<Swing Dev> [9] Review request for 8163167: [PIT] javax/swing/JTextArea/ScrollbarFlicker/ScrollFlickerTest.java always fail

[Semyon Sadetsky]

On 8/23/2016 9:29 PM, Sergey Bylokhov wrote:
> On 23.08.16 20:57, Semyon Sadetsky wrote:
>>>>> Just to clarify, on what L&f the bug is reproduced? Why we call the
>>>>> listener 6 times when we set the size of scroll only once?
>>>>> I tried to print the bounds of the viewport in the listener and it
>>>>> seems that they are the same most of the time:
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=15,height=46]
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=15,height=46]
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=0,height=46]
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=0,height=46]
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=0,height=46]
>>>>> bounds = java.awt.Rectangle[x=2,y=2,width=0,height=46]
>>>>>
>>>>> So probably it is possible to minimize the number of calls?
>>>> This is expected behavior. It is because JScrollPane consists of 
>>>> several
>>>> areas which may report changes each time they got a size.
>>>
>>> But in some cases the size is the same, for example in the text above
>>> notification occurred twice for [x=2,y=2,width=15,height=46].
>> This is how the internal JScrollPane layout algorithm works. It is most
>> optimal way to layout the viewport, the text inside it along with the
>> scroll bars. It requires several iterations usually.
>
> Yes, we can validate/revalidate do some other stuff internally, but it 
> is unclear why we call the listener when actually nothing was changed 
> from the user point of view(bounds are the same). I see that in the 
> code we have some check to block such noop notifications, but probably 
> in some cases they are missed?
I'm not sure that "nothing is changed". The external visible size is not 
changed but the internal state does. The internal state may include a 
set of different areas sizes, vertical/horizontal scroll bars 
visible/hidden.
>
>>>>>
>>>>> On 23.08.16 11:59, Alexander Scherbatiy wrote:
>>>>>> The fix looks good to me.
>>>>>>
>>>>>> Thanks,
>>>>>> Alexandr.
>>>>>>
>>>>>> On 23/08/16 11:40, Semyon Sadetsky wrote:
>>>>>>> Hello,
>>>>>>>
>>>>>>> Please review fix for JDK9:
>>>>>>>
>>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8163167
>>>>>>>
>>>>>>> webrev: http://cr.openjdk.java.net/~ssadetsky/8163167/webrev.00/
>>>>>>>
>>>>>>> The cause of this test bug is revalidating JScrollPane layout may
>>>>>>> take
>>>>>>> various number of iterations on different L&Fs.
>>>>>>>
>>>>>>> To fix the test the counter listener is added after the layout
>>>>>>> revalidation has been started.
>>>>>>>
>>>>>>> --Semyon
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>