<Swing Dev> How to resolve image tearing

[Anthony Petrov]

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 "hole" 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, perhaps 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.

--
best regards,
Anthony