PropertyAction，PauseAnimation

SequentialAnimation {
    PropertyAction { target: img; property: "opacity"; value: .5 }
    NumberAnimation { target: img; property: "width"; to: 300; duration: 1000 }
    PropertyAction { target: img; property: "opacity"; value: 1 }
}

SequentialAnimation {
    NumberAnimation { ... duration: 200 }
    PauseAnimation { duration: 100 }
    NumberAnimation { ... duration: 200 }
}