vexflow/src/stavevolta.js

A JavaScript library for rendering music notation and guitar tablature

// [VexFlow](http://vexflow.com) - Copyright (c) Mohit Muthanna 2010.
// Author Larry Kuhns 2011

import { StaveModifier } from './stavemodifier';

export class Volta extends StaveModifier {
  static get CATEGORY() { return 'voltas'; }
  static get type() {
    return {
      NONE: 1,
      BEGIN: 2,
      MID: 3,
      END: 4,
      BEGIN_END: 5,
    };
  }

  constructor(type, number, x, y_shift) {
    super();
    this.setAttribute('type', 'Volta');
    this.volta = type;
    this.x = x;
    this.y_shift = y_shift;
    this.number = number;
    this.font = {
      family: 'sans-serif',
      size: 9,
      weight: 'bold',
    };
  }

  getCategory() { return Volta.CATEGORY; }
  setShiftY(y) { this.y_shift = y; return this; }

  draw(stave, x) {
    const ctx = stave.checkContext();
    this.setRendered();

    let width = stave.width;
    const top_y = stave.getYForTopText(stave.options.num_lines) + this.y_shift;
    const vert_height = 1.5 * stave.options.spacing_between_lines_px;
    switch (this.volta) {
      case Volta.type.BEGIN:
        ctx.fillRect(this.x + x, top_y, 1, vert_height);
        break;
      case Volta.type.END:
        width -= 5;
        ctx.fillRect(this.x + x + width, top_y, 1, vert_height);
        break;
      case Volta.type.BEGIN_END:
        width -= 3;
        ctx.fillRect(this.x + x, top_y, 1, vert_height);
        ctx.fillRect(this.x + x + width, top_y, 1, vert_height);
        break;
      default:
        break;
    }
    // If the beginning of a volta, draw measure number
    if (this.volta === Volta.type.BEGIN || this.volta === Volta.type.BEGIN_END) {
      ctx.save();
      ctx.setFont(this.font.family, this.font.size, this.font.weight);
      ctx.fillText(this.number, this.x + x + 5, top_y + 15);
      ctx.restore();
    }

    ctx.fillRect(this.x + x, top_y, width, 1);
    return this;
  }
}