feat: add thumbhashes to images closes #6

lib/thumbhash.ts

@@ -0,0 +1,17 @@
+import * as thumbhash from "https://esm.sh/thumbhash@0.1.1";
+
+export function generateThumbhash(buffer: Uint8Array, w: number, h: number) {
+  return thumbhash.rgbaToThumbHash(w, h, buffer);
+}
+
+export function generateDataURL(hash: string) {
+  const decodedString = atob(hash);
+
+  // Create Uint8Array from decoded string
+  const uint8Array = new Uint8Array(decodedString.length);
+  for (let i = 0; i < decodedString.length; i++) {
+    uint8Array[i] = decodedString.charCodeAt(i);
+  }
+
+  return thumbhash.thumbHashToDataURL(uint8Array);
+}