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Date: Tue, 18 Sep 2007 08:23:43 -0700 (PDT)
From: "Chunrong Lai (JIRA)" <jira@apache.org>
To: commits@harmony.apache.org
Subject: [jira] Commented: (HARMONY-4803) [classlib][awt] firepropertyChange
 only when it really change?
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    [ https://issues.apache.org/jira/browse/HARMONY-4803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12528411 ] 

Chunrong Lai commented on HARMONY-4803:
---------------------------------------


 It is understandable that RI also repaint when setBackground. 
 Below class MyPanel introduces dead loop (with a changing background color) both in RI  and Harmony.

class   MyPanel   extends   Panel{   
  int   flag   =   0   ;   
    
  public   void   paint(Graphics   g){   
    if(flag==0){   
      setBackground(Color.green)   ;   
      flag++   ;   
    } else   if(flag==1){   
      setBackground(Color.red)   ;   
      flag++   ;   
    } else   if(flag==2){   
      setBackground(Color.blue)   ;   
      flag=0   ;   
    }   
    System.out.println   ("hi")   ;   
  }   
}   

  But for the original test, Harmony does avoid the dead loop by color comparison.


> [classlib][awt] firepropertyChange only when it really change?
> --------------------------------------------------------------
>
>                 Key: HARMONY-4803
>                 URL: https://issues.apache.org/jira/browse/HARMONY-4803
>             Project: Harmony
>          Issue Type: Bug
>          Components: Classlib
>         Environment: Win32 + Linux32
>            Reporter: Chunrong Lai
>            Assignee: Alexei Zakharov
>         Attachments: H4803.fixedforeground.patch, H4803.fixedreproducer.patch
>
>
>  Below reproducer shows the reaint and  firePropertyChange triggered from setBackground().
>  Harmony falls into a dead loop setBackground()->repaint()->update()->paint()->setBackground().
>  It is easy to break the loop if we only repaint (and firepropertyChange) when the old background does not equal to the new background.
>  I believe there are other similar issues like this.
> import   java.awt.*   ;   
> import   java.awt.event.*   ;   
>     
> class   MyPanel   extends   Panel{   
>   int   flag   =   0   ;   
>     
>   public   void   paint(Graphics   g){   
>     setBackground(Color.blue)   ;   
>     System.out.println   ("hi")   ;   
>   }   
> }   
>     
> public class   MyFrame   extends   Frame{   
>   MyFrame(){   
>     add(new MyPanel())   ;   
>     setSize(300,200)   ;   
>     setVisible(true)   ;   
>   }   
>   public   static   void   main(String   args[]){   
>     new   MyFrame()   ;   
>   }   
> } 

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