ProgressBar {
    id: pb
    value: progress

    property real progress: 0
    SequentialAnimation on progress {
        loops: Animation.Infinite
        running: true
        NumberAnimation {
            from: 0
            to: 1
            duration: 3000
        }
        NumberAnimation {
            from: 1
            to: 0
            duration: 3000
        }
    }

    onValueChanged: print(value)
}