feat: generate og images in png format

In production mode, generate og images from svg to png format.

fix #40

astro.config.mjs

@@ -33,4 +33,9 @@ export default defineConfig({
     },
     extendDefaultPlugins: true,
   },
+  vite: {
+    optimizeDeps: {
+      exclude: ["@resvg/resvg-js"],
+    },
+  },
 });

package.json

@@ -17,6 +17,7 @@
   },
   "dependencies": {
     "@astrojs/rss": "^2.1.0",
+    "@resvg/resvg-js": "^2.4.1",
     "astro": "^2.0.8",
     "fuse.js": "^6.6.2",
     "github-slugger": "^2.0.0",

src/utils/generateOgImage.tsx

@@ -1,5 +1,7 @@
 import satori, { SatoriOptions } from "satori";
 import { SITE } from "@config";
+import { writeFile } from "node:fs/promises";
+import { Resvg } from "@resvg/resvg-js";
 
 const fetchFonts = async () => {
   // Regular Font
@@ -133,7 +135,21 @@ const options: SatoriOptions = {
   ],
 };
 
-const generateOgImage = async (mytext = SITE.title) =>
-  await satori(ogImage(mytext), options);
+const generateOgImage = async (mytext = SITE.title) => {
+  const svg = await satori(ogImage(mytext), options);
+
+  // render png in production mode
+  if (import.meta.env.MODE === "production") {
+    const resvg = new Resvg(svg);
+    const pngData = resvg.render();
+    const pngBuffer = pngData.asPng();
+
+    console.info("Output PNG Image  :", `${mytext}.png`);
+
+    await writeFile(`./dist/${mytext}.png`, pngBuffer);
+  }
+
+  return svg;
+};
 
 export default generateOgImage;