Add Elixir example

examples/signature.ex

@@ -0,0 +1,37 @@
+defmodule App.Imgproxy do
+  @prefix "https://imgproxy.mybiz.xyz"
+  @key Base.decode16!("943b421c9eb07c830af81030552c86009268de4e532ba2ee2eab8247c6da0881")
+  @salt Base.decode16!("520f986b998545b4785e0defbc4f3c1203f22de2374a3d53cb7a7fe9fea309c5")
+
+  def build_url(img_url, opts) do
+    path = build_path(img_url, opts)
+    signature = gen_signature(path)
+
+    Path.join([@prefix, signature, path])
+  end
+
+  defp build_path(img_url, opts) do
+    Path.join([
+      "/",
+      opts.resize,
+      to_string(opts.width),
+      to_string(opts.height),
+      opts.gravity,
+      to_string(opts.enlarge),
+      Base.url_encode64(img_url, padding: false) <> "." <> opts.extension
+    ])
+  end
+
+  defp gen_signature(path) do
+    :sha256
+    |> :crypto.hmac(@key, @salt <> path)
+    |> Base.url_encode64(padding: false)
+  end
+end
+
+# Usage
+#
+# App.Imgproxy.build_url(
+#   "https://myawesomedomain.com/raw-image.png",
+#   %{resize: "fit", width: 1000, height: 400, gravity: "ce", enlarge: 0, extension: "jpg"}
+# )