jianghh-canvas/es/utils/Marker.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 h = {
  pointerdown({ offsetX: i, offsetY: s }) {
    this.points.push({ x: i >> 0, y: s >> 0 }), this.ctx.beginPath(), this.ctx.arc(this.beginPoint.x, this.beginPoint.y, this.lineWidth / 2, 0, 2 * Math.PI), this.ctx.fill(), this.ctx.closePath();
  },
  pointermove({ offsetX: i, offsetY: s }) {
    if (this.points.push({ x: i >> 0, y: s >> 0 }), this.points.length < 3)
      return;
    const t = this.points.slice(-2), o = t[0], n = {
      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(o.x, o.y, n.x, n.y), this.ctx.stroke(), this.beginPoint = n;
  },
  pointerup() {
    this.ctx.beginPath(), this.ctx.arc(this.beginPoint.x, this.beginPoint.y, this.lineWidth / 2, 0, 2 * Math.PI), this.ctx.fill();
  }
};
export {
  h as Marker
};