Book Image

Google Maps JavaScript API Cookbook

Book Image

Google Maps JavaScript API Cookbook

Overview of this book

Day by day, the use of location data is becoming more and more popular, and Google is one of the main game changers in this area. The Google Maps JavaScript API is one of the most functional and robust mapping APIs used among Geo developers. With Google Maps, you can build location-based apps, maps for mobile apps, visualize geospatial data, and customize your own maps.Google Maps JavaScript API Cookbook is a practical, hands-on guide that provides you with a number of clear, step-by-step recipes that will help you to unleash the capabilities of the Google Maps JavaScript API in conjunction with open source or commercial GIS servers and services through a number of practical examples of real world scenarios. This book begins by covering the essentials of including simple maps for Web and mobile, adding vector and raster layers, styling your own base maps, creating your own controls and responding to events, and including your own events.You will learn how to integrate open source or commercial GIS servers and services including ArcGIS Server, GeoServer, CartoDB, Fusion Tables, and Google Maps Engine with the Google Maps JavaScript API. You will also extend the Google Maps JavaScript API to push its capabilities to the limit with additional libraries and services including geometry, AdSense, geocoding, directions, and StreetView.This book covers everything you need to know about creating a web map or GIS applications using the Google Maps JavaScript API on multiple platforms.
Table of Contents (15 chapters)
Google Maps JavaScript API Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Changing the transparency of overlays


The Google Maps JavaScript API supports third-party tiled map services or images to be overlaid on top of base maps. However, there is a problem with the overlay layers; they come on top of base maps and make them invisible. Of course, you can turn them on or off according to your choice; however, this is not a solution if you want to see the base maps together with the overlay layers.

In fact, you can just modify the opacity of the overlay layers to see the base maps and the overlay layers.

This recipe is focused on changing the transparency of the overlay layers introduced in the last two recipes.

Getting ready

We can use the code introduced in the Adding tile overlays to maps recipe of this chapter and modify it a little to achieve the result. Be sure to copy the code of the recipe first.

How to do it…

You will be able to make your overlay layer transparent after completing the one-step operation presented in the following code:

  1. Just change the osmMapType...