const watermark = {}
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const setWatermark = (text, sourceBody) => {
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const id = Math.random() * 10000 + '-' + Math.random() * 10000 + '/' + Math.random() * 10000
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if (document.getElementById(id) !== null) {
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document.body.removeChild(document.getElementById(id))
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}
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const can = document.createElement('canvas')
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can.width = 100
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can.height = 100
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const cans = can.getContext('2d')
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// cans.rotate(0 * Math.PI / 180)
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// cans.rotate(-20 * Math.PI / 180)
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cans.font = '16px Vedana'
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can.fontWeight = 'bolder'
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cans.fillStyle = 'rgba(0, 0, 0, .5)'
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cans.textAlign = 'left'
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cans.textBaseline = 'Middle'
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cans.fillText(text, can.width / 6, can.height / 2)
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// cans.fillText(text, can.width/20, can.height)
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const water_div = document.createElement('div')
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water_div.id = id
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water_div.style.pointerEvents = 'none'
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// water_div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat'
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water_div.style.background = 'url(' + can.toDataURL('image/png') + ') repeat'
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if (sourceBody) {
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water_div.style.width = '100%'
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water_div.style.height = '100%'
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sourceBody.appendChild(water_div)
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} else {
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// water_div.style.top = '3px'
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// water_div.style.left = '0px'
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water_div.style.position = 'fixed'
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water_div.style.zIndex = '100000'
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water_div.style.width = document.documentElement.clientWidth + 'px'
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water_div.style.height = document.documentElement.clientHeight + 'px'
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document.body.appendChild(water_div)
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}
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return id
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}
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/**
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* 该方法只允许调用一次
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* @param:
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* @text == 水印内容
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* @sourceBody == 水印添加在哪里，不传就是body
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* */
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watermark.set = (text, sourceBody) => {
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let id = setWatermark(text, sourceBody)
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setInterval(() => {
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if (document.getElementById(id) === null) {
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id = setWatermark(text, sourceBody)
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}
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}, 2000)
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// window.onresize = () => {//防止水印重复添加
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// setWatermark(text, sourceBody)
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// }
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}
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export default watermark
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