# react-pdf-engine
Offline Chromium PDF rendering for React and Tauri applications.
`react-pdf-engine` is only an HTML to PDF engine. It does not build documents,
inject dynamic fields, process forms, or provide a designer. Compose the HTML in
your app, then pass the final HTML string to this package.
## Install
```sh
npm install react-pdf-engine
```
The package uses `puppeteer-core`, so it does not download Chromium during npm
install. It resolves browsers in this order:
1. `executablePath` passed to `renderPdf`
2. Google Chrome on Windows
3. Microsoft Edge on Windows
4. bundled Chromium paths, including `REACT_PDF_ENGINE_CHROMIUM_PATH`
## Runtime
This package is a Node-side library. In a Tauri app, run it from a local sidecar
or service layer and call that layer from the React WebView.
## Usage
```ts
import { closePdfEngine, renderPdf } from "react-pdf-engine";
const pdf = await renderPdf({
html: "Certificate
",
size: {
width: "210mm",
height: "297mm"
},
output: "buffer"
});
await renderPdf({
html: "Marksheet
",
size: {
width: "210mm",
height: "297mm"
},
output: "file",
outputPath: "C:/documents/marksheet.pdf"
});
await closePdfEngine();
```
## Options
```ts
type RenderPdfOptions = {
html: string;
size: {
width: string;
height: string;
};
margins?: {
top?: string;
right?: string;
bottom?: string;
left?: string;
};
landscape?: boolean;
output?: "buffer" | "file";
outputPath?: string;
scale?: number;
timeout?: number;
executablePath?: string;
};
```
`output` defaults to `"buffer"`. When `output` is `"file"`, `outputPath` is
required and the parent directory must already exist.
## Rendering Guarantees
The engine uses Chromium's native print pipeline through `page.pdf()` with:
- `printBackground: true`
- `preferCSSPageSize: true`
- explicit viewport with `deviceScaleFactor: 2`
- print CSS injection for zero body/page margins and exact color printing
It does not use `html2canvas`, screenshots, canvas rasterization, or remote
rendering APIs.
## Assets And Fonts
Supported inputs include base64 images, file URLs, HTTPS images, SVG, PNG, JPEG,
WebP, and CSS `@font-face` declarations. The renderer waits for network idle,
`document.fonts.ready`, and image load/decode before generating the PDF.
If an asset fails to load, `renderPdf` throws `PdfEngineError` with code
`ASSET_LOAD_FAILED` and details about the failed asset URLs.
## Smoke Test
```sh
npm run smoke
```
The smoke script builds the package and renders `examples/output/smoke.pdf`
using the locally detected Chrome, Edge, or bundled Chromium path.