dynamic opengraph images

app/notes/[slug]/opengraph-image.tsx

@@ -0,0 +1,135 @@
+/* eslint-disable jsx-a11y/alt-text */
+
+import { ImageResponse } from "next/og";
+import { notFound } from "next/navigation";
+import path from "path";
+import fs from "fs/promises";
+import glob from "fast-glob";
+import { getPostSlugs, getFrontMatter } from "../../../lib/helpers/posts";
+
+export const dynamicParams = false;
+export const contentType = "image/png";
+export const size = {
+  // https://developers.facebook.com/docs/sharing/webmasters/images/
+  width: 1200,
+  height: 630,
+};
+
+export const generateStaticParams = async () => {
+  const slugs = await getPostSlugs();
+
+  // map slugs into a static paths object required by next.js
+  return slugs.map((slug) => ({
+    slug,
+  }));
+};
+
+const getLocalImage = async (src: string) => {
+  const imagePath = await glob(src);
+  if (imagePath.length > 0) {
+    const imageData = await fs.readFile(path.join(process.cwd(), imagePath[0]));
+    return Uint8Array.from(imageData).buffer;
+  }
+
+  // image doesn't exist
+  return null;
+};
+
+const Image = async ({ params }: { params: Promise<{ slug: string }> }) => {
+  try {
+    const { slug } = await params;
+
+    // get the note's title and image filename from its frontmatter
+    const { title, image } = await getFrontMatter(slug);
+
+    // load the image specified in the note's frontmatter from its directory
+    const imageSrc = await getLocalImage(`notes/${slug}/${image}`);
+
+    // load the author avatar
+    const avatarSrc = await getLocalImage("public/static/me.jpg");
+
+    return new ImageResponse(
+      (
+        <div
+          style={{
+            display: "flex",
+            flexDirection: "column",
+            height: "100%",
+            width: "100%",
+            background: "linear-gradient(0deg, hsla(197, 14%, 57%, 1) 0%, hsla(192, 17%, 94%, 1) 100%)",
+          }}
+        >
+          {imageSrc && (
+            <div
+              style={{
+                display: "flex",
+                height: "100%",
+                width: "100%",
+              }}
+            >
+              <img
+                // @ts-expect-error
+                src={imageSrc}
+                style={{ objectFit: "cover", height: "100%", width: "100%" }}
+              />
+            </div>
+          )}
+          {avatarSrc && (
+            <div
+              style={{
+                display: "flex",
+                position: "absolute",
+                left: 42,
+                top: 42,
+              }}
+            >
+              <img
+                // @ts-expect-error
+                src={avatarSrc}
+                style={{ height: 96, width: 96, borderRadius: "100%" }}
+              />
+            </div>
+          )}
+          <div
+            style={{
+              display: "flex",
+              position: "absolute",
+              left: 0,
+              bottom: 42,
+              padding: "12px 20px",
+              margin: "0 42px",
+              backgroundColor: "rgba(16, 16, 16, 0.85)",
+              fontFamily: "Geist",
+              fontSize: 40,
+              fontWeight: 600,
+              lineHeight: 1.4,
+              letterSpacing: -0.5,
+              color: "#fefefe",
+            }}
+          >
+            {title}
+          </div>
+        </div>
+      ),
+      {
+        ...size,
+        fonts: [
+          {
+            name: "Geist",
+            // load the Geist font directly from its npm package
+            data: await fs.readFile(
+              path.join(process.cwd(), "node_modules/geist/dist/fonts/geist-sans/Geist-SemiBold.ttf")
+            ),
+            style: "normal",
+            weight: 600,
+          },
+        ],
+      }
+    );
+  } catch (error) {
+    console.error("[og-image] Error generating image:", error);
+    notFound();
+  }
+};
+
+export default Image;

app/notes/[slug]/page.tsx

@@ -45,9 +45,10 @@ export const generateMetadata = async ({ params }: { params: Promise<{ slug: str
       tags: frontmatter.tags,
       publishedTime: frontmatter.date,
       modifiedTime: frontmatter.date,
-      images: frontmatter.image
-        ? [{ url: frontmatter.image, alt: frontmatter.title }]
-        : defaultMetadata.openGraph?.images,
+    },
+    twitter: {
+      ...defaultMetadata.twitter,
+      card: "summary_large_image",
     },
     alternates: {
       ...defaultMetadata.alternates,
@@ -66,7 +67,6 @@ const Page = async ({ params }: { params: Promise<{ slug: string }> }) => {
     name: frontmatter.title,
     description: frontmatter.description || config.longDescription,
     url: frontmatter.permalink,
-    image: frontmatter.image,
     datePublished: frontmatter.date,
     dateModified: frontmatter.date,
     author: {