@cf-wasm/og/README.md

Generate Open Graph Images dynamically from HTML/CSS without a browser.

# @cf-wasm/og

Generate Open Graph Images dynamically from HTML/CSS without a browser.

Powered by [satori](https://github.com/vercel/satori) and [resvg-js](https://github.com/thx/resvg-js).

> [!WARNING]
> Breaking changes may be introduced without following semantic versioning.  
> Please note that this package may undergo breaking changes between versions without adhering strictly to semantic versioning (SemVer). While efforts will be made to minimize disruptions, it's recommended to review release notes carefully before upgrading to a new version. We apologize for any inconvenience this may cause and appreciate your understanding.

## Installation

```shell
npm install @cf-wasm/og       # npm
yarn add @cf-wasm/og          # yarn
pnpm add @cf-wasm/og          # pnpm
```

## Usage

- Cloudflare Workers / Pages (Wrangler):

  ```ts
  import { ImageResponse } from "@cf-wasm/og/workerd";
  ```

- Next.js Edge Runtime:

  ```ts
  import { ImageResponse } from "@cf-wasm/og/edge-light";
  ```

- Node.js (file base):

  ```ts
  import { ImageResponse } from "@cf-wasm/og/node";
  ```

## Documentation

### Use `ImageResponse.async`

It is recommended to use `ImageResponse.async()` async static method instead of `new ImageResponse()` constructor:

```tsx
import React from "react";
import { ImageResponse } from "@cf-wasm/og/node";

// this is recommended
await ImageResponse.async(<>Hello World!</>);

// instead of
new ImageResponse(<>Hello World!</>);
```

### Cloudflare Workers/Pages

If you are using Cloudflare Workers/Pages, you must set the execution context as shown:

```tsx
import React from "react";
import { ImageResponse, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    // Set execution context
    cache.setExecutionContext(ctx);

    return await ImageResponse.async(<>Hello World!</>);
  },
} satisfies ExportedHandler;
```

### Font Loaders

You can load Google fonts and Custom fonts with ease using `GoogleFont` and `CustomFont` classes respectively:

```tsx
import React from "react";
import {
  ImageResponse,
  GoogleFont,
  CustomFont,
  cache,
} from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    return await ImageResponse.async(
      <div
        style={{
          display: "flex",
          flexDirection: "column",
          alignItems: "center",
          justifyContent: "center",
          width: "100%",
          height: "100%",
        }}
      >
        <p>Text with Default font</p>
        <p style={{ fontFamily: "Inclusive Sans" }}>Text with Google font</p>
        <p style={{ fontFamily: "JetBrains Mono" }}>Text with Custom font</p>
      </div>,
      {
        fonts: [
          // Using Google font loader
          new GoogleFont("Inclusive Sans"),
          // Using Custom font loader
          new CustomFont("JetBrains Mono", () =>
            fetch(
              "https://github.com/JetBrains/JetBrainsMono/raw/master/fonts/ttf/JetBrainsMono-Regular.ttf"
            ).then((res) => res.arrayBuffer())
          ),
        ],
      }
    );
  },
} satisfies ExportedHandler;
```

### Default font

You can set global default font using `GoogleFont` or `CustomFont` classes:

```tsx
import React from "react";
import {
  ImageResponse,
  CustomFont,
  GoogleFont,
  defaultFont,
  cache,
} from "@cf-wasm/og/workerd";

// By using Google font loader
defaultFont.set(new GoogleFont("Merriweather"));

// or
// By using Custom font loader
defaultFont.set(
  new CustomFont("JetBrains Mono", () =>
    fetch(
      "https://github.com/JetBrains/JetBrainsMono/raw/master/fonts/ttf/JetBrainsMono-Regular.ttf"
    ).then((res) => res.arrayBuffer())
  )
);

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    // It should render with JetBrains Mono font
    return await ImageResponse.async(<>Hello World!</>);
  },
} satisfies ExportedHandler;
```

You can also set default font using `defaultFont` option:

```tsx
import React from "react";
import { ImageResponse, GoogleFont, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    return await ImageResponse.async(<>Hello World!</>, {
      // Set default font
      defaultFont: new GoogleFont("Merriweather"),
    });
  },
} satisfies ExportedHandler;
```

### SVG format

By default `ImageResponse` renders to `PNG` but you can use `format` option to render to `SVG`:

```tsx
import React from "react";
import { ImageResponse, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    return await ImageResponse.async(<>Hello World!</>, {
      // Set format
      format: "svg",
    });
  },
} satisfies ExportedHandler;
```

### Render HTML

The `@cf-wasm/og/html-to-react` submodule provides a function `t` which can be used to transform html to `ReactElement` making it possible to render html as well:

```tsx
import { ImageResponse, cache } from "@cf-wasm/og/workerd";
import { t } from "@cf-wasm/og/html-to-react";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    const html = `<div style="display: flex; flex-direction: column; align-items: center; justify-content: center; width: 100%; height: 100%;">
        <p>Renders HTML</p>
        <p>Hello World!</p>
      </div>`;

    return await ImageResponse.async(t(html));
  },
} satisfies ExportedHandler;
```

### `render` function

You can also use `render` function instead of `ImageResponse` to catch errors or for other use cases:

```tsx
import React from "react";
import { render, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    try {
      const { image } = await render(<>Hello World!</>).asPng();

      return new Response(image, {
        headers: {
          "Content-Type": "image/png",
        },
      });
    } catch {
      return new Response("Not found", {
        status: 404,
      });
    }
  },
} satisfies ExportedHandler;
```

### Tailwind CSS

Satori has experimental support for Tailwind CSS, you can use it by passing Tailwind CSS classes to `tw` prop of `ReactElement`.

```tsx
import React from "react";
import { ImageResponse, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    cache.setExecutionContext(ctx);

    return await ImageResponse.async(
      <div tw="flex w-full h-full items-center justify-center">
        Hello World!
      </div>
    );
  },
} satisfies ExportedHandler;
```

## Examples

Following are some examples for using this library:

### Cloudflare Workers

If you are using Cloudflare Workers, you can use it as shown below:

```tsx
// src/index.tsx
import React from "react";
import { ImageResponse, GoogleFont, cache } from "@cf-wasm/og/workerd";

export default {
  async fetch(req, env, ctx) {
    // Make sure to set the execution context
    cache.setExecutionContext(ctx);

    const { searchParams } = new URL(req.url);
    const parameters = Object.fromEntries(searchParams.entries());

    return await ImageResponse.async(
      <div
        style={{
          display: "flex",
          flexDirection: "column",
          width: "100%",
          height: "100%",
          alignItems: "center",
          justifyContent: "center",
          backgroundColor: "#6f90ab",
          fontSize: "2rem",
          color: "#fff",
        }}
      >
        <span>Noto Sans (Default Font)</span>
        <span
          style={{
            fontFamily: "JetBrains Mono",
          }}
        >
          JetBrains Mono (using GoogleFont class)
        </span>
        <span>These are emojis: 😎🌩️</span>
        <span
          style={{
            fontFamily: "JetBrains Mono",
          }}
        >
          Parameters: {JSON.stringify(parameters)}
        </span>
      </div>,
      {
        fonts: [new GoogleFont("JetBrains Mono")],
        emoji: "fluent",
      }
    );
  },
} satisfies ExportedHandler;
```

> [!WARNING]
> If you are using `@cf-wasm/og` on `Cloudflare Workers/Pages`, you may hit the [CPU time limit](https://developers.cloudflare.com/workers/platform/limits/#cpu-time), [128 MB Memory limit](https://developers.cloudflare.com/workers/platform/limits/#memory) or `3 MB` script size limit (Workers Free Plan).  
> Avoid loading multiple fonts and assets in memory.

### Next.js (App Router)

If you are using Next.js (App router) with edge runtime, you can use it as shown below:

```tsx
// (src/)app/api/og/route.tsx
import React from "react";
import { type NextRequest } from "next/server";
import { ImageResponse, GoogleFont } from "@cf-wasm/og/edge-light";

export const runtime = "edge";

export async function GET(req: NextRequest) {
  const { searchParams } = req.nextUrl;
  const parameters = Object.fromEntries(searchParams.entries());

  return await ImageResponse.async(
    <div
      style={{
        display: "flex",
        flexDirection: "column",
        width: "100%",
        height: "100%",
        alignItems: "center",
        justifyContent: "center",
        backgroundColor: "#6f90ab",
        fontSize: "2rem",
        color: "#fff",
      }}
    >
      <span>Noto Sans (Default Font)</span>
      <span
        style={{
          fontFamily: "JetBrains Mono",
        }}
      >
        JetBrains Mono (using GoogleFont class)
      </span>
      <span>These are emojis: 😎🌩️</span>
      <span
        style={{
          fontFamily: "JetBrains Mono",
        }}
      >
        Parameters: {JSON.stringify(parameters)}
      </span>
    </div>,
    {
      fonts: [new GoogleFont("JetBrains Mono")],
      emoji: "fluent",
    }
  );
}
```

### Next.js (Pages Router)

If you are using Next.js (Pages router) with edge runtime, you can use it as shown below:

```tsx
// (src/)pages/api/og.tsx
import React from "react";
import { type NextRequest } from "next/server";
import { ImageResponse, GoogleFont } from "@cf-wasm/og/edge-light";

export const config = {
  runtime: "edge",
};

export default async function handler(req: NextRequest) {
  const { searchParams } = req.nextUrl;
  const parameters = Object.fromEntries(searchParams.entries());

  return await ImageResponse.async(
    <div
      style={{
        display: "flex",
        flexDirection: "column",
        width: "100%",
        height: "100%",
        alignItems: "center",
        justifyContent: "center",
        backgroundColor: "#6f90ab",
        fontSize: "2rem",
        color: "#fff",
      }}
    >
      <span>Noto Sans (Default Font)</span>
      <span
        style={{
          fontFamily: "JetBrains Mono",
        }}
      >
        JetBrains Mono (using GoogleFont class)
      </span>
      <span>These are emojis: 😎🌩️</span>
      <span
        style={{
          fontFamily: "JetBrains Mono",
        }}
      >
        Parameters: {JSON.stringify(parameters)}
      </span>
    </div>,
    {
      fonts: [new GoogleFont("JetBrains Mono")],
      emoji: "fluent",
    }
  );
}
```