新开发的业务涉及到签字功能，由于是动态的表单，无法确定它会出现在哪里，不得已封装模块。
其中涉及到一个难点就是this的指向性问题，
第二个是微信小程序写法，
我这个写法里用了u-view的写法，可以自己修改组件
首先是封装的内容
1、props接收父级传过来的参数，这些数据是因为我是动态多级表单、可按需传值
2、imageUpload是我上传后台的地址。可自己修改，或者自己封装参数
3、this.canvasadd()是定义画布，一定要放在mounted(),放在其他位置会出现this指向性报错，或者返回位置不一致问题。
<template>
<!-- 签名组件 -->
<view class="container">
<view class="fatherWrite" @click="showWrite">
<div class="sonWrite">
<text v-if="write">点击签名</text>
</div>
<image :src="value" v-model="image" style="border:1px solid #ccc;width: 100%;" />
</view>
<uni-popup ref="popup" background-color="#fff" >
<h1 style="text-align: center;margin: 20rpx;">签字板</h1>
<uni-row class="demo-uni-row" :gutter='10' style="padding: 20rpx;" >
<uni-col :span="8">
<u-button text="取消" color="linear-gradient(to right, rgb(66, 83, 216), rgb(213, 51, 186))"
@tap="handleCancel"></u-button>
</uni-col>
<uni-col :span="8">
<u-button text="重写" color="linear-gradient(to right, rgb(66, 83, 216), rgb(213, 51, 186))"
@tap="handleReset"></u-button>
</uni-col>
<uni-col :span="8">
<u-button text="确认" color="linear-gradient(to right, rgb(66, 83, 216), rgb(213, 51, 186))"
@tap="handleConfirm"></u-button>
</uni-col>
</uni-row>
<view class="sign-box">
<canvas class="mycanvas" canvas-id="mycanvas" @touchstart="touchstart" @touchmove="touchmove"
@touchend="touchend"></canvas>
</view>
</uni-popup>
</view>
</template>
<script>
var x = 20;
var y = 20;
var tempPoint = []; //用来存放当前画纸上的轨迹点
var id = 0;
var type = '';
let that;
let canvasw;
let canvash;
import {
imageUpload
} from '@/api/system/applet.js' //
export default {
name: 'Handwriting',
props: {
image: String, //判断当前是否有照片
writeIndex: Number, //下标
writeChildrenIndex: Number, //子级下标
},
data() {
return {
ctx: '', //绘图图像
points: [], //路径点集合,
width: 0,
height: 0,
write: true,
value: this.image,
};
},
mounted() {
this.canvasadd()
},
methods: {
canvasadd() {
this.ctx = uni.createCanvasContext('mycanvas', this); //创建绘图对象
//设置画笔样式
this.ctx.lineWidth = 4;
this.ctx.lineCap = 'round';
this.ctx.lineJoin = 'round';
that = this;
uni.getSystemInfo({
success: function(res) {
that.width = res.windowWidth;
that.height = res.windowHeight;
}
});
},
//签名填写
showWrite() {
this.canvasadd()
if (this.image == null || this.image == '') {
that.$refs.popup.open('bottom')
} else {
uni.showModal({
content: "是否重写签名",
cancelText: '取消',
confirmText: '确定',
success: function(res) {
if (res.confirm) {
that.$refs.popup.open('bottom')
} else {
that.$refs.popup.close()
}
}
})
}
},
//触摸开始，获取到起点
touchstart: function(e) {
let startX = e.changedTouches[0].x;
let startY = e.changedTouches[0].y;
let startPoint = {
X: startX,
Y: startY
};
/* **************************************************
#由于uni对canvas的实现有所不同，这里需要把起点存起来
* **************************************************/
this.points.push(startPoint);
//每次触摸开始，开启新的路径
this.ctx.beginPath();
},
//触摸移动，获取到路径点
touchmove: function(e) {
let moveX = e.changedTouches[0].x;
let moveY = e.changedTouches[0].y;
let movePoint = {
X: moveX,
Y: moveY
};
this.points.push(movePoint); //存点
let len = this.points.length;
if (len >= 2) {
this.draw(); //绘制路径
}
tempPoint.push(movePoint);
},
// 触摸结束，将未绘制的点清空防止对后续路径产生干扰
touchend: function() {
this.points = [];
},
/* ***********************************************
# 绘制笔迹
# 1.为保证笔迹实时显示，必须在移动的同时绘制笔迹
# 2.为保证笔迹连续，每次从路径集合中区两个点作为起点（moveTo）和终点(lineTo)
# 3.将上一次的终点作为下一次绘制的起点（即清除第一个点）
************************************************ */
draw: function() {
let point1 = this.points[0];
let point2 = this.points[1];
this.points.shift();
this.ctx.lineWidth = 4;
this.ctx.lineCap = 'round';
this.ctx.lineJoin = 'round';
this.ctx.moveTo(point1.X, point1.Y);
this.ctx.lineTo(point2.X, point2.Y);
this.ctx.stroke();
this.ctx.draw(true);
},
//取消绘制
handleCancel() {
this.handleReset()
that.$refs.popup.close()
},
//清空画布
handleReset: function() {
this.ctx.clearRect(0, 0, that.width, that.height);
this.ctx.draw(true);
tempPoint = [];
},
//将签名笔迹上传到服务器，并将返回来的地址存到本地
handleConfirm: function() {
if (tempPoint.length == 0) {
that.$modal.msgError('请先签名')
return;
} else {
setTimeout(() => {
uni.canvasToTempFilePath({
canvasId: 'mycanvas',
destWidth: that.width,
destHeight: that.height,
fileType: 'png',
quality: 1, //图片质量
success: function(res) {
let tempPath = res.tempFilePath;
//图片上传拿url
let data = {
filePath: tempPath,
formData: {
isSystem: 'true'
}
}
imageUpload(data).then(response => {
//向上一个页面传参
that.value = response.data.url
that.handleReset()
if (that.value) {
that.write = false
}
that.$emit("writeValue", {
value: that.value,
index: that.writeIndex,
childrenIndex: that.writeChildrenIndex
}) //返回父级数组下标
that.$refs.popup.close()
})
}
}, this);
}, 500)
}
}
}
};
</script>
<style lang="scss" scoped>
.sign-box {
width: 100%;
height: 100%;
margin: auto;
}
.demo-uni-row {
margin: 20rpx 20rpx;
padding: 20rpx;
}
.mycanvas {
margin: 20rpx;
width: auto;
height: 60vh;
border: 1px solid #c6ceff;
background-color: #ececec;
}
.canvsborder {
position: fixed;
}
.fatherWrite {
position: relative;
.sonWrite {
position: absolute;
color: #ccc;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
}
</style>
页面引用
<template>
<view>
//这里简单放置，具体使用，按照规范填写
//普通写法
<uni-forms-item :label="index+1+'、'+item.label" required
:rules=item.rules :name="['dynamicLists',index,'images']" >
<writeName :image="item.images" :value="item.images" :writeIndex="index"
@writeValue="writeValue"></writeName>
</uni-forms-item>
//多级动态提交
uni-forms-item :label="index+1+'.'+ide+1+'、'+ite.itemName" required
:rules="[{required: true,errorMessage: '请填写'}]"
:name="['dynamicLists',index,'children',ide,'images']">
<writeName :image="dynamicFormData.dynamicLists[index].children[ide].images"
:value="dynamicFormData.dynamicLists[index].children[ide].images"
:writeIndex="index" :writeChildrenIndex="ide"
@writeValue="writeValueChildren">
</writeName>
</uni-forms-item>
</view>
</template>
import writeName from '@/pages/public/Handwriting/Handwriting.vue'
export default {
components: {
writeName
},
methods:{
writeValueChildren(val) {
this.dynamicFormData.dynamicLists[val.index].children[val.childrenIndex].images = val.value
},
writeValue(val) {
this.dynamicFormData.dynamicLists[val.index].images = val.value
},
}
}
以上是我的写法，不足之处还望指出
