2021-08-31 设置水印

const watermark: any = {}

const setWatermark: any = str => {
const id: any = '1.23452384164.123412416'

if (document.getElementById(id) !== null) {
//@ts-ignore
document.body.removeChild(document.getElementById(id))
}

//创建一个画布
const can: any = document.createElement('canvas')
//设置画布的长宽
can.width = 180
can.height = 120

const cans = can.getContext('2d')
//旋转角度
cans.rotate((-15 * Math.PI) / 180)
cans.font = '18px Vedana'
//设置填充绘画的颜色、渐变或者模式
cans.fillStyle = 'rgba(200, 200, 200, 0.40)'
//设置文本内容的当前对齐方式
cans.textAlign = 'left'
//设置在绘制文本时使用的当前文本基线
cans.textBaseline = 'Middle'
//在画布上绘制填色的文本（输出的文本，开始绘制文本的X坐标位置，开始绘制文本的Y坐标位置）
cans.fillText(str, can.width / 8, can.height / 2)

const div = document.createElement('div')
div.id = id
div.style.pointerEvents = 'none'
div.style.top = '30px'
div.style.left = '0px'
div.style.position = 'fixed'
div.style.opacity = '.9'
div.style.zIndex = '100000'
div.style.width = document.documentElement.clientWidth + 'px'
div.style.height = document.documentElement.clientHeight + 'px'
div.style.background =
'url(' + can.toDataURL('image/png') + ') left top repeat'
document.body.appendChild(div)
return id
}

// 该方法只允许调用一次
watermark.set = str => {
let id = setWatermark(str)
setInterval(() => {
if (document.getElementById(id) === null) {
id = setWatermark(str)
}
}, 500)
window.onresize = () => {
setWatermark(str)
}
}

export default watermark