ManifestoCanvas.js

/**
 * ManifestoCanvas - adds additional, testable logic around Manifesto's Canvas
 * https://iiif-commons.github.io/manifesto/classes/_canvas_.manifesto.canvas.html
 */
export default class ManifestoCanvas {
  /**
   * @param {ManifestoCanvas} canvas
   */
  constructor(canvas) {
    this.canvas = canvas;
  }

  /**
   */
  get canonicalImageUri() {
    return this.canvas.getCanonicalImageUri();
  }

  /**
   */
  get aspectRatio() {
    return this.canvas.getWidth() / this.canvas.getHeight();
  }

  /**
   */
  get imageInformationUri() {
    if (!(
      this.canvas.getImages()[0]
      && this.canvas.getImages()[0].getResource()
      && this.canvas.getImages()[0].getResource().getServices()[0]
      && this.canvas.getImages()[0].getResource().getServices()[0].id
    )) {
      return undefined;
    }

    return `${
      this.canvas.getImages()[0].getResource().getServices()[0].id.replace(/\/$/, '')
    }/info.json`;
  }

  /**
   * checks whether the canvas has a valid height
   */
  get hasValidHeight() {
    return (
      typeof this.canvas.getHeight() === 'number'
      && this.canvas.getHeight() > 0
    );
  }

  /**
   * checks whether the canvas has a valid height
   */
  get hasValidWidth() {
    return (
      typeof this.canvas.getHeight() === 'number'
      && this.canvas.getHeight() > 0
    );
  }

  /**
   * checks whether the canvas has valid dimensions
   */
  get hasValidDimensions() {
    return (
      this.hasValidHeight
      && this.hasValidWidth
    );
  }