jQuery QR Codeの問題点と解決 ref: https://qiita.com/Shino3/items/8373e4c96a354d6c38cc

file0.txt

    $("#tipQR").html("");
    $("#tipQR").qrcode({ width: 240, height: 240, text: "Shino3(e)" });

file1.txt

            // compute tileW/tileH based on options.width/options.height
-           var tileW   = options.width  / qrcode.getModuleCount();
-           var tileH   = options.height / qrcode.getModuleCount();
+           var tileW   = options.width / (qrcode.getModuleCount() + 8);
+           var tileH   = options.height / (qrcode.getModuleCount() + 8);

file2.txt

            // draw in the canvas
-           for( var row = 0; row < qrcode.getModuleCount(); row++ ){
-               for( var col = 0; col < qrcode.getModuleCount(); col++ ){
-                   ctx.fillStyle = qrcode.isDark(row, col) ? options.foreground : options.background;
-                   var w = (Math.ceil((col+1)*tileW) - Math.floor(col*tileW));
-                   var h = (Math.ceil((row+1)*tileH) - Math.floor(row*tileH));
-                   ctx.fillRect(Math.round(col*tileW),Math.round(row*tileH), w, h);
-               }   
-           }
+           for (var row = 0; row < (qrcode.getModuleCount() + 8); row++) {
+               for (var col = 0; col < (qrcode.getModuleCount() + 8); col++) {
+                   if ((row < 4) || (row >= (qrcode.getModuleCount() + 4))) {
+                       ctx.fillStyle = options.background;
+                   }
+                   else if ((col < 4) || (col >= (qrcode.getModuleCount() + 4)))
+                   {
+                       ctx.fillStyle = options.background;
+                   }
+                   else
+                   {
+                       ctx.fillStyle = qrcode.isDark(row - 4, col - 4) ? options.foreground : options.background;
+                   }
+                   var w = (Math.ceil((col + 1) * tileW) - Math.floor(col * tileW));
+                   var h = (Math.ceil((row + 1) * tileH) - Math.floor(row * tileH));
+                   ctx.fillRect(Math.round(col * tileW), Math.round(row * tileH), w, h);
+               }   
+           }