lib-font/src/opentype/tables/simple/SVG.js

A JS based OpenType font inspector

import { ParsedData } from "../../../parser.js";
import { SimpleTable } from "../simple-table.js";

/**
 * The OpenType `SVG` table.
 *
 * See https://docs.microsoft.com/en-us/typography/opentype/spec/SVG
 */
class SVG extends SimpleTable {
  constructor(dict, dataview) {
    const { p } = super(dict, dataview);

    this.version = p.uint16;
    this.offsetToSVGDocumentList = p.Offset32; // from the start of the SVG table

    p.currentPosition = this.tableStart + this.offsetToSVGDocumentList;
    this.documentList = new SVGDocumentList(p);
  }
}

/**
 * The SVG document list.
 */
class SVGDocumentList extends ParsedData {
  constructor(p) {
    super(p);
    this.numEntries = p.uint16;
    this.documentRecords = [...new Array(this.numEntries)].map(
      (_) => new SVGDocumentRecord(p)
    );
  }

  /**
   * Get an SVG document by ID
   */
  getDocument(documentID) {
    let record = this.documentRecords[documentID];
    if (!record) return "";

    let offset = this.start + record.svgDocOffset;
    this.parser.currentPosition = offset;
    return this.parser.readBytes(record.svgDocLength);
  }

  /**
   * Get an SVG document given a glyphID
   */
  getDocumentForGlyph(glyphID) {
    let id = this.documentRecords.findIndex(
      (d) => d.startGlyphID <= glyphID && glyphID <= d.endGlyphID
    );
    if (id === -1) return "";
    return this.getDocument(id);
  }
}

/**
 * SVG document record, pointing to a specific SVG document encoding a
 * range of glyphs as <g id="glyph{NUM}>...</g> where {NUM} is a number
 * in the range [startGlyphId, endGlyphId].
 */
class SVGDocumentRecord {
  constructor(p) {
    this.startGlyphID = p.uint16;
    this.endGlyphID = p.uint16;
    this.svgDocOffset = p.Offset32; // from the beginning of the SVGDocumentList
    this.svgDocLength = p.uint32;
  }
}

export { SVG };