[Interest] Input Latency Issues in QtQuick

[Damian Ivanov]

hmm I can confirm the problem with the test case, depending on what
application you have this can be from absolutely not important to
quite a deal-breaker...
I would fill a bug.

2014-03-22 23:09 GMT+02:00 Willem Bennekom <cumulatm at gmail.com>:
> For me, the lagging is clearly noticeable on all platforms where vsync is
> enabled.
> (Macbook Pro (Nvidia), Linux/Windows Desktop with Nvidia, Windows Desktop
> with AMD + Angle.
> It hapopens with all Qt Quick versions.)
>
> Here's a minimal test scene (rectangle follows mouse):
> http://pastie.org/pastes/8959817
>
> 2014-03-22 18:37 GMT+01:00 Damian Ivanov <damianatorrpm at gmail.com>:
>
>> for the record: I can't confirm this, QML input is instantly here free
>> radeon driver (5series) on openSUSE 13.1 64bit.
>>
>> 2014-03-22 15:46 GMT+01:00 Willem Bennekom <cumulatm at gmail.com>:
>> > With its current architecture, QtQuick has input latency issues:
>> > The scene reacts to user input with a slight, but noticeable delay,
>> > which
>> > makes
>> > QtQuick apps feel clumsy and unpleasant to use.
>> >
>> > I guess this is related to vsync handling, where input events don't
>> > immediately
>> > trigger a repaint while the render thread waits until the framebuffer is
>> > swapped.
>> >
>> > The only exception are Windows platforms with native OpenGL on ATI
>> > cards,
>> > where the framerate seems to be uncapped:
>> > The rendering is super responsive, almost like Qt Widgets.
>> > The drawback is that render thread animators are broken, as they aren't
>> > synced to 60 Hz.
>> >
>> > 1. Is there a way to hack Qt to get this Windows+OpenGL+ATI rendering
>> > behavior on all platforms?
>> >    Maybe some tweaks in qsg*renderloop.cpp?
>> >
>> > 2. Are there plans to implement a rendering scheme that reduces input
>> > latency?
>> >
>> > Thanks
>> > Willem
>> >
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>> >
>
>