Lib: Implement image downscaling + avif conversion helper

src/lib/server/image.ts

@@ -0,0 +1,23 @@
+import sharp from "sharp";
+
+/**
+ * Convert any [ArrayBuffer] containing image data to an [avif] [Blob].
+ * Also allows downscaling and lossy compression.
+ * Set either [width] or [height] to downscale while keeping the aspect ratio.
+ */
+export const image_to_avif = async (
+  data: ArrayBuffer,
+  width: number | undefined = undefined,
+  height: number | undefined = undefined,
+  quality: number = 50,
+  effort: number = 4,
+): Promise<Blob> => {
+  const compressed: Buffer = await sharp(data)
+    .resize(width, height)
+    .avif({ quality: quality, effort: effort })
+    .toBuffer();
+
+  console.log(`image_to_avif: ${data.byteLength} Bytes -> ${compressed.length} Bytes`);
+
+  return new Blob([compressed]);
+};