QtQuick 2 animation performance issue

dvolosnykh

Consider example below:

@
import QtQuick 2.0

PathView {
width: 1280
height: 720
cacheItemCount: 7
pathItemCount: 7
preferredHighlightBegin: 0.5
preferredHighlightEnd: 0.5
model: ListModel {
ListElement {
color: "orange"
text: "first"
}
ListElement {
color: "lightgreen"
text: "second"
}
ListElement {
color: "orchid"
text: "third"
}
ListElement {
color: "tomato"
text: "fourth"
}
ListElement {
color: "skyblue"
text: "fifth"
}
ListElement {
color: "hotpink"
text: "sixth"
}
ListElement {
color: "darkseagreen"
text: "seventh"
}
ListElement {
color: "salmon"
text: "eightth"
}
ListElement {
color: "darkolivegreen"
text: "nineth"
}
ListElement {
color: "navy"
text: "tenth"
}
}
delegate: Item {
width: 150
height: 150

    Rectangle {
        id: rect
        anchors.fill: parent
        color: model.color
        opacity: 0.8
    }

    Text {
        anchors.centerIn: parent
        text: model.text
        color: "white"
        font.pixelSize: 24
    }
}
path: Path {
    startX: -150
    startY: height / 2
    PathLine {
        x: width + 150
        relativeY: 0
    }
}

NumberAnimation on offset {
    from: 0
    to: count
    loops: Animation.Infinite
    duration: 4000
    Component.onCompleted: start()
}

}
@

The animation is jerky for Qt versions 5.1.1 and 5.3.2 (Ubuntu 14.04), and 5.2.1 (embedded Linux). I guess, this is the garbage collector affecting performance, but since UI structure does not change such suggestion might be irrelevant. Is there anything can be done to make animation run smoothly?

Gianluca

Strange usage of "offset" property. From what I know should be used only for setting the initial configuration of the PathView.
Try to animate the currentIndex property.

dvolosnykh

Interesting, I don't experience this issue on Mac OS X 10.10.

Torgeir

This seems smooth to my eyes in both Windows 7 and Kubuntu 14.10.

Is the jerkyness very subtle? If not, can you check if any processes are possibly loading your CPU? Is vsync enabled or disabled?

Anyway I really do not think QML garbage collection plays any part in this performance.

dvolosnykh

I've checked that on Windows 7 and its rather smooth, too, even that it runs on 10 years old laptop.

Jerkyness is easily noticeable and reproduces constantly and consistently: extremely jerky at the very start of the application and then it becomes acceptably smooth with periodical (approximately over a constant time period) freezes for a short time.

Veryfied issue on Ubuntu 12.04 laptop. Sync to VBlank is enabled in NVIDIA X Server Settings.

dvolosnykh

I've updated my video graphics adapter driver to the most recent version, and now animation is rather smooth, except for some flickering.