1 files changed, 27 insertions, 0 deletions
diff --git a/src/qr.js b/src/qr.js
new file mode 100644
index 0000000..eab74a7
--- /dev/null
+++ b/src/qr.js
@@ -0,0 +1,27 @@
+// QR rendering via the zero-dependency `qrcode-generator` library, output as a
+// crisp SVG path (scales perfectly, no canvas, prints well on a paper wallet).
+
+import qrcode from 'qrcode-generator';
+
+export function qrSvg(text, { margin = 2 } = {}) {
+  const qr = qrcode(0, 'M'); // type 0 = auto-size, error correction M
+  qr.addData(text);
+  qr.make();
+
+  const count = qr.getModuleCount();
+  const size = count + margin * 2;
+
+  let path = '';
+  for (let r = 0; r < count; r++) {
+    for (let c = 0; c < count; c++) {
+      if (qr.isDark(r, c)) {
+        path += `M${c + margin},${r + margin}h1v1h-1z`;
+      }
+    }
+  }
+
+  return `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${size} ${size}" shape-rendering="crispEdges" class="qr">
+    <rect width="${size}" height="${size}" fill="#fff"/>
+    <path d="${path}" fill="#111"/>
+  </svg>`;
+}