<Swing Dev> How to resolve image tearing

[Alexander Potochkin]

Hello Ximalaya
> Hi Artem,
> Nice to get your quick reply.
> It's really a surprise "JComponent.repaint() is no longer thread safe".
>
> Regarding question 1, I ever looked into JDK source code, it seems 
> JComponent.paint only takes care of lw sub-components.

We didn't change JComponent.repaint() to make it "no longer thread safe"
and I don't see why someone may think about it

Actually the whole blog
http://stevensrmiller.com/wordpress/?p=567
doesn't seem to be very informative

In the provided changeset from Netbeans
http://hg.netbeans.org/jet-main/rev/7aeb7cd8f1d0

they call their internal method on EDT (not JComponent.repaint())
ViewUtils.repaint(textComponent, repaintBounds);
and I don't know what exactly it does

Thanks
alexp
>
> Thanks,
> Xmly
> At 2011-05-27 02:41:17£¬"Artem Ananiev" <artem.ananiev at oracle.com> 
> wrote: > >On 5/26/2011 10:16 PM, ximalaya wrote: >> Hi Anthony, >> 
> Thanks for your replies in last month. I still still have some 
> questions >> and need your help. >> >> 1. Method paint of Canvas(hw 
> component) is not called when its container >> JPanel repaints >> I 
> have a JFrame. Inside the JFrame, there is a JPanel. And inside the >> 
> JPanel there is a Canvas. I found Canvas.paint was never called when I 
> >> call JPanel.repaint(). Is it normal? Is it just another case we 
> simply >> can't sync up with repainting of lw and hw components? >> >> 
> 2. Thread safe of Componet.repaint//JComponent.repaint()/ >> I ever 
> read some articles about JComponet.repaint. It was said that it >> was 
> thread safe. But I learn from an article that JComponet.repaint is >> 
> no longer thread safe since JDK 6 update 22 - >> "/do not call 
> JComponent.repaint() outside the Swing Event Dispatch >> Thread" , >> 
> / You can find the article here, 
> http://stevensrmiller.com/wordpress/?p=567 > >It's the first time I've 
> heard about it. Looks like a terrible Swing >bug, doesn't it? 
> Unfortunately, there is no information about why >exactly repaint() is 
> no longer thread-safe, so I'm very skeptic about >this post. Let other 
> Swing team members comment. > >Thanks, > >Artem > >> Does it apply to 
> Componet.repaint also? >> >> Thanks and Best Regards, >> Xmly >> On 
> 4/18/2011 8:51 PM, ximalaya wrote: >> > Sorry, I don't quite 
> understand why we simply can't sync up with >> > repainting of lw and 
> hw components. Could you please give me more >> > information? >> >> 
> We can't determine when a third-party hw component repaints itself. >> 
> Therefore we can't simply paint non-opaque lw components onto the >> 
> surface of the hw component. >> >> The only way to implement mixing 
> for non-opaque lw components, as we see >> it currently, is to turn 
> them into hw components and recalculate their >> shapes each time the 
> lw components paints anything onto itself. >> Alternatively, we could 
> leave lw component being lw, and instead >> calculate the shape of a 
> "ho! le" to cut off of underneath components. >> Either way, the 
> performance of such solutions leaves much to be desired >> because lw 
> components may repaint themselves very frequently. >> >> Note that 
> currently mixing is implemented by cutting off hw components >> based 
> on shapes of lw components (i.e. the second option above). And >> 
> since we support opaque lw components only, their shape is always >> 
> rectangular, which doesn't hurt the performance of the hw/lw mixing 
> feature. >> >> In your case, you update the content of your own hw 
> canvas yourself. >> Hence, as a final step you can simply paint your 
> text for each frame of >> your graphics right onto the canvas, and 
> (baring the vertical sync >> issues) this should provide reliable 
> results. >> >> >> > For the difference between openJDK 1.6.0_18 and 
> latest openJDK, please >> > pay attention that, openJDK was used in 
> our test. I am not sure the code >> > base of openJDK 1.6.0_18 is same 
> as JDK 1.6.0 u18, per! haps you can have >> > a try with openJDK? >> 
> >> I'm still unable to identify any change that could break the hw/lw 
> >> mixing in 6u18. Could you please provide more details of what exact 
> >> issue you're experiencing? A small test application that 
> demonstrates >> the issue would be very helpful. Thanks. >> >> >>
>