region-labels v1.0.1

region-labels

The region-labels package is aimed to algorithmically generate labels for two-dimensional geographic regions which will best adapt to the shape and size of the region to attempt to maximally fill the space.

JSFiddle Demo

Here is a JSFiddle demo: https://jsfiddle.net/sikanrong/8304Lpvr/

Documentation

####constructor

Generally the RegionLabel class constructor takes a GeoJSON object as the fist parameter, and an options object as the second. The GeoJSON object can either be a single Feature or a FeatureCollection. Geometry of Polygon and MultiPolygon are accepted.

The following options are accepted:

• margin - accepts an integer of how many pixels to leave as margin between the label and the edge of the canvas
• canvasDims - the dimensions of the desired label must be passed in as options so that the given geography and label can be centered within those dimensions
• canvas - optionally an existing canvas of desired size can be passed instead of canvasDims
• label - the desired label for the region. If label is a string, the passed GeoJSON FeatureCollection will be labeled as a group. If label is a function, the function will be called to determine the label to draw for each Feature within the FeatureCollection.
• excludeFeatures - A function to which the properties of each Feature is passed. If the function returns true, that feature will be excluded from the labeling; e.g. the label will actively avoid that feature and label the rest as a group. Useful for countries or administrative areas landlocked entrely within some other single region.

rl = new RegionLabel(geojson, {
    margin: 20,
    canvasDims: [256, 256],
    label: 'United States',
});

####drawLabels The drawLabels function will draw all of the generated labels to a canvas, and return that canvas.

var labelCanvas = rl.drawLabels();
//Draws the generated labels to some other canvas
ctx.drawImage(labelCanvas, 0, 0); 

####drawGeometries The drawGeometries function will draw all of the passed GeoJSON to a canvas and return that canvas.

var geometryCanvas = rl.drawGeometries();
ctx.drawImage(geometryCanvas, 0, 0);

####debugDraw This will return a canvas with some colored lines and points which are mathematically meaninful in terms of how final the label spline is calculated. Primarily used for debugging; useful as an overlay atop the label/geometry data.

var debugCanvas = rl.debugDraw();
ctx.drawImage(debugCanvas, 0, 0);

###Tests Run tests just by executing node ./test.js

###Authors

Written in Barcelona and Santa Cruz de Tenerife, Spain. 2017-2018

Alexander Pilafian <sikanrong@gmail.com>
Aleksandra Gabka <rivvel@gmail.com>