node-pango

A high-fidelity Node.js wrapper for the pango-view CLI utility with advanced features including HTML support and font-by-path rendering.

Features

• 🚀 Async Process Management: Uses execa for robust subprocess handling
• 🎨 Font-by-Path Support: Render fonts directly from .ttf or .otf files
• 🌐 HTML-to-Pango Conversion: Automatic translation of HTML tags to Pango markup
• 📐 Full API Coverage: Supports all pango-view flags and options
• 🖼️ Multiple Output Formats: PNG, SVG, and PDF rendering via Cairo backend
• 💪 TypeScript Support: Full type definitions included

Installation

npm install node-pango

Prerequisites: You must have pango-view installed on your system.

Installing pango-view

macOS:

brew install pango

Ubuntu/Debian:

sudo apt-get install libpango1.0-dev pango1.0-tools

Fedora:

sudo dnf install pango-devel pango-tools

Quick Start

const PangoView = require('node-pango');

const pango = new PangoView({
  text: 'Hello, <b>World</b>!',
  width: 300,
  output: 'output.png'
});

await pango.render();

API Reference

Constructor Options

const pango = new PangoView({
  // Text content (required)
  text: 'Your text here',
  
  // Output file (required)
  output: 'output.png',
  
  // Font options
  font: 'Sans 12',
  fontFile: './path/to/font.ttf', // Font-by-path support
  
  // Dimensions
  width: 400,
  height: 300,
  
  // Layout options
  align: 'left',        // left, right, center
  justify: false,
  indent: 0,
  spacing: 0,
  lineSpacing: 1.0,
  
  // Format options
  markup: false,        // Set to true if text already contains Pango markup
  htmlMode: true,       // Parse HTML tags (default: true)
  
  // Advanced options
  wrap: 'word',         // word, char, word-char
  ellipsize: 'end',     // start, middle, end
  annotate: 0,          // Rectangle annotation level (0-2)
  
  // Cairo backend options
  backend: 'png',       // png, svg, pdf
  dpi: 96,
  
  // Environment
  pangoViewPath: 'pango-view' // Custom path to pango-view binary
});

Methods

render()

Renders the text and writes output to the specified file.

await pango.render();

Returns: Promise<void>

renderToBuffer()

Renders the text and returns the output as a Buffer.

const buffer = await pango.renderToBuffer();

Returns: Promise<Buffer>

getMarkup()

Returns the Pango markup that will be rendered (useful for debugging).

const markup = pango.getMarkup();
console.log(markup);

Returns: string

HTML Support

The package automatically converts HTML tags to Pango markup:

const pango = new PangoView({
  text: `
    <h1>Title</h1>
    <p>This is <strong>bold</strong> and <em>italic</em> text.</p>
    <p>You can also use <u>underline</u> and <font color="red">colors</font>.</p>
  `,
  output: 'output.png',
  htmlMode: true
});

await pango.render();

Supported HTML Tags

HTML Tag	Pango Markup	Description
<strong>, <b>	<span weight="bold">	Bold text
<em>, <i>	<span style="italic">	Italic text
<u>	<span underline="single">	Underlined text
<s>, <strike>	<span strikethrough="true">	Strikethrough
<font color="...">	<span foreground="...">	Text color
<font size="...">	<span size="...">	Font size
<font face="...">	<span font_family="...">	Font family
<sup>	<span rise="positive">	Superscript
<sub>	<span rise="negative">	Subscript
<small>	<span size="small">	Small text
<big>	<span size="large">	Large text

Font-by-Path Support

Render text using a specific font file without installing it system-wide:

const pango = new PangoView({
  text: 'Custom Font Rendering',
  fontFile: './fonts/MyCustomFont.ttf',
  font: 'MyCustomFont 24',
  output: 'output.png'
});

await pango.render();

This feature:

• Dynamically generates a temporary fonts.conf XML file
• Sets the FONTCONFIG_FILE environment variable
• Cleans up temporary files after rendering

Advanced Examples

SVG Output with Custom Layout

const pango = new PangoView({
  text: 'Lorem ipsum dolor sit amet...',
  output: 'output.svg',
  backend: 'svg',
  width: 500,
  align: 'justify',
  wrap: 'word',
  font: 'Serif 14',
  lineSpacing: 1.5
});

await pango.render();

PDF Output with Annotations

const pango = new PangoView({
  text: 'Annotated Text',
  output: 'output.pdf',
  backend: 'pdf',
  annotate: 2, // Full annotation
  font: 'Mono 10'
});

await pango.render();

Buffer Output for Streaming

const pango = new PangoView({
  text: 'Buffer output',
  output: 'temp.png'
});

const buffer = await pango.renderToBuffer();
// Use buffer for streaming, uploading, etc.

Error Handling

try {
  await pango.render();
} catch (error) {
  if (error.code === 'ENOENT') {
    console.error('pango-view not found. Please install Pango.');
  } else {
    console.error('Rendering failed:', error.message);
  }
}

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.