<Swing Dev> Review request #3: 6852592 (revalidate() must be smarter)

[Alexander Potochkin]

Hello Christopher

> Anthony,
> 
> I think I disagree with Applet returning true to isValidateRoot. If I
> am not mistaken, I think I saw some people placing an applet in their
> component hierarchy as if it was a normal component. Invalidation
> should propagate so that outer components can revalidate and thus have
> proper layout calculations. Thus I think the only AWT components that
> should return true are the ones with an outer parent (window class
> hierarchy).

It is actually not recommended to tread Applet as a normal component

The javadoc says:

  * An applet is a small program that is intended not to be run on
  * its own, but rather to be embedded inside another application.

I would expect some strange bugs in an application that uses JApplet
or Applet instead of general containers like JPanel

Swing code treats Applet like a topLevel component
which reflects in different places

see
SwingUtilities.convertPointToScreen():
SwingUtilities.getRoot(Component)
KeyboardManager.getTopAncestor()
PopupFactory.ContainerPopup.fitsOnScreen()

and so on...

RepaintManager.addInvalidComponent() also uses the same logic for 
Windows and Applets, please have a look at the method's implementation

By the way, when isValidateRoot() method will be brought up to 
Component, I expect the cast to be removed

if ((c instanceof JComponent) && (((JComponent)c).isValidateRoot()))

But, when addInvalidComponent() finds no vaidateRoot,
it immediately returns, and this behavior will be affected

I see no strong reasons to make Windows and Applets to be validate 
roots, just because it won't give us any benefits and may break the 
existing code

Thanks
alexp

> 
> For the window method, shouldn't it be marked as final?
> 
> And what about the AWT ScrollPane? Shouldn't it return true as well?
> 
> Hope this helps,
> -Christopher
> 
> 
> On Thu, Jul 23, 2009 at 1:57 PM, Anthony Petrov<Anthony.Petrov at sun.com> wrote:
>> Hello Swing and AWT teams,
>>
>> So here's the latest version of the fix:
>>
>> http://cr.openjdk.java.net/~anthony/7-23-invalidate-6852592.2/
>>
>> The specification has been modified, some stuff has been moved around.
>> Currently the spec is being reviewed by the CCC at Sun, and therefore is
>> kind of frozen. However, if anyone happen to find major problems with the
>> javadoc, please feel free to speak up.
>>
>> Suggestions for the code changes are still very welcome. Thank you in
>> advance!
>>
>> --
>> best regards,
>> Anthony
>>