How on earth do I stop my Applet from flickering

[Orangy Tang]

Right, I'm about to give up on this, but maybe one of you lot can figure this out - I cannot create a non-trivial applet that doesn't flicker something awful at seemingly random intervals. Here's a few links:

1. Albion
2. Test 2
3. Test 3

All of these will flicker for me, in both Safari and Chrome on OSX. Some more than others - Albion appears to be the most stable.

Albion is using a BufferStrategy created on a Canvas inside a JApplet.
Test 2 internally draws onto a BufferedImage, then uses a class derived from Canvas to display that backbuffer. Again, inside a JApplet.
Test 3 is cribbed from Oracle's applet example, and draws to an image backbuffer, then to a custom JPanel inside a JApplet.

Points of interest:
 - Chrome flickers much worse, but Safari also flickers.
 - All of these are rock solid in AppletViewer.
 - The flicker colour is very odd. It's sometimes the background colour of the Canvas/JPanel. It's not the background colour of the applet tag. But it is sometimes the background colour of the webpage, or just white (not a colour used for any of the above).
 - Even the animated Java logo displayed while the applet is loading flickers.
 - Pulpcore example applets flicker too in Chrome. They don't start in Safari (thinks Java is not installed!).
 - The Oracle example applet doesn't flicker, until you add more drawing code, at which point it does.
 - The LWJGL applet? Works just fine. >_<

For reference, this is the code for Test 3:

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package prototype.move; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Toolkit; import java.awt.image.BufferedImage; import java.io.BufferedInputStream; import java.io.InputStream; import java.util.ArrayList; import javax.swing.ImageIcon; import javax.swing.JApplet; import javax.swing.JPanel; import javax.swing.SwingUtilities; import com.triangularpixels.rebirth.resources.ResourcePool; import com.triangularpixels.rebirth.resources.Resources; import prototype.move.renderer.Util; public class MainTest extends JApplet implements Runnable {    private final static String dir = "Creatures"; // dir to load the images from   private final static int nimgs = 2; // number of images to animate      int loopslot = -1; // the current frame number   ImageIcon imgs[]; // the images    private boolean debug;        private CustomPanel panel;        private BufferedImage framebuffer, backbuffer;        private Thread gameThread;    private boolean running = true;        private long lastFrameTime;        private ArrayList<Long> frameTimes;        private ResourcePool resources;    private Flow flow;        @Override    public void init()    {       super.init();             try       {          SwingUtilities.invokeAndWait(new Runnable()          {             public void run()             {                initialiseInternal();             }          });       }       catch (Exception e)       {          e.printStackTrace();       }                       running = true;             gameThread = new Thread(this);       gameThread.start();    }        @Override    public void stop()    {             super.stop();             if (gameThread != null)       {          running = false;                    try          {             gameThread.wait();          }          catch (Exception e) {}       }    }        private void initialiseInternal()    {       applySleepWorkaround();             panel = new CustomPanel();    //   panel.setOpaque(true);      panel.setBackground(Color.blue);       setContentPane(panel);             framebuffer = Util.createImage(320, 180, false);       backbuffer = Util.createImage(getWidth(), getHeight(), false);             try       {          debug = false;          assert (debug = true);                    resources = Resources.createPool("Data", Resources.DecoderGroup.CORE, debug, true);                    resources.parse("resources.xml");                    // Temp hack until we get a proper loading screen         resources.requestCreateAll();          while (!resources.areAllCreated())          {             resources.update();             Thread.yield();          }                    flow = new Flow(resources, framebuffer.getWidth(), framebuffer.getHeight(), panel);       }       catch(Exception e)       {          System.err.println("Couldn't create resource pool");          e.printStackTrace();       }             frameTimes = new ArrayList<Long>();             imgs = new ImageIcon[nimgs];       for (int i = 0; i < nimgs; i++)       {          imgs[i] = loadImage(i + 1);       }    }        private synchronized void paintInternal(Graphics g)    {       if (backbuffer != null)       {          g.drawImage(backbuffer, 0, 0, null);       }    }        @Override    public void run()    {       while (running)       {          updateInternal();          drawInternal();                    panel.repaint();                    sync(60);       }    }        private void updateInternal()    {       resources.update();             flow.update(isPaused());    }        private boolean isPaused()    {       final boolean hasFocus = this.isFocusOwner() || this.hasFocus();       return !hasFocus;    }        private synchronized void drawInternal()    {       if (!isVisible())          return;             Graphics2D g = (Graphics2D)backbuffer.getGraphics();       g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);             Graphics2D frameGraphics = framebuffer.createGraphics();       frameGraphics.setColor(Color.black);       frameGraphics.fillRect(0, 0, framebuffer.getWidth(), framebuffer.getHeight());               flow.draw(frameGraphics, isPaused());       frameGraphics.dispose();             g.drawImage(framebuffer, 0, 0, panel.getWidth(), panel.getHeight(), null);             while (frameTimes.size() > 20)          frameTimes.remove(0);             if (frameTimes.size() > 1)       {          long totalDelta = 0;          for (int i=0; i<frameTimes.size()-1; i++)          {             long delta = frameTimes.get(i+1) - frameTimes.get(i);             totalDelta += delta;          }          totalDelta /= (frameTimes.size()-1);                    int fps = totalDelta > 0 ? (int)(1000 / totalDelta) : 0;                    int x = 800;          int y = 20;          String fpsString = fps +" fps";                    g.setColor(Color.white);          g.drawString(fpsString, x-1, y-1);          g.drawString(fpsString, x+1, y-1);          g.drawString(fpsString, x-1, y+1);          g.drawString(fpsString, x+1, y+1);                    g.setColor(Color.black);          g.drawString(fpsString, x, y);       }       g.dispose();    }        @Override    public synchronized void paint(Graphics g)    {       super.paint(g);    }        @Override    public synchronized void paintComponents(Graphics g)    {       super.paintComponents(g);    }        /** Starts a long running thread that sleeps for a non-divisible-by-ten amount of time to force the hi-res sleep timer */    private static void applySleepWorkaround()    {       new Thread("SleepTimerHack")       {             { this.setDaemon(true); this.start(); }             public void run()             {             while(true)             {                try { Thread.sleep(Integer.MAX_VALUE); } catch(InterruptedException ex) {}             }             }         };    }        public void sync(final int framerate)    {       final int framerateMillis = 1000 / framerate;             long current = System.nanoTime() / 1000000;       long elapsed = current - lastFrameTime;             do       {          try          {             Thread.sleep(0);          }          catch (InterruptedException e) {}                    current = System.nanoTime() / 1000000;          elapsed = current - lastFrameTime;       }       while (elapsed < framerateMillis);             lastFrameTime = current;             frameTimes.add(current);    }        public class CustomPanel extends JPanel    {       public CustomPanel()       {          super(new BorderLayout());       }             @Override       public synchronized void paint(Graphics g)       {          super.paint(g);       }             protected synchronized void paintComponent(Graphics g)       {          super.paintComponent(g);                    paintInternal(g);       }    }                protected ImageIcon loadImage(final int imageNum)    {       String path = dir + "/T" + imageNum + ".png";       final int MAX_IMAGE_SIZE = 1024 * 16;             InputStream in = this.getClass().getClassLoader().getResourceAsStream(path);       BufferedInputStream imgStream = new BufferedInputStream(in);             if (imgStream != null)       {          byte buf[] = new byte[MAX_IMAGE_SIZE];                    int count;          try          {             count = imgStream.read(buf);             imgStream.close();          }          catch (java.io.IOException ioe)          {             System.err.println("Couldn't read stream from file: " + path);             return null;          }                    if (count <= 0)          {             System.err.println("Empty file: " + path);             return null;          }          return new ImageIcon(Toolkit.getDefaultToolkit().createImage(buf));       }       return null;    } }

Very confused.

[theagentd]

Chrome, not a flicker in sight.

[Orangy Tang]

Chrome, not a flicker in sight.

On all of them? What Java vm and OS?

I'm on 1.6.0_26 and OSX 10.6.8.

Games published by our own members! Check 'em out!

[theagentd]

Yeah, but the 3rd test only shows a white screen.

[Cero]

Albion and Test 2 work beautifully

Test 3 stays white

Win 7, Opera

Edit: Java Version: 1.7.0_01  21.1-b02  (32-bit)

[SimonH]

Same as Cero - FFox, java 6

[BoBear2681]

OS X 10.5, Firefox, Java 1.6.0_26.

Albion runs smoothly, looks good.
The second applet flickers white so much it's unbearable.
The third applet is just a white rectangle.

[Riven]

Test 3

1   2   3   4   5   6   7   8   9

network: Connecting http://triangularpixels.com/MovementPrototype/Creatures/Baron_Casual.png with proxy=DIRECT Couldn't load 'Creatures/Baron_Casual.png' java.lang.NullPointerException    at prototype.move.renderer.ImageResource.loadImage(ImageResource.java:42)    at prototype.move.renderer.ImageResource.create(ImageResource.java:27)    at com.triangularpixels.rebirth.resources.ResourceHandle.create(ResourceHandle.java:88)    at com.triangularpixels.rebirth.resources.ResourcePool.processCreateQueue(ResourcePool.java:211)    at com.triangularpixels.rebirth.resources.ResourcePool$BgCreator.run(ResourcePool.java:509)    at java.lang.Thread.run(Unknown Source)

[ra4king]

I get the same exception as Riven for Test 3 but Albion and Test 2 work beautifully.

I blame OS X and Apple's new applet changes as the cause of your flickering.

[jonjava]

Albion and Test 2 work beautifully

Test 3 stays white

Win 7, Opera and FFox

Java Version: 1.6.0_27

Games published by our own members! Check 'em out!

[JL235]

This is a known issue with applets on OSX. Here on the Apple Java Dev mailing list you can see an approximate cause of the issue, that the applet now lives out of the browser process. That mail is talking about it in relation to drag and drop, but it summarizes the problem.

Yes, the windows plugin is also NPAPI, but the problem lies in the way the windowing system delivers events and controls access to windowing resources between processes. On Windows, it is perfectly reasonable and possible to have process A own a window/control that is parented in a window created by process B. This is not the case on Mac OS X, Mac OS X will not let process A parent its window in process B's window hierarchy without explicit permission from process B (the host process). Since the host process in this case is the browser, and the only aperture through which we interact with the browser is NPAPI and it does not have a way to tell the browser to execute arbitrary native code in the browser's process space, there are lots of issues that arise from this limitation. On Windows and Linux the Java applet process creates windows and controls inside the browsers window hierarchy, which is just not possible on Mac OS X without browser participation (this is a security feature).

How we manage to show the Applet UI inside the browser is through some cross-process magic that is provided to us by CoreAnimation remote layers, but CA does not remote the events itself. ...

Here is another discussion about it on the Chromium bug list.

[ava]

Albion doesn't flicker, but it's unbelievably slow (~4 fps). Test 2 doesn't flicker either, but it runs a lot better than the first one (62 fps). Test 3 stays white.

Ubuntu 10.04
Firefox 7.0.1
Java 1.6.0_26

[loom_weaver]

1. Blank black screen
2. Flickers
3. Blank white screen

MacBook, Safari running in Snow Leopard.

 

[Orangy Tang]

So applets on osx suck then. Yey! 

[theagentd]

So? OpenGL on OSX sucks too. There are lots of things that suck on Macs.

[kappa]

- The LWJGL applet? Works just fine. >_<

Just make the switch then and get on with the game

Quite a bit of effort went into finally making LWJGL applets work again on OS X after Apple crippled/broke the Java plugin with the switch to CoreAnimation. The performance on both Java2D and PulpCore is now massively crippled making them unusable for certain types of games. On the other hand OS X has solid support for OpenGL (since the OS uses it) and therefore LWJGL applets are a pretty good option there.

[Orangy Tang]

So? OpenGL on OSX sucks too. There are lots of things that suck on Macs.

Lets not turn this into a platform fanboy thread please.

[loom_weaver]

Just trying to be helpful here.  If you're creating a game would you like to know if it can run on Macs?  Or would you rather that I say nothing?

[Cero]

Just trying to be helpful here.  If you're creating a game would you like to know if it can run on Macs?  Or would you rather that I say nothing?

his reply to you was sarcastic and disappointed, that it doesnt work on mac - not critical

[loom_weaver]

Just trying to be helpful here.  If you're creating a game would you like to know if it can run on Macs?  Or would you rather that I say nothing?

his reply to you was sarcastic and disappointed, that it doesnt work on mac - not critical

Nod, I kind of figured that after I saw the second post.  My question is aimed more at the general audience.  I've noticed a slight trend of "don't bother me about the problems running your platform (which is different from mine)" attitude.

[h3ckboy]

I think it is just sort of a killing the messenger kind of thing, and being frustrated at the problem and maybe leaking some of that frustration into the conversation.

[ra4king]

In the end, Apple is slowly killing Java applets

[Orangy Tang]

Just trying to be helpful here.  If you're creating a game would you like to know if it can run on Macs?  Or would you rather that I say nothing?

Sorry didn't mean to imply your response was unwanted. I'm just pretty miffed at how hard it seems to be to get a consistant experience across platforms. Especially since your setup appears to be near identical to mine.

[JL235]

Just trying to be helpful here.  If you're creating a game would you like to know if it can run on Macs?  Or would you rather that I say nothing?

Sorry didn't mean to imply your response was unwanted. I'm just pretty miffed at how hard it seems to be to get a consistant experience across platforms. Especially since your setup appears to be near identical to mine.

Welcome to Java!

[Mads]

Yeah, but the 3rd test only shows a white screen.

Same exact result. Chrome, win7.

(build 1.6.0_26-b03)

[theagentd]

I didn't mean to insult anyone who favors Macs (AKA "I'll buy anything that's shiny and made by Apple!" xDDDDD), but game support on Macs has always been pretty bad in my experience. Considering the really old version of OpenGL supported by Macs along with the bugs I hear about all the time, it just isn't worth my time to look into it as a person interested in graphics programming. I am in no way fanboying Windows here, I'm just saying that at least I can haz tessellation, texture arrays and samplers and multisampling coverage masks in my shaders there.

[ra4king]

I am in no way fanboying Windows here, I'm just saying that at least I can haz tessellation, texture arrays and samplers and multisampling coverage masks in my shaders there.

Well that is if the user is running a decent graphics card with decent OpenGL support too

[JL235]

I am in no way fanboying Windows here, I'm just saying that at least I can haz tessellation, texture arrays and samplers and multisampling coverage masks in my shaders there.

Well that is if the user is running a decent graphics card with decent OpenGL support too

NVidia drivers are (mostly) excellent these days, and can even ignore/workaround OpenGL bugs in your code. The Intel chipsets and drivers are also no where near as bad as they used to be.

[theagentd]

I am in no way fanboying Windows here, I'm just saying that at least I can haz tessellation, texture arrays and samplers and multisampling coverage masks in my shaders there.

Well that is if the user is running a decent graphics card with decent OpenGL support too

NVidia drivers are (mostly) excellent these days, and can even ignore/workaround OpenGL bugs in your code. The Intel chipsets and drivers are also no where near as bad as they used to be.

My experience with Radeon is limited to the antique Radeon card in my family's old computer. It had FBO support, but it apparently couldn't handle colors in them. I have no idea what the hell was going on, and I never even bothered to investigate such a ridiculous bug. xD
Nah, I haven't found any really serious bugs yet in any drivers today. Granted I've been ignoring Intel, but Radeon and NVidia is fine. I do have a few bugs concerning antialiasing though. Reading sample positions when using driver forced antialiasing will give you some very interesting positions. Multisampled HDR FBO rendering is limited to 4xMSAA Retested it, and it's fixed in the latest drivers. For some reason, the driver reports that "16xMSAA" is available, but when you use it it gives you 2x2 OGSSAA + 4xMSAA. "32xMSAA" is also available, being 2x2 OGSSAA + 8xMSAA. Coverage sampling also works. The funny thing is that this is only with FBOs.

There are some bugs with getting antialiasing on the main screen buffer (Display.create()). The only coverage sample mode supported is 32xCSAA (based on 8xMSAA). Everything under that just gives the number of coverage samples requested as color samples, e.g. if I say 4 color, 16 coverage (=16xQ) I get 16xMSAA (see above). It works if I force it through my drivers though. Could be either the OpenGL driver or LWJGL. The .withCoverageSamples() methods seem very unreliable.

[gbeebe]

I have found that if I'm using an image as a buffer, adding

1	setIgnoreRepaint(true);

to init() stops people complaining about flickering (and freezing) when I don't even experience it on my machine.