jianghh-canvas/es/utils/Pen.js

canvas画板，支持笔写、手写、鼠标流畅绘图，自动保存，撤销重做

const e = {
  pointerdown({ offsetX: i, offsetY: s }) {
    this.ctx.beginPath(), this.points.push({ x: i, y: s });
  },
  pointermove({ offsetX: i, offsetY: s }) {
    if (this.points.push({ x: i, y: s }), this.points.length < 3)
      return;
    const t = this.points.slice(-2), n = t[0], o = {
      x: (t[0].x + t[1].x) / 2,
      y: (t[0].y + t[1].y) / 2
    };
    this.ctx.beginPath(), this.ctx.moveTo(this.beginPoint.x, this.beginPoint.y), this.ctx.quadraticCurveTo(n.x, n.y, o.x, o.y), this.ctx.stroke(), this.ctx.closePath(), this.beginPoint = o;
  }
};
export {
  e as Pen
};