Calculate the area of a simple 2D polygon given its vertices.

This is a port of the math-utils/area-polygon library written in JavaScript.

Usage

List<Offset> points = [
    // your points here, e.g. a 4x4 square:
    Offset(0, 0),
    Offset(0, 4),
    Offset(4, 4),
    Offset(4, 0),
];
double area = calculateArea(points); // 16
print('Area: $area');

The points must also trace the edge of the polygon. The last point is assumed to be connected to the first point.

If signed is true, this will return the signed area. This is helpful to determine the orientation of points.

Signed area is positive if the points are counter-clockwise, or negative if the points are clockwise.