<Swing Dev> 7189299 DefaultButtonModel instance keeps stale listeners of JButton in case of multiple SwingUtilities.updateComponentTreeUI() calls

[Alexander Scherbatiy]

On 11/1/2012 10:35 AM, Frank Ding wrote:
> Hi Alexandr,
>   Thanks for your review.  The problem that the JButton does not 
> release itself as you mentioned is, after taking closer look at 
> relevant code again, that I removed instance AbstractButton.Handler as 
> change listener where repainting the button press animation is 
> defined.  So this time I get around this issue and here comes v6 patch @
> http://cr.openjdk.java.net/~dingxmin/7189299/webrev.06/
>
>   Below are answers to what you have raised in previous email.
> 1. if ( if (!listener.equals(this)) { that 'this' means the 
> JButtonWrapper instead of an action listener.
>   'this' refers to JButtonWrapper.this because the closest class 
> definition is JButtonWrapper.  I also verified it during my debugging.

     Could you give an example there this check is useful? It seems that 
the JButtonWrapper does not implement ActionListener interface and so 
the listener and the this always should not be equal.


    I dumped action listeners from the button and model before the fix 
and after it.
    Before the fix the button has the latest FormView listener and the 
model has AbstractButton$Handler added each time after a component input 
creation.
    After the fix both the button and the model have the FormView 
listener and the button does not have the AbstractButton$Handler.
    Could you preserve the listeners location and just remove old 
listeners from the model?

    The fix sets the model to the JButtonWrapper first and than removes 
unneccessary listeners from the model. Is it possible to rearrange order 
of these operations?

    I see that you check number of the listeners in the test. Could you 
add the check that the action listener is invoked only once after a 
component tree updating and
    the action does the same that it does before a component tree updating.

    Thanks,
    Alexandr.
>
> 2. Why are two FormViews created in this sample?
> SwingUtilities.updateComponentTreeUI() triggers html View hierarchy to 
> update by instantiating new UI instances involved in the html form.  
> It could have been avoided to have 2 View instances but we are 
> restricted to current design that LF change causes creation of View 
> instance which further leads to creation of new UI instances.  
> Creation of new UI instances upon LF change can be referenced in 
> BasicTextUI.modelChanged().
>
> 3. Why are there 2 listeners added to the button model in this sample?
> The issue is caused by combination of the 2 factors.  First, a shared 
> ButtonModel is created per html Element.  Second, JButton.setModel() 
> automatically registers its private Handler in the new model but no 
> way to deregister it.  The first is a design choice but the second is 
> a design flaw.  Consequence is that the shared ButtonModel instance 
> bears more and more JButton.Handler.
>
> I think v6 patch is promising as a final fix.  If you have any further 
> concern or comment, please don't hesitate to let me know. Thanks again 
> for your careful review.
>
> Best regards,
> Frank
>
> On 10/30/2012 9:38 PM, Alexander Scherbatiy wrote:
>> Hi Frank,
>>
>> I tried your V5 patch and run the test described in the issue (see 
>> below).
>> I pressed the button and it does not release. This is because the 
>> AbstractButton.Handler listener is removed because of the fix.
>> You could check the line
>>     941   if (!listener.equals(this)) {
>> that 'this' means the JButtonWrapper instead of an action listener.
>>
>> Could you also look deeper in the code and say why two FormViews are 
>> created (and each adds it's own listener to the button model) in this 
>> sample?
>>
>> -----------------------------------------------
>> import java.awt.*;
>> import javax.swing.*;
>>
>> public class FormSubmit {
>>
>>     public static void main(String[] args) throws Exception {
>>         SwingUtilities.invokeAndWait(new Runnable() {
>>
>>             @Override
>>             public void run() {
>>
>>                 JEditorPane html = new JEditorPane("text/html", 
>> "<html><body><FORM ACTION=\"examplescript.cgi\"><INPUT 
>> type=\"submit\" value=\"Submit\"></FORM></BODY></HTML>");
>>                 JFrame frame = new JFrame()
>>                 frame.setLayout(new BorderLayout());
>>                 frame.add(html, BorderLayout.CENTER);
>>                 frame.setSize(200, 100);
>> frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
>>                 frame.setVisible(true); // Uncomment this line to see 
>> the Exception on JDK 7
>>                 SwingUtilities.updateComponentTreeUI(html);
>>             }
>>         });
>>     }
>> }
>> -----------------------------------------------
>>
>> Thanks,
>> Alexandr.
>>
>> On 10/29/2012 11:48 AM, Frank Ding wrote:
>>> Hi all,
>>>   Seems Pavel has been busy these days.  Is anybody willing to 
>>> review v5 change?
>>>
>>> Thanks,
>>> Frank
>>>
>