<Swing Dev> How to resolve image tearing

[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.

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. >> >> >>
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