gpi-mapbox-gl-draw-freehand-mode

Mapbox Free Draw Mode

This is a custom mode for @mapbox/mapbox-gl-draw that adds draw functionality to the draw polygon mode.

Demo

https://bemky.github.io/mapbox-gl-draw-freehand-mode/

Dependencies

@mapbox/mapbox-gl-draw

@turf/simplify

Usage

To Install:

npm i mapbox-gl-draw-freehand-mode

To Use:

import FreehandMode from 'mapbox-gl-draw-freehand-mode'

const Draw = new MapboxDraw({
  modes: Object.assign(MapboxDraw.modes, {
    draw_polygon: FreehandMode
  })
});

var map = new mapboxgl.Map({
  container: 'map',
  style: 'mapbox://styles/mapbox/streets-v8',
  center: [40, -74.50],
  zoom: 9
});
map.addControl(Draw)

Configuration

Simplification

By default FreehandMode will simplify. Turf's simplify method takes a polygon and simplifies it based on a tolerance. The tolerance is corelated to meters, so tolerance must change based on the zoom, if not simplification will vary wildly based on zoom level. Thus, FreehandMode's simplify calculates a tolerance based on zoom.

You can configure you're own simplify method by redefing it on the object

Example removing simplification

import FreehandMode from 'mapbox-gl-draw-freehand-mode';

FreehandMode.simplify = function (polygon, zoom) {}

Example with your own tolerance calculation

import FreehandMode from 'mapbox-gl-draw-freehand';

FreehandMode.simplify = function (polygon, zoom) {
    simplify(polygon, {
        mutate: true,
        tolerance: 1 / Math.pow(2, zoom),
        highQuality: true
    });
}

Development

Build or serve the example via Webpack

Build

npm run build

Serve

npm run start