56 lines
1.5 KiB
TypeScript
56 lines
1.5 KiB
TypeScript
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const domSymbol = Symbol('watermark-dom')
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export function useWatermark(appendEl: HTMLElement | null = document.body) {
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let func: Fn = () => {}
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const id = domSymbol.toString()
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const clear = () => {
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const domId = document.getElementById(id)
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if (domId) {
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const el = appendEl
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el && el.removeChild(domId)
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}
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window.removeEventListener('resize', func)
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}
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const createWatermark = (str: string) => {
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clear()
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const can = document.createElement('canvas')
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can.width = 300
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can.height = 240
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const cans = can.getContext('2d')
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if (cans) {
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cans.rotate((-20 * Math.PI) / 120)
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cans.font = '15px Vedana'
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cans.fillStyle = 'rgba(0, 0, 0, 0.15)'
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cans.textAlign = 'left'
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cans.textBaseline = 'middle'
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cans.fillText(str, can.width / 20, can.height)
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}
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const div = document.createElement('div')
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div.id = id
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div.style.pointerEvents = 'none'
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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 = '100000000'
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div.style.width = document.documentElement.clientWidth + 'px'
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div.style.height = document.documentElement.clientHeight + 'px'
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div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat'
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const el = appendEl
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el && el.appendChild(div)
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return id
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}
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function setWatermark(str: string) {
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createWatermark(str)
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func = () => {
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createWatermark(str)
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}
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window.addEventListener('resize', func)
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}
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return { setWatermark, clear }
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}
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