d3-geo-zoom

Zoom and Pan D3 Geo projections (Ported from vasturiano/d3-geo-zoom)

This library provides smooth zooming and panning functionality for D3 geographic projections using quaternion interpolation for rotation transitions.

Live Demo & Documentation

Installation

npm install @fxi/d3-geo-zoom

Quick Start

import { GeoZoom } from '@fxi/d3-geo-zoom';
import { select } from 'd3-selection';
import { geoOrthographic, geoPath } from 'd3-geo';

// Create SVG element
const svg = select('body')
  .append('svg')
  .attr('width', 800)
  .attr('height', 600);

// Setup projection
const projection = geoOrthographic()
  .scale(250)
  .translate([400, 300]);

// Create path generator
const path = geoPath()
  .projection(projection);

// Initialize zoom behavior
const zoom = new GeoZoom(svg.node());

// Configure zoom behavior
zoom
  .setProjection(projection)
  .setNorthUp(true)
  .onMove(() => {
    // Update map on zoom/pan
    svg.selectAll('path').attr('d', path);
  });

API Reference

Constructor

new GeoZoom(element)

Creates a new GeoZoom instance.

• element: DOM element to attach the zoom behavior to (typically an SVG element)

Methods

setProjection(projection)

Sets the D3 geographic projection to use.

• projection: A D3 geographic projection (e.g., geoOrthographic, geoMercator)
• Returns: this (for method chaining)

rotateTo(rotation)

Smoothly rotates to the specified rotation angles.

• rotation: Array of [lambda, phi, gamma] rotation angles in degrees
• Returns: this (for method chaining)

move(direction, step = 10)

Moves the projection in the specified direction.

• direction: One of 'left', 'right', 'up', 'down', or 'north'
• step: Step size in degrees (default: 10)
• Returns: this (for method chaining)

reset()

Resets zoom and rotation to initial state.

• Returns: this (for method chaining)

setNorthUp(enabled)

Enables/disables north-up constraint.

• enabled: Boolean to enable/disable north-up mode
• Returns: this (for method chaining)

setScaleExtent(extent)

Sets the allowed scale range.

• extent: Array of [minimum, maximum] scale values
• Returns: this (for method chaining)

setTransitionDuration(duration)

Sets the duration for smooth transitions.

• duration: Duration in milliseconds
• Returns: this (for method chaining)

onMove(callback)

Sets a callback function to be called when the projection moves.

• callback: Function that receives { scale, rotation } as parameter
• Returns: this (for method chaining)

getZoom()

Gets the underlying D3 zoom behavior.

• Returns: D3 zoom behavior instance

For more examples and detailed API documentation, visit our documentation site.

Development

Setup

1. Clone the repository
2. Install dependencies:

   npm install

Available Scripts

Development

• npm run dev: Start development server for demo
• npm run dev:docs: Start development server for documentation site
• npm run build: Build library for production
• npm run build:docs: Build documentation site
• npm run preview: Preview production build

Testing

• npm test: Run tests in watch mode (for development)
• npm run test:ci: Run tests once (used in CI and git hooks)
• npm run test:ui: Open test UI
• npm run coverage: Generate test coverage report

Documentation Development

The documentation site is built using Vite and hosted on GitHub Pages. To work on the documentation:

1. Run npm run dev:docs to start the documentation development server
2. Edit files in the docs/src directory:
   • index.html: Main documentation page
   • style.css: Documentation styles
   • main.js: Interactive examples and demos

The documentation site is automatically deployed to GitHub Pages when changes are pushed to the main branch.

Contributing

Creating Commits

This project uses Commitizen for standardized commit messages. Instead of using git commit, use:

npm run commit

This will:

1. Run tests in non-watch mode (via pre-commit hook)
2. Start an interactive prompt to create a properly formatted commit message
3. Validate the commit message format

The prompt will help you create a commit message with:

1. Type of change (feat, fix, docs, etc.)
2. Scope (optional)
3. Description
4. Breaking changes (if any)
5. Issues being closed (if any)

Continuous Integration and Deployment

This project uses GitHub Actions for:

Testing and Publishing

• Runs on every push and pull request
• Tests against Node.js 18.x and 20.x
• Automatically publishes to npm on release

Documentation

• Automatically builds and deploys documentation to GitHub Pages
• Triggered on push to main branch
• Available at https://fxi.github.io/d3-geo-zoom

Version Control

This project uses semantic-release for automated versioning:

• fix: commits trigger a patch release (1.0.0 -> 1.0.1)
• feat: commits trigger a minor release (1.0.0 -> 1.1.0)
• BREAKING CHANGE: in commit body triggers a major release (1.0.0 -> 2.0.0)

Original Repository

This is a port of the original d3-geo-zoom by Vasco Asturiano.

License

See the LICENSE file for details.