import 'dart:ui' show Offset; extension OffsetCartesionOps on Offset { double distanceSquared(Offset other) { final dx = this.dx - other.dx; final dy = this.dy - other.dy; return dx * dx + dy * dy; } Offset operator -(Offset other) { return Offset(dx - other.dx, dy - other.dy); } String coord() { return '(${dx.toStringAsFixed(2)}, ${dy.toStringAsFixed(2)})'; } }