Class Section

src/triangles_pattern_factory.ts:8–97

import {type KnitTexture, texturesMap} from './texture.js';

class Section {
  widthTop: PatternFactoryInput;
  widthBottom: PatternFactoryInput;
  texture: PatternFactoryInput;
  inputs: PatternFactoryInput[];
  knittingStyleInput: PatternFactoryInput;

  constructor(
      sectionId: number, sectionCountInput: PatternFactoryInput,
      knittingStyleInput: PatternFactoryInput) {
    this.widthTop = new PatternFactoryInput(
        `${sectionId}: Top Width`,
        `How wide should section ${sectionId} be at the top?`, 3, 'stitches');
    this.widthBottom = new PatternFactoryInput(
        `${sectionId}: Bottom Width`,
        `How wide should section ${sectionId} be at the bottom?`, 30,
        'stitches');
    this.texture = new PatternFactoryInput(
        `${sectionId}: Texture`,
        `What type of pattern should section ${sectionId} use?`, 'Stockinette',
        null, Array.from(texturesMap.keys()));
    this.inputs = [this.widthTop, this.widthBottom, this.texture];
    this.knittingStyleInput = knittingStyleInput;
    this.inputs.forEach(
        (i) => i.addVisibilityRequirement(
            () => sectionCountInput.numberValue() > sectionId));
    sectionCountInput.listener.addListener(
        () => this.inputs.forEach((i) => i.adjustVisibility()));
  }

  getInputs(): PatternFactoryInput[] {
    return this.inputs;
  }

  getStitches(rowIndex: number, rowLength: number): Stitch[] {
    const previousWidth = rowIndex === 0 ?
        this.widthTop.numberValue() :
        this.#getRowWidth(rowIndex - 1, rowLength);
    const desiredWidth = this.#getRowWidth(rowIndex, rowLength);
    const textureValue = this.texture.value();
    if (textureValue === undefined || typeof textureValue !== 'string') {
      throw new Error(`Invalid texture value: ${textureValue}`);
    }

    const currentIncreaseAmount =
        (desiredWidth > previousWidth) ? (desiredWidth - previousWidth) : 0;

    const rawTextureOutput: Stitch[] =
        this.#applyTexture(textureValue, rowIndex);

    // The core texture needs to be `desiredWidth - currentIncreaseAmount` long.
    // The `widthBottom` will be used as the base width for generating the
    // texture. The `startTrim` is to center the `desiredWidth` segment within
    // the `widthBottom`.
    const stitchesToExtract = desiredWidth - currentIncreaseAmount;
    const totalTrim = this.widthBottom.numberValue() - stitchesToExtract;
    const startTrim = totalTrim / 2;