需求：小程序开发中入会的时候需要验证本人签名已计算优惠折扣，需要在入会的时候上传手写签名信息，查了下资料，有几个不同的版本，个人修改测试了两版，觉得各有千秋，第一款偶尔会有卡顿的现象（android系统，重写两次以后），但是笔记连贯，自己看起来比较舒服，第二种卡顿感较弱，但是笔迹不精确，签名看起来不精细，所以选择了第一种进行改写
代码部分
html部分功能点根据项目需求适当放开，注意btn解开的话需要看下btn的位置样式！调整下left top值至合适的位置即可（目前有切换笔迹颜色，重写，保存到本地，上传，确认签名等功能点）
手写板
js部分
data() {
return {
phone: '',
nick: "",
name: "",
saveArr: [0, 0, 0],
sourceCode: '',
blackImg: require("../../static/images/sign/color_black.png"),
blackImgSelcected: require("../../static/images/sign/color_black_selected.png"),
redImg: require("../../static/images/sign/color_red.png"),
redImgSelcected: require("../../static/images/sign/color_red_selected.png"),
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
baseAddress: ''
}
},
/**
* 生命周期函数--监听页面加载
*/
onLoad: function(options) {
let that = this;
that.phone = options.phone
that.sourceCode = options.sourceCode;
let canvasName = this.canvasName
let ctx = uni.createCanvasContext(canvasName)
this.ctx = ctx
var query = uni.createSelectorQuery();
query.select('.handCenter').boundingClientRect(rect => {
this.canvasWidth = rect.width
this.canvasHeight = rect.height
/* 将canvas背景设置为 白底，不设置 导出的canvas的背景为透明 */
// console.log(this, 'hahah');
this.setCanvasBg('#fff');
}).exec();
},
methods: {
/*======所有自定义函数======*/
// 笔迹开始
uploadScaleStart(e) {
if (e.type != 'touchstart') return false;
let ctx = this.ctx;
ctx.setFillStyle(this.lineColor); // 初始线条设置颜色
ctx.setGlobalAlpha(this.transparent); // 设置半透明
let currentPoint = {
x: e.touches[0].x,
y: e.touches[0].y
}
let currentLine = this.currentLine;
currentLine.unshift({
time: new Date().getTime(),
dis: 0,
x: currentPoint.x,
y: currentPoint.y
})
this.currentPoint = currentPoint
if (this.firstTouch) {
this.cutArea = {
top: currentPoint.y,
right: currentPoint.x,
bottom: currentPoint.y,
left: currentPoint.x
}
this.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.cutArea.top) {
this.cutArea.top = point.y;
}
if (point.y < 0) this.cutArea.top = 0;
if (point.x > this.cutArea.right) {
this.cutArea.right = point.x;
}
if (this.canvasWidth - point.x <= 0) {
this.cutArea.right = this.canvasWidth;
}
if (point.y > this.cutArea.bottom) {
this.cutArea.bottom = point.y;
}
if (this.canvasHeight - point.y <= 0) {
this.cutArea.bottom = this.canvasHeight;
}
if (point.x < this.cutArea.left) {
this.cutArea.left = point.x;
}
if (point.x < 0) this.cutArea.left = 0;
this.lastPoint = this.currentPoint
this.currentPoint = point
let currentLine = this.currentLine
currentLine.unshift({
time: new Date().getTime(),
dis: this.distance(this.currentPoint, this.lastPoint),
x: point.x,
y: point.y
})
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.lastPoint = this.currentPoint,
this.currentPoint = point
let currentLine = this.currentLine
currentLine.unshift({
time: new Date().getTime(),
dis: this.distance(this.currentPoint, this.lastPoint),
x: point.x,
y: point.y
})
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.lineSize,
lineColor: this.lineColor
};
var chirography = this.chirography
chirography.unshift(currentChirography);
this.chirography = chirography
var linePrack = this.linePrack
linePrack.unshift(this.currentLine);
this.linePrack = linePrack
this.currentLine = []
},
retDraw() {
this.ctx.clearRect(0, 0, 700, 730)
this.ctx.draw();
//设置canvas背景
this.setCanvasBg("#fff");
},
//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.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.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.smoothness) break;
}
this.radius = Math.min(time / len * this.pressure + this.lineMin, this.lineMax) * this.lineSize
line[0].r = this.radius;
//计算笔迹半径；
if (line.length <= 2) {
r0 = (lastRadius + this.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.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.lineColor;
this.bethelDraw(a, 1);
point = [{
x: x,
y: y,
r: r
}];
}
}
this.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.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.selectColor = colorSelected
this.lineColor = color
},
//将Canvas内容转成 临时图片 --> cb 为回调函数 形参 tempImgPath 为 生成的图片临时路径
canvasToImg(cb) { //这种写法移动端 出不来
this.ctx.draw(true, () => {
uni.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'png',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
uni.showToast({
title: '执行了吗？',
})
cb(res.tempFilePath);
}
})
});
},
//完成
subCanvas() {
let that = this
uni.canvasToTempFilePath({
x: 0, // 起点坐标
y: 0,
// 宽高位置信息根据项目实际情况调整
width: 343, // canvas 宽
height: 200, // canvas 高
canvasId: 'handWriting', // canvas id
success(res) {
console.log(res)
uni.request({
url: res.tempFilePath, //临时路径
responseType: 'arraybuffer', //设置返回的数据格式为arraybuffer
success: res => {
const base64 = "data:image/png;base64," + uni.arrayBufferToBase64(res.data)
console.log(base64)
// that.baseAddress = base64
}
})
}
})
},
//保存到相册
saveCanvasAsImg() {
/*
this.canvasToImg( tempImgPath=>{
// console.log(tempImgPath, '临时路径');
uni.saveImageToPhotosAlbum({
filePath: tempImgPath,
success(res) {
uni.showToast({
title: '已保存到相册',
duration: 2000
});
}
})
} );
*/
uni.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'png',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
uni.saveImageToPhotosAlbum({
filePath: res.tempFilePath,
success(res) {
uni.showToast({
title: '已保存到相册',
duration: 2000
});
}
})
}
})
},
//预览
previewCanvasImg() {
uni.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'jpg',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
uni.previewImage({
urls: [res.tempFilePath], //预览图片 数组
})
}
})
/* //移动端出不来 ^~^！！
this.canvasToImg( tempImgPath=>{
uni.previewImage({
urls: [tempImgPath], //预览图片 数组
})
} );
*/
},
//上传
uploadCanvasImg() {
// console.log(999);
uni.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'png',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
//上传
uni.uploadFile({
url: 'https://example.weixin.qq.com/upload', // 仅为示例，非真实的接口地址
filePath: res.tempFilePath,
name: 'file_signature',
formData: {
user: 'test'
},
success(res) {
const data = res.data
// do something
}
})
}
})
},
//设置canvas背景色 不设置 导出的canvas的背景为透明
//@params：字符串 color
setCanvasBg(color) {
/* 将canvas背景设置为 白底，不设置 导出的canvas的背景为透明 */
//rect() 参数说明 矩形路径左上角的横坐标，左上角的纵坐标, 矩形路径的宽度, 矩形路径的高度
//这里是 canvasHeight - 4 是因为下边盖住边框了，所以手动减了写
this.ctx.rect(0, 0, this.canvasWidth, this.canvasHeight - 4);
// ctx.setFillStyle('red')
this.ctx.setFillStyle(color)
this.ctx.fill() //设置填充
this.ctx.draw() //开画
}
}
获取到base64图片地址以后根据项目需求与后端交互保存信息即可
css部分
.wrapper {
font-size: 28rpx;
padding: 0 30rpx;
}
.pageTitle {
font-size: 30rpx;
text-align: center;
border-bottom: 1px solid #7f7f7f;
padding: 60rpx 0;
margin-bottom: 50rpx;
color: #000;
font-family: syNORMAL;
font-weight: bold;
}
.userInfo {
display: flex;
justify-content: space-between;
margin-bottom: 65rpx;
}
.userInfo .item {
color: #000;
}
.userInfo .input {
background-color: #f0f0f0;
height: 60rpx;
line-height: 60rpx;
padding-left: 10rpx;
margin-top: 10rpx;
}
.textBox {
display: block;
color: #777;
margin-bottom: 65rpx;
}
.checkBox {
margin-bottom: 75rpx;
color: #777;
padding-left: 74rpx;
text-align: justify;
position: relative;
line-height: 46rpx;
}
.checkBox .check_1 {
position: absolute;
left: 0;
top: 6rpx;
/* width: 28rpx;height:29rpx;border: 1px solid #000; */
padding: 1rpx;
font-size: 24rpx;
line-height: 24rpx;
}
.checkBox .mf-check {
background-color: #000;
color: #fff;
}
.checkBox .link {
display: inline-block;
border-bottom: 1px solid #777;
padding: 0 4rpx;
}
.black-select,
.red-select {
display: none;
}
.autograph {
margin: 240rpx 0 100rpx;
}
.autograph .title {
display: flex;
justify-content: space-between;
margin-bottom: 20rpx;
}
.autograph .title label {
color: #000;
}
.autograph .title .link {
border-bottom: 1px solid #777;
padding: 0 4rpx;
color: #777;
}
.handWriting {
background: #fff;
width: 100%;
height: 200px;
}
.handRight {
/* display: inline-flex;
align-items: center; */
}
.handCenter {
border: 1px solid #000;
/* flex: 5; */
overflow: hidden;
box-sizing: border-box;
}
.handTitle {
/* transform: rotate(90deg);
flex: 1; */
color: #666;
}
.handBtn button {
font-size: 28rpx;
border-radius: 0;
margin: 30rpx 0 0 30rpx;
}
.handBtn button:after {
border-radius: 0;
border: none
}
.handBtn {
/* height: 95vh;
display: inline-flex;
flex-direction: column;
justify-content: space-between;
align-content: space-between;
flex: 1;*/
display: flex;
justify-content: flex-end;
}
.delBtn {
/* position: absolute;
top: 250rpx;
left: 0rpx;*/
/* transform: rotate(90deg); */
color: #000;
background-color: #fff;
border: 1px solid #000;
}
.delBtn image {
/* position: absolute;
top: 13rpx;
left: 25rpx;*/
}
.subBtn {
/* position: absolute;
bottom: 52rpx;
left: -3rpx;*/
/* display: inline-flex; */
/* transform: rotate(90deg); */
background: #000;
color: #fff;
margin-bottom: 30rpx;
/* text-align: center;
justify-content: center; */
}
/*Peach - 新增 - 保存*/
.saveBtn {
/* position: absolute;
top: 375rpx;
left: 0rpx;
transform: rotate(90deg); */
color: #666;
}
.previewBtn {
/* position: absolute; */
/* top: 500rpx; */
/* top: 375rpx;
left: 0rpx; */
/* transform: rotate(90deg); */
color: #666;
display: none;
}
.uploadBtn {
/* position: absolute;
top: 625rpx;
left: 0rpx;*/
/* transform: rotate(90deg); */
color: #666;
}
/*Peach - 新增 - 保存*/
.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; */
}
附带第二版代码
时间稍微有点久了，找不到借鉴原素材的地址了！如有冒犯，还望海涵！有原文地址的童鞋可以留言一下 会添加超链