node-pptx-png

High-fidelity PPTX to PNG converter for Node.js.

Overview

node-pptx-png is a pure JavaScript/TypeScript library for converting PowerPoint (PPTX) presentations to high-quality PNG images. It uses native canvas rendering (via skia-canvas) for accurate slide reproduction without relying on LibreOffice, Puppeteer, or other external dependencies.

Features

- Pure Node.js - No external dependencies like LibreOffice or headless browsers
- High fidelity - Skia-based rendering for accurate slide reproduction
- TypeScript - Full type definitions included
- Configurable - Control output size, format, and quality
- PNG optimization - Optional Sharp integration for 60-70% smaller files
- Theme support - Proper resolution of PowerPoint theme colors and fonts
- Rich content support:
- Shapes with preset geometries (rectangles, chevrons, arrows, etc.)
- Text with full styling (fonts, colors, bullets, alignment)
- Images (embedded and linked)
- Tables with cell formatting
- Charts (bar, line, pie)
- Backgrounds (solid, gradient, image)
- Master/layout inheritance

Installation

``bash
npm install node-pptx-png
`

$3

This library uses skia-canvas for rendering. It should work out of the box on most systems, but you may need:

On macOS:
`bash
brew install pkg-config
`

On Ubuntu/Debian:
`bash
sudo apt-get install build-essential libfontconfig1-dev
`

Usage

$3

`typescript
import { PptxImageRenderer } from 'node-pptx-png';
import * as fs from 'fs';

const renderer = new PptxImageRenderer();

// Render all slides
const result = await renderer.renderPresentation('./presentation.pptx', {
format: 'png',
scale: 1.0
});

for (const slide of result.slides) {
if (slide.imageData) {
fs.writeFileSync(slide-${slide.slideNumber}.png, slide.imageData);
}
}
`

$3

`typescript
import { PptxImageRenderer } from 'node-pptx-png';

const renderer = new PptxImageRenderer({ logLevel: 'info' });

const result = await renderer.renderPresentation('./presentation.pptx', {
scale: 0.5, // Scale factor (0.5 = half size)
format: 'png', // Output format
slideNumbers: [1, 2, 3], // Optional: render only specific slides
});
`

$3

For smaller file sizes, enable PNG optimization (requires sharp to be installed):

`bash
npm install sharp
`

`typescript
import { PptxImageRenderer } from 'node-pptx-png';

const renderer = new PptxImageRenderer();

// Use the 'web' preset for maximum compression (60-70% smaller)
const result = await renderer.renderPresentation('./presentation.pptx', {
pngOptimization: 'web'
});

// Or use other presets
const result2 = await renderer.renderPresentation('./presentation.pptx', {
pngOptimization: 'balanced' // ~2-3% smaller, lossless
});

// Or use custom options
const result3 = await renderer.renderPresentation('./presentation.pptx', {
pngOptimization: {
compressionLevel: 9,
adaptiveFiltering: true,
palette: true,
colors: 128,
quality: 80
}
});
`

$3

`typescript
import { PptxImageRenderer } from 'node-pptx-png';
import * as fs from 'fs';

const pptxBuffer = fs.readFileSync('./presentation.pptx');
const renderer = new PptxImageRenderer();
const result = await renderer.renderPresentation(pptxBuffer);
`

API Reference

$3

Main class for rendering presentations.

#### Constructor

`typescript
new PptxImageRenderer(options?: { logLevel?: 'debug' | 'info' | 'warn' | 'error' | 'silent' })
`

#### Methods

##### renderPresentation(input, options?)

Renders all slides (or specified slides) in a presentation.

- input: Buffer | string - File path or buffer containing PPTX data
- options: RenderOptions - Optional rendering options
- Returns: Promise

##### getSlideCount(input)

Gets the number of slides in a presentation.

- input: Buffer | string - File path or buffer containing PPTX data
- Returns: Promise

$3

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| scale | number | 1.0 | Scale factor for output size |
| format | 'png' | 'png' | Output format |
| slideNumbers | number[] | all | Specific slides to render (1-based) |
| pngOptimization | string \| object | 'none' | PNG optimization preset or custom options |

$3

| Preset | Size Reduction | Description |
|--------|----------------|-------------|
| 'none' | 0% | No optimization (fastest) |
| 'fast' | ~1-2% | Quick lossless compression |
| 'balanced' | ~2-3% | Lossless with adaptive filtering |
| 'maximum' | ~2-3% | Best lossless compression |
| 'web' | 60-70% | Palette quantization (may affect photo quality) |

$3

For custom PNG optimization:

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| compressionLevel | number | 6 | Compression level (0-9, higher = smaller) |
| adaptiveFiltering | boolean | true | Use adaptive row filtering |
| palette | boolean | false | Convert to indexed PNG (max 256 colors) |
| colors | number | 256 | Max colors for palette mode (2-256) |
| quality | number | 90 | Palette quantization quality (1-100) |
| dither | number | 1.0 | Dithering strength for palette mode (0-1) |

$3

| Property | Type | Description |
|----------|------|-------------|
| slideIndex | number | Zero-based slide index |
| slideNumber | number | One-based slide number |
| imageData | Buffer | Rendered image data |
| width | number | Image width in pixels |
| height | number | Image height in pixels |
| success | boolean | Whether rendering succeeded |
| errorMessage | string? | Error message if failed |

$3

| Property | Type | Description |
|----------|------|-------------|
| slides | SlideRenderResult[] | Results for each slide |
| totalSlides | number | Total number of slides |
| successfulSlides | number | Number of successfully rendered slides |
| allSuccessful | boolean | Whether all slides rendered successfully |

Supported Features

$3

- Rectangles, rounded rectangles
- Chevrons, arrows, pentagons
- Ellipses, circles
- Lines and connectors
- Custom geometries

$3

- Font families and sizes
- Bold, italic, underline, strikethrough
- Text colors (solid and theme colors)
- Bullet points and numbered lists
- Paragraph alignment
- Line spacing
- Superscript/subscript

$3

- Solid colors
- Theme/scheme colors (accent1-6, dk1, lt1, etc.)
- Gradients (linear)
- Picture fills

$3

- Cell backgrounds
- Borders
- Merged cells
- Text formatting within cells

$3

- Bar/column charts
- Line charts
- Pie charts
- Chart titles and legends

$3

- Background images
- Master slide inheritance
- Layout inheritance
- Placeholder resolution
- Shape effects (shadows)

Development

`bash


Install dependencies

npm install

Build

npm run build

Run tests

npm test

Type check

npx tsc --noEmit

Render a test presentation

npx ts-node scripts/render-pptx.ts ./test.pptx ./output
``

License

MIT