Book Image

Mastering OpenLayers 3

By : Gábor Farkas
Book Image

Mastering OpenLayers 3

By: Gábor Farkas

Overview of this book

OpenLayers 3 allows you to create stunning web mapping and WebGIS applications. It uses modern, cutting edge browser technologies. It is written with Closure Library, enabling you to build browser-independent applications without painful debugging ceremonies, which even have some limited fallback options for older browsers. With this guide, you will be introduced to the world of advanced web mapping and WebGIS. First, you will be introduced to the advanced features and functionalities available in OpenLayers 3. Next, you will be taken through the key points of creating custom applications with OpenLayers 3. You will then learn how to create the web mapping application of yours (or your company's) dream with this open source, expense-free, yet very powerful library. We’ll also show you how to make amazing looking thematic maps and create great effects with canvas manipulation. By the end of this book, you will have a strong command of web mapping and will be well on your way to creating amazing applications using OpenLayers 3.
Table of Contents (17 chapters)
Mastering OpenLayers 3
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Generating geocaches


In the next example, called ch08_points, we create some random geocaches based on the user's location. As server-side scripting and client-server connections are also out of the scope of this book, we make our application viable by adding random points within 500 meters of our position. Firstly, we create an empty layer for the points and initialize Geolocation:

var geoloc = new ol.Geolocation({
    projection: map.getView().getProjection(),
    tracking: true
});
var geoCaching = new ol.layer.Vector({
    source: new ol.source.Vector()
});
map.addLayer(geoCaching);

The ol.Geolocation constructor creates a simple wrapper object around the HTML5 Geolocation API. It is capable of everything the Geolocation API can do, and provides convenience methods to register listeners on changes and access Geolocation-related information. As we need our position to generate local points, we must register a listener to the Geolocation object's change:position event. As we do not want...