<!-- wxml -->
<view class="hxt-flex-column">    
<view class="hxt-flex" style="font-size: 30rpx;padding: 30rpx;">
     <view>
      <text wx:if="{{!tempFilePath}}">尚未签名，请点击“签名”开始签字</text>
      <image wx:if="{{tempFilePath}}" src="{{tempFilePath}}"></image>
     </view>
     <view style="color: #319987;" bindtap="autograph">
      <van-icon name="edit" />签名
     </view>
    </view>
</view>
<page-container show="{{show}}" style="height: 100vh;width: 100vm;" position="center" bind:clickoverlay="closeSheet" bind:afterleave="closeSheet">
 <view class="wrapper">
  <view class="handBtn">
   <image catchtap="selectColorEvent" src="{{ selectColor === 'black' ? '//img.jbzj.com/file_images/article/202207/20227875050855.png' : '//img.jbzj.com/file_images/article/202207/20227875216713.png' }}" class="{{ selectColor === 'black' ? 'color_select' : '' }} black-select" data-color="black" data-color-value="#1A1A1A"></image>
   <image catchtap="selectColorEvent" src="{{ selectColor === 'red' ? '//img.jbzj.com/file_images/article/202207/20227875248330.png' : '//img.jbzj.com/file_images/article/202207/20227875312284.png' }}" class="{{ selectColor === 'red' ? 'color_select' : '' }} red-select" data-color="red" data-color-value="#ca262a"></image>
   <button catchtap="retDraw" class="delBtn">重写</button>
   <button catchtap="saveCanvasAsImg" class="subBtn">完成</button>
  </view>
  <view class="handCenter">
   <canvas class="handWriting" disable-scroll="true" bindtouchstart="uploadScaleStart" bindtouchmove="uploadScaleMove" bindtouchend="uploadScaleEnd" bindtap="mouseDown" canvas-id="handWriting">
   </canvas>
  </view>
  <view class="handRight">
   <view class="handTitle">手写板</view>
  </view>
 </view>
</page-container>

js:

// index.js
var QQMapWX = require('../../utils/qqmap-wx-jssdk.js');
var qqmapsdk = new QQMapWX({
 key: 'H2RBZ-MGCC3-N4G3I-YCX6A-IKB5J-WIBTW' // 必填
});
Page({
 data: {
  show: false,
  canvasName: 'handWriting',
  ctx: '',
  canvasWidth: 0,
  canvasHeight: 0,
  transparent: 1, // 透明度
  selectColor: 'black',
  lineColor: '#1A1A1A', // 颜色
  lineSize: 1.5, // 笔记倍数
  lineMin: 0.5,  // 最小笔画半径
  lineMax: 4,   // 最大笔画半径
  pressure: 1,   // 默认压力
  smoothness: 60, //顺滑度，用60的距离来计算速度
  currentPoint: {},
  currentLine: [], // 当前线条
  firstTouch: true, // 第一次触发
  radius: 1, //画圆的半径
  cutArea: { top: 0, right: 0, bottom: 0, left: 0 }, //裁剪区域
  bethelPoint: [], //保存所有线条 生成的贝塞尔点；
  lastPoint: 0,
  chirography: [], //笔迹
  currentChirography: {}, //当前笔迹
  linePrack: [] //划线轨迹 , 生成线条的实际点
 },

 onLoad() {
  let canvasName = this.data.canvasName
  let ctx = wx.createCanvasContext(canvasName)
  this.setData({
   ctx: ctx
  })
  var query = wx.createSelectorQuery();
  query.select('.handCenter').boundingClientRect(rect => {
   this.setData({
    canvasWidth: rect.width,
    canvasHeight: rect.height
   })
  }).exec();
 },
 // 笔迹开始
 uploadScaleStart(e) {
  if (e.type != 'touchstart') return false;
  let ctx = this.data.ctx;
  ctx.setFillStyle(this.data.lineColor); // 初始线条设置颜色
  ctx.setGlobalAlpha(this.data.transparent); // 设置半透明
  let currentPoint = {
   x: e.touches[0].x,
   y: e.touches[0].y
  }
  let currentLine = this.data.currentLine;
  currentLine.unshift({
   time: new Date().getTime(),
   dis: 0,
   x: currentPoint.x,
   y: currentPoint.y
  })
  this.setData({
   currentPoint,
   // currentLine
  })
  if (this.data.firstTouch) {
   this.setData({
    cutArea: { top: currentPoint.y, right: currentPoint.x, bottom: currentPoint.y, left: currentPoint.x },
    firstTouch: false
   })
  }
  this.pointToLine(currentLine);
 },
 // 笔迹移动
 uploadScaleMove(e) {
  if (e.type != 'touchmove') return false;
  if (e.cancelable) {
   // 判断默认行为是否已经被禁用
   if (!e.defaultPrevented) {
    e.preventDefault();
   }
  }
  let point = {
   x: e.touches[0].x,
   y: e.touches[0].y
  }

  //测试裁剪
  if (point.y < this.data.cutArea.top) {
   this.data.cutArea.top = point.y;
  }
  if (point.y < 0) this.data.cutArea.top = 0;

  if (point.x > this.data.cutArea.right) {
   this.data.cutArea.right = point.x;
  }
  if (this.data.canvasWidth - point.x <= 0) {
   this.data.cutArea.right = this.data.canvasWidth;
  }
  if (point.y > this.data.cutArea.bottom) {
   this.data.cutArea.bottom = point.y;
  }
  if (this.data.canvasHeight - point.y <= 0) {
   this.data.cutArea.bottom = this.data.canvasHeight;
  }
  if (point.x < this.data.cutArea.left) {
   this.data.cutArea.left = point.x;
  }
  if (point.x < 0) this.data.cutArea.left = 0;

  this.setData({
   lastPoint: this.data.currentPoint,
   currentPoint: point
  })
  let currentLine = this.data.currentLine
  currentLine.unshift({
   time: new Date().getTime(),
   dis: this.distance(this.data.currentPoint, this.data.lastPoint),
   x: point.x,
   y: point.y
  })
  // this.setData({
  //  currentLine
  // })
  this.pointToLine(currentLine);
 },// 笔迹结束
 uploadScaleEnd(e) {
  if (e.type != 'touchend') return 0;
  let point = {
   x: e.changedTouches[0].x,
   y: e.changedTouches[0].y
  }
  this.setData({
   lastPoint: this.data.currentPoint,
   currentPoint: point
  })
  let currentLine = this.data.currentLine
  currentLine.unshift({
   time: new Date().getTime(),
   dis: this.distance(this.data.currentPoint, this.data.lastPoint),
   x: point.x,
   y: point.y
  })
  // this.setData({
  //  currentLine
  // })
  if (currentLine.length > 2) {
   var info = (currentLine[0].time - currentLine[currentLine.length - 1].time) / currentLine.length;
   //$("#info").text(info.toFixed(2));
  }
  //一笔结束，保存笔迹的坐标点，清空，当前笔迹
  //增加判断是否在手写区域；
  this.pointToLine(currentLine);
  var currentChirography = {
   lineSize: this.data.lineSize,
   lineColor: this.data.lineColor
  };
  var chirography = this.data.chirography
  chirography.unshift(currentChirography);
  this.setData({
   chirography
  })
  var linePrack = this.data.linePrack
  linePrack.unshift(this.data.currentLine);
  this.setData({
   linePrack,
   currentLine: []
  })
 }, retDraw() {
  this.data.ctx.clearRect(0, 0, 700, 730)
  this.data.ctx.draw()
 },

 //画两点之间的线条；参数为:line，会绘制最近的开始的两个点；
 pointToLine(line) {
  this.calcBethelLine(line);
  return;
 },
 //计算插值的方式；
 calcBethelLine(line) {
  if (line.length <= 1) {
   line[0].r = this.data.radius;
   return;
  }
  let x0, x1, x2, y0, y1, y2, r0, r1, r2, len, lastRadius, dis = 0, time = 0, curveValue = 0.5;
  if (line.length <= 2) {
   x0 = line[1].x
   y0 = line[1].y
   x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
   y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
   //x2 = line[1].x;
   //y2 = line[1].y;
   x1 = x0 + (x2 - x0) * curveValue;
   y1 = y0 + (y2 - y0) * curveValue;;

  } else {
   x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
   y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
   x1 = line[1].x;
   y1 = line[1].y;
   x2 = x1 + (line[0].x - x1) * curveValue;
   y2 = y1 + (line[0].y - y1) * curveValue;
  }
  //从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
  len = this.distance({ x: x2, y: y2 }, { x: x0, y: y0 });
  lastRadius = this.data.radius;
  for (let n = 0; n < line.length - 1; n++) {
   dis += line[n].dis;
   time += line[n].time - line[n + 1].time;
   if (dis > this.data.smoothness) break;
  }
  this.setData({
   radius: Math.min(time / len * this.data.pressure + this.data.lineMin, this.data.lineMax) * this.data.lineSize
  });
  line[0].r = this.data.radius;
  //计算笔迹半径；
  if (line.length <= 2) {
   r0 = (lastRadius + this.data.radius) / 2;
   r1 = r0;
   r2 = r1;
   //return;
  } else {
   r0 = (line[2].r + line[1].r) / 2;
   r1 = line[1].r;
   r2 = (line[1].r + line[0].r) / 2;
  }
  let n = 5;
  let point = [];
  for (let i = 0; i < n; i++) {
   let t = i / (n - 1);
   let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
   let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
   let r = lastRadius + (this.data.radius - lastRadius) / n * i;
   point.push({ x: x, y: y, r: r });
   if (point.length == 3) {
    let a = this.ctaCalc(point[0].x, point[0].y, point[0].r, point[1].x, point[1].y, point[1].r, point[2].x, point[2].y, point[2].r);
    a[0].color = this.data.lineColor;
    // let bethelPoint = this.data.bethelPoint;
    // console.log(a)
    // console.log(this.data.bethelPoint)
    // bethelPoint = bethelPoint.push(a);
    this.bethelDraw(a, 1);
    point = [{ x: x, y: y, r: r }];
   }
  }
  this.setData({
   currentLine: line
  })
 },
 //求两点之间距离
 distance(a, b) {
  let x = b.x - a.x;
  let y = b.y - a.y;
  return Math.sqrt(x * x + y * y);
 },
 ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
  let a = [], vx01, vy01, norm, n_x0, n_y0, vx21, vy21, n_x2, n_y2;
  vx01 = x1 - x0;
  vy01 = y1 - y0;
  norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
  vx01 = vx01 / norm * r0;
  vy01 = vy01 / norm * r0;
  n_x0 = vy01;
  n_y0 = -vx01;
  vx21 = x1 - x2;
  vy21 = y1 - y2;
  norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
  vx21 = vx21 / norm * r2;
  vy21 = vy21 / norm * r2;
  n_x2 = -vy21;
  n_y2 = vx21;
  a.push({ mx: x0 + n_x0, my: y0 + n_y0, color: "#1A1A1A" });
  a.push({ c1x: x1 + n_x0, c1y: y1 + n_y0, c2x: x1 + n_x2, c2y: y1 + n_y2, ex: x2 + n_x2, ey: y2 + n_y2 });
  a.push({ c1x: x2 + n_x2 - vx21, c1y: y2 + n_y2 - vy21, c2x: x2 - n_x2 - vx21, c2y: y2 - n_y2 - vy21, ex: x2 - n_x2, ey: y2 - n_y2 });
  a.push({ c1x: x1 - n_x2, c1y: y1 - n_y2, c2x: x1 - n_x0, c2y: y1 - n_y0, ex: x0 - n_x0, ey: y0 - n_y0 });
  a.push({ c1x: x0 - n_x0 - vx01, c1y: y0 - n_y0 - vy01, c2x: x0 + n_x0 - vx01, c2y: y0 + n_y0 - vy01, ex: x0 + n_x0, ey: y0 + n_y0 });
  a[0].mx = a[0].mx.toFixed(1);
  a[0].mx = parseFloat(a[0].mx);
  a[0].my = a[0].my.toFixed(1);
  a[0].my = parseFloat(a[0].my);
  for (let i = 1; i < a.length; i++) {
   a[i].c1x = a[i].c1x.toFixed(1);
   a[i].c1x = parseFloat(a[i].c1x);
   a[i].c1y = a[i].c1y.toFixed(1);
   a[i].c1y = parseFloat(a[i].c1y);
   a[i].c2x = a[i].c2x.toFixed(1);
   a[i].c2x = parseFloat(a[i].c2x);
   a[i].c2y = a[i].c2y.toFixed(1);
   a[i].c2y = parseFloat(a[i].c2y);
   a[i].ex = a[i].ex.toFixed(1);
   a[i].ex = parseFloat(a[i].ex);
   a[i].ey = a[i].ey.toFixed(1);
   a[i].ey = parseFloat(a[i].ey);
  }
  return a;
 },
 bethelDraw(point, is_fill, color) {
  let ctx = this.data.ctx;
  ctx.beginPath();
  ctx.moveTo(point[0].mx, point[0].my);
  if (undefined != color) {
   ctx.setFillStyle(color);
   ctx.setStrokeStyle(color);
  } else {
   ctx.setFillStyle(point[0].color);
   ctx.setStrokeStyle(point[0].color);
  }
  for (let i = 1; i < point.length; i++) {
   ctx.bezierCurveTo(point[i].c1x, point[i].c1y, point[i].c2x, point[i].c2y, point[i].ex, point[i].ey);
  }
  ctx.stroke();
  if (undefined != is_fill) {
   ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
  }
  ctx.draw(true)
 },
 selectColorEvent(event) {
  console.log(event)
  var color = event.currentTarget.dataset.colorValue;
  var colorSelected = event.currentTarget.dataset.color;
  this.setData({
   selectColor: colorSelected,
   lineColor: color
  })
 },
 //保存到相册
 saveCanvasAsImg() {
  var _this = this;
  wx.canvasToTempFilePath({
   canvasId: 'handWriting',
   fileType: 'png',
   destWidth: 600,
   destHeight: 300,
   quality: 1, //图片质量
   success(res) {
    console.log(res.tempFilePath, 'canvas生成图片地址');
    _this.setData({ show: false,tempFilePath: res.tempFilePath});
   }
  })
 },
 , autograph: function (e) {
  this.setData({ show: true })
 }
 , closeSheet: function (e) {
  this.setData({ show: false })
 }
})

/*wxss*/
.wrapper {
 width: 100%;
 height: 95vh;
 margin: 30rpx 0;
 overflow: hidden;
 display: flex;
 align-content: center;
 flex-direction: row;
 justify-content: center;
 font-size: 28rpx;
}

.handWriting {
 background: #fff;
 width: 100%;
 height: 95vh;
}

.handRight {
 display: inline-flex;
 align-items: center;
}

.handCenter {
 border: 4rpx dashed #e9e9e9;
 flex: 5;
 overflow: hidden;
 box-sizing: border-box;
}

.handTitle {
 transform: rotate(90deg);
 flex: 1;
 color: #666;
}

.handBtn button {
 font-size: 28rpx;
}

.handBtn {
 height: 95vh;
 display: inline-flex;
 flex-direction: column;
 justify-content: space-between;
 align-content: space-between;
 flex: 1;
}

.delBtn {
 position: absolute;
 top: 250rpx;
 left: 0rpx;
 transform: rotate(90deg);
 color: #666;
}

.delBtn image {
 position: absolute;
 top: 13rpx;
 left: 25rpx;
}

.subBtn {
 position: absolute;
 bottom: 52rpx;
 left: -3rpx;
 display: inline-flex;
 transform: rotate(90deg);
 background: #008ef6;
 color: #fff;
 margin-bottom: 30rpx;
 text-align: center;
 justify-content: center;
}

.black-select {
 width: 60rpx;
 height: 60rpx;
 position: absolute;
 top: 30rpx;
 left: 25rpx;
}
.black-select.color_select {
 width: 90rpx;
 height: 90rpx;
 top: 30rpx;
 left: 10rpx;
}
.red-select {
 width: 60rpx;
 height: 60rpx;
 position: absolute;
 top:140rpx;
 left:25rpx;
}
.red-select.color_select {
 width: 90rpx;
 height: 90rpx;
 top: 120rpx;
 left: 10rpx;
}