如何在JS中實(shí)現(xiàn)一個(gè)用戶禁止保存圖片功能

export function preventDefaultListener(e: any) {
 e.preventDefault()
}

;<img
 src={props.url}
 alt=""
 style={{
  //禁止用戶選擇
  userSelect: 'none',
  //禁止所有鼠標(biāo)事件，過于強(qiáng)大，圖片僅用于展示可用
  // pointerEvents: 'none',
 }}
 onTouchStart={preventDefaultListener}
 onContextMenu={preventDefaultListener}
 onDragStart={preventDefaultListener}
/>

export async function imageToCanvas(url: string, canvas: HTMLCanvasElement) {
 return new Promise((resolve, reject) => {
  //新建Image對(duì)象，引入當(dāng)前目錄下的圖片
  const img = new Image()
  img.src = url
  const c = canvas.getContext('2d')!

  //圖片初始化完成后調(diào)用
  img.onload = function () {
   //將canvas的寬高設(shè)置為圖像的寬高
   canvas.width = img.width
   canvas.height = img.height

   //canvas畫圖片
   c.drawImage(img, 0, 0, img.width, img.height)
   resolve()
  }
  img.addEventListener('error', (e) => {
   reject(e)
  })
 })
}

const throwFn = () => {
 throw new Error(
  "Uncaught DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.",
 )
}

const $canvasRef = useRef<HTMLCanvasElement>(null)
 useEffect(() => {
   ;(async () => {
     await imageToCanvas(props.url, $canvasRef.current!)
     $canvasRef.current!.toBlob = throwFn
     $canvasRef.current!.toDataURL = throwFn
   })()
 }, [])
 return (
   <canvas
     ref={$canvasRef}
     onTouchStart={preventDefaultListener}
     onContextMenu={preventDefaultListener}
   />
 )

/**
 * 兼容異步函數(shù)的返回值
 * @param res 返回值
 * @param callback 同步/異步結(jié)果的回調(diào)函數(shù)
 * @typeparam T 處理參數(shù)的類型，如果是 Promise 類型，則取出其泛型類型
 * @typeparam Param 處理參數(shù)具體的類型，如果是 Promise 類型，則指定為原類型
 * @typeparam R 返回值具體的類型，如果是 Promise 類型，則指定為 Promise 類型，否則為原類型
 * @returns 處理后的結(jié)果，如果是同步的，則返回結(jié)果是同步的，否則為異步的
 */
export function compatibleAsync<T = any, Param = T | Promise<T>, R = T>(
 res: Param,
 callback: (r: T) => R,
): Param extends Promise<T> &#63; Promise<R> : R {
 return (res instanceof Promise
  &#63; res.then(callback)
  : callback(res as any)) as any
}

/**
 * 測(cè)試函數(shù)的執(zhí)行時(shí)間
 * 注：如果函數(shù)返回 Promise，則該函數(shù)也會(huì)返回 Promise，否則直接返回執(zhí)行時(shí)間
 * @param fn 需要測(cè)試的函數(shù)
 * @returns 執(zhí)行的毫秒數(shù)
 */
export function timing<R>(
 fn: (...args: any[]) => R,
 // 函數(shù)返回類型是 Promise 的話，則返回 Promise<number>，否則返回 number
): R extends Promise<any> &#63; Promise<number> : number {
 const begin = performance.now()
 const res = fn()
 return compatibleAsync(res, () => performance.now() - begin)
}
/**
 * 禁止他人調(diào)試網(wǎng)站相關(guān)方法的集合對(duì)象
 */
export class AntiDebug {
 /**
  * 不停循環(huán) debugger 防止有人調(diào)試代碼
  * @returns 取消函數(shù)
  */
 public static cyclingDebugger(): Function {
  const res = setInterval(() => {
   debugger
  }, 100)
  return () => clearInterval(res)
 }
 /**
  * 檢查是否正在 debugger 并調(diào)用回調(diào)函數(shù)
  * @param fn 回調(diào)函數(shù)，默認(rèn)為重載頁面
  * @returns 取消函數(shù)
  */
 public static checkDebug(
  fn: Function = () => window.location.reload(),
 ): Function {
  const res = setInterval(() => {
   const diff = timing(() => {
    debugger
   })
   if (diff > 500) {
    console.log(diff)
    fn()
   }
  }, 1000)
  return () => clearInterval(res)
 }
}