Hi Gunnar, I'll see if I can create a small example that reproduces it. Cheers, Ola
2013/11/13 Sletta Gunnar <gunnar.sle...@digia.com> > If this consistently reproducible across desktop and device, then I > would appreciate a bugreport with an example that reproduces it. It is not > a known issue to me at least. (bugreports.qt-project.org) > > Clipping is implemented using scissor or stencil depending on the > complexity of the mask, no intermediate texture is involved. > > cheers, > Gunnar > > ------------------------------ > *Fra:* > interest-bounces+gunnar.sletta=digia....@qt-project.org[interest-bounces+gunnar.sletta= > digia....@qt-project.org] på vegne av Ola Røer Thorsen [o...@silentwings.no > ] > *Sendt:* 13. november 2013 15:29 > *To:* interest@qt-project.org > *Emne:* [Interest] Tearing in Quick2 flickable-based items with clipping > enabled > > Hi all, > > I'm seeing tearing-effects when scrolling in ListView and other items > based on Flickable when clipping is enabled. This is running on both a > Linux desktop as well as an embedded Linux device (eglfs). The Qt version > is 5.1.1. > > The systems are running with vsync enabled and double-buffering. There > is no tearing in any other items except the ones with clipping enabled. > Tearing is especially noticeable on the embedded device. The GPU is a > PowerVR SGX chip which is tile-based, so the tearing "lines" are actually > vertical. Also the framerate is mostly somewhere between 30-60. > > Tearing appears maybe 20% of the time spent scrolling. > > I'm wondering if the core issue is this: > > I assume clipping is implemented as rendering the item into a temporary > texture, and the clipped area is of this is finally rendered to the screen > buffer. This temporary texture is not double-buffered. This means it would > be possible that the render pipeline starts writing into a texture (next > frame) that is being drawing into the screen buffer (current frame). > > Any thoughts? The tearing is really bad sometimes, and I don't really > have the option of disabling clipping either. > > Cheers, > Ola > > > >
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