[Interest] QML animation flicker

[Jarno Seppänen]

hi,

On Mon, Oct 15, 2012 at 11:29 AM, Samuel Rødal <samuel.rodal at digia.com> wrote:
> On 10/12/2012 11:10 PM, Jarno Seppänen wrote:
>> Hi,
>> I'm trying out Qt 5.0.0-beta1, but I'm seeing some unexpected
>> animation flicker. I have a rotating rectangle which starts to flicker
>> during a simultaneous ColorAnimation, without it the rotation is
>> smooth. Is this an issue with my setup and should I change my QML code
>> somehow? I've gotten similar results on two Ubuntu laptops, running
>> 11.04 and 12.04.
>
> Hmm, I was not able to reproduce this with a recent build of Qt 5. What
> kind of flicker are you talking about?

The animation movement jerks back and forth very fast, as if every two
frames were being displayed in swapped order. The effect is especially
disturbing on scrolling text. I tried to capture a video of the
flicker, but it seems that the screen recording software does
something that makes the problem disappear. I also noticed that the
flicker is much diminished if I run qmlscene in a window, running qml
--fullscreen gives "best" flicker.

Example with text flicker:

import QtQuick 2.0
import QtGraphicalEffects 1.0

FocusScope {
    id:screen

    SequentialAnimation {
        loops: Animation.Infinite; running: true
        PauseAnimation { duration: 1000 }
        ColorAnimation { target: glow; property: "color"; to: "navy";
duration: 1000; easing.type: Easing.InOutQuad }
        PauseAnimation { duration: 1000 }
        ColorAnimation { target: glow; property: "color"; to: "blue";
duration: 1000; easing.type: Easing.InOutQuad }
    }

    RadialGradient {
        gradient: Gradient {
            GradientStop { id: glow; position: 0.0; color: "blue" }
            GradientStop { position: .7; color: "blue" }
        }
        anchors.fill: parent
    }

    Text {
        id:txt
        width:600
        color:"white"
        text: "Lorem ipsum dolor sit amet, consectetur adipisicing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna
aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco
laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla
pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
culpa qui officia deserunt mollit anim id est laborum."
        font.weight:Text.Bold
        font.pointSize:30
        wrapMode: Text.Wrap
        NumberAnimation on y {
            from:-txt.contentHeight
            to:txt.contentHeight+500
            loops:-1
            duration:6000
        }
        anchors.horizontalCenter:parent.horizontalCenter
    }
}

Jarno