Configure Leaflet for retina displays

GeoBlacklight allows implementers to configure the way in which basemaps and tile layers (WMS) are displayed on high pixel density 'retina' screens. When retina detection settings are enabled, Leaflet will request larger tiles to take advantage of the increased resolution.

Tile layers

In your application's settings.yml, find DETECT_RETINA and set it to true or false.

...
LEAFLET:
  MAP:
  LAYERS:
    DETECT_RETINA: true
...

When set to true, Leaflet will load 512 pixel tiles on retina displays.

Basemaps

To configure the stock CartoDB basemaps for higher resolution display you will have to override the GeoBlacklight.Basemaps javascript module. In your application, create a geoblacklight directory in app/assets/javascripts/ and then create a new file called basemaps.js in that directory.

Now copy the contents of the Geoblacklight basemaps.js file into your new file. On any basemaps that you want to enable retina, set detectRetina to true. Your file should look something like this:

// basemaps

GeoBlacklight.Basemaps = {
  darkMatter: L.tileLayer(
    'https://cartodb-basemaps-{s}.global.ssl.fastly.net/dark_all/{z}/{x}/{y}{retina}.png', {
      attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors, &copy; <a href="http://cartodb.com/attributions">CartoDB</a>',
      maxZoom: 18,
      worldCopyJump: true,
      retina: '@2x',
      detectRetina: true
    }
  ),
  positron: L.tileLayer(
    'https://cartodb-basemaps-{s}.global.ssl.fastly.net/light_all/{z}/{x}/{y}{retina}.png', {
      attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors, &copy; <a href="http://cartodb.com/attributions">CartoDB</a>',
      maxZoom: 18,
      worldCopyJump: true,
      retina: '@2x',
      detectRetina: true
    }
  )
};