angle property Null safety
The direction of the curve at position.
This value is in radians, with 0.0 meaning pointing along the x axis in the positive x-axis direction, positive numbers pointing downward toward the negative y-axis, i.e. in a clockwise direction, and negative numbers pointing upward toward the positive y-axis, i.e. in a counter-clockwise direction.
// flip the sign to be consistent with [Path.arcTo]'s `sweepAngle` double get angle => -math.atan2(vector.dy, vector.dx);