微信小程序实现横屏和竖屏签名功能
作者：烂泥也能扶上墙
这篇文章主要为大家详细介绍了微信小程序实现横屏和竖屏签名功能，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
本文实例为大家分享了微信小程序实现横屏和竖屏签名的具体代码，供大家参考，具体内容如下
wxml
<view class="container"> <canvas canvas-id="firstCanvas" id="firstCanvas" bindtouchstart="bindtouchstart" bindtouchmove="bindtouchmove"></canvas> <view class="btn"> <button type="warn" bindtap="clear"> 清除 </button> <button type="primary" bindtap="export"> 确定 </button> </view> </view>
wxss
#firstCanvas{
width: 750rpx;
height: 600rpx;
background-color: #fff;
}js
const app = getApp()
Page({
data: {
context: null,
index: 0,
height: 0,
width: 0
},
/**记录开始点 */
bindtouchstart: function(e) {
this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y)
},
/**记录移动点，刷新绘制 */
bindtouchmove: function(e) {
this.data.context.lineTo(e.changedTouches[0].x, e.changedTouches[0].y);
this.data.context.stroke();
this.data.context.draw(true);
this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y);
},
/**清空画布 */
clear: function() {
this.data.context.clearRect(0, 0, this.data.width, this.data.height);
this.data.context.draw();
this.data.context.setStrokeStyle('#00ff00')
this.data.context.setLineWidth(2)
this.data.context.setFontSize(20)
let str = "签名区域";
this.data.context.fillText(str, Math.ceil((this.data.width - this.data.context.measureText(str).width) / 2), Math.ceil(this.data.height / 2) - 20)
this.data.context.draw()
},
base64(url, type) {
return new Promise((resolve, reject) => {
wx.getFileSystemManager().readFile({
filePath: url,
encoding: 'base64',
success(res){
resolve('data:img/'+type.toLocaleLowerCase()+':base64,'+res.data)
},
fail(){
reject()
}
})
})
},
/**导出图片 */
export: function() {
const that=this;
this.data.context.draw(false, wx.canvasToTempFilePath({
x: 0,
y: 0,
width: that.data.width,
height: that.data.height,
destWidth: that.data.width,
destHeight: that.data.height,
fileType: 'jpg',
canvasId: 'firstCanvas',
success(res) {
let url = res.tempFilePath
that.base64(url, 'jpg').then(res => {
console.log('base64数据流',res);
var pages = getCurrentPages();
var prevPage = pages[pages.length - 2]; //上一个页面
//直接调用上一个页面的setData()方法，把数据存到上一个页面中去
prevPage.setData({
sign: {
sign:res,
}
})
wx.navigateBack({//返回
delta: 1
})
})
},
fail() {
wx.showToast({
title: '导出失败',
icon: 'none',
duration: 2000
})
}
}))
},
onShow: function() {
let query = wx.createSelectorQuery();
const that = this;
query.select('#firstCanvas').boundingClientRect();
query.exec((rect) => {
let width = rect[0].width;
let height = rect[0].height;
that.setData({
width,
height
});
const context = wx.createCanvasContext('firstCanvas')
that.setData({
context: context
})
that.data.context.setLineWidth(2)
that.data.context.setLineCap('round')
});
},
})效果
横屏
<view class="wrapper">
<view class="handBtn">
<image catchtap="selectColorEvent" src="{{ selectColor === 'black' ? '../../public/image/index/sign/color_black_selected.png' : '../../public/image/index/sign/color_black.png' }}" class="{{ selectColor === 'black' ? 'color_select' : '' }} black-select" data-color="black"
data-color-value="#1A1A1A"></image>
<image catchtap="selectColorEvent" src="{{ selectColor === 'red' ? '../../public/image/index/sign/color_red_selected.png' : '../../public/image/index/sign/color_red.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="saveBtn">保存</button>
<button catchtap="previewCanvasImg" class="previewBtn">预览</button>
<button catchtap="uploadCanvasImg" class="uploadBtn">上传</button>
<button catchtap="subCanvas" 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>wxss
page {
background: #fbfbfb;
height: auto;
overflow: hidden;
}
.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;
align-items: center;
flex: 1;
}
.delBtn,
.saveBtn,
.previewBtn,
.uploadBtn,
.subBtn{
width: 160rpx !important;
height: 70rpx;
border: 2rpx solid #eeeeee;
transform: rotate(90deg);
color: #666;
}
.delBtn{
position: absolute;
bottom: 850rpx;
}
.saveBtn{
position: absolute;
bottom: 660rpx;
}
.previewBtn{
position: absolute;
bottom: 470rpx;
}
.uploadBtn{
position: absolute;
bottom: 280rpx;
}
.subBtn {
position: absolute;
bottom: 52rpx;
display: inline-flex;
transform: rotate(90deg);
background: #218FFC;
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;
}js
Page({
data: {
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
signImg: 'signImg',
linePrack: [] //划线轨迹 , 生成线条的实际点
},
onLoad (options) {
this.setData({
signImg: options.names,
})
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
})
/* 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();
},
// 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();
//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.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
})
},
// 设置背景函数
//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.data.ctx.rect(0, 0, this.data.canvasWidth, this.data.canvasHeight - 4);
// ctx.setFillStyle('red')
this.data.ctx.setFillStyle( color )
this.data.ctx.fill() //设置填充
this.data.ctx.draw() //开画
},
//保存到相册
saveCanvasAsImg(){
wx.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'png',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
wx.saveImageToPhotosAlbum({
filePath: res.tempFilePath,
success(res) {
wx.showToast({
title: '已保存到相册',
duration: 2000
});
}
})
}
})
},
//预览
previewCanvasImg(){
wx.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'jpg',
quality: 1, //图片质量
success(res) {
// console.log(res.tempFilePath, 'canvas生成图片地址');
wx.previewImage({
urls: [res.tempFilePath], //预览图片 数组
})
}
})
},
//上传
uploadCanvasImg() {
wx.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
wx.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
}
})
}
})
},
// 完成 导出图片
base64(url, type) {
return new Promise((resolve, reject) => {
wx.getFileSystemManager().readFile({
filePath: url,
encoding: 'base64',
success(res){
resolve('data:image/'+type.toLocaleLowerCase()+';base64,'+res.data)
},
fail(){
reject()
}
})
})
},
subCanvas(){
const that=this;
this.data.ctx.draw(false, wx.canvasToTempFilePath({
canvasId: 'handWriting',
fileType: 'jpg',
quality: 1, //图片质量
success(res) {
let url = res.tempFilePath
that.base64(url, 'jpg').then(res => {
var pages = getCurrentPages();
var prevPage = pages[pages.length - 2]; //上一个页面
//直接调用上一个页面的setData()方法，把数据存到上一个页面中去
prevPage.setSign(res)
wx.navigateBack({//返回
delta: 1
})
})
},
fail() {
wx.showToast({
title: '导出失败',
icon: 'none',
duration: 2000
})
}
})
)
}
})调用页面引入
wxml
<view class="sign" bindtap="signName">
<view class="sign-title">检查员签名：
</view>
<view class="sign-img">
<image src="{{base64ImgUrl}}"></image>
</view>
</view>js
// 跳签名板页面
setSign(value) {
wx.setStorageSync('signImg2', value)
this.setData({
base64ImgUrl: value
})
},
signName() {
wx.navigateTo({
url: '../sign_name/index?names=signImg2',
})
},效果
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脚本之家。