[JS]轉換svg成png檔 svgToPng

  const svgToPNG = (svgElement) => {
    let svgData = new XMLSerializer().serializeToString(svgElement);
    //將svg資料序列話成 string
    let canvas = document.createElement( "canvas" ); 
    //會了 把svg轉成png的 canvas
    let ctx = canvas.getContext( "2d" );

    let img = new Image();
    // (btoa 把 string to base64)
    img.setAttribute( "src", "data:image/svg+xml;base64," + btoa( svgData ) );
    
    img.onload = function() {
      canvas.width = img.width;
      canvas.height = img.height;
      ctx.drawImage( img, 0, 0 );
      
      let a = document.createElement("a");
      a.download = "QRcode.png";
      a.href = canvas.toDataURL( "image/png" );
      a.click();
    }
  };