Jakar.Shapes 10.2.0

Jakar.Shapes

A dependency-light 2D geometry library for .NET. Every shape is a struct, every operation is [Pure], and the shared behaviour lives on generic interfaces with static abstract members so algorithms can be written once against IShape<TSelf> and reused for every model.

Contributions and ideas are welcome.

• Target framework: net10.0 (C# 14 — uses the new extension member blocks)
• Dependencies: Jakar.Extensions, ZLinq
• License: MIT

Installation

dotnet add package Jakar.Shapes

Design

Interface hierarchy

IShape<TSelf>  : IValidator, IFormattable, IJsonSerializable<TSelf>, IEqualComparable<TSelf>
  ├── IPoint<TSelf>            + IShapeLocation
  ├── ISize<TSelf>             + IShapeSize
  ├── IThickness<TSelf>
  ├── ILine<TSelf, TPoint>     (+ ILine<TSelf> bound to ReadOnlyPoint)
  ├── ISpline<TSelf, TPoint>   + IStructuralComparable<TSelf>, IValueEnumerable<…>
  ├── IRectangle<TSelf>        + IShapeSize, IShapeLocation
  │     └── IMutableRectangle<TSelf>
  ├── ICircle<TSelf>           + IShapeLocation
  ├── IEllipse<TSelf>          + IShapeLocation
  ├── ITriangle<TSelf>         + IShapeLocation
  ├── IQuadrilateral<TSelf>    + IShapeLocation
  └── IRegularPolygon<TSelf>   + IShapeLocation

IShapeLocation supplies Location, X, Y; IShapeSize supplies Size, Width, Height.

Models

Primitives

Rectangles

Lines and curves

Curved shapes

Triangles and quadrilaterals

The quadrilateral specialisations are distinguished by name, not by invariant — nothing stops a Square holding four arbitrary points. When the classification has to hold, call the matching predicate: IsSquare, IsRhombus, IsRectangle, IsTrapezoid, IsKite, IsParallelogram, IsConvex.

Regular polygons

Each is a readonly struct (ReadOnlyPoint center, double circumradius, Radians rotation) implementing IRegularPolygon<TSelf>, with SideCount fixed per type so you can overload on the shape:

Rotation is applied about the centre; zero places the first vertex along +X.

Fitting

Enumerations

Extension surface

Because the members live on generic extension blocks, everything below works on any implementer of the interface — including your own types.

Every extension block also carries the common validity set: IsValid, IsNaN, IsFinite, IsInfinity, IsInteger, IsNegative, IsPositive, IsZero, plus Abs, Round, Floor, Deconstruct, and a ToString(format) accepting "json", ",", "-", or null.

Usage

using Jakar.Shapes;

// Points, sizes and rectangles interop with System.Drawing and with scalars.
ReadOnlyPoint     a    = new(3, 4);
ReadOnlyPoint     b    = 10;                         // (10, 10)
double            dist = a.DistanceTo(b);
ReadOnlyRectangle rect = ReadOnlyRectangle.Create(0, 0, 100, 50);
bool              hit  = rect.Contains(a);
ReadOnlyLine      top  = rect.TopSide;

// Circles.
Circle circle = Circle.Create(new ReadOnlyPoint(0, 0), 5);
double area   = circle.Area;
Polygon approx = circle.ToPolygon(64);
CircleLineRelation relation = circle.GetLineRelation(top);

// Regular polygons — rotation in radians, angles reported in degrees.
Hexagon hex     = Hexagon.Create(ReadOnlyPoint.Zero, circumradius: 10, rotation: Radians.Zero);
Degrees interior = hex.InteriorAngle;                // 120°
Circle  inner    = hex.InscribedCircle;

// Quadrilaterals classify on demand.
Square square = Square.Create(new(0, 0), new(4, 0), new(4, 4), new(0, 4));
bool   real   = square.IsSquare;

// Curve fitting.
Spline         points = Spline.Create(new ReadOnlyPoint(0, 1), new(1, 3), new(2, 7), new(3, 13));
PolynomialFit  fit    = LineOfBestFit.Fit(points.Span);
CalculatedLine line   = fit.ToCalculatedLine();
ReadOnlyPoint  at5    = line.Get(5);

// JSON round-trip.
string json  = circle.ToJson();
Circle again = Circle.FromJson(json);

Repository layout

Jakar.Shapes/
  Enumerations/   CircleLineRelation, Quadrant
  Interfaces/     IShape and friends, RefSelect delegates
  Geometry/       the concrete models
  Extensions/     the generic extension blocks
Jakar.Shapes.Tests/          unit tests
Jakar.Shapes.Experiments/    scratch console project

License

MIT — see LICENSE.txt.

Contributions are welcome; please open an issue or submit a pull request on GitHub.