Prevent window repaint when minimizing

Question

Can you stop a program repainting a panel when the program is minimized? * Used Swing

Why does it matter if repainting occurs? This makes me suspect a bigger problem is lurking underneath such as having program logic in your `paint` or `paintComponent` method. — Hovercraft Full Of Eels, Mar 07 '12 at 17:43
In my program I have a thread that calls repaint every 1 sec which repaints a graph that simulates a bank account balance. if I repaint when I shouldn't this throws off the graph — Chris Mowbray, Mar 07 '12 at 17:47
Your Jar file has no source code. More importantly, I did some *major* work trying to help you in this thread: [graph-plotting-issue](http://stackoverflow.com/questions/9557633/graph-plotting-issue) including a demonstration program, and you didn't reply. What's with that?? I felt as if I wasted a great deal of time with this. That's not how to motivate folks to help you further you know. — Hovercraft Full Of Eels, Mar 07 '12 at 17:57
Im real sorry man i thought i replied :/ the help was greatly appreciated :) — Chris Mowbray, Mar 07 '12 at 18:06
Sure one can execute, but source is everything. Without source, we have no idea why your application is behaving as it's behaving. — Hovercraft Full Of Eels, Mar 07 '12 at 18:11
I know i was just showing what the problem was, im having trouble understanding what the timer class has to do with the JFrame repainting. — Chris Mowbray, Mar 07 '12 at 18:12
If you take my sample program from my previous question, make the Timer a final local variable, and add a WindowListener or WindowAdapter to the JFrame you can see a solution. — Hovercraft Full Of Eels, Mar 07 '12 at 22:15

Ted Hopp · Answer 1 · 2012-03-07T20:40:02.550

2

The real issue, I guess, is suspending animation loops and the like when minimized. If you're using a JFrame, you can detect window minimization events with:

myFrame.addWindowStateListener(
    new WindowStateListener() {
        @Override
        public void windowStateChanged(WindowEvent evt) {
            if (myFrame.getState() == Frame.ICONIFIED) {
                // suspend painting/animation loops
            } else {
                // resume or continue painting/animation loops
            }
        }
    }
);

edited Mar 07 '12 at 20:40

answered Mar 07 '12 at 17:50

Ted Hopp

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@Chris: look at methods available for Swing Timers. You'll figure it out. – Hovercraft Full Of Eels Mar 07 '12 at 18:07
@Chris - If your animation is driven by a `javax.swing.Timer`, you can simply call the timer's `stop()` and `start()` methods to suspend/resume the animation. See the article [Threads and Swing](http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html) for some sample code. – Ted Hopp Mar 07 '12 at 18:13
There's a `Timer` related example [here](http://stackoverflow.com/a/5529043/230513). – trashgod Mar 07 '12 at 18:32
@TedHopp i am familiar with those methods as i have used them in this program on the start and stop buttons on the jar file above – Chris Mowbray Mar 07 '12 at 18:38
@Chris - So why can't you just use them to suspend and resume the painting? It's easy to use a `Timer` object to drive the animation, as the link in my previous comment shows. – Ted Hopp Mar 07 '12 at 19:02
@TedHopp The frame is always showing for some reason, it never reaches the else when I minimize – Chris Mowbray Mar 07 '12 at 20:25
@Chris - I modified the logic for testing the window state. See if using `getState()` provides better behavior. – Ted Hopp Mar 07 '12 at 20:40
@TedHopp I have used .getExtendedState() == frame.ICONIFIED i think it works, i have declared my timer in another class, how can i call that timer to stop and start from the JFrame class i am currently in? – Chris Mowbray Mar 07 '12 at 20:46
@Chris You'll need to either make the timer visible to the JFrame code or else provide methods in the other class to relay the start/stop requests to the timer. (I'd recommend the latter.) – Ted Hopp Mar 07 '12 at 20:54
@TedHopp Thanks for your help ive done that and i dont think it has fixed my problem, Thankyou anyway – Chris Mowbray Mar 07 '12 at 20:55

score 1 · Accepted Answer · edited May 23 '17 at 12:12

An example of using a WindowListener could be as simple as making a small modification to my previous example which can be found here:

private static void createAndShowGui() {
  ShowGraph showGraphPanel = new ShowGraph(MAX_POINTS);
  TimerListener timerListener = new TimerListener(MAX_POINTS, showGraphPanel);

  JFrame frame = new JFrame("TestShowGraph");
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.getContentPane().add(showGraphPanel);
  frame.pack();
  frame.setLocationByPlatform(true);
  frame.setVisible(true);

  // Timer now made a final variable so it can be referred to
  final Timer timer = new Timer(TIMER_DELAY, timerListener);
  timer.start();

  frame.addWindowListener(new WindowAdapter() {

     @Override
     public void windowOpened(WindowEvent arg0) {
        timer.start();
     }

     @Override
     public void windowIconified(WindowEvent arg0) {
        timer.stop();
     }

     @Override
     public void windowDeiconified(WindowEvent arg0) {
        timer.start();
     }

     @Override
     public void windowActivated(WindowEvent arg0) {
        timer.start();
     }
  });
}

Prevent window repaint when minimizing

2 Answers2