Requirements: uniapp applet custom signature panel component, canvas handwritten signature drawing board, applet page reference to realize horizontal screen signature
Realize the effect:
1. Custom components
Create the components folder in the project, create the my-sign component under the folder, and create my-sign.vue and index.js under the component
my-sign.vue component code:
<template>
<view class="signature-wrap">
<canvas
:canvas-id="cid"
:id="cid"
@touchstart="onTouchStart"
@touchmove="onTouchMove"
@touchend="onTouchEnd"
disable-scroll
:style="[
{
width: width && formatSize(width),
height: height && formatSize(height)
},
customStyle
]"
></canvas>
<slot />
</view>
</template>
<script>
/**
* sign canvas 手写签名
* @description 设置线条宽度、颜色，撤回，清空
* @tutorial
* @property {String} cid canvas id 不设置则默认为 v-sign-时间戳
* @property {String, Number} width canvas 宽度
* @property {String, Number} height canvas 高度
* @property {bgColor} bgColor 画布背景颜色
* @property {Object} customStyle canvas 自定义样式
* @property {String} lineWidth 画笔大小，权重小于 v-sign-pen 组件设置的画笔大小
* @property {Number} lineColor 画笔颜色，权重小于 v-sign-pen 组件设置的画笔大小
* @event {Function} init 当创建完 canvas 实例后触发，向外提供 canvas实例，撤回，清空方法
* @example <v-sign @init="signInit"></v-sign>
*/
import {
formatSize } from './index.js'
export default {
name: 'my-sign',
props: {
// canvas id
cid: {
type: String,
default: `v-sign-${
Date.now()}`
// required: true
},
// canvas 宽度
width: {
type: [String, Number]
},
// canvas 高度
height: {
type: [String, Number]
},
// 画笔大小，权重小于 v-sign-pen 组件设置的画笔大小 penLineWidth
lineWidth: {
type: Number,
default: 4
},
// 线颜色，权重小于 v-sign-color 组件设置的画笔颜色 penLineColor
lineColor: {
type: String,
default: '#333'
},
// 画布背景颜色
bgColor: {
type: String,
default: '#fff'
},
// canvas自定义样式
customStyle: {
type: Object,
default: () => ({
})
}
},
provide() {
return {
getSignInterface: this.provideSignInterface
}
},
data() {
return {
formatSize,
lineData: [],
winWidth: 0,
winHeight: 0,
penLineWidth: null, // v-sign-pen 组件设置的画笔大小
penLineColor: null // v-sign-color 组件设置的颜色
}
},
created() {
// 获取窗口宽高
const {
windowWidth, windowHeight } = uni.getSystemInfoSync()
this.winWidth = windowWidth
this.winHeight = windowHeight
},
mounted() {
this.canvasCtx = uni.createCanvasContext(this.cid, this)
// h5 需延迟绘制，否则绘制失败
// #ifdef H5
setTimeout(() => {
// #endif
this.setBackgroundColor(this.bgColor)
// #ifdef H5
}, 10)
// #endif
// 初始化完成，触发 init 事件
this.$emit('init', this.provideSignInterface())
},
methods: {
onTouchStart(e) {
const pos = e.touches[0]
this.lineData.push({
style: {
color: this.penLineColor || this.lineColor,
width: this.penLineWidth || this.lineWidth
},
// 屏幕坐标
coordinates: [
{
type: e.type,
x: pos.x,
y: pos.y
}
]
})
this.drawLine()
},
onTouchMove(e) {
const pos = e.touches[0]
this.lineData[this.lineData.length - 1].coordinates.push({
type: e.type,
x: pos.x,
y: pos.y
})
this.drawLine()
},
onTouchEnd(e) {
this.$emit('end', this.lineData)
},
// 清空画布
clear() {
this.lineData = []
this.canvasCtx.clearRect(0, 0, this.winWidth, this.winHeight)
this.canvasCtx.draw()
this.setBackgroundColor(this.bgColor)
this.$emit('clear')
},
// 撤销
revoke() {
this.setBackgroundColor(this.bgColor)
this.lineData.pop()
this.lineData.forEach((item, index) => {
this.canvasCtx.beginPath()
this.canvasCtx.setLineCap('round')
this.canvasCtx.setStrokeStyle(item.style.color)
this.canvasCtx.setLineWidth(item.style.width)
if (item.coordinates.length < 2) {
const pos = item.coordinates[0]
this.canvasCtx.moveTo(pos.x, pos.y)
this.canvasCtx.lineTo(pos.x + 1, pos.y)
} else {
item.coordinates.forEach(pos => {
if (pos.type == 'touchstart') {
this.canvasCtx.moveTo(pos.x, pos.y)
} else {
this.canvasCtx.lineTo(pos.x, pos.y)
}
})
}
this.canvasCtx.stroke()
})
this.canvasCtx.draw(true)
this.$emit('revoke', this.lineData)
},
// 绘制线条
drawLine() {
const lineDataLen = this.lineData.length
if (!lineDataLen) return
const currentLineData = this.lineData[lineDataLen - 1]
const coordinates = currentLineData.coordinates
const coordinatesLen = coordinates.length
if (!coordinatesLen) return
let startPos
let endPos
if (coordinatesLen < 2) {
// only start, no move event
startPos = coordinates[coordinatesLen - 1]
endPos = {
x: startPos.x + 1,
y: startPos.y
}
} else {
startPos = coordinates[coordinatesLen - 2]
endPos = coordinates[coordinatesLen - 1]
}
const style = currentLineData.style
this.canvasCtx.beginPath()
this.canvasCtx.setLineCap('round')
this.canvasCtx.setStrokeStyle(style.color)
this.canvasCtx.setLineWidth(style.width)
this.canvasCtx.moveTo(startPos.x, startPos.y)
this.canvasCtx.lineTo(endPos.x, endPos.y)
// const P1 = this.caculateBezier(startPos, endPos, centerPos)
// console.log(P1.x, P1.y)
// this.canvasCtx.moveTo(startPos.x, startPos.y)
// this.canvasCtx.quadraticCurveTo(P1.x, P1.y, endPos.x, endPos.y)
this.canvasCtx.stroke()
this.canvasCtx.draw(true)
},
// 保存png图片，文件名配置 filename 仅支持 h5
async saveImage(filename = '签名') {
const tempFilePath = await this.canvasToTempFilePath()
return new Promise((resolve, reject) => {
// #ifdef H5
try {
const a = document.createElement('a')
a.href = tempFilePath
a.download = filename
document.body.appendChild(a)
a.click()
a.remove()
resolve({
errMsg: 'saveImageH5:ok'
})
} catch (e) {
console.error(e)
reject(e)
}
// #endif
// #ifndef H5
uni.saveImageToPhotosAlbum({
filePath: tempFilePath,
success(resObj) {
resolve(resObj)
},
fail(err) {
reject(err)
}
})
// #endif
})
},
// canvas 保存为临时图片路径，h5返回 base64
canvasToTempFilePath(conf = {
}) {
return new Promise((resolve, reject) => {
uni.canvasToTempFilePath(
{
canvasId: this.cid,
...conf,
success: res => {
resolve(res.tempFilePath)
},
fail: err => {
console.log('fail', err)
reject(err)
}
},
this
)
})
},
setBackgroundColor(color = '#fff') {
this.canvasCtx.beginPath()
this.canvasCtx.setFillStyle(color)
this.canvasCtx.fillRect(0, 0, this.winWidth, this.winHeight)
this.canvasCtx.fill()
this.canvasCtx.draw(true)
},
setLineWidth(numberVal) {
this.penLineWidth = numberVal
},
setLineColor(strValue) {
this.penLineColor = strValue
},
// 向外暴露内部方法
provideSignInterface() {
return {
cid: this.cid,
ctx: this.canvasCtx,
clear: this.clear,
revoke: this.revoke,
saveImage: this.saveImage,
canvasToTempFilePath: this.canvasToTempFilePath,
setLineWidth: this.setLineWidth,
setLineColor: this.setLineColor,
setBackgroundColor: this.setBackgroundColor,
getLineData: () => this.lineData
}
},
/**
* 计算二次贝塞尔曲线 控制点 P1
* 起点 P0(x0,y0)、控制点P1(x1, y1)、P2(x2, y2)、曲线上任意点B(x, y)
* 二次贝塞尔公式：B(t) = (1-t)²P0 + 2t(1-t)P1 + t²P2
* 代入坐标得：
* x = (1-t)²*x0 + 2t(1-t)*x1 + t²*x2
* y = (1-t)²*y0 + 2t(1-t)*y1 + t²*y2
*/
caculateBezier(P0, P2, B, t = 0.5) {
const {
x: x0, y: y0 } = P0
const {
x: x2, y: y2 } = P2
const {
x, y } = B
let x1 = (x - (1 - t) * (1 - t) * x0 - t * t * x2) / (2 * t * (1 - t))
let y1 = (y - (1 - t) * (1 - t) * y0 - t * t * y2) / (2 * t * (1 - t))
return {
x: x1,
y: y1
}
}
}
}
</script>
<style lang="scss" scoped>
.signature-wrap {
position: relative;
}
</style>
index.js code:
/**
* 判断是否未数值
* @param {Object} val
*/
export function isNumber(val) {
return !isNaN(Number(val))
}
/**
* 处理大小单位
* @param {Object} val
*/
export function formatSize(val, unit = 'rpx') {
return isNumber(val) ? `${
val}${
unit}` : val
}
2. Configure the applet page to be horizontal
Add "pageOrientation": "landscape" in pages.json, pageOrientation is set to landscape, which means it is fixed to horizontal screen display
{
"pages": [ //pages数组中第一项表示应用启动页，参考：https://uniapp.dcloud.io/collocation/pages
{
"path": "pages/index/index",
"style": {
"navigationBarTitleText": "签字",
"enablePullDownRefresh": false,
"pageOrientation": "landscape",
"backgroundColor": "#f8f8f8",
"navigationStyle": "custom"
}
}
],
"globalStyle": {
"navigationBarTextStyle": "black",
"navigationBarTitleText": "uni-app",
"navigationBarBackgroundColor": "#F8F8F8",
"backgroundColor": "#F8F8F8"
},
"uniIdRouter": {
}
}
3. Use in the page
code:
<template>
<view class="sign-contain">
<view class="sign-top">
请在空白处签字
</view>
<my-sign @init="onSignInit" @end="endConfirm" bgColor="#fff" width="100%" :height="signHeight">
</my-sign>
<!-- 按钮 -->
<view class="signBtn-box">
<view class="signBtn-item1">
<button type="default" plain="true" class="lnvestor-btn" hover-class="hover"
@click="cancelBtn">取消</button>
</view>
<view class="signBtn-item2">
<button type="default" plain="true" class="lnvestor-btn1" hover-class="hover"
@click="clear">清空重写</button>
<button type="primary" class="lnvestor-btn2" hover-class="hover"
@click="submitBtn" :disabled="vsignDisabled">提交签名</button>
</view>
</view>
</view>
</template>
<script>
export default {
data() {
return {
signHeight: '375px',
vsignDisabled: true
}
},
onLoad() {
var that = this;
uni.getSystemInfo({
success: function(res) {
console.log('屏幕信息', res)
that.signHeight = (res.windowHeight-130)+"px";
}
})
},
methods: {
submitBtn(){
uni.redirectTo({
url: '/qualifyLnvestor/qualifyLnvestor/result'
})
},
// 取消
cancelBtn(){
uni.navigateBack({
delta: 1
})
},
// 清除
clear() {
this.signCtx.clear();
this.vsignDisabled = true;
},
onSignInit(signCtx) {
this.signCtx = signCtx
},
// 绘画结束触发
endConfirm() {
this.vsignDisabled = false;
}
}
}
</script>
<style lang="scss">
.sign-contain {
padding-left: 35rpx;
padding-right: 35rpx;
.sign-top {
width: 100%;
height: 50px;
line-height: 50px;
font-size: 16px;
text-align: center;
color: #999999;
}
.signBtn-box {
display: flex;
justify-content: space-between;
align-items: center;
.signBtn-item1 {
// 按钮样式
.lnvestor-btn {
margin-top: 11px;
width: 94px;
height: 40px;
border-radius: 20px;
display: flex;
justify-content: center;
align-items: center;
font-size: 16px;
}
.hover {
border: 1px solid #ccc !important;
color: #ccc !important;
font-size: 16px !important;
}
}
.signBtn-item2 {
display: flex;
// 按钮样式
.lnvestor-btn1 {
margin-top: 11px;
width: 128px;
height: 40px;
border-radius: 20px;
display: flex;
justify-content: center;
align-items: center;
font-size: 16px;
margin-right: 16px;
}
.lnvestor-btn2 {
margin-top: 11px;
width: 128px;
height: 40px;
border-radius: 20px;
display: flex;
justify-content: center;
align-items: center;
background: #b99c65;
font-size: 16px;
}
.hover {
border: 1px solid #ccc !important;
color: #ccc !important;
font-size: 16px !important;
}
}
}
}
</style>
Effect:
