It's impossible to assign transform QML types to transform property using Property editor

    Image {
        id: bg;
        width: implicitWidth
        height: implicitHeight
        anchors.centerIn: parent;
        source: "images/gauge-gauge-frame.png"
// it's impossible to achieve the code below in GUI way.
// Users have to manually write code to achieve this.
        transform: [
            Scale {
                origin.x: bg.implicitWidth / 2;
                xScale: left ? 1 : -1;
            },
            Scale {
                origin.x: transformOriginX - bg.x
                origin.y: 340 - bg.y
                xScale: root.scale
                yScale: root.scale
            }
        ]
    }