Details
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Bug
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Resolution: Unresolved
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P3: Somewhat important
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None
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5.0.0 Beta 1
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None
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Reproduced on four machines: Ubuntu 11.04 with Intel Poulsbo and Qt 5.0.0-beta1 built from source; Ubuntu 12.04.1 with Intel GMA4500MHD and Qt 5.0.0-beta1 binaries; Ubuntu 12.04.1 with Nvidia GeForce GT 520 and Qt 5.0.0-beta1 binaries; Ubuntu 12.04.1 with Quadro FX 3800 running Qt5 and qtgraphicaleffects master repositories as of Oct 14thReproduced on four machines: Ubuntu 11.04 with Intel Poulsbo and Qt 5.0.0-beta1 built from source; Ubuntu 12.04.1 with Intel GMA4500MHD and Qt 5.0.0-beta1 binaries; Ubuntu 12.04.1 with Nvidia GeForce GT 520 and Qt 5.0.0-beta1 binaries; Ubuntu 12.04.1 with Quadro FX 3800 running Qt5 and qtgraphicaleffects master repositories as of Oct 14th
Description
Animated movements such as rectangle rotation or text scrolling start to flicker/stutter under certain conditions:
- there is a RadialGradient in the background (from QtGraphicalEffects)
- gradient color is changed with ColorAnimation
The flicker looks like the animation movement jerking back and forth very fast, as if every two frames were being displayed in swapped order. The effect is especially disturbing on scrolling text (see attached flicker.qml). I also noticed that the flicker is much diminished if I run qmlscene in a window, running qmlscene --fullscreen gives "best" flicker.
The problem doesn't appear if the RadialGradient is switched to a Rectangle having a linear gradient, or the ColorAnimation is removed. Also, trying to record a video with gtk-recordmydesktop makes the flicker disappear. Further, on Nvidia, the flicker disappears if "Sync to VBlank" is turned off from OpenGL Settings in nvidia settings panel (but other problems appear, obviously).
Original discussion: http://lists.qt-project.org/pipermail/interest/2012-October/004361.html
Jarno