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Android: SurfaceView stops repainting after surfaceDestroyed()

I know similar questions have been asked before but none of those solutions worked for me.
I'm trying to create a small 2D game for Android and I am having some problems using SurfaceView.
My main activity currently looks like this:
public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
private DrawingSurface drawingsurface;
private Game game;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate()");
setFullscreen();
game = new Game();
drawingsurface = new DrawingSurface(this, game);
setContentView(drawingsurface);
}
private void setFullscreen() {
// ...
}
}
As you can see, I set my activity to fullscreen, create a new SurfaceView (called drawingSurface) and create a new game instance.
My SurfaceView (called DrawingSurface) looks like this:
public class DrawingSurface extends SurfaceView implements SurfaceHolder.Callback {
private GameThread thread;
private static final String TAG = "DrawingSurface";
public DrawingSurface(Context context, Game game) {
super(context);
getHolder().addCallback(this);
setFocusable(true);
// create a new game rendering thread and pass it game so it can call the update() and render() functions of game:
thread = new GameThread(getHolder(), this, game);
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
Log.v(TAG, "surfaceCreated()");
// start the rendering thread:
thread.setRunning(true);
thread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
Log.v(TAG, "surfaceChanged()");
// do I need to do anything in here?
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
// stop the rendering thread:
Log.v(TAG, "surfaceDestroyed()");
thread.setRunning(false);
boolean retry = true;
while (retry) {
try {
thread.join();
} catch (InterruptedException e) {
// try again shutting down the thread
}
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
// pass the touch event to the Game instance (to keep everything in on place)
thread.game.onTouchEvent(event);
return super.onTouchEvent(event);
}
#Override
protected void onDraw(Canvas canvas) {
// I don't use onDraw(), instead I have my own update() and render() functions in my game thread
super.onDraw(canvas);
}
}
This is my game thread:
public class GameThread extends Thread {
private boolean running;
private SurfaceHolder surfaceHolder;
private DrawingSurface drawingSurface;
private static final String TAG = GameThread.class.getSimpleName();
protected Game game;
public GameThread(SurfaceHolder surfaceHolder, DrawingSurface drawingSurface, Game game) {
super();
this.surfaceHolder = surfaceHolder;
this.drawingSurface = drawingSurface;
this.game = game;
}
public void setRunning(boolean running) {
this.running = running;
}
#SuppressLint("WrongCall")
#Override
public void run() {
Log.d(TAG, "Starting game loop");
long now;
long dt;
long last = System.currentTimeMillis();
Canvas canvas;
while (running) {
Log.v(TAG, "GameThread running");
canvas = null;
/* try locking the canvas for exclusive
pixel editing in the surface */
try {
canvas = this.surfaceHolder.lockCanvas();
synchronized (this.surfaceHolder) {
now = System.currentTimeMillis();
dt = (now - last);
this.game.update(dt);
if(canvas != null)
this.game.render(canvas, dt);
last = now;
}
} finally {
/*in case of an exception the surface
is not left in an inconsistent state */
if (canvas != null) {
this.surfaceHolder.unlockCanvasAndPost(canvas);
}
}
if (dt < 16) {
try {
Thread.sleep(16 - dt);
} catch (InterruptedException e) {
}
}
}
}
}
And this is the Game class:
public class Game {
private static final String TAG = "Game";
private static int playerRefPosX = 40;
private int playerY = 0;
private int playerVelY = 1;
public Game() {
Log.v(TAG, "Game instance created");
}
public void update(long dt) {
playerY += playerVelY * dt;
if (playerY > 1800) {
playerVelY = -playerVelY;
}
if (playerY < 0) {
playerVelY = -playerVelY;
}
}
public void render(Canvas canvas, long dt) {
canvas.drawColor(Color.BLACK);
// draw Player
Paint paint = new Paint();
paint.setTextSize(100);
paint.setColor(new Color().rgb(255, 0, 0));
canvas.drawRect(playerRefPosX, playerY + 100, playerRefPosX + 200, playerY - 100, paint);
canvas.drawText(String.valueOf(1000/dt), canvas.getWidth()/2, canvas.getWidth()/2, paint);
}
public void onTouchEvent(MotionEvent event) {
Log.v(TAG, "received touch event..");
}
}
The problems I am have right now:
When I press the home button and reenter the app OR rotate my device it calls surfaceDestroyed() but doesn't recreate it afterwards (the canvas doesn't get repainted)
The game rendering thread never stops (as indicated by the log messages)

Make a sprite jump

I want to make a sprite\bitmap jump using only android (no game engines). I wasn't able to find tutorials on how to do so in android using only canvas and views, but I did find a tutorial for xna(http://www.xnadevelopment.com/tutorials/thewizardjumping/thewizardjumping.shtml), and I tried to recreate it with the tools android offers. I was able to make the character move left and right using the tutorial code but making it jump just won't work.
this is my sprite class:
package com.example.spiceup;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Point;
import android.view.KeyEvent;
import android.widget.Toast;
public class Sprite {
enum State
{
Walking, Standing, Jumping
}
State mCurrentState = State.Standing;
Point mDirection;
int mSpeed = 0;
Context cc;
int mPreviousKeyboardState;
private String spriteName;
Bitmap sprite;
private int rows;
private int rows2;
int START_POSITION_X = 125;
int START_POSITION_Y = 245;
int SPRITE_SPEED = 6;
int MOVE_UP = -1;
int MOVE_DOWN = 1;
int MOVE_LEFT = -1;
int MOVE_RIGHT = 1;
Point mStartingPosition;
int aCurrentKeyboardState;
private float mScale = 1.0f;
Point Position;
public Sprite(String name,Bitmap sprite) {
this.sprite=sprite;
this.spriteName=name;
Position=new Point(150,150);
mStartingPosition=new Point(150,150);
mDirection=new Point(0,0);
}
public void Update()
{
UpdateMovement(aCurrentKeyboardState);
UpdateJump(aCurrentKeyboardState);
}
public void setkeyboard(int keyboard){
aCurrentKeyboardState = keyboard;
}
public void setLastKeyboard(int keyboard){
mPreviousKeyboardState = keyboard;
}
private void UpdateMovement(int aCurrentKeyboardState)
{
if (mCurrentState == State.Walking)
{
mSpeed = 0;
mDirection.x = 0;
if (aCurrentKeyboardState==KeyEvent.KEYCODE_A)
{
mSpeed = SPRITE_SPEED;
mDirection.x = MOVE_LEFT;
}
else if(aCurrentKeyboardState==KeyEvent.KEYCODE_D)
{
mSpeed = SPRITE_SPEED;
mDirection.x= MOVE_RIGHT;
}
Position.x += mDirection.x * mSpeed;
}
}
private void UpdateJump(int aCurrentKeyboardState)
{
if (mCurrentState == State.Walking)
{
if (aCurrentKeyboardState==KeyEvent.KEYCODE_SPACE && mPreviousKeyboardState!=KeyEvent.KEYCODE_SPACE)
{
Jump();
}
}
if (mCurrentState == State.Jumping)
{
if (mStartingPosition.y - Position.y> 150)
{
Position.y += mDirection.y * mSpeed;
mDirection.y = MOVE_DOWN;
}
if (Position.y > mStartingPosition.y)
{
Position.y = mStartingPosition.y;
mCurrentState = State.Walking;
}
}
}
private void Jump()
{
if (mCurrentState != State.Jumping)
{
mCurrentState = State.Jumping;
mStartingPosition = Position;
mDirection.y = MOVE_UP;
mSpeed = 6;
Position.y += mDirection.y * mSpeed;
}
}
public void Draw(Canvas c)
{
c.drawBitmap(sprite, Position.x,Position.y, null);
}
public void setmCurrentState(State mCurrentState) {
this.mCurrentState = mCurrentState;
}
}
this is the surfaceview:
import com.example.spiceup.Sprite.State;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.os.Handler;
import android.view.KeyEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class GameView extends SurfaceView {
Context cc;
Bitmap Sprite;
Sprite sprite2;
Handler handlerAnimation100;
private GameLoopThread gameLoopThread;
private SurfaceHolder holder;
public GameView(Context c) {
// TODO Auto-generated constructor stub
super(c);
gameLoopThread = new GameLoopThread(this);
this.cc=c;
this.Sprite=BitmapFactory.decodeResource(getResources(), R.drawable.walk1);
this.Sprite=Bitmap.createScaledBitmap(Sprite, Sprite.getWidth()*2, Sprite.getHeight()*2, false);
sprite2=new Sprite("Spicy",Sprite);
this.requestFocus();
this.setFocusableInTouchMode(true);
holder = getHolder();
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
gameLoopThread.setRunning(false);
while (retry) {
try {
gameLoopThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
gameLoopThread.setRunning(true);
gameLoopThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.BLACK);
sprite2.Update();
sprite2.Draw(canvas);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
sprite2.setkeyboard(keyCode);
sprite2.setmCurrentState(State.Walking);
return false;
}
#Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
sprite2.setmCurrentState(State.Standing);
sprite2.setLastKeyboard(keyCode);
return false;
}
}
if anyone knows where is my error or has a better code to show me I'll be happy, all I'm trying to do is to create a bitmap that moves around and can jump (but also jump while walking)

So I think what is happening in your code is that it's hitting the max height in the game loop and adding back to the y of the sprite. Second game loop run it is no longer above or near the max height distance therefore you stop going down and your start position becomes that position in the air. On a third loop through you hit spacebar again and your sprite starts the whole jumping processes over and the same thing happens on the next to loops through or however many it takes to trigger that if statement to get the sprite to start falling.
Good place to start is have a persistent boolean that determines whether or not the sprite is actually done climbing and jumping state should stay true while climbing and falling. See below.
boolean maxJumpAchieved = false;
if (mCurrentState == State.Jumping)
{
if (mStartingPosition.y - Position.y> 150)
{
maxJumpAchieved = true;
}
if (maxJumpAchieved) {
mDirection.y = MOVE_DOWN;
Position.y += mDirection.y * mSpeed;
}
if (Position.y > mStartingPosition.y)
{
maxJumpAchieved = false;
Position.y = mStartingPosition.y;
mCurrentState = State.Walking;
}
}
I think this should get you in the right direction but if you have issues let me know and I can edit my answer.
Another thing to note is don't set the mCurrentState to State.Walking until you know for sure you're on the ground otherwise you could double jump for days.

moving sprites in Android

I am making a game which requires the sprites to move towards the bottom of the screen. You can imagine it a bit like a rhythm game(guitar hero). However, I am having problems as the sprites are not moving at all even if the loop seems to work fine.
The GamePanel-
package com.jollygent.tapthepointer;
import java.util.ArrayList;
import java.util.Random;
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.view.SurfaceHolder;
import android.view.SurfaceView;
public class GamePanel extends SurfaceView{
SurfaceHolder holder;
GameLoopThread loop;
GamePanel game = this;
Random rand;
int y;
//ArrayList<Pointers> pointers = new ArrayList<Pointers>();
Pointers pointers;
public GamePanel(Context context) {
super(context);
holder = getHolder();
loop = new GameLoopThread(this);
rand = new Random();
pointers = new Pointers(rand.nextInt(4)+1,getWidth()/2,0,this);
//placeholder
this.setBackgroundColor(Color.WHITE);
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder arg0) {
// TODO Auto-generated method stub
loop.setRunning(false);
}
#Override
public void surfaceCreated(SurfaceHolder arg0) {
loop = new GameLoopThread(game);
if(!loop.isRunning()){
loop.setRunning(true);
loop.start();
}
else{
loop.setPause(false);
}
}
#Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stubn
}
});
}
public GameLoopThread getLoop(){
return loop;
}
public void update(){
}
public void draw(Canvas canvas){
pointers.draw(canvas);
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStrokeWidth(20);
paint.setStyle(Paint.Style.STROKE);
canvas.drawLine(0,getHeight()/2 + 50,getWidth(),getHeight()/2 + 50, paint);
}
}
The Pointer class
package com.jollygent.tapthepointer;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
public class Pointers {
GamePanel game;
private int x,y;
Bitmap pointer;
Bitmap rotated_pointer;
Matrix matrix;
public Pointers(int type,int x,int y,GamePanel game){
this.game = game;
this.x = x;
this.y = y;
pointer = BitmapFactory.decodeResource(game.getResources(),R.drawable.pointer_xx);
matrix = new Matrix();
switch(type){
//points right
case 1:
matrix.postRotate(90);
break;
//points left
case 2:
matrix.postRotate(-90);
break;
//points up
case 3:
rotated_pointer = pointer;
break;
//points down
case 4:
matrix.postRotate(180);
break;
}
rotated_pointer = Bitmap.createBitmap(pointer,0,0,pointer.getHeight(),pointer.getWidth(), matrix,true);
}
public void update(){
/*if(y < game.getHeight()){
y += pointer.getHeight();
}*/
}
public int getHeight(){
return pointer.getHeight();
}
public void draw(Canvas canvas){
y++;//placeholder movement to see if the sprite actually moves. It doesn't.
canvas.drawBitmap(rotated_pointer,x,y,null);
}
}
Finally, I think it's necessary to post the GameLoopThread-
package com.jollygent.tapthepointer;
import android.graphics.Canvas;
public class GameLoopThread extends Thread{
GamePanel game;
boolean running = false;
boolean paused = false;
Canvas canvas;
static final int FPS = 10;
public GameLoopThread(GamePanel game){
this.game = game;
}
public boolean isRunning(){
return running;
}
public void setRunning(boolean b){
this.running = b;
}
public void setPause(boolean b){
this.paused = b;
}
#Override
public void run() {
// TODO Auto-generated method stub
long beginTime;
long ticks = 1000/FPS;
long sleepTime;
while(running){
if(!paused){
beginTime = System.currentTimeMillis();
canvas = null;
try{
canvas = game.holder.lockCanvas();
synchronized(game.getHolder()){
game.draw(canvas);
}
}finally{
if(canvas != null){
game.getHolder().unlockCanvasAndPost(canvas);
}
}
sleepTime = (System.currentTimeMillis() - beginTime)/ticks;
try{
if(sleepTime > 0)
Thread.sleep(sleepTime);
else
Thread.sleep(10);
}catch(Exception e){
e.printStackTrace();
}
}
}
}
}
I'm probably making a very stupid mistake, but no matter how much I scan into the code and change around few bits I can't seem to figure out how exactly to move the sprite. Also, how can I make it so the sprite is centered exactly in any device?
Thank you.
EDIT:
package com.jollygent.tapthepointer;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
public class GameActivity extends Activity {
GamePanel game;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
game = new GamePanel(this);
setContentView(game);
}
#Override
public void onPause(){
super.onPause();
game.getLoop().setPaused(true);
}
#Override
public void onResume(){
super.onResume();
game.getLoop().setPaused(false);
}
}
The problem is that the loop only runs once and once only. Perhaps the GameActivity is the problem?

Sprite drawing every few secs

i want to execute this code in the following code again and again in defined intervals
for (Sprite sprite : sprites) {
sprite.onDraw(canvas);
}
i tryed few methods but i am stuck with errors . because i have all my animation timed with sleep and thread extended class
package com.okok;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class GameView extends SurfaceView {
private Bitmap bmp;
private SurfaceHolder holder;
private GameLoopThread gameLoopThread;
private List<Sprite> sprites = new ArrayList<Sprite>();
private long lastClick;
private Bitmap bmpBlood;
private List<TempSprite> temps = new ArrayList<TempSprite>();
private int mint;
public GameView(Context context) {
super(context);
gameLoopThread = new GameLoopThread(this);
holder = getHolder();
holder.addCallback(new Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
createSprites();
gameLoopThread.setRunning(true);
gameLoopThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
bmpBlood = BitmapFactory.decodeResource(getResources(), R.drawable.blast);
}
private void createSprites() {
sprites.add(createSprite(R.drawable.greenenact));
sprites.add(createSprite(R.drawable.greenenact));
sprites.add(createSprite(R.drawable.greenenact));
}
private Sprite createSprite(int resouce) {
Bitmap bmp = BitmapFactory.decodeResource(getResources(), resouce);
return new Sprite(this, bmp);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.rgb(21, 181, 195));
for (int i = temps.size() - 1; i >= 0; i--) {
temps.get(i).onDraw(canvas);
}
for (Sprite sprite : sprites) {
sprite.onDraw(canvas);
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if (System.currentTimeMillis() - lastClick > 500) {
lastClick = System.currentTimeMillis();
synchronized (getHolder()) {
float x = event.getX();
float y =event.getY();
for (int i = sprites.size() - 1; i >= 0; i--) {
Sprite sprite = sprites.get(i);
if (sprite.isCollition(x, y)) {
sprites.remove(sprite);
temps.add(new TempSprite(temps, this, x, y, bmpBlood));
break;
}
}
}
}
return true;
}
}
This is the GameLoopThread class i used to move things
package com.okok;
import android.graphics.Canvas;
public class GameLoopThread extends Thread {
static final long FPS = 10;
private GameView view;
private boolean running = false;
public GameLoopThread(GameView view) {
this.view = view;
}
public void setRunning(boolean run) {
running = run;
}
#Override
public void run() {
long ticksPS = 1000 / FPS;
long startTime;
long sleepTime;
while (running) {
Canvas c = null;
startTime = System.currentTimeMillis();
try {
c = view.getHolder().lockCanvas();
synchronized (view.getHolder()) {
view.onDraw(c);
}
} finally {
if (c != null) {
view.getHolder().unlockCanvasAndPost(c);
}
}
sleepTime = ticksPS - (System.currentTimeMillis() - startTime);
try {
if (sleepTime > 0)
sleep(sleepTime);
else
sleep(10);
} catch (Exception e) {}
}
}
}

Try something like:
private void createSprites() {
{
new Thread(new Runnable() {
public void run() {
for (int z =0; z<20; z++ ) // total of 20 sprites
try
{
Thread.sleep(5000); // new enemy every 5 seconds
sprites.add(createSprite(R.drawable.image));
z++;
}
catch(InterruptedException e)
{
e.printStackTrace();
}
}
}).start();
}

Android nothing being drawn when onDraw is called?

Ok, so I've been working on a little game, and there's a problem in the rendering code. So, I tried to follow a tutorial for working with the SurfaceView, and so this is what I have so far:
GameSurface.java
package com.spng453.afirelitroom;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class GameSurface extends SurfaceView implements SurfaceHolder.Callback {
private GameThread thread;
public SurfaceHolder surfaceHolder;
DisplayMetrics metrics = GameActivity.metrics;
final private int sX = metrics.widthPixels;
final private int sY = metrics.heightPixels;
private Paint mainBTheme = new Paint();
Rect fireButton = new Rect(0, sY/2+50, sX, sY/2-50);
public GameSurface(Context context) {
super(context);
surfaceHolder = getHolder();
surfaceHolder.addCallback(this);
this.setWillNotDraw(false);
thread = new GameThread(surfaceHolder, this);
this.setFocusable(true);
}
#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.run();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean done = false;
while(!done) {
try {
thread.join();
done = true;
}
catch (InterruptedException e) {
}
}
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawRGB(255, 255, 0);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
return true;
}
}
and the code in
GameThread.java:
package com.spng453.afirelitroom;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.SurfaceHolder;
public class GameThread extends Thread {
DisplayMetrics metrics = GameActivity.metrics;
final private int sX = metrics.widthPixels;
final private int sY = metrics.heightPixels;
private int FPS = 30;
private boolean running;
public SurfaceHolder surfaceHolder;
public GameSurface gameSurface;
public Canvas canvas;
private long firstTime = 0L, secondTime = 0L; //fps stuff
private Paint mainBTheme = new Paint();
//fire page
Rect fireButton = new Rect(0, sY/2+50, sX, sY/2-50);
Rect leftButton = new Rect();
Rect rightButton = new Rect();
//city/resources page
public void setRunning(boolean running) {
this.running = running;
}
public GameThread(SurfaceHolder surfaceHolder, GameSurface gameSurface) {
super();
this.surfaceHolder = surfaceHolder;
this.gameSurface = gameSurface;
mainBTheme.setColor(Color.BLACK);
}
#Override
public void run() {
while (running) {
//hey i guess i have to cap fps :(
firstTime = System.nanoTime();
//do the game here
canvas = null;
canvas = surfaceHolder.lockCanvas();
gameSurface.onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
secondTime = System.nanoTime();
if (secondTime/1000000 - firstTime/1000000 < 1000/FPS) { //the if the lag is less than the distance between frames at 30 fps
try {
Thread.sleep(1000/FPS - (secondTime/1000000 - firstTime/1000000));
} catch (InterruptedException e) {
}
}
}
}
}
So, my problem is that when I try to call onDraw in the GameThread here:
canvas = null;
canvas = surfaceHolder.lockCanvas();
gameSurface.onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
it does absolutely nothing. It doesn't draw whatever I put in onDraw, though if I put a Log call in the onDraw I know it executes. It doesn't produce an error message, either. Thanks for help in advanced!

Try this:
Change your method:
#Override
protected void onDraw(Canvas canvas) {
canvas.drawRGB(255, 255, 0);
}
By this:
#Override
protected void onDraw(Canvas canvas) {
canvas.drawRGB(255, 255, 0);
super.onDraw(canvas);
}
Also, try change this lines:
//do the game here
canvas = null;
canvas = surfaceHolder.lockCanvas();
gameSurface.onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
By this ones:
Canvas canvas = null;
try {
canvas = surfaceHolder.lockCanvas();
synchronized (surfaceHolder) {
gameSurface.onDraw(canvas);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (canvas != null)
surfaceHolder.unlockCanvasAndPost(canvas);
}
Also keep note that the while loop it's running really fast no giving chance to draw the canvas. The thread sleep isn't working very well. Look at this resources, there is explained how do the game loop properly. And if you wanna test it right now, just erase the while.
Android game loop explained
Android game basic structure
Hope this helps :]

Okay, so it turns out that it was a problem with the FPS code executing too fast. I solved it by doing this:
#Override
public void run() {
// TODO Auto-generated method stub
final int fps = 30;
Timer fpsTimer = new Timer();
fpsTimer.scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
Canvas canvas;
canvas = null;
try {
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
onDraw(canvas);
}
} finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}, 0, 1000/fps);
}