import sharp from 'sharp'
const svg = receiptline.transform(...)
const png = await sharp(svg).png().toBuffer()

const custom = {
  ...receiptline.commands.svg,
  ...{
    close: function() {
      return receiptline.commands.svg.close.bind(this)()
        .replace('>', '><rect width="100%" height="100%" fill="white"/>')
        .replace('<filter id="receiptlineinvert" x="0" y="0" width="100%" height="100%">', '<filter id="receiptlineinvert" x="-1%" y="-15%" width="102%" height="150%">')
    },
    text: function (text, encoding) {
      let p = this.textPosition;
      const attr = Object.keys(this.textAttributes).reduce((a, key) => a   ` ${key}="${this.textAttributes[key]}"`, '');
      this.textElement  = `<text${attr}>`
      for (const character of Array.from(text)) {
        const q = this.measureText(character, encoding) * this.textScale;
        const r = (p   q / 2) * this.charWidth / this.textScale;
        p  = q;
        this.textElement  = `<tspan x="${r}">${character.replace(/[ &<>]/g, r => ({' ': '&#xa0;', '&': '&amp;', '<': '&lt;', '>': '&gt;'}[r]))}</tspan>`;
      }
      this.textElement  = `</text>`
      this.textPosition  = this.measureText(text, encoding) * this.textScale;
      return '';
    },
  }
}