svg-pathdata/src/tests/arc.test.ts

Manipulate SVG path data (path[d] attribute content) simply and efficiently.

import { describe, test, expect } from '@jest/globals';
import { SVGPathData } from '../index.js';
import { type CommandA } from '../types.js';

describe('Parsing elliptical arc commands', () => {
  test('should not work when badly declared', () => {
    expect(() => new SVGPathData('A')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(() => new SVGPathData('A 30')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(() => new SVGPathData('A 30 50')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );

    expect(() => new SVGPathData('A 30 50 0')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(() => new SVGPathData('A 30 50 0 0')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(() => new SVGPathData('A 30 50 0 0 1')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(() => new SVGPathData('A 30 50 0 0 1 162.55')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
    expect(
      () => new SVGPathData('A 30 50 0 0 1 A 30 50 0 0 1 162.55 162.45'),
    ).toThrow(new SyntaxError('Unterminated command at index 14.'));
  });

  test('should not work with bad rX value', () => {
    expect(() => new SVGPathData('A-30,50,0,0,1,162.55,162.45')).toThrow(
      new SyntaxError('Expected positive number, got "-30" at index "4"'),
    );
  });

  test('should not work with bad rY value', () => {
    expect(() => new SVGPathData('A30,-50,0,0,1,162.55,162.45')).toThrow(
      new SyntaxError('Expected positive number, got "-50" at index "7"'),
    );
  });

  test('should not work with bad lArcFlag value', () => {
    expect(() => new SVGPathData('A30,50,0,15,1,162.55,162.45')).toThrow(
      new SyntaxError('Expected a flag, got "5" at index "11"'),
    );
  });

  test('should not work with bad sweepFlag value', () => {
    expect(() => new SVGPathData('A30,50,0,0,15,162.55,162.45')).toThrow(
      new SyntaxError('Unterminated command at the path end.'),
    );
  });

  test('should work with comma separated coordinates', () => {
    const commands = new SVGPathData('A 30,50,0,0,1,162.55,162.45')
      .commands as [CommandA];

    expect(commands[0].type).toEqual(SVGPathData.ARC);
    expect(commands[0].relative).toEqual(false);
    expect(commands[0].rX).toEqual(30);
    expect(commands[0].rY).toEqual(50);
    expect(commands[0].xRot).toEqual(0);
    expect(commands[0].lArcFlag).toEqual(0);
    expect(commands[0].sweepFlag).toEqual(1);
    expect(commands[0].x).toEqual(162.55);
    expect(commands[0].y).toEqual(162.45);
  });

  test('should not work with a comma immediately after A', () => {
    expect(() => new SVGPathData('A,30,50,0,0,1,162.55,162.45')).toThrow(
      new SyntaxError(
        'Unexpected character "," at index 1. Command cannot follow comma',
      ),
    );
  });

  test('should work with space separated coordinates', () => {
    const commands = new SVGPathData('A 30 50 0 0 1 162.55 162.45')
      .commands as [CommandA];

    expect(commands[0].type).toEqual(SVGPathData.ARC);
    expect(commands[0].relative).toEqual(false);
    expect(commands[0].rX).toEqual(30);
    expect(commands[0].rY).toEqual(50);
    expect(commands[0].xRot).toEqual(0);
    expect(commands[0].lArcFlag).toEqual(0);
    expect(commands[0].sweepFlag).toEqual(1);
    expect(commands[0].x).toEqual(162.55);
    expect(commands[0].y).toEqual(162.45);
  });

  test('should work with nested separated complexer coordinate pairs', () => {
    const commands = new SVGPathData('A 30,50 0 0 1 162.55,162.45')
      .commands as [CommandA];

    expect(commands[0].type).toEqual(SVGPathData.ARC);
    expect(commands[0].relative).toEqual(false);
    expect(commands[0].rX).toEqual(30);
    expect(commands[0].rY).toEqual(50);
    expect(commands[0].xRot).toEqual(0);
    expect(commands[0].lArcFlag).toEqual(0);
    expect(commands[0].sweepFlag).toEqual(1);
    expect(commands[0].x).toEqual(162.55);
    expect(commands[0].y).toEqual(162.45);
  });

  test('should work with multiple pairs of coordinates', () => {
    const commands = new SVGPathData(`
      A 10.0032e-5,20.0032e-5 0 0 1 -30.0032e-5,-40.0032e-5
      50.0032e-5,60.0032e-5 0 1 0 -70.0032e-5,-80.0032e-5
      90.0032e-5,90.0032e-5 0 0 1 -80.0032e-5,-70.0032e-5
    `).commands as [CommandA, CommandA, CommandA];

    expect(commands[0].type).toEqual(SVGPathData.ARC);
    expect(commands[0].relative).toEqual(false);
    expect(commands[0].rX).toEqual(10.0032e-5);
    expect(commands[0].rY).toEqual(20.0032e-5);
    expect(commands[0].xRot).toEqual(0);
    expect(commands[0].lArcFlag).toEqual(0);
    expect(commands[0].sweepFlag).toEqual(1);
    expect(commands[0].x).toEqual(-30.0032e-5);
    expect(commands[0].y).toEqual(-40.0032e-5);
    expect(commands[1].type).toEqual(SVGPathData.ARC);
    expect(commands[1].relative).toEqual(false);
    expect(commands[1].rX).toEqual(50.0032e-5);
    expect(commands[1].rY).toEqual(60.0032e-5);
    expect(commands[1].xRot).toEqual(0);
    expect(commands[1].lArcFlag).toEqual(1);
    expect(commands[1].sweepFlag).toEqual(0);
    expect(commands[1].x).toEqual(-70.0032e-5);
    expect(commands[1].y).toEqual(-80.0032e-5);
    expect(commands[2].type).toEqual(SVGPathData.ARC);
    expect(commands[2].relative).toEqual(false);
    expect(commands[2].rX).toEqual(90.0032e-5);
    expect(commands[2].rY).toEqual(90.0032e-5);
    expect(commands[2].xRot).toEqual(0);
    expect(commands[2].lArcFlag).toEqual(0);
    expect(commands[2].sweepFlag).toEqual(1);
    expect(commands[2].x).toEqual(-80.0032e-5);
    expect(commands[2].y).toEqual(-70.0032e-5);
  });

  test('should work with multiple declared pairs of coordinates', () => {
    const commands = new SVGPathData(`
      A 10.0032e-5,20.0032e-5 0 0 1 -30.0032e-5,-40.0032e-5
      a50.0032e-5,60.0032e-5 0 1 0 -70.0032e-5,-80.0032e-5
      A90.0032e-5,90.0032e-5 0 0 1 -80.0032e-5,-70.0032e-5
    `).commands as [CommandA, CommandA, CommandA];

    expect(commands[0].type).toEqual(SVGPathData.ARC);
    expect(commands[0].relative).toEqual(false);
    expect(commands[0].rX).toEqual(10.0032e-5);
    expect(commands[0].rY).toEqual(20.0032e-5);
    expect(commands[0].xRot).toEqual(0);
    expect(commands[0].lArcFlag).toEqual(0);
    expect(commands[0].sweepFlag).toEqual(1);
    expect(commands[0].x).toEqual(-30.0032e-5);
    expect(commands[0].y).toEqual(-40.0032e-5);
    expect(commands[1].type).toEqual(SVGPathData.ARC);
    expect(commands[1].relative).toEqual(true);
    expect(commands[1].rX).toEqual(50.0032e-5);
    expect(commands[1].rY).toEqual(60.0032e-5);
    expect(commands[1].xRot).toEqual(0);
    expect(commands[1].lArcFlag).toEqual(1);
    expect(commands[1].sweepFlag).toEqual(0);
    expect(commands[1].x).toEqual(-70.0032e-5);
    expect(commands[1].y).toEqual(-80.0032e-5);
    expect(commands[2].type).toEqual(SVGPathData.ARC);
    expect(commands[2].relative).toEqual(false);
    expect(commands[2].rX).toEqual(90.0032e-5);
    expect(commands[2].rY).toEqual(90.0032e-5);
    expect(commands[2].xRot).toEqual(0);
    expect(commands[2].lArcFlag).toEqual(0);
    expect(commands[2].sweepFlag).toEqual(1);
    expect(commands[2].x).toEqual(-80.0032e-5);
    expect(commands[2].y).toEqual(-70.0032e-5);
  });
});

describe('Encoding eliptical arc commands', () => {
  test('should work with one command', () => {
    expect(new SVGPathData('A30 50 0 0 1 162.55 162.45').encode()).toEqual(
      'A30 50 0 0 1 162.55 162.45',
    );
  });

  test('should work with several commands', () => {
    expect(
      new SVGPathData(
        'A30 50 0 0 1 162.55 162.45A30 50 0 0 1 162.55 162.45A30 50 0 0 1 162.55 162.45',
      ).encode(),
    ).toEqual(
      'A30 50 0 0 1 162.55 162.45A30 50 0 0 1 162.55 162.45A30 50 0 0 1 162.55 162.45',
    );
  });
});

describe('Transforming elliptical arc commands', () => {
  function assertDeepCloseTo(x, y, delta) {
    if (typeof x === 'number' && typeof y === 'number') {
      expect(x).toBeCloseTo(y, delta);
    } else if (typeof x === 'object' && typeof y === 'object') {
      const keys = Object.getOwnPropertyNames(x);

      expect(keys).toEqual(Object.getOwnPropertyNames(y));
      for (let i = 0; i < keys.length; i++) {
        assertDeepCloseTo(x[keys[i]], y[keys[i]], delta);
      }
    } else if (x instanceof Array && y instanceof Array) {
      expect(x.length).toEqual(y.length);
      for (let i = 0; i < x.length; i++) {
        assertDeepCloseTo(x[i], y[i], delta);
      }
    } else {
      expect(x).toEqual(y);
    }
  }

  test('should rotate an axis-aligned arc', () => {
    assertDeepCloseTo(
      new SVGPathData('M 0,0 A 100,50 0 0 1 100,50z').rotate(Math.PI / 6)
        .commands,
      new SVGPathData('M 0,0 A 100,50 30 0 1 61.6,93.3z').commands,
      0.1,
    );
  });

  test('should rotate an arbitrary arc', () => {
    assertDeepCloseTo(
      new SVGPathData('M 0,0 A 100,50 -15 0 1 100,0z').rotate(Math.PI / 4)
        .commands,
      new SVGPathData('M 0,0 A 100,50 30 0 1 70.7,70.7z').commands,
      0.1,
    );
  });

  test('should skew by -45deg', () => {
    function degToRad(deg: number): number {
      return deg * (Math.PI / 180);
    }

    assertDeepCloseTo(
      new SVGPathData('M 0,0 A 50,100 0 0 1 50,100z').skewX(degToRad(-45))
        .commands,
      new SVGPathData('M 0,0 A 34.2,146.0 48.6 0 1 -50,100 Z').commands,
      0.1,
    );
  });

  test('should tolerate singular matrices', () => {
    assertDeepCloseTo(
      new SVGPathData('M 0,0 A 80,80 0 0 1 50,100z').matrix(
        0.8,
        2,
        0.5,
        1.25,
        0,
        0,
      ).commands,
      new SVGPathData('M 0,0 L 90,225 Z').commands,
      0.1,
    );
  });

  test('should match what Inkscape does on this random case', () => {
    assertDeepCloseTo(
      new SVGPathData(
        'M 170.19275,911.55263 A 61.42857,154.28572 21.033507 0 1 57.481868,1033.5109 61.42857,154.28572 21.033507 0 1 55.521508,867.4575 61.42857,154.28572 21.033507 0 1 168.2324,745.4993 A 61.42857,154.28572 21.033507 0 1 170.19275,911.55263 z',
      ).matrix(
        -0.10825745,
        -0.37157241,
        0.77029181,
        0.3345653,
        -560.10375,
        633.84215,
      ).commands,
      new SVGPathData(
        'M 123.63314,875.5771 A 135.65735,17.465974 30.334289 0 1 229.77839,958.26036 135.65735,17.465974 30.334289 0 1 102.08104,903.43307 135.65735,17.465974 30.334289 0 1 -4.0641555,820.74983 135.65735,17.465974 30.334289 0 1 123.63314,875.5771 z',
      ).commands,
      0.0001,
    );
  });

  test('should reflect the sweep flag any time the determinant is negative', () => {
    assertDeepCloseTo(
      new SVGPathData('M 0,0 A 50,100 -30 1 1 80,80 Z').matrix(
        -1,
        0,
        0,
        1,
        0,
        0,
      ).commands,
      new SVGPathData('M 0,0 A 50,100 30 1 0 -80,80 Z').commands,
      0.1,
    );
  });
});