cgeo

This is a collection of geometry / geography data types. They're very lightweight and perfect for holding data from a spatial database.

Additional features such as reading / writing different formats or rendering can be added through mixins / module augmentation from add-on packages. All classes are carefully written in TypeScript so that the add-ons can extend all classes while remaining fully typed.

Compatible add-ons:

• cgeo-wkb
• cgeo-wkt
• cgeo-cpak

The supported data types are as follows (nesting indicates inheritance):

• Geometry
  • Point
  • Curve
    • LineString
    • CircularString
    • CompoundCurve
  • Surface
    • Polygon
    • CurvePolygon
  • GeometryCollection
    • MultiPoint
    • MultiCurve
      • MultiLineString
    • MultiSurface
      • MultiPolygon

Usage

Point

An object with 4 properties:

• x (default 0)
• y (default 0)
• z (optional)
• m (optional)

It can be initialized in multiple ways:

let a = new Point(1, 2);
let b = new Point(1, 2, 3, 4);
let c = new Point({ x: 1, y: 2, z: 3, m: 4 });
let d = new Point(b);

The above initialize b, c and d with the same contents. a only has fields x and y.

LineString

Represents a polyline with coordinates stored in separate arrays for each dimension:

• x (array of numbers, empty by default)
• y (array of numbers, empty by default)
• z (optional)
• m (optional)

This representation was chosen due to a compact in-memory representation (typically only two arrays, x and y) that also supports additional dimensions without complicating code that only uses the first two.

It can be initialized in two ways:

let a = new LineString({ x: [ 1, 3 ], y: [ 2, 4 ] });
let b = new LineString([ { x: 1, y: 2 }, { x: 2, y: 4 } ]);

The above initializes a and b with equivalent contents, but only a directly references the input arrays without copying data.

License

The MIT License

Copyright (c) 2017 BusFaster Ltd