You definitely need to do your game loop on a different thread. If
your game loop is running in the main UI thread then while it is
running the screen can't update and you can't get input events. The UI
thread is what does these things.
On Apr 15, 10:25 pm, Warren <warrenba...@gmail.com> wrote:
> Sarnoth, I appreciate you taking the time to comment.
>
> Does that matter - if the thread isn't different?
>
> Just in case there were problems with the thread, I rewrote the
> program not to use a second thread and just execute the drawing loop
> in the view.
>
> In the code sample, I also changed draw() to drawSprites(), as I
> described in an earlier post. Neither of these things helped.
>
> ====== Begin Code ======
>
> package com.baltz.scorched;
>
> import android.content.Context;
> import android.content.res.Resources;
> import android.graphics.Bitmap;
> import android.graphics.BitmapFactory;
> import android.graphics.Canvas;
> import android.util.AttributeSet;
> import android.util.Log;
> import android.view.SurfaceHolder;
> import android.view.SurfaceView;
>
> class ScorchedView extends SurfaceView implements
> SurfaceHolder.Callback {
>
> private Context context;
> private SurfaceHolder holder;
>
> private Bitmap backgroundImage;
> private Bitmap foregroundImage;
> private Bitmap spriteImage;
>
> private Resources resources;
> private ScorchedTerrain terrain;
> private Engine engine;
>
> public ScorchedView(Context c, AttributeSet attrs) {
> super(c, attrs);
> // register our interest in hearing about changes to our
> surface
> holder = getHolder();
> holder.addCallback(this);
>
> context = c;
>
> resources = context.getResources();
>
> // load background image as a Bitmap instead of a Dable b/c
> // we don't need to transform it and it's faster to d this way
> backgroundImage = BitmapFactory.decodeResource(resources,
> R.drawable.earthrise);
>
> foregroundImage = BitmapFactory.decodeResource(resources,
> R.drawable.foreground1);
>
> spriteImage = BitmapFactory.decodeResource(resources,
> R.drawable.sprite1);
>
> terrain = new ScorchedTerrain(foregroundImage);
>
> engine = new Engine();
> Body body;
>
> body = new Body(spriteImage);
> body.setLocation(50, 50);
> engine.addBody(body);
>
> body = new Body(spriteImage);
> body.setLocation(40, 100);
> engine.addBody(body);
> }
>
> /* Callback invoked when the surface dimensions change. */
> public void surfaceChanged(SurfaceHolder h, int format, int width,
> int height) {
> holder = h;
> }
>
> /*
> * Callback invoked when the Surface has been created and is ready
> to be
> * used.
> */
> public void surfaceCreated(SurfaceHolder h) {
> holder = h;
> gameLoop();
> }
>
> /*
> * Callback invoked when the Surface has been destroyed and must
> no longer
> * be touched. WARNING: after this method returns, the Surface/
> Canvas must
> * never be touched again!
> */
> public void surfaceDestroyed(SurfaceHolder holder) {
> }
>
> private void gameLoop(){
>
> Canvas canvas;
>
> int i=0;
> while(i<30){
> canvas = null;
> try {
> canvas = holder.lockCanvas(null);
> engine.update();
> drawSprites(canvas);
> } finally {
> // do this in a finally so that if an exception is thrown
> // during the above, we don't leave the Surface in an
> // inconsistent state
> if (canvas != null) {
> Log.w("dbg", "unlocking canvas" + i);
> holder.unlockCanvasAndPost(canvas);
> }
> }
>
> try{
> Thread.currentThread().sleep(300);
> }
> catch(Exception e){
> }
> i++;
> }
> }
>
> /**
> * Draws the sprites and background to the provided
> * Canvas.
> */
> public void drawSprites(Canvas canvas) {
> // Draw the background image. Operations on the Canvas
> accumulate
> // so this is like clearing the screen.
> canvas.drawBitmap(backgroundImage, 0, 0, null);
>
> //draw the up-to-date, deformed foreground
> terrain.draw(canvas);
>
> //draw all bodies (players, projectiles, etc) on the screen
> engine.drawAll(canvas);
> }
>
> }
>
> On Apr 15, 4:47 pm, Sarnoth <jesse.st...@gmail.com> wrote:
>
> > I can't really say without seeing more of the code, but based on your
> > description of the problem I wonder if your thread is in fact a
> > separate thread or if the run method is simply being executed in the
> > main UI thread. Something worth checking. You can log
> > Thread.currentThread().getName() from inside your run method and from
> > inside your activity's onCreate method to make sure they are
> > different.
>
> > On Apr 15, 9:57 am, Warren <warrenba...@gmail.com> wrote:
>
> > > I may have found my problem.
>
> > > The SurfaceView class implements a function called draw(Canvas).
>
> > > I unwittingly created my own function draw() with the same signature,
> > > overriding the original. I'm guessing that the SurfaceView probably
> > > calls draw() duringunlockCanvasAndPost(). But instead of executing
> > > its original draw() method and doing what it is supposed to do, it
> > > calls my function - simply overwriting the canvas buffer without
> > > affecting the Surface at all... thus theblackscreen. I'm still
> > > confused about why it eventually shows. Perhaps some final cleanup
> > > code...
>
> > > I will test this tonight when I have access to my development computer
> > > and post my findings.
>
> > > On Apr 15, 8:48 am, Warren <warrenba...@gmail.com> wrote:
>
> > > > Thanks for the comment ellipsoidmobile.
>
> > > > If I remove the sleep, I still don't see anything until the very end.
> > > > I don't need that sleep in there for the application. I only put it in
> > > > so that, hopefully, I could see what was happening a little better.
>
> > > > Also, I thought that the SurfaceView allowed you to write to the
> > > >screenat your own pace, whatever that may be. So in this case, there
> > > > would be nothing "from the outside" that's causing ascreenrefresh.
> > > > Thescreenshould stay how I left it until I post a new canvas. Am I
> > > > misunderstanding this?
>
> > > > What really confuses me is why the last call tounlockCanvasAndPost()
> > > > does work. It seems like if an error prevented the first calls from
> > > > functioning, then it would also prevent the last.
>
> > > > On Apr 15, 3:09 am, "ellipsoidmob...@googlemail.com"
>
> > > > <ellipsoidmob...@googlemail.com> wrote:
> > > > > The problem is your line Thread.currentThread().sleep(1000);//sleep
> > > > > for 1000 ms
>
> > > > > I believe with SurfaceView you have to draw your whole view on
> > > > > everyscreenrefresh. You just need to loop as fast as possible and the
> > > > > system will throttle the speed in the calls to lockCanvas(). By
> > > > > sleeping for 1 second you are failing to provide a canvas for every
> > > > > refresh so thescreenappears blank.
>
> > > > > What I don't know is whether there is any guidance on how quickly you
> > > > > have to get through your loop, i.e. what the maximum refresh rate is
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