Horizontally flipping component changes x position

[eragon]

I am attempting to horizontally flip a QML component. I have the below shape:

And I am attempting to flip/reflect it horizontally to produce:

I can flip the component using Matrix4x4 (see below code) but it also changes the x position. See below image.

How can I preserve the x position when flipping the component? Ie, how can I keep it in the same place?

In the below ignore the blue label. The green line should sit more right, ie, have the same x position as the above.

Shape {
    id: annotationHLine;
    anchors.left: annotationShp.right;
    anchors.top: annotationShp.top;
    anchors.topMargin: annotationShp.height * 0.5;

    ShapePath {
        strokeWidth: 2;
        strokeColor: "Green";
        fillColor: "transparent";
        startX: -slant; startY: 0;
        PathLine { x: relativeTargetX*0.5; y: 0 }
        PathLine { x: relativeTargetX; y: relativeTargetY }
    }

    transform: Matrix4x4 {
      matrix: Qt.matrix4x4(-1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)
    }
}

[sierdzio]

Maybe try the Rotation API instead? It's simpler.