Table of Contents for
OpenLayers 3 : Beginner's Guide

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition OpenLayers 3 : Beginner's Guide by Erik Hazzard Published by Packt Publishing, 2015
  1. Cover
  2. Table of Contents
  3. OpenLayers 3 Beginner's Guide
  4. OpenLayers 3 Beginner's Guide
  5. Credits
  6. About the Authors
  7. About the Reviewers
  8. www.PacktPub.com
  9. Preface
  10. What you need for this book
  11. Who this book is for
  12. Sections
  13. Time for action – heading
  14. Conventions
  15. Reader feedback
  16. Customer support
  17. 1. Getting Started with OpenLayers
  18. Advantages of using OpenLayers
  19. What, technically, is OpenLayers?
  20. Anatomy of a web mapping application
  21. Connecting to Google, Bing Maps, and other mapping APIs
  22. Time for action – downloading OpenLayers
  23. Time for action – creating your first map
  24. Where to go for help
  25. OpenLayers issues
  26. OpenLayers source code repository
  27. Getting live news from RSS and social networks
  28. Summary
  29. 2. Key Concepts in OpenLayers
  30. Time for action – creating a map
  31. Time for action – using the JavaScript console
  32. Time for action – overlaying information
  33. OpenLayers' super classes
  34. Key-Value Observing with the Object class
  35. Time for action – using bindTo
  36. Working with collections
  37. Summary
  38. 3. Charting the Map Class
  39. Time for action – creating a map
  40. Map renderers
  41. Time for action – rendering a masterpiece
  42. Map properties
  43. Time for action – target practice
  44. Map methods
  45. Time for action – creating animated maps
  46. Events
  47. Views
  48. Time for action – linking two views
  49. Summary
  50. 4. Interacting with Raster Data Source
  51. Layers in OpenLayers 3
  52. Common operations on layers
  53. Time for action – changing layer properties
  54. Tiled versus untiled layers
  55. Types of raster sources
  56. Tiled images' layers and their sources
  57. Time for action – creating a Stamen layer
  58. Time for action – creating a Bing Maps layer
  59. Time for action – creating tiles and adding Zoomify layer
  60. Image layers and their sources
  61. Using Spherical Mercator raster data with other layers
  62. Time For action – playing with various sources and layers together
  63. Time For action – applying Zoomify sample knowledge to a single raw image
  64. Summary
  65. 5. Using Vector Layers
  66. Time for action – creating a vector layer
  67. How the vector layer works
  68. The vector layer class
  69. Vector sources
  70. Time for action – using the cluster source
  71. Time for action – creating a loader function
  72. Time for action – working with the TileVector source
  73. Time for action – a drag and drop viewer for vector files
  74. Features and geometries
  75. Time for action – geometries in action
  76. Time for action – interacting with features
  77. Summary
  78. 6. Styling Vector Layers
  79. Time for action – basic styling
  80. The style class
  81. Time for action – using the icon style
  82. Have a go hero – using the circle style
  83. Multiple styles
  84. Time for action – using multiple styles
  85. Style functions
  86. Time for action – using properties to style features
  87. Interactive styles
  88. Time for action – creating interactive styles
  89. Summary
  90. 7. Wrapping Our Heads Around Projections
  91. Time for action – using different projection codes
  92. Time for action – determining coordinates
  93. OpenLayers projection class
  94. Transforming coordinates
  95. Time for action – coordinate transforms
  96. Time for action – setting up Proj4js.org
  97. Time for action – reprojecting extent
  98. Time for action – using custom projection with WMS sources
  99. Time for action – reprojecting geometries in vector layers
  100. Summary
  101. 8. Interacting with Your Map
  102. Time for action – converting your local or national authorities data into web mapping formats
  103. Time for action – testing the use cases for ol.interaction.Select
  104. Time for action – more options with ol.interaction.Select
  105. Introducing methods to get information from your map
  106. Time for action – understanding the forEachFeatureAtPixel method
  107. Time for action – understanding the getGetFeatureInfoUrl method
  108. Adding a pop-up on your map
  109. Time for action – introducing ol.Overlay with a static example
  110. Time for action – using ol.Overlay dynamically with layers information
  111. Time for action – using ol.interaction.Draw to share new information on the Web
  112. Time for action – using ol.interaction.Modify to update drawing
  113. Understanding interactions and their architecture
  114. Time for action – configuring default interactions
  115. Discovering the other interactions
  116. Time for action – using ol.interaction.DragRotateAndZoom
  117. Time for action – making rectangle export to GeoJSON with ol.interaction.DragBox
  118. Summary
  119. 9. Taking Control of Controls
  120. Adding controls to your map
  121. Time for action – starting with the default controls
  122. Controls overview
  123. Time for action – changing the default attribution styles
  124. Time for action – finding your mouse position
  125. Time for action – configuring ZoomToExtent and manipulate controls
  126. Creating a custom control
  127. Time for action – extending ol.control.Control to make your own control
  128. Summary
  129. 10. OpenLayers Goes Mobile
  130. Using a web server
  131. Time for action – go mobile!
  132. The Geolocation class
  133. Time for action – location, location, location
  134. The DeviceOrientation class
  135. Time for action – a sense of direction
  136. Debugging mobile web applications
  137. Debugging on iOS
  138. Debugging on Android
  139. Going offline
  140. Time for action – MANIFEST destiny
  141. Going native with web applications
  142. Time for action – track me
  143. Summary
  144. 11. Creating Web Map Apps
  145. Using geospatial data from Flickr
  146. Time for action – getting Flickr data
  147. A simple application
  148. Time for Action – adding data to your map
  149. Styling the features
  150. Time for action – creating a style function
  151. Creating a thumbnail style
  152. Time for action – switching to JSON data
  153. Time for action – creating a thumbnail style
  154. Turning our example into an application
  155. Time for action – adding the select interaction
  156. Time for action – handling selection events
  157. Time for action – displaying photo information
  158. Using real time data
  159. Time for action – getting dynamic data
  160. Wrapping up the application
  161. Time for action – adding dynamic tags to your map
  162. Deploying an application
  163. Creating custom builds
  164. Creating a combined build
  165. Time for action – creating a combined build
  166. Creating a separate build
  167. Time for action – creating a separate build
  168. Summary
  169. A. Object-oriented Programming – Introduction and Concepts
  170. Going further
  171. B. More details on Closure Tools and Code Optimization Techniques
  172. Introducing Closure Library, yet another JavaScript library
  173. Time for action – first steps with Closure Library
  174. Making custom build for optimizing performance
  175. Time for action – playing with Closure Compiler
  176. Applying your knowledge to the OpenLayers case
  177. Time for action - running official examples with the internal OpenLayers toolkit
  178. Time for action - building your custom OpenLayers library
  179. Syntax and styles
  180. Time for action – using Closure Linter to fix JavaScript
  181. Summary
  182. C. Squashing Bugs with Web Debuggers
  183. Time for action – opening Chrome Developer Tools
  184. Explaining Chrome Developer debugging controls
  185. Time for action – using DOM manipulation with OpenStreetMap map images
  186. Time for action – using breakpoints to explore your code
  187. Time for action – playing with zoom button and map copyrights
  188. Using the Console panel
  189. Time for action – executing code in the Console
  190. Time for action – creating object literals
  191. Time for action – interacting with a map
  192. Improving Chrome and Developer Tools with extensions
  193. Debugging in other browsers
  194. Summary
  195. D. Pop Quiz Answers
  196. Chapter 5, Using Vector Layers
  197. Chapter 7, Wrapping Our Heads Around Projections
  198. Chapter 8, Interacting with Your Map
  199. Chapter 9, Taking Control of Controls
  200. Chapter 10, OpenLayers Goes Mobile
  201. Appendix B, More details on Closure Tools and Code Optimization Techniques
  202. Appendix C, Squashing Bugs with Web Debuggers
  203. Index

Chapter 2. Key Concepts in OpenLayers

Now that we've seen the basics and made our first map with OpenLayers, let's take a step back and look at the big picture. OpenLayers is a software library based on an Object-oriented design principles, which means that it contains classes to encapsulate behavior, formal relationships between those classes, and standardized mechanisms for communication between objects. While OpenLayers contains many classes, there are just a few that form the foundation of the OpenLayers architecture. In this chapter, we will introduce these core components of the library and also two key concepts— events and observable properties—that are the basis for standardized communication between objects. Along the way, we'll use concrete examples and introduce some basic debugging techniques you can use to solve problems and explore the relationships between objects in a running application.

In this chapter, we will:

  • Illustrate the key classes that form the basis of the OpenLayers architecture
  • Discover the relationship between these classes
  • Understand the roles of the key classes
  • Introduce basic debugging techniques that will allow you to solve problems with your application and to explore the relationship between instances of the key classes in a running application
  • Understand what events and observable properties are, and how to use them
  • Understand collections

OpenLayers' key components

The OpenLayers library provides web developers with components useful to build web mapping applications. Following the principles of an Object-oriented design, these components are called classes. The relationship between all the classes in the OpenLayers library is part of the deliberate design, or architecture, of the library. There are two types of relationships that we, as developers using the library, need to know about: relationships between classes and inheritance between classes. We briefly talked about object-oriented programming in Chapter 1, Getting Started with OpenLayers and a more detailed discussion is included in Appendix A, Object-oriented Programming – Introduction and Concepts but for the purpose of this chapter, let's summarize the two types of relationships we are interested in:

  • Relationships between classes describe how classes, or more specifically, instances of classes, are related to each other. There are several different conceptual ways that classes can be related, but basically a relationship between two classes implies that one of the class uses the other in some way, and often vice versa.
  • Inheritance between classes shows how behavior of classes, and their relationships are shared with other classes. Inheritance is really just a way of sharing common behavior between several different classes.

We'll start our discussion of the key components of OpenLayers by focusing on the first of these—the relationship between classes. OpenLayers includes a lot of classes for our use, and we'll cover a lot of these in later chapters, but for now, we'll start by looking at the Map class—ol.Map.

It's all about the map

Instances of the map class are at the center of every OpenLayers application. These objects are instances of the ol.Map class and they use instances of other classes to do their job, which is to put an interactive map onto a web page. Almost every other class in the OpenLayers is related to the Map class in some direct or indirect relationship. The following diagram illustrates the direct relationships that we are most interested in:

It's all about the map

The preceding diagram shows the most important relationships between the Map class and other classes it uses to do its job. It tells us several important things:

  • A map has 0 or 1 view instances and it uses the name view to refer to it. A view may be associated with multiple maps, however.
  • A map may have 0 or more instances of layers managed by a Collection class and a layer may be associated with 0 or one Map class. The Map class has a member variable named layers that it uses to refer to this collection.
  • A map may have 0 or more instances of overlays managed by a Collection class and an overlay may be associated with 0 or one Map class. The Map class has a member variable named overlays that it uses to refer to this collection.
  • A map may have 0 or more instances of controls managed by a class called ol.Collection (more on collections at the end of this chapter) and controls may be associated with 0 or one Map class. The Map class has a member variable named controls that it uses to refer to this collection.
  • A map may have 0 or more instances of interactions managed by a Collection class and an interaction may be associated with 0 or one Map class. The Map class has a member variable named interactions that it uses to refer to this collection.

    Although these are not the only relationships between the Map class and other classes, these are the ones we'll be working with the most. We've already seen some of these classes in action in the examples from the previous chapter. We'll do another example in a moment, but first let's introduce each of these new classes.

  • The View class (ol.View) manages information about the current position of the Map class.

    Note

    If you are familiar with the programming concept of MVC (Model-View-Controller), be aware that the view class is not a View in the MVC sense. It does not provide the presentation layer for the map, rather it acts more like a controller (although there is not an exact parallel because OpenLayers was not designed with MVC in mind.)

  • The Layer class (ol.layer.Base) is the base class for classes that provide data to the map to be rendered.
  • The Overlay class (ol.Overlay) is an interactive visual element like a control, but it is tied to a specific geographic position.
  • The Control class (ol.control.Control) is the base class for a group of classes that collectively provide the ability to a user to interact with the map. Controls have a visible user interface element (such as a button or a form input element) with which the user interacts.
  • The Interaction class (ol.interaction.Interaction) is the base class for a group of classes that also allow the user to interact with the map, but differ from controls in which they have no visible user interface element. For example, the DragPan interaction allows the user to click on and drag the map to pan around.