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Merged
johannschopplich merged 5 commits into from
Aug 21, 2025
Merged

feat: add toDataURL option to renderPageAsImage function #41

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caec052
feat: add `toDataURL` option to `renderPageAsImage` function
vladiantio Aug 19, 2025
d94f9b8
test: add unit test for rendering PDF as data URL
vladiantio Aug 19, 2025
f7c3aab
docs(readme): add `renderPageAsImage` usage examples for `toDataURL` …
vladiantio Aug 19, 2025
db60b22
docs(readme): update type for `data` parameter in `renderPageAsImage`…
vladiantio Aug 19, 2025
bcdef7e
Merge branch 'unjs:main' into feat/add-data-url-to-render-page-as-image
vladiantio Aug 20, 2025
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51 changes: 47 additions & 4 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -273,7 +273,7 @@ extractPdfImages().catch(console.error)

### `renderPageAsImage`

To render a PDF page as an image, you can use the `renderPageAsImage` method. This method will return an `ArrayBuffer` of the rendered image.
To render a PDF page as an image, you can use the `renderPageAsImage` method. This method will return an `ArrayBuffer` of the rendered image. It can also return a data URL (`string`) if `toDataURL` option is set to `true`.

> [!NOTE]
> This method will only work in Node.js and browser environments.
Expand All @@ -286,20 +286,33 @@ In order to use this method, make sure to meet the following requirements:
**Type Declaration**

```ts
declare function renderPageAsImage(
data: DocumentInitParameters['data'],
function renderPageAsImage(
data: DocumentInitParameters['data'] | PDFDocumentProxy,
pageNumber: number,
options?: {
canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
/** @default 1.0 */
scale?: number
width?: number
height?: number
toDataURL?: false
},
): Promise<ArrayBuffer>
function renderPageAsImage(
data: DocumentInitParameters['data'] | PDFDocumentProxy,
pageNumber: number,
options: {
canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
/** @default 1.0 */
scale?: number
width?: number
height?: number
toDataURL: true
},
): Promise<string>
```

**Example**
**Examples**

```ts
import { definePDFJSModule, renderPageAsImage } from 'unpdf'
Expand All @@ -318,6 +331,36 @@ const result = await renderPageAsImage(buffer, pageNumber, {
await writeFile('dummy-page-1.png', new Uint8Array(result))
```

```ts
import { definePDFJSModule, renderPageAsImage } from 'unpdf'

await definePDFJSModule(() => import('pdfjs-dist'))

const pdf = await readFile('./dummy.pdf')
const buffer = new Uint8Array(pdf)
const pageNumber = 1

const result = await renderPageAsImage(buffer, pageNumber, {
canvasImport: () => import('@napi-rs/canvas'),
scale: 2,
toDataURL: true,
})

const html = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Dummy Page</title>
</head>
<body>
<img alt="Example Page" src="${result}">
</body>
</html>`

await writeFile('dummy-page-1.html', html)
```

## License

[MIT](./LICENSE) License © 2023-PRESENT [Johann Schopplich](https://github.com/johannschopplich)
30 changes: 30 additions & 0 deletions src/image.ts
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Expand Up @@ -88,6 +88,30 @@ export async function extractImages(
return images
}

export function renderPageAsImage(
data: DocumentInitParameters['data'] | PDFDocumentProxy,
pageNumber: number,
options?: {
canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
/** @default 1.0 */
scale?: number
width?: number
height?: number
toDataURL?: false
}
): Promise<ArrayBuffer>
export function renderPageAsImage(
data: DocumentInitParameters['data'] | PDFDocumentProxy,
pageNumber: number,
options: {
canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
/** @default 1.0 */
scale?: number
width?: number
height?: number
toDataURL: true
}
): Promise<string>
export async function renderPageAsImage(
data: DocumentInitParameters['data'] | PDFDocumentProxy,
pageNumber: number,
Expand All @@ -97,6 +121,7 @@ export async function renderPageAsImage(
scale?: number
width?: number
height?: number
toDataURL?: boolean
} = {},
) {
const CanvasFactory = await createIsomorphicCanvasFactory(options.canvasImport)
Expand Down Expand Up @@ -133,6 +158,11 @@ export async function renderPageAsImage(
}).promise

const dataUrl = drawingContext.canvas.toDataURL()

if (options.toDataURL) {
return dataUrl
}

const response = await fetch(dataUrl)

return await response.arrayBuffer()
Expand Down
2 changes: 1 addition & 1 deletion src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ export const extractImages: typeof _extractImages = async (...args) => {

export const renderPageAsImage: typeof _renderPageAsImage = async (...args) => {
await resolvePDFJSImport()
return await _renderPageAsImage(...args)
return await (_renderPageAsImage as any)(...args)
}

export const extractLinks: typeof _extractLinks = async (...args) => {
Expand Down
25 changes: 25 additions & 0 deletions test/index.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,31 @@ describe('unpdf', () => {
expect(Array.from(headerBytes)).toEqual([137, 80, 78, 71, 13, 10, 26, 10])
})

it('renders a PDF as data URL', async () => {
const result = await renderPageAsImage(await getPDF('pdflatex-image.pdf'), 1, {
canvasImport: () => import('@napi-rs/canvas'),
toDataURL: true,
})

const html = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PDFLatex Image</title>
</head>
<body>
<img alt="Image" src="${result}">
</body>
</html>`
await writeFile(
new URL('artifacts/pdflatex-image.html', import.meta.url),
html,
)

expect(result.startsWith('data:image/png;base64,')).toBe(true)
})

it('supports passing PDFDocumentProxy', async () => {
const pdf = await getDocumentProxy(await getPDF())
const { info } = await getMeta(pdf)
Expand Down