOrderOnTop(true); // necessary
SurfaceHolder sfhTrack = sfvTrack.getHolder();
sfhTrack.setFormat(PixelFormat.TRANSLUCENT);
}
}
Surface Code
package com.fmech.zenclock.surface;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PixelFormat;
import android.graphics.Region;
import android.util.AttributeSet;
import android.view.Surface.OutOfResourcesException;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class ZenClockSurface extends SurfaceView implements
SurfaceHolder.Callback {
private DrawClock drawClock;
public ZenClockSurface(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context) {
super(context);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
drawClock = new DrawClock(getHolder(), getResources());
drawClock.setRunning(true);
drawClock.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
drawClock.setRunning(false);
while (retry) {
try {
drawClock.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
class DrawClock extends Thread {
private boolean runFlag = false;
private SurfaceHolder surfaceHolder;
private Bitmap picture;
private Matrix matrix;
private Paint painter;
public DrawClock(SurfaceHolder surfaceHolder, Resources resources) {
this.surfaceHolder = surfaceHolder;
picture = BitmapFactory.decodeResource(resources,
R.drawable.ic_launcher);
matrix = new Matrix();
this.painter = new Paint();
this.painter.setStyle(Paint.Style.FILL);
this.painter.setAntiAlias(true);
this.painter.setFilterBitmap(true);
}
public void setRunning(boolean run) {
runFlag = run;
}
#Override
public void run() {
Canvas canvas;
while (runFlag) {
matrix.preRotate(1.0f, picture.getWidth() / 2,
picture.getHeight() / 2);
canvas = null;
try {
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
canvas.drawBitmap(picture, matrix, this.painter);
}
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
}
It's work.

In API 3 and 4, you cannot put anything behind a SurfaceView. Quoting Dianne Hackborn:
The surface view is actually BEHIND your window, and a hole punched in the window for you to see it. You thus can put things on top of it in your window, but nothing in your window can appear behind it.
http://groups.google.com/group/android-developers/browse_thread/thread/8d88ef9bb22da574
From API 5 onwards you can use setZOrderOnTop. The trick is that you have to do it in your constructor so it gets called before the view is attached to the window:
public ZenClockSurface(Context context, AttributeSet attrs) {
super(context, attrs);
setZOrderOnTop(true);
SurfaceHolder holder = getHolder();
holder.setFormat(PixelFormat.TRANSLUCENT);
}

Android Surfaceview Threads and memory leaks

Im creating a game in android, and i noticed that the game has a memory leak. Iv managed to isolate the memory leak into a smaller application so that i can see well try and work out, how to fix it.
The application uses a surfaceview for its view and has a thread attached to that in order to do all the drawing to the screen. The memory leak happens when i start a new activity and close the one that im currently using. I can see this when i do a memory dump on my test application as all it does is open and close an activity (activity a -> activity b -> activity a). Iv kind of ran out of ideas as to how i can fix this as iv tried nulling all my references that i do create to the view (inside the thread), iv tried removing the callback from the surfaceview when i destroy the view, and also inside the activity, it doesn't seem to make any difference.
MemoryLeakActivity.java
package memory.leak;
import memory.leak.view.MemoryLeak;
import android.app.Activity;
import android.os.Bundle;
public class MemoryLeakActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MemoryLeak(this));
}
}
MemoryLeakViewThread.java
package memory.leak.thread;
import memory.leak.view.MemoryLeak;
import android.view.SurfaceHolder;
import android.graphics.Canvas;
public class MemoryLeakViewThread extends Thread {
private MemoryLeak view;
private boolean run =false;
public MemoryLeakViewThread(MemoryLeak view) {
this.view =view;
}
public void setRunning(boolean run) {
this.run =run;
}
#Override
public void run() {
Canvas canvas =null;
SurfaceHolder holder =this.view.getHolder();
while(this.run) {
canvas =holder.lockCanvas();
if(canvas !=null) {
this.view.onDraw(canvas);
holder.unlockCanvasAndPost(canvas);
}
}
holder =null;
this.view =null;
}
}
MemoryLeak.java
package memory.leak.view;
import memory.leak.TestActivity;
import memory.leak.thread.MemoryLeakViewThread;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.GestureDetector.OnGestureListener;
public class MemoryLeak extends SurfaceView implements SurfaceHolder.Callback, OnGestureListener {
private GestureDetector gesture;
private MemoryLeakViewThread vThread;
private Context context;
public MemoryLeak(Context context) {
super(context);
this.getHolder().addCallback(this);
this.vThread =new MemoryLeakViewThread(this);
this.gesture =new GestureDetector(this);
this.context =context;
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
public void surfaceCreated(SurfaceHolder holder) {
if(!this.vThread.isAlive()) {
this.vThread =new MemoryLeakViewThread(this);
this.vThread.setRunning(true);
this.vThread.start();
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
if(this.vThread.isAlive()) {
this.vThread.setRunning(false);
while(retry) {
try {
this.vThread.join();
retry =false;
} catch(Exception ee) {}
}
}
this.vThread =null;
this.context =null;
}
public boolean onTouchEvent(MotionEvent event) {
return this.gesture.onTouchEvent(event);
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
}
#Override
public void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);
}
#Override
public boolean onDown(MotionEvent e) {
return true;
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}
#Override
public void onLongPress(MotionEvent e) {}
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return false;
}
#Override
public void onShowPress(MotionEvent e) {}
#Override
public boolean onSingleTapUp(MotionEvent e) {
Intent helpScreenIntent =new Intent(this.context, TestActivity.class);
this.context.startActivity(helpScreenIntent);
if (this.context instanceof Activity)
((Activity) this.context).finish();
return true;
}
}
TestActivity.java
package memory.leak;
import memory.leak.view.Test;
import android.app.Activity;
import android.os.Bundle;
public class TestActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new Test(this));
}
}
TestViewThread.java
package memory.leak.thread;
import memory.leak.view.Test;
import android.view.SurfaceHolder;
import android.graphics.Canvas;
public class TestViewThread extends Thread {
private Test panel;
private boolean run =false;
public TestViewThread(Test panel) {
this.panel =panel;
}
public void setRunning(boolean run) {
this.run =run;
}
#Override
public void run() {
Canvas canvas =null;
SurfaceHolder holder =this.panel.getHolder();
while(this.run) {
canvas =holder.lockCanvas();
if(canvas !=null) {
this.panel.onDraw(canvas);
holder.unlockCanvasAndPost(canvas);
}
}
holder =null;
this.panel =null;
}
}
Test.java
package memory.leak.view;
import memory.leak.MemoryLeakActivity;
import memory.leak.thread.TestViewThread;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.GestureDetector.OnGestureListener;
public class Test extends SurfaceView implements SurfaceHolder.Callback, OnGestureListener {
private GestureDetector gesture;
private TestViewThread vThread;
private Context context;
public Test(Context context) {
super(context);
this.getHolder().addCallback(this);
this.vThread =new TestViewThread(this);
this.gesture =new GestureDetector(this);
this.context =context;
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
public void surfaceCreated(SurfaceHolder holder) {
if(!this.vThread.isAlive()) {
this.vThread =new TestViewThread(this);
this.vThread.setRunning(true);
this.vThread.start();
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
if(this.vThread.isAlive()) {
this.vThread.setRunning(false);
while(retry) {
try {
this.vThread.join();
retry =false;
} catch(Exception ee) {}
}
}
this.vThread =null;
this.context =null;
}
public boolean onTouchEvent(MotionEvent event) {
return this.gesture.onTouchEvent(event);
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
}
#Override
public void onDraw(Canvas canvas) {
canvas.drawColor(Color.RED);
}
#Override
public boolean onDown(MotionEvent e) {
return true;
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}
#Override
public void onLongPress(MotionEvent e) {}
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return false;
}
#Override
public void onShowPress(MotionEvent e) {}
#Override
public boolean onSingleTapUp(MotionEvent e) {
Intent helpScreenIntent =new Intent(this.context, MemoryLeakActivity.class);
this.context.startActivity(helpScreenIntent);
if (this.context instanceof Activity)
((Activity) this.context).finish();
return true;
}
}
--Edit--
I made changes to the view class to its surfaceDestroyed(SurfaceHolder holder) so that it will set the view that the thread has to null when the thread is told to stop. The changes i made are
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
if(this.vThread.isAlive()) {
this.vThread.setRunning(false);
while(retry) {
try {
this.vThread.join();
retry =false;
} catch(Exception ee) {}
}
this.vThread.setRunning(false, null);
}
this.vThread =null;
this.context =null;
this.gesture =null;
}
you also need to change the surfaceCreated(SurfaceHolder holder) method to
public void surfaceCreated(SurfaceHolder holder) {
if(!this.vThread.isAlive()) {
this.vThread =new MemoryLeakViewThread();
this.vThread.setRunning(true, this);
this.vThread.start();
}
}
then on the thread class we need to change the following
public MemoryLeakViewThread() {
}
public void setRunning(boolean run) {
this.run =run;
}
public void setRunning(boolean run, MemoryLeak view) {
this.run =run;
this.view =view;
}
By doing this it seemed to of fixed the problem, the only problem now is the thread seems to stay in memory, due to the thread class and thread group. But im thinking this might be due to the debugger.

You should not create new Thread in the constructor when you are creating it in onSurfaceCreated. Compare your code to my example: How can I use the animation framework inside the canvas?

As you can see here:
http://developer.android.com/resources/articles/avoiding-memory-leaks.html
The easiest way to start a memory leak in Android is to pass a view's constructor the whole activity instead of the application context. Have you try to change this line:
setContentView(new MemoryLeak(this));
into this one:
setContentView(new MemoryLeak(Context.getApplicationContext()));
?
Hope it helps.