https://bugs.kde.org/show_bug.cgi?id=427504
--- Comment #5 from David Hurka <david.hu...@mailbox.org> --- Created attachment 132319 --> https://bugs.kde.org/attachment.cgi?id=132319&action=edit Slightly jittery scrolling with `xdotool key Down` This is what I get with `xdotool key --delay 5 Down Down [...] Down`. Afaik arrow key events go the same code path as wheel events. These are arrow key events at 200Hz. Scrolling is slightly jittery, but not always. This is the relevant code from slotScrollDown(): > d->scroller->scrollTo(d->scroller->finalPosition() + QPoint(0, 100 * nSteps), > 100); This makes an undamped regulator/controller. If you consider the animation timer a feedback loop, the feedback loop is probably undamped too. The 100ms could be considered the “length” of the feedback loop. If you generate a constant stream of scroll events, the way you begin the stream can make the regulator oscillate. Since there is no damping, oscillation will continue until you accelerate or decelerate. I don’t think we should include damping code in Okular, it is more a QScroller bug. At least I don’t know what would work in Okular. Maybe we should reduce the 100ms at high event frequencies, like Nate indicated(?); or maybe it is enough to add a random component to the 100ms. -- You are receiving this mail because: You are the assignee for the bug.
