随着技术的发展，开发的复杂度也越来越高，传统开发方式将一个系统做成了整块应用，经常出现的情况就是一个小小的改动或者一个小功能的增加可能会引起整体逻辑的修改，造成牵一发而动全身。通过组件化开发，可以有效实现单独开发，单独维护，而且他们之间可以随意的进行组合。大大提升开发效率低，降低维护成本。
组件化对于任何一个业务场景复杂的前端应用以及经过多次迭代之后的产品来说都是必经之路。组件化要做的不仅仅是表面上看到的模块拆分解耦，其背后还有很多工作来支撑组件化的进行，例如结合业务特性的模块拆分策略、模块间的交互方式和构建系统等等 。
本文给大家介绍的组件是：
基于html2canva jspdf 实现前端页面加水印 并导出页面PDF; 下载完整代码请访问uni-app插件市场地址：https://ext.dcloud.net.cn/plugin?id=12761
更多前端组件信息请关注微信公众号： 前端组件开发
效果图如下:
代码实现如下:
# 使用方法
```使用方法
<!-- 引入加入 导出pdf插件 -->
<script type="text/javascript" src="./static/html2canvas.js"></script>
<script type="text/javascript" src="./static/jspdf.debug.js"></script>
// 调用页面加水印方法
this.watermark({
"watermark_txt": "中国广东cc.gd"
});
// 调用下载pdf报告方法
downKcReport();
```
#### HTML代码部分
```html
<template>
<view class="content">
<view class="exportPdfBtn" @click="downKcReport()">导出PDF</view>
<!-- 可视化 -->
<view style="background-color: white; border-radius: 4px; margin-top: -4px;">
<!-- 柱形图 堆叠 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px;"> 柱形图 堆叠
</h4>
<div class="mui-content-padded">
<div id="dsj_zscq" style="width: calc(100vw - 40px); height: 280px;"></div>
</div>
<!-- 折线图 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px;"> 折线图
</h4>
<div class="mui-content-padded">
<div id="dsj_cxcg" style="width: calc(100vw - 40px); margin: -18px 0px; height: 280px;">
</div>
</div>
<!-- 柱状图 + 折线图-->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
柱状图 + 折线图 </h4>
<div class="mui-content-padded">
<div id="dsj_zlhjl" style="width: calc(100vw - 40px); height: 290px;"></div>
</div>
<!-- 有效知识产权结构 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
饼图 </h4>
<div class="mui-content-padded">
<div id="dsj_zscqjg" style="width: calc(100vw - 40px); height: 306px;"></div>
</div>
<!-- 专利iPC结构 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
树形结构图 </h4>
<div class="mui-content-padded">
<div id="dsj_zlipc_content"
style="margin-left: -10px; width: calc(100vw - 40px); height: auto; margin-bottom: 30px;">
</div>
</div>
<!-- 柱状图 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
柱状图 </h4>
<div class="mui-content-padded">
<div id="dsj_zljz" style="width: calc(100vw - 40px); height: 280px;"></div>
</div>
<!-- 专利法律状态分布 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
饼图 </h4>
<div class="mui-content-padded">
<div id="dsj_zlfl" style="width: calc(100vw - 40px); height: 280px;"></div>
</div>
<!-- 专利寿命分布 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
柱状图 </h4>
<div class="mui-content-padded">
<div id="dsj_zlsm" style="width: calc(100vw - 40px); height: 280px;"></div>
</div>
<!-- 树形结构图 -->
<h4 style="margin-left: 12px; font-size: 16px; height: 30px; line-height: 30px; margin-top: 0px;">
树形结构图 </h4>
<div class="mui-content-padded">
<div id="dsj_zllhsq" style="width: calc(100vw - 40px); height: auto; margin-bottom: 30px;">
</div>
</div>
</view>
</view>
</template>
```
#### JS代码 （引入组件 填充数据）
```javascript
<script>
import myIndex from '../index/index.js'
export default {
data() {
return {
title: 'Hello'
}
},
mounted() {
// 刷新Echart数据
this.refreshEchartData();
},
onLoad() {
// 页面加水印方法
this.watermark({
"watermark_txt": "中国广东cc.gd"
});
},
methods: {
// 页面加水印方法
watermark(settings) {
//默认设置
var defaultSettings = {
watermark_txt: "text",
watermark_x: 20, //水印起始位置x轴坐标
watermark_y: 80, //水印起始位置Y轴坐标
watermark_rows: 80, //水印行数
watermark_cols: 20, //水印列数
watermark_x_space: 80, //水印x轴间隔
watermark_y_space: 102, //水印y轴间隔
watermark_color: '#aaa', //水印字体颜色
watermark_alpha: 0.4, //水印透明度
watermark_fontsize: '14px', //水印字体大小
watermark_font: '微软雅黑', //水印字体
watermark_width: 180, //水印宽度
watermark_height: 80, //水印长度
watermark_angle: 20 //水印倾斜度数
};
//采用配置项替换默认值，作用类似jquery.extend
if (arguments.length === 1 && typeof arguments[0] === "object") {
console.log("arguments = " + JSON.stringify(arguments[0]));
// 获取参数配置
var src = arguments[0];
for (let key in src) {
if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key])
continue;
else if (src[key])
defaultSettings[key] = src[key];
}
}
var oTemp = document.createDocumentFragment();
//获取页面最大宽度
var page_width = Math.max(document.body.scrollWidth, document.body.clientWidth);
var cutWidth = page_width * 0.0150;
var page_width = page_width - cutWidth;
//获取页面最大高度
var page_height = Math.max(document.body.scrollHeight, document.body.clientHeight) + 2860;
// var page_height = document.body.scrollHeight+document.body.scrollTop;
//如果将水印列数设置为0，或水印列数设置过大，超过页面最大宽度，则重新计算水印列数和水印x轴间隔
if (defaultSettings.watermark_cols == 0 || (parseInt(defaultSettings.watermark_x + defaultSettings
.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (
defaultSettings.watermark_cols - 1)) > page_width)) {
defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x + defaultSettings
.watermark_x_space) / (defaultSettings.watermark_width + defaultSettings
.watermark_x_space));
defaultSettings.watermark_x_space = parseInt((page_width - defaultSettings.watermark_x -
defaultSettings
.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols - 1));
}
//如果将水印行数设置为0，或水印行数设置过大，超过页面最大长度，则重新计算水印行数和水印y轴间隔
if (defaultSettings.watermark_rows == 0 || (parseInt(defaultSettings.watermark_y + defaultSettings
.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (
defaultSettings.watermark_rows - 1)) > page_height)) {
defaultSettings.watermark_rows = parseInt((defaultSettings.watermark_y_space + page_height -
defaultSettings
.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
defaultSettings.watermark_y_space = parseInt(((page_height - defaultSettings.watermark_y) -
defaultSettings
.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows - 1));
}
var x;
var y;
for (var i = 0; i < defaultSettings.watermark_rows; i++) {
y = defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings
.watermark_height) * i;
for (var j = 0; j < defaultSettings.watermark_cols; j++) {
x = defaultSettings.watermark_x + (defaultSettings.watermark_width + defaultSettings
.watermark_x_space) *
j;
var mask_div = document.createElement('div');
mask_div.id = 'mask_div' + i + j;
mask_div.className = 'mask_div';
mask_div.appendChild(document.createTextNode(defaultSettings.watermark_txt));
//设置水印div倾斜显示
mask_div.style.webkitTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.MozTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.msTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.OTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.transform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.visibility = "";
mask_div.style.position = "absolute";
mask_div.style.left = x + 'px';
mask_div.style.top = y + 'px';
mask_div.style.overflow = "hidden";
mask_div.style.zIndex = "9999";
mask_div.style.pointerEvents = 'none'; //pointer-events:none 让水印不遮挡页面的点击事件
//mask_div.style.border="solid #eee 1px";
mask_div.style.opacity = defaultSettings.watermark_alpha;
mask_div.style.fontSize = defaultSettings.watermark_fontsize;
mask_div.style.fontFamily = defaultSettings.watermark_font;
mask_div.style.color = defaultSettings.watermark_color;
mask_div.style.textAlign = "center";
mask_div.style.width = defaultSettings.watermark_width + 'px';
mask_div.style.height = defaultSettings.watermark_height + 'px';
mask_div.style.display = "block";
oTemp.appendChild(mask_div);
};
};
document.body.appendChild(oTemp);
},
// 下载pdf报告
downKcReport() {
html2canvas(
document.body, {
scale: 2,
dpi: 192, //导出pdf清晰度
onrendered: function(canvas) {
var contentWidth = canvas.width;
var contentHeight = canvas.height;
//一页pdf显示html页面生成的canvas高度;
var pageHeight = contentWidth / 592.28 * 841.89;
//未生成pdf的html页面高度
var leftHeight = contentHeight;
//pdf页面偏移
var position = 0;
//html页面生成的canvas在pdf中图片的宽高（a4纸的尺寸[595.28,841.89]）
var imgWidth = 595.28;
var imgHeight = 592.28 / contentWidth * contentHeight;
var pageData = canvas.toDataURL('image/jpeg', 1.0);
var pdf = new jsPDF('', 'pt', 'a4');
//有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
//当内容未超过pdf一页显示的范围，无需分页
if (leftHeight < pageHeight) {
pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight);
} else {
while (leftHeight > 0) {
pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
leftHeight -= pageHeight;
position -= 841.89;
//避免添加空白页
if (leftHeight > 0) {
pdf.addPage();
}
}
}
pdf.save(name + '.pdf');
console.log('成功导出pdf');
},
//背景设为白色（默认为黑色）
background: "#fff"
})
},
refreshEchartData() {
// 返回数据需在json转换格式工具 转成Json格式
let result = {
"data": {
"unionCompanyNum": 4,
"goldList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"fmsqYx": "1",
"cfmwyxzscqsl": "1",
"years": "1",
"yxzscqsl": "1",
"dnzlhjl": "1"
}],
"patentLifeList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"percentage": "1",
"quantity": "1",
"scope": "1-3",
"totalNum": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"percentage": "1",
"quantity": "1",
"scope": "3-5",
"totalNum": "2"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"percentage": "1",
"quantity": "3",
"scope": "5-10",
"totalNum": "3"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"percentage": "1",
"quantity": "3",
"scope": "10-",
"totalNum": "4"
}],
"patentValueList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"fmgbZs": "1",
"fmsqYx": "1",
"syxxYx": "1",
"wgsjYx": "1",
"scope": "0-5",
"totalNum": "1",
"percentageHighRights": "1",
"percentageHigh": "1",
"dspw": "1",
"jslypw": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"fmgbZs": "1",
"fmsqYx": "1",
"syxxYx": "1",
"wgsjYx": "1",
"scope": "5-10",
"totalNum": "1",
"percentageHighRights": "1",
"percentageHigh": "1",
"dspw": "1",
"jslypw": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"fmgbZs": "1",
"fmsqYx": "2",
"syxxYx": "3",
"wgsjYx": "4",
"scope": "90-100",
"totalNum": "10"
}],
"legalList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"underTrial": "1",
"invalid": "1",
"efficient": "1",
"totalNum": "1",
"percentage": "1"
}],
"propertyRightList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"fmgbZs": "1",
"fmgbZsP": "1",
"fmsqYx": "1",
"fmsqYxP": "1",
"syxxYx": "1",
"syxxYxP": "1",
"wgsjYx": "1",
"wgsjYxP": "1",
"rzYx": "1",
"rzYxP": "1",
"maxPercentage": "1",
"maxPercentageRights": "1",
"dspw": "1",
"jslypw": "1"
}],
"unionPatentNum": 13,
"ipcList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"ipcDept": "1",
"ipcClass": "1",
"ipcNum": "1",
"ipcZbClass": "1",
"ipcZb": "1",
"dspw": "1",
"jslypw": "1"
}],
"yearList": [{
"isNewRecord": true,
"comId": "1",
"fmgbZs": "1",
"fmsqYx": "1",
"syxxYx": "1",
"wgsjYx": "1",
"rzYx": "1",
"years": "2022",
"dnkjcxcgkbjshl": "1",
"socialCode": "123456"
}, {
"isNewRecord": true,
"comId": "1",
"years": "2023",
"dnkjcxcgkbjshl": "2",
"socialCode": "123456"
}, {
"isNewRecord": true,
"comId": "1",
"years": "2026",
"dnkjcxcgkbjshl": "6",
"socialCode": "123456"
}, {
"isNewRecord": true,
"comId": "1",
"years": "2027",
"dnkjcxcgkbjshl": "7",
"socialCode": "123456"
}],
"unionList": [{
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"unionName": "测试5",
"unionNum": "5",
"unionCompany": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"unionName": "测试4",
"unionNum": "4",
"unionCompany": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"unionName": "测试3",
"unionNum": "3",
"unionCompany": "1"
}, {
"isNewRecord": true,
"comId": "1",
"socialCode": "123456",
"unionName": "测试1",
"unionNum": "1",
"unionCompany": "1"
}]
},
"statusCode": 200,
"header": {
"date": "Tue, 30 May 2023 07:08:28 GMT",
"powered-by": "JeeSite V5.0.1 0",
"transfer-encoding": "chunked",
"content-type": "application/json"
},
"errMsg": "request:ok"
};
let resultData = result.data;
if (resultData.yearList != undefined && resultData.yearList.length > 0) {
console.log('执行图表1');
// 填充图表1 2
myIndex.fillChartOneTwo(resultData.yearList);
}
if (resultData.goldList != undefined && resultData.goldList.length > 0) {
// 填充图表3
myIndex.fillChartThree(resultData.goldList);
}
if (resultData.propertyRightList != undefined && resultData.propertyRightList.length > 0) {
// 填充图表4
myIndex.fillChartFour(resultData.propertyRightList);
}
if (resultData.ipcList != undefined && resultData.ipcList.length > 0) {
// 填充图表5
myIndex.fillChartFive(resultData.ipcList);
}
if (resultData.patentValueList != undefined && resultData.patentValueList.length > 0) {
// 填充图表6
myIndex.fillChartSix(resultData.patentValueList);
}
if (resultData.legalList != undefined && resultData.legalList.length > 0) {
// 填充图表7 法律
myIndex.fillChartSeven(resultData.legalList);
}
if (resultData.patentLifeList != undefined && resultData.patentLifeList.length > 0) {
// 填充图表8 寿命
myIndex.fillChartEight(resultData.patentLifeList);
}
if (resultData.unionList != undefined && resultData.unionList.length > 0) {
// 填充图表9 专利联合
myIndex.fillChartNine(resultData, "广汽集团");
}
}
}
}
</script>
```
#### CSS
```CSS
<style>
.content {
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
}
.mui-content-padded {
margin: 10px 8px;
}
.mui-content-padded div {
font-size: 13px;
}
.exportPdfBtn {
width: 100px;
height: 40px;
line-height: 40px;
margin-top: 20px;
background-color: greenyellow;
text-align: center;
}
</style>
```