*如果是React开发,这个功能在Ant Design中就有,但是Vue开发Elementui和Ant DesignVue没有这个组件。参考# MutationObserver在页面水印实现起到的作用详解:*实现思路如下:
-
1、如何生成水印?
在区域加一个div,加一个背景图(使用canvas来画图)在repeat加重复属性,通过定位覆盖到div上。具体实现在img.js文件中,通过计算属性,然后创建一个canvas(createElement),设置字体大小,把文字通过fillText()方法画到画布上去,可以设置旋转的画布,字体就斜体了。
-
2、如何防止篡改?
通过MutationObserver监听DOM的变化,通过 childList: true( 观察目标子节点的变化,是否有添加或者删除);attributes: true(观察属性变动),subtree: true (观察后代节点,默认为 false)。具体实现在Watermark.vue文件中,设置样式在style内联在组件中,使用watchEffect来监听,里面设置内联样式(动态生成div且不用class去设置样式),防止在调试工具修改在MutationObserver的回调函数中,通过里面的observer设置参数即监听的对象(监听不到class样式表所以采用内联样式),在回调函数加入设置水印的方法,当我们在控制台中删除节点时,方法中当前元素div跟遍历移除的dom元素做对比,如果相等,就会重新执行生成这个canvas的方法;那么在控制台修改内联样式时,通过当前元素div跟遍历出修改的dom做对比,如果相等就会监听到修改了,重新执行生成canvas的方法。所以,当在控制台删除dom节点或者修改内联样式都会先移除这个canvas再迅速生成一个,dom节点会快速更新,使其不能更改。 img.js文件
import { computed } from "vue";
// 计算属性,创建一个canvas
export default function unseWatermarkBg(props) {
return computed(() => {
const canvas = document.createElement("canvas");
const devicePixelRatio = window.devicePixelRatio || 1;
const fontSize = props.fontSize * devicePixelRatio;
const font = fontSize + "px serif";
const ctx = canvas.getContext("2d");
// 获取文字宽度
const { width } = ctx.measureText(props.text);
const canvasSize = Math.max(100, width) + props.gap * devicePixelRatio;
canvas.width = canvasSize;
canvas.height = canvasSize;
ctx.translate(canvas.width / 2, canvas.height / 2);
ctx.rotate((Math.PI / 180) * -45);
ctx.fillStyle = "rgba(0,0,0,0.3)";
ctx.font = font;
ctx.textAlign = "center";
ctx.textBaseline = "middle";
ctx.fillText(props.text, 0, 0);
return {
base64: canvas.toDataURL(),
size: canvasSize,
styleSize: canvas / devicePixelRatio,
};
});
}
Watermark.vue文件
<template>
<div class="watermark-contaner" ref="parentRef">
<slot></slot>
</div>
</template>
<script setup>
import unseWatermarkBg from './img'
const props = defineProps({
text:{
type:String,
required:true,
default:'watermark'
},
fontSize:{
type:Number,
default:40
},
gap:{
type:Number,
default:20
}
})
const bg = unseWatermarkBg(props)
const{ base64, styleSize} = bg.value
console.log(bg.value,'bg.value');
const parentRef = ref(null)
let div
const flag = ref(0)
watchEffect(()=>{
flag.value
if(!parentRef.value){
return
}
if(div){
div.remove()
}
div = document.createElement('div')
// 内联元素防篡改
div.style.backgroundImage = `url(${base64})`
div.style.backgroundSize = `${styleSize}px ${styleSize}px`
div.style.backgroundRepeat = 'repeat'
div.style.width='100%'
div.style.height='100%'
div.style.zIndex = 9999
div.style.position ='absolute'
div.style.inset = 0
parentRef.value.appendChild(div)
})
let ob;
// 监控手动删除的操作
onMounted(() => {
ob = new MutationObserver((records)=>{
for (const record of records) {
for (const dom of record.removedNodes) {
// 监控到了删除,div是当前元素,而dom是遍历移除的dom元素
if(dom ===div){
flag.value++
return
console.log('sanshussss');
}
}
if(record.target ===div){
// record.target是修改的dom元素
flag.value++
return
}
}
console.log('records',records);
// flag.value++
})
ob.observe(parentRef.value,{
childList:true,
attributes:true,
subtree:true
})
})
onUnmounted(() => {
ob && ob.disconnect() // 取消监听
div = null
})
</script>
<style></style>
index.vue文件
<template>
<div class="container">
<Watermark text="禁止转载" fontSize="18">
<img src="@/assets/images/logo.png" alt="">
</Watermark>
</div>
</template>
<script setup>
import Watermark from './Watermark.vue'
// watermark
// vue 中elementui和andesing没有这个水印组件
</script>
<style></style>
看看github大佬的水印js方法:
/**
* 提取自 watermark-dom
* https://github.com/saucxs/watermark-dom
*/
var watermark = {}
var forceRemove = false
var defaultSettings = {
watermark_id: 'wm_div_id', // 水印总体的id
watermark_prefix: 'mask_div_id', // 小水印的id前缀
watermark_txt: '测试水印', // 水印的内容
watermark_x: 20, // 水印起始位置x轴坐标
watermark_y: 20, // 水印起始位置Y轴坐标
watermark_rows: 0, // 水印行数
watermark_cols: 0, // 水印列数
watermark_x_space: 50, // 水印x轴间隔
watermark_y_space: 50, // 水印y轴间隔
watermark_font: '微软雅黑', // 水印字体
watermark_color: 'black', // 水印字体颜色
watermark_fontsize: '18px', // 水印字体大小
watermark_alpha: 0.15, // 水印透明度,要求设置在大于等于0.005
watermark_width: 100, // 水印宽度
watermark_height: 100, // 水印长度
watermark_angle: 15, // 水印倾斜度数
watermark_parent_width: 0, // 水印的总体宽度(默认值:body的scrollWidth和clientWidth的较大值)
watermark_parent_height: 0, // 水印的总体高度(默认值:body的scrollHeight和clientHeight的较大值)
watermark_parent_node: null, // 水印插件挂载的父元素element,不输入则默认挂在body上
monitor: true // monitor 是否监控, true: 不可删除水印; false: 可删水印。
}
const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver
// 监听dom是否被移除或者改变属性的回调函数
var domChangeCallback = function(records) {
if (forceRemove) {
forceRemove = false
return
}
if (
(globalSetting && records.length === 1) ||
(records.length === 1 && records[0].removedNodes.length >= 1)
) {
loadMark(globalSetting)
}
}
var hasObserver = MutationObserver !== undefined
var watermarkDom = hasObserver
? new MutationObserver(domChangeCallback)
: null
var option = {
childList: true,
attributes: true,
subtree: true
}
/* 加载水印*/
var loadMark = function(settings) {
/* 采用配置项替换默认值,作用类似jquery.extend*/
if (arguments.length === 1 && typeof arguments[0] === 'object') {
var src = arguments[0] || {}
for (let key in src) {
if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key]) {
continue
} else if (src[key] || src[key] === 0) {
/* veronic: resolution of watermark_angle=0 not in force*/
defaultSettings[key] = src[key]
}
}
}
/* 如果元素存在则移除*/
var watermark_element = document.getElementById(
defaultSettings.watermark_id
)
watermark_element &&
watermark_element.parentNode &&
watermark_element.parentNode.removeChild(watermark_element)
/* 如果设置水印挂载的父元素的id*/
var watermark_parent_element = document.getElementById(
defaultSettings.watermark_parent_node
)
var watermark_hook_element = watermark_parent_element || document.body
/* 获取页面宽度*/
var page_width = Math.max(watermark_hook_element.scrollWidth, watermark_hook_element.clientWidth)
/* 获取页面最大长度*/
var page_height = Math.max(watermark_hook_element.scrollHeight, watermark_hook_element.clientHeight)
var setting = arguments[0] || {}
var parentEle = watermark_hook_element
var page_offsetTop = 0
var page_offsetLeft = 0
if (setting.watermark_parent_width || setting.watermark_parent_height) {
/* 指定父元素同时指定了宽或高*/
if (parentEle) {
page_offsetTop = parentEle.offsetTop || 0
page_offsetLeft = parentEle.offsetLeft || 0
defaultSettings.watermark_x = defaultSettings.watermark_x + page_offsetLeft
defaultSettings.watermark_y = defaultSettings.watermark_y + page_offsetTop
}
} else {
if (parentEle) {
page_offsetTop = parentEle.offsetTop || 0
page_offsetLeft = parentEle.offsetLeft || 0
}
}
/* 创建水印外壳div*/
var otdiv = document.getElementById(defaultSettings.watermark_id)
var shadowRoot = null
if (!otdiv) {
otdiv = document.createElement('div')
/* 创建shadow dom*/
otdiv.id = defaultSettings.watermark_id
otdiv.setAttribute('style', 'pointer-events: none !important; display: block !important')
/* 判断浏览器是否支持attachShadow方法*/
if (typeof otdiv.attachShadow === 'function') {
/* createShadowRoot Deprecated. Not for use in new websites. Use attachShadow*/
shadowRoot = otdiv.attachShadow({ mode: 'open' })
} else {
shadowRoot = otdiv
}
/* 将shadow dom随机插入body内的任意位置*/
var nodeList = watermark_hook_element.children
var index = Math.floor(Math.random() * (nodeList.length - 1))
if (nodeList[index]) {
watermark_hook_element.insertBefore(otdiv, nodeList[index])
} else {
watermark_hook_element.appendChild(otdiv)
}
} else if (otdiv.shadowRoot) {
shadowRoot = otdiv.shadowRoot
}
/* 三种情况下会重新计算水印列数和x方向水印间隔:1、水印列数设置为0,2、水印宽度大于页面宽度,3、水印宽度小于于页面宽度*/
defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space))
var temp_watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols))
defaultSettings.watermark_x_space = temp_watermark_x_space ? defaultSettings.watermark_x_space : temp_watermark_x_space
var allWatermarkWidth
/* 三种情况下会重新计算水印行数和y方向水印间隔:1、水印行数设置为0,2、水印长度大于页面长度,3、水印长度小于于页面长度*/
defaultSettings.watermark_rows = parseInt((page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space))
var temp_watermark_y_space = parseInt((page_height - defaultSettings.watermark_y - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows))
defaultSettings.watermark_y_space = temp_watermark_y_space ? defaultSettings.watermark_y_space : temp_watermark_y_space
var allWatermarkHeight
if (watermark_parent_element) {
allWatermarkWidth = defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)
allWatermarkHeight = defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)
} else {
allWatermarkWidth = page_offsetLeft + defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)
allWatermarkHeight = page_offsetTop + defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)
}
var x
var y
for (var i = 0; i < defaultSettings.watermark_rows; i++) {
if (watermark_parent_element) {
y = page_offsetTop + defaultSettings.watermark_y + (page_height - allWatermarkHeight) / 2 + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i
} else {
y = defaultSettings.watermark_y + (page_height - allWatermarkHeight) / 2 + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i
}
for (var j = 0; j < defaultSettings.watermark_cols; j++) {
if (watermark_parent_element) {
x = page_offsetLeft + defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j
} else {
x = defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j
}
var mask_div = document.createElement('div')
var oText = document.createTextNode(defaultSettings.watermark_txt)
mask_div.appendChild(oText)
/* 设置水印相关属性start*/
mask_div.id = defaultSettings.watermark_prefix + i + j
/* 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'
/* 选不中*/
mask_div.style.left = x + 'px'
mask_div.style.top = y + 'px'
mask_div.style.overflow = 'hidden'
mask_div.style.zIndex = '9999999'
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'
mask_div.style['-ms-user-select'] = 'none'
/* 设置水印相关属性end*/
shadowRoot.appendChild(mask_div)
}
}
// monitor 是否监控, true: 不可删除水印; false: 可删水印。
const minotor = settings.monitor === undefined ? defaultSettings.monitor : settings.monitor
if (minotor && hasObserver) {
watermarkDom.observe(watermark_hook_element, option)
watermarkDom.observe(document.getElementById(defaultSettings.watermark_id).shadowRoot, option)
}
}
/* 移除水印*/
var removeMark = function() {
/* 采用配置项替换默认值,作用类似jquery.extend*/
if (arguments.length === 1 && typeof arguments[0] === 'object') {
var src = arguments[0] || {}
for (let key in src) {
if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key]) continue
/* veronic: resolution of watermark_angle=0 not in force*/
else if (src[key] || src[key] === 0) defaultSettings[key] = src[key]
}
}
/* 移除水印*/
var watermark_element = document.getElementById(defaultSettings.watermark_id)
var _parentElement = watermark_element.parentNode
_parentElement.removeChild(watermark_element)
// :ambulance: remove()
// minotor 这个配置有些冗余
// 如果用 MutationObserver 来监听dom变化防止删除水印
// remove() 方法里用 MutationObserver 的 disconnect() 解除监听即可
watermarkDom.disconnect()
}
var globalSetting
/* 初始化水印,添加load和resize事件*/
watermark.init = function(settings) {
globalSetting = settings
loadMark(settings)
window.addEventListener('onload', function() {
loadMark(settings)
})
window.addEventListener('resize', function() {
loadMark(settings)
})
}
/* 手动加载水印*/
watermark.load = function(settings) {
globalSetting = settings
loadMark(settings)
}
/* 手动移除水印*/
watermark.remove = function() {
forceRemove = true
removeMark()
}
// 监听dom是否被移除或者改变属性的回调函数
var callback = function(records) {
var watermark_parent_element = document.getElementById(
defaultSettings.watermark_parent_node
)
var watermark_hook_element = watermark_parent_element || document.body
var watermark_element = document.getElementById(
defaultSettings.watermark_id
)
if (watermark_element === records[0].target || watermark_hook_element === records[0].target) {
if (
(globalSetting && records.length === 1) ||
(records.length === 1 && records[0].removedNodes.length >= 1)
) {
loadMark(globalSetting)
return
}
}
// 监听父节点的尺寸是否发生了变化, 如果发生改变, 则进行重新绘制
// var watermark_parent_element = document.getElementById(defaultSettings.watermark_parent_node)
if (watermark_parent_element) {
var newWidth = getComputedStyle(watermark_parent_element).getPropertyValue('width')
var newHeight = getComputedStyle(watermark_parent_element).getPropertyValue('height')
if (newWidth !== recordOldValue.width || newHeight !== recordOldValue.height) {
recordOldValue.width = newWidth
recordOldValue.height = newHeight
loadMark(globalSetting)
}
}
}
watermarkDom = new MutationObserver(callback)
option = {
childList: true,
attributes: true,
subtree: true,
attributeFilter: ['style'],
attributeOldValue: true
}
var recordOldValue = {
width: 0,
height: 0
}
export default watermark
所以我的水印功能有优化的点:
- z-index层级问题(比如样式覆盖了按钮,pointer-events: none;)
- 水印只是覆盖操作,并不是在源信息修改
- 前端:svg方式类似(都是明水印);后端:数据库水印算法(实现暗水印,在数据中加入隐藏标记)
- 水印可拓展其他css属性、加入resize事件、扩大水印的范围使水印覆盖到整个body上而不是组件区域,使的功能更完善等,或者绑定到自定义指令中