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Re: Can a jPanel's backgr

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  To: comp.lang.java.gui
Andrew Thompson a |-crit :
> JT wrote:
>>> In any case, it is possible to *extend* JPanel (or jPanel, 
>>> I am guessing) to provide a method that will do that.
>> Sometimes the fonts on my machine make jPanel and JPanel look the same, 
>> especially if it's late at night.  
> 
> Please either get a better font, or better excuses..
> 
>> ...But, to answer your question, I am 
>> looking for a way to make my "flashing green" light flash.  I looked in 
>> the API but could not find anything which would do what I wanted, 
> 
> I find that completely unsurprising.  I cannot imagine
> it is often that a GUI requires *flashing* panels.  
> (muses) Perhaps slightly more common than a 
> requirement for panels with polka dots, but not 
> much so.
> 
>> ...so I 
>> thought someone might have done something similar in the past and would 
>> be willing to share their ideas.
> 
> I haven't, but a slight tweak of my earlier code should
> point *a* way to go about it.  Note that this is still using
> AWT (just because I'm feeling perverse) and uses the 
> centred circle (rather than the background) to change 
> color.  Further, no logic is performed to ensure that only
> one signal is flashing at any instant.  
> 
> Adapt as needed ('batteries not included').
> 
> <sscce>
> import java.awt.*;
> import java.awt.event.*;
> 
> class TrafficLight {
> 
>   public static void main(String[] args) {
>     Frame f = new Frame("Lights");
>     Panel lightboard = new Panel( new GridLayout(0,1) );
> 
>     lightboard.add( new TrafficSignal(Color.green) );
>     lightboard.add( new TrafficSignal(Color.yellow) );
>     lightboard.add( new TrafficSignal(Color.red) );
> 
>     f.add( lightboard );
>     f.pack();
>     f.addWindowListener( new WindowAdapter() {
>       public void windowClosing(WindowEvent we) {
>         System.exit(0);
>       }
>     } );
>     f.setLocationRelativeTo(null);
>     f.setVisible(true);
>   }
> }
> 
> class TrafficSignal extends Panel implements Runnable {
> 
>   Color on;
>   int radius = 55;
>   int border = 10;
>   boolean active;
> 
>   boolean flashing = false;
>   long startFlash = 0;
>   /** It should flash for 10 seconds. */
>   long lengthFlash = 10000;
> 
> 
>   TrafficSignal(Color color) {
>     on = color;
>     active = true;
>     this.addMouseListener( new MouseAdapter() {
>       public void mouseClicked(MouseEvent me) {
>         setFlashing(true);
>       }
>     } );
>     Thread t = new Thread(this);
>     t.start();
>   }
> 
>   public Dimension getPreferredSize() {
>     int size = (radius+border)*2;
>     return new Dimension( size, size );
>   }
> 
>   public void run() {
>     while (true) {
>       if ( flashing ) {
>         active = !active;
>         repaint();
>         if ( System.currentTimeMillis()-startFlash>lengthFlash ) {
>           flashing = false;
>         }
>       }
>       try {
>         Thread.sleep(400);
>       } catch (InterruptedException ie) {
>         // wake and continue
>       }
>     }
>   }
> 
>   public void setFlashing(boolean flash) {
>     flashing = flash;
>     startFlash = System.currentTimeMillis();
>   }
> 
>   public void paint(Graphics g) {
>     g.setColor( Color.black );
>     g.fillRect(0,0,getWidth(),getHeight());
> 
>     if (active) {
>       g.setColor( on );
>     } else {
>       g.setColor( on.darker().darker().darker() );
>     }
>     g.fillOval( border,border,2*radius,2*radius );
>   }
> }
> </sscce>

Shouldn't the GUI be updated from the EDT thread? How would this be done?

If I understand your SSCCE correctly, the frame is shown from the "main" 
thread. And the blinking is updated from your "TrafficLight" thread.

Thanks for your insight
Phil

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Thread

Can a jPanel's background "JT" <jt@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
  Re: Can a jPanel's backgr "Andrew Thompson" <andrew.thompson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
  Re: Can a jPanel's backgr "Andrew Thompson" <andrew.thompson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
    Re: Can a jPanel's backgr "JT" <jt@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
      Re: Can a jPanel's backgr "Andrew Thompson" <andrew.thompson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
        Re: Can a jPanel's backgr "Philipp" <philipp@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
          Re: Can a jPanel's backgr "Andrew Thompson" <andrew.thompson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
            Re: Can a jPanel's backgr "Philipp" <philipp@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
            Re: Can a jPanel's backgr "Knute Johnson" <knute.johnson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
              Re: Can a jPanel's backgr "Philipp" <philipp@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
                Re: Can a jPanel's backgr "JT" <jt@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
                Re: Can a jPanel's backgr "Knute Johnson" <knute.johnson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
            Re: Can a jPanel's backgr "Tom Hawtin" <tom.hawtin@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
          Re: Can a jPanel's backgr "Tom Hawtin" <tom.hawtin@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
        Re: Can a jPanel's backgr "JT" <jt@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
          Re: Can a jPanel's backgr "Philipp" <philipp@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000

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