import { getDocument,GlobalWorkerOptions } from 'pdfjs-dist'
import workerUrl from 'pdfjs-dist/build/pdf.worker.min.mjs?url'
GlobalWorkerOptions.workerSrc=workerUrl
declare global { interface Window {renderPdf:(base64:string,dpi:number)=>Promise<string>} }
window.renderPdf=async(base64,dpi)=>{
 const data=Uint8Array.from(atob(base64),v=>v.charCodeAt(0))
 const doc=await getDocument({data}).promise
 try{
  const page=await doc.getPage(1),viewport=page.getViewport({scale:dpi/72})
  const canvas=document.getElementById('canvas') as HTMLCanvasElement
  canvas.width=Math.ceil(viewport.width);canvas.height=Math.ceil(viewport.height)
  await page.render({canvas,canvasContext:canvas.getContext('2d')!,viewport,background:'white'}).promise
  return canvas.toDataURL('image/png')
 }finally{await doc.destroy()}
}