const dt = new DrawTarget(400, 400);
const gradient = Source.createRadialGradient(
  new Gradient()
    .addStop(0.2, new Color(0xff, 0, 0xff, 0))
    .addStop(0.8, new Color(0xff, 0xff, 0xff, 0xff))
    .addStop(1, new Color(0xff, 0xff, 0, 0xff))
    .stops,
  new Point(150, 150),
  128,
  Spread.Pad
);

dt.fill(
  new PathBuilder()
    .moveTo(100, 10)
    .cubicTo(150, 40, 175, 0, 200, 10)
    .quadTo(120, 100, 80, 200)
    .quadTo(150, 180, 300, 300)
    .close(),
  gradient
);

dt.stroke(
  new PathBuilder()
    .moveTo(100, 100)
    .lineTo(300, 300)
    .lineTo(200, 300),
  {
    cap: LineCap.Round,
    join: LineJoin.Round,
    width: 10,
    miter_limit: 2,
    dash_array: [10, 18],
    dash_offset: 16,
  },
  Source.Solid(new Color(0x80, 0x0, 0x0, 0x80))
);

dt.writePNG("example.png");