Dr. Dobb's Journal - December 2007 - (Page 39)

d12synd_p4ma 10/17/07 11:40 AM Page 39 Markup Language” (code.google.com/apis/kml/documentation), an XML-based language for managing three-dimensional geospatial data. This file contained coordinates, labels, and even HTML descriptions, in a format that was human readable and easy to process using XSLT. Listing One, for instance, is the location of my office in KML. Want to move on C# 3.0? We’ve got you covered. Once you know C# 3.0, you can develop any web or Windows application on the .NET framework with ease. And we’ll help you do it. With our top-notch tutorial, programming guide, cookbook, reference, and design pattern book, you get everything you need to hone your C# skills. Initializing the Map Although the Map API is free, to embed a map in a web pages you first have to sign up for an API key. A single key is valid for a single “directory” on your web server, so if you sign up for the URL “www.mycompany.com/mysite,” the key you get will be good for all URLs in the “www.mygooglemapssite.com/mysite/” directory. You must have a Google Account to get a Maps API key, and your API key is connected to your Google Account. These keys are generated in real time and are required to import the core library in your JavaScript code: and s, Web Window th C# 3.0 Building plications wi ht Ap Silverlig 5th Co v LIN ers V E Q, isu dit .N al ET Stu ion 3.5 d an io 20 d M 08 ore , More tha n 250 C# 3.0 pro solutions for grammers mming Progra C# 3.0 Jesse Lib erty on iti ed .5 Ed ly revis ET 3 3rdrough and .N o .0 Th # 3 rC fo Cookb0o ok Jay Hilyard or te-f C# 3. C# 3.0 TM For a basic map to appear, the API requires that the construction be made while the body of the page loads with a function similar to Listing Two. In this way, you first check if the browser is compatible with your JavaScript API (most are), then construct a new map object. For our purposes, we added some controls on the map to help us zoom in/out, and change modes between satellite imagery and geopolitical view. Also, we defined the initial center of the map and provided a welcome message window that contains HTML code. Our API also gave us a built-in function GUnload() for cleanup purposes on exiting the map page. Desi n Pattegn rs C # 3.0 Use the to Solve Power of C# Real-Wo rld Pr 3.0 oblem s Up -to -da & Stephen Teilhet Judith Bishop Printing Markers, Polylines, and Polygons Adding elements on an embedded map is done in a similar way using the coordinates that are contained in the KML file; see Listing Three. We’ve taken it a step further to register listeners every time an element is printed and also have added every element in an array. This way we are able to reference these element in the future, while our application is executed; for example, to remove them from the map using the map.removeOverlay() function, you would use map.removeOverlay(permarkers[4]). The API has several facilities for customizing the way the different kinds of elements appear on the map. The markers can have custom size, icon, and shadows, and we can assign specific color, width, and transparency for polylines and polygons. For a small number of locations, it is fairly easy to copy the coordinates by hand and insert them in JavaScript code. But as the number of locations increase, it is harder to manipulate these 16-digit numbers and it becomes necessary to use programming to extract them for the KML file. In our project, the number of locations was big! There were several polylines that were described using more than 60 different points that accounted for 100+ different 16-digit numbers. To overcome this, we had to develop XSL filters for the KML file that contained Buy two, get one FREE! Use offer code OPC166 when you order directly from O’Reilly at http://www.oreilly.com/go/ddjcshrp Spreading the knowledge of innovators www.oreilly.com ©2007 O’Reilly Media, Inc. O’Reilly logo is a registered trademark of O’Reilly Media, Inc. 70686 December 2007 l www.ddj.com l Dr. Dobb’s Journal 39 http://code.google.com/apis/kml/documentation http://www.oreilly.com/go/ddjcshrp http://www.oreilly.com http://www.oreilly.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - December 2007

Dr. Dobb's Journal - December 2007 Contents Hmmmm Alia Vox Developer Diaries Developer’s Notebook Computer Books: Reading Between the Lines Conversations Query Anything with SQLite XQuery Web Maps with the Google Map API OpenALM and Its Manifesto Transactional Programming Effective Concurrency The Agile Edge Swaine’s Flames

Dr. Dobb's Journal - December 2007

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