Question

I’m using a SurfaceView and I have to update it as fast as I can. Since the onDraw method isn’t called automatically I have to call explicitly. So my first attempt was on threads, but I got some lag. There is a better way to do this? If there is a better solution, can you, please, explain me? I’m new on Android’s World!

---

What I have so far

public void run() {
    while(running){
        Canvas c = null;
        try {
            c = view.getHolder().lockCanvas();
            synchronized (view.getHolder()) {
                view.onDraw(c);
            }
        } finally {
            if (c != null) {
                view.getHolder().unlockCanvasAndPost(c);
            }
        }
    }
}

Answer 1

Here’s my code that I use as a rendering thread. The fps is updated frame dependent. I usually run my games at 30 fps.
(There’s some code you won’t need, but I’m sire you’ll be able to find the pieces you are looking for.)

public class RenderView extends SurfaceView implements Runnable {


    Game game;
    Bitmap gameScreen;
    Thread gameloop;
    SurfaceHolder holder;
    boolean running;

    int sleepTime;
    int numberOfFramesSkipped;
    int maxFrameSkips;
    long beginTime;
    long endTime;
    long lastTime;
    int differenceTime;
    int framePeriod;
    Canvas frameBuffer;
    int frameCount;

    public RenderView(int fps, int maxFrameSkips) {
        super(game);
        this.gameScreen = gameScreen;
        this.holder = getHolder();
        this.framePeriod = 1000/fps;
        this.maxFrameSkips = maxFrameSkips;
        lastTime = System.currentTimeMillis();
        beginTime = System.currentTimeMillis();
    }

    @Override
    public void run() {

        while(running == true) {
            if(holder.getSurface().isValid()) {

                beginTime = System.currentTimeMillis();

                    // call your update method here
                // render here
                    frameBuffer = holder.lockCanvas();
                    this.onDraw();
                    holder.unlockCanvasAndPost(frameBuffer);

                // Frame Per Second Count
                frameCount++;

                if(lastTime + 1000 < System.currentTimeMillis()) {
                    lastTime = System.currentTimeMillis();
                    frameCount = 0;
                }

                endTime = System.currentTimeMillis();;
                differenceTime = (int) (endTime - beginTime);
                sleepTime = (int) (framePeriod - differenceTime);

                if(sleepTime > 0) {
                    try {
                        Thread.sleep(sleepTime);
                    } catch (InterruptedException exception) {
                        exception.printStackTrace();
                    }
                }
                else {
                    while(sleepTime < 0 && numberOfFramesSkipped < this.maxFrameSkips) {
                        // Call your update method here
                        sleepTime += framePeriod;
                        numberOfFramesSkipped++;
                    }
                }


            }


        }

    }

    private void renderFrameBuffer() {
        // Update the current virtual screen image
        game.getCurrentScreen().render();
        // Render the current virtual screen to the real phone screen
        frameBuffer = holder.lockCanvas();
        if(frameBuffer != null) { // Fix for mysterious bug ( FATAL EXCEPTION: Thread)
            // The viewing area of our virtual screen on our real screen
            // Composition
            // First layer (bottom)
                frameBuffer.drawBitmap(this.gameScreen, null, game.getWSScreen().getGameScreendst(), null);
            // Second layer (top)
                frameBuffer.drawBitmap(this.gameScreenExtended, null, game.getWSScreen().getGameScreenextendeddst(), null);

            holder.unlockCanvasAndPost(frameBuffer);
        }
        else {
            gameEngineLog.e(classTAG, "Surface has not been created or otherwise cannot be edited");
        }
    }

    public void resume() { 
        this.running = true;
        gameloop = new Thread(this);
        gameloop.start();         
    }   

    public void pause() { 
        this.running = false;
        running = false;                        
        while(true) {
            try {
                gameloop.join();
                break;
            } catch (InterruptedException e) {
                // retry
            }
        }
    }

}

public void onDraw() {

}

I suggest you take a look at this link or have a look at
http://code.google.com/p/beginning-android-games/
or http://www.edu4java.com/en/androidgame/androidgame3.html