ListView {
    id: list
    clip: true
    model: 20
    width: 200
    height: 400
    spacing: 20
    snapMode: ListView.SnapToItem
    delegate: Rectangle {
        width: 200
        height: 100
        border.color: "blue"
        Text {
            anchors.centerIn: parent
            font.pixelSize: 25
            text: index
        }
    }
}

Button {
    font.pixelSize: 20
    text: list.contentY.toFixed(0)
    onClicked: {
        list.returnToBounds()
    }
}