screenToWorld method
Implementation
DiagramPoint screenToWorld(DiagramPoint screen) => DiagramPoint(
(screen.x - viewportSize.width / 2) / zoom + center.x,
(screen.y - viewportSize.height / 2) / zoom + center.y,
);
DiagramPoint screenToWorld(DiagramPoint screen) => DiagramPoint(
(screen.x - viewportSize.width / 2) / zoom + center.x,
(screen.y - viewportSize.height / 2) / zoom + center.y,
);