本文实例为大家分享了微信小程序用canvas实现电子签名的具体代码，供大家参考，具体内容如下
<view class="sign-contain">
<view class="signName">
<canvas id="canvas" canvas-id="canvas" class="{{ sysType === 'iOS' ? 'canvas' : 'canvas bg000'}}" disable-scroll="true" bindtouchstart="canvasStart" bindtouchmove="canvasMove" bindtouchend="canvasEnd" touchcancel="canvasEnd" binderror="canvasIdErrorCallback"></canvas>
</view>
<view class="btn-wrap">
<button catchtap="cleardraw">清除签名</button>
<button catchtap="uploadImg">上传签名</button>
</view>
</view>var context = null;// 使用 wx.createContext 获取绘图上下文 context
var isButtonDown = false;//是否在绘制中
var arrx = [];//动作横坐标
var arry = [];//动作纵坐标
var arrz = [];//总做状态，标识按下到抬起的一个组合
var canvasw = 0;//画布宽度
var canvash = 0;//画布高度
Page({
data: {
canvasw: '',
canvash: '',
imgUrl: '',
info: {},
signBase64: '',
sysType: '' // 判断机型
},
onLoad: function (options) {
let that = this
let res = wx.getSystemInfoSync()
const system = res.system.split(' ')
that.setData({
sysType: system[0],
})
let params = JSON.parse(options.params)
that.setData({
info: params,
})
that.startCanvas();
that.initCanvas()
},
/**
* 以下 - 手写签名 / 上传签名
*/
startCanvas() {//画布初始化执行
var that = this;
//获取系统信息
wx.getSystemInfo({
success: function (res) {
canvasw = res.windowWidth;
canvash = res.windowHeight;
that.setData({ canvasw: canvasw });
that.setData({ canvash: canvash });
}
});
this.initCanvas();
this.cleardraw();
},
//初始化函数
initCanvas() {
context = wx.createCanvasContext('canvas');
context.beginPath()
if(this.data.sysType === 'iOS') {
context.fillStyle = 'rgba(255, 255, 255, 1)';
context.setStrokeStyle('#444');
} else {
context.fillStyle = 'rgba(0, 0, 0, 1)';
context.setStrokeStyle('#aaa');
}
context.setLineWidth(4);
context.setLineCap('round');
context.setLineJoin('round');
},
canvasStart(event) {
isButtonDown = true;
arrz.push(0);
arrx.push(event.changedTouches[0].x);
arry.push(event.changedTouches[0].y);
},
canvasMove(event) {
if (isButtonDown) {
arrz.push(1);
arrx.push(event.changedTouches[0].x);
arry.push(event.changedTouches[0].y);
}
for (var i = 0; i < arrx.length; i ) {
if (arrz[i] == 0) {
context.moveTo(arrx[i], arry[i])
} else {
context.lineTo(arrx[i], arry[i])
}
}
context.clearRect(0, 0, canvasw, canvash);
if(this.data.sysType === 'iOS') {
context.fillStyle = 'rgba(255, 255, 255, 1)';
context.setStrokeStyle('#444');
} else {
context.fillStyle = 'rgba(0, 0, 0, 1)';
context.setStrokeStyle('#aaa');
}
context.setLineWidth(3);
context.setLineCap('round');
context.setLineJoin('round');
context.stroke();
context.draw(false);
},
canvasEnd(event) {
isButtonDown = false;
},
//清除画布
cleardraw() {
arrx = [];
arry = [];
arrz = [];
context.clearRect(0, 0, canvasw, canvash);
if(this.data.sysType === 'iOS') {
context.fillStyle = 'rgba(255, 255, 255, 1)';
context.setStrokeStyle('#444');
} else {
context.fillStyle = 'rgba(0, 0, 0, 1)';
context.setStrokeStyle('#aaa');
}
context.draw(true);
},
uploadImg() {
var that = this
//生成图片
// context.draw(true,()=> {
setTimeout(() => {
wx.canvasToTempFilePath({
canvasId: 'canvas',
//设置输出图片的宽高
fileType: 'jpg',
quality: 1,
success: function (res) {
// canvas图片地址 res.tempFilePath
let imgBase64 = wx.getFileSystemManager().readFileSync(res.tempFilePath, 'base64')
that.setData({
imgUrl: res.tempFilePath,
signBase64: imgBase64
})
that.submitSign()
console.log('imgBase64', 'data:image/jpeg;base64,' imgBase64)
// wx.saveImageToPhotosAlbum({
// filePath: res.tempFilePath,
// success(res4) {
// console.log(res,'保存res4');
// wx.showToast( {
// title: '已成功保存到相册',
// duration: 2000
// } );
// }
// })
},
fail: function () {
wx.showModal({
title: '提示',
content: 'canvas生成图片失败。微信当前版本不支持，请更新到最新版本！',
showCancel: false
});
},
complete: function () { }
}, 5000)
})
// })
},
// 提交签名
submitSign() {
let that = this
wx.showLoading({
title: '正在提交...',
mask: true
})
let type = '1'
if(that.data.sysType === 'iOS') {
type = '0'
} else {
type = '1'
}
wx.$getWxLoginCode(resp => {
const params = {
qmbase64: that.data.signBase64,
}
console.info("入参", params)
wx.kservice.yyyurl(params, res => {
wx.hideLoading()
if (res.statusCode === '200') {
wx.showModal({
title: '提示',
content: res.message,
showCancel: false,
confirmText: '返回首页',
success(res) {
if (res.confirm) {
wx.reLaunch({
url: '/pages/index/index'
})
}
}
})
} else {
wx.showModal({
title: '提示',
content: res.message,
showCancel: true,
cancelText: '返回首页',
confirmText: '重新提交',
success: (result) => {
if (result.cancel) {
// 取消停留
wx.reLaunch({
url: '/pages/index/index'
})
} else if (result.confirm) {
//重新提交
that.submitSign()
}
},
});
}
}, {}, true, true)
})
},
/**
* 生命周期函数--监听页面卸载
*/
onUnload: function () {
},
/**
* 页面相关事件处理函数--监听用户下拉动作
*/
onPullDownRefresh: function () {
},
/**
* 页面上拉触底事件的处理函数
*/
onReachBottom: function () {
},
/**
* 用户点击右上角分享
*/
onShareAppMessage: function () {
}
}).sign-contain {
display: flex;
flex-direction:column;
width: 100%;
height: 100%;
}
.signName {
flex: 1;
}
.canvas {
width: 100%;
height: 100%;
}
.bg000{
background-color: #000;
}
.btn-wrap{
display: block;
width:100%;
height: 100rpx;
margin: 20rpx 0;
position: relative;
}
.btn-wrap button{
width: 43%;
}以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持Devmax。