Mastering OpenLayers 3

Creating thematic layers

In this example, called ch04_thematic, we will create an automatic solution for thematic mapping. It will include graduated and categorized symbology. To keep the example as simple as possible, we will make some generally incorrect assumptions. Firstly, we assume that we only have to style polygon layers. For graduated symbology, we hard code the intervals to five and also the color ramp starting from a beige tone and ending in a burgundy color. We will implement the whole code into our layer tree.

Extending the layer tree

We create the required GUI options in the layer tree. Firstly, we check against the origin of the layer. If it is a vector layer, we create an empty list and three buttons for the different styling options. ...