Let QPainter draw custom shape along line/arc/polygon/etc., or let QGraphicsScene lay out items likewise

class CustomGraphicsItem : public QGraphicsItem
{
public:
    QRectF boundingRect() const override
    {
        qreal penWidth = 1;
        return QRectF(-10 - penWidth / 2, -10 - penWidth / 2, 20 + penWidth, 20 + penWidth);
    }

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
    {
        painter->drawImage(this->boundingRect(), QImage("stroke.png"));
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    //The polygon contour
    QPolygonF polygon;
    polygon << QPoint(0, 0) << QPoint(100, 100) << QPoint(200, 100) << QPoint(300, 0);

    QGraphicsScene scene;

    //Loop through polygon vertices
    for (int i = 0; i < polygon.size(); ++i) {
        QPointF p1 = polygon[i];
        QPointF p2 = polygon[(i + 1) % polygon.size()]; // next point, with wraparound

        //Reference item just for better clearity
        CustomGraphicsItem *ref = new CustomGraphicsItem();
        ref->setPos(p1);
        scene.addItem(ref);

        // CInterpolated item
        CustomGraphicsItem *item = new CustomGraphicsItem();

        // Position item at midpoint of polygon side
        item->setPos((p1 + p2) / 2.0);

        // Calculate angle between horizontal and the side of the polygon
        qreal angle = std::atan2(p2.y() - p1.y(), p2.x() - p1.x());

        // Rotate item to align with polygon side
        QTransform t;
        t.rotateRadians(angle);
        item->setTransform(t);

        scene.addItem(item);
    }

    QGraphicsView view(&scene);
    view.show();

    return app.exec();
}