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56 lines
1.9 KiB
56 lines
1.9 KiB
1 year ago
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'use strict'
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const watermark = {}
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const setWatermark = (str, container) => {
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const id = '1.23452384164.123412415'
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if (container === undefined) {
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return
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}
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// 查看页面上有没有，如果有则删除
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if (document.getElementById(id) !== null) {
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const childelement = document.getElementById(id)
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childelement.parentNode.removeChild(childelement)
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}
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var containerWidth = container.offsetWidth // 获取父容器宽
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var containerHeight = container.offsetHeight // 获取父容器高
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container.style.position = 'relative' // 设置布局为相对布局
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// 创建canvas元素(先制作一块背景图)
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const can = document.createElement('canvas')
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can.width = 300 // 设置每一块的宽度
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can.height = 300 // 高度
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const cans = can.getContext('2d') // 获取canvas画布
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cans.rotate(-20 * Math.PI / 180) // 逆时针旋转π/9
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cans.font = '20px Vedana' // 设置字体
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cans.fillStyle = 'rgba(0, 0, 0, 0.1)' // 设置字体的颜色
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cans.textAlign = 'left' // 文本对齐方式
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cans.textBaseline = 'Middle' // 文本基线
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cans.fillText(str, 0, 4 * can.height / 5) // 绘制文字
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// 创建一个div元素
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const div = document.createElement('div')
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div.id = id // 设置id
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div.style.pointerEvents = 'none' // 取消所有事件
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div.style.top = '0px'
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div.style.left = '0px'
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div.style.position = 'absolute'
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div.style.zIndex = '100000'
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div.style.width = containerWidth + 'px'
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div.style.height = containerHeight + 'px'
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div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat'
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container.appendChild(div) // 追加到页面
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return id
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}
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// 该方法只允许调用一次
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watermark.set = (str, container) => {
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let id = setWatermark(str, container)
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setInterval(() => {
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if (document.getElementById(id) === null) {
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id = setWatermark(str, container)
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}
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}, 500)
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// 监听页面大小的变化
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window.onresize = () => {
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setWatermark(str, container)
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}
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}
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export default watermark
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