<Swing Dev> <AWT Dev> [9] Review request for JDK-8039383: NPE when changing Windows Theme

[Alexey Ivanov]

Hi Anthony,

Thank you for your review and your concern.

I'll try another solution.

Regards,
Alexey.

On 18.04.2014 18:52, Anthony Petrov wrote:
> Hi Alexey,
>
> No, unfortunately I don't have any suggestions right now.
>
> As for allowing executing user code on the toolkit thread, we can't 
> accept such a fix. Sorry about that.
>
> -- 
> best regards,
> Anthony
>
> On 4/18/2014 6:48 PM, Alexey Ivanov wrote:
>> Hi Anthony,
>>
>> Thank you for your review.
>>
>> Yes, user code can install a property change listener... It was my
>> concern too, that's why I explicitly noted about this.
>>
>> Do you have any suggestion how this situation can be handled?
>> Is it a general rule that all desktop property change listeners must be
>> called on EDT?
>>
>>
>> Thanks,
>> Alexey.
>>
>> On 18.04.2014 16:02, Anthony Petrov wrote:
>>> Hi Alexey,
>>>
>>>> With this change, property "win.xpstyle.themeActive" change is fired
>>>> on the toolkit thread
>>>
>>> Is it possible to install a change listener for this property from
>>> user code, and hence eventually allow executing some user code on the
>>> toolkit thread with your fix?
>>>
>>> -- 
>>> best regards,
>>> Anthony
>>>
>>> On 4/18/2014 12:09 PM, Alexey Ivanov wrote:
>>>> Hello Swing and AWT teams,
>>>>
>>>> Could you please review the fix for jdk9:
>>>>      bug: https://bugs.openjdk.java.net/browse/JDK-8039383
>>>>      webrev: 
>>>> http://cr.openjdk.java.net/~dmarkov/8039383/jdk9/webrev.00/
>>>>
>>>> Problem description:
>>>> When changing Windows themes from a theme with visual styles (Windows
>>>> Aero or Windows Basic) to a classic one, NullPointerException could be
>>>> thrown from Swing code during component tree validation, or
>>>> InternalError could be thrown during component painting.
>>>>
>>>> Root cause:
>>>> Windows theme data are "cached" in XPStyle object. When the theme is
>>>> switched to a classic one, HTHEME handle becomes unavailable and data
>>>> cannot be accessed from the theme any more. The change in theme in
>>>> posted to EDT via invokeLater. At the same time, the UI needs to 
>>>> repaint
>>>> itself as soon as Windows changed the theme, and paint code is often
>>>> called before the theme change is handled in Java. This leads to 
>>>> NPE and
>>>> InternalError as the code tries to access the data that has become
>>>> unavailable.
>>>>
>>>> The fix:
>>>> Update "win.xpstyle.themeActive" desktop property and invalidate the
>>>> cached XPStyle as soon as windowsSettingChange() is called from native
>>>> code. Thus when Swing code needs to access theme data, it will see no
>>>> theme is available and will fallback to classic painting.
>>>>
>>>> Note: Before the fix, PropertyChangeEvents for desktop properties in
>>>> Windows were fired on the Event Dispatch Thread. With this change,
>>>> property "win.xpstyle.themeActive" change is fired on the toolkit
>>>> thread; all other properties are changed on the EDT as before.
>>>>
>>>>
>>>> Regards,
>>>> Alexey.
>>