You are previewing HTML5: Up and Running.

HTML5: Up and Running

Cover of HTML5: Up and Running by Mark Pilgrim Published by O'Reilly Media, Inc.
  1. HTML5: Up and Running
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. Preface
      1. Diving In
      2. Conventions Used in This Book
      3. Using Code Examples
      4. A Note on the Editions of This Book
      5. Safari® Books Online
      6. How to Contact Us
    3. 1. How Did We Get Here?
      1. Diving In
      2. MIME Types
      3. A Long Digression into How Standards Are Made
      4. An Unbroken Line
      5. A Timeline of HTML Development from 1997 to 2004
      6. Everything You Know About XHTML Is Wrong
      7. A Competing Vision
      8. What Working Group?
      9. Back to the W3C
      10. Postscript
      11. Further Reading
    4. 2. Detecting HTML5 Features
      1. Diving In
      2. Detection Techniques
      3. Modernizr: An HTML5 Detection Library
      4. Canvas
      5. Canvas Text
      6. Video
      7. Video Formats
      8. Local Storage
      9. Web Workers
      10. Offline Web Applications
      11. Geolocation
      12. Input Types
      13. Placeholder Text
      14. Form Autofocus
      15. Microdata
      16. Further Reading
    5. 3. What Does It All Mean?
      1. Diving In
      2. The Doctype
      3. The Root Element
      4. The <head> Element
      5. New Semantic Elements in HTML5
      6. A Long Digression into How Browsers Handle Unknown Elements
      7. Headers
      8. Articles
      9. Dates and Times
      10. Navigation
      11. Footers
      12. Further Reading
    6. 4. Let’s Call It a Draw(ing Surface)
      1. Diving In
      2. Simple Shapes
      3. Canvas Coordinates
      4. Paths
      5. Text
      6. Gradients
      7. Images
      8. What About IE?
      9. A Complete Example
      10. Further Reading
    7. 5. Video on the Web
      1. Diving In
      2. Video Containers
      3. Video Codecs
      4. Audio Codecs
      5. What Works on the Web
      6. Licensing Issues with H.264 Video
      7. Encoding Ogg Video with Firefogg
      8. Batch Encoding Ogg Video with ffmpeg2theora
      9. Encoding H.264 Video with HandBrake
      10. Batch Encoding H.264 Video with HandBrake
      11. Encoding WebM Video with ffmpeg
      12. At Last, the Markup
      13. What About IE?
      14. A Complete Example
      15. Further Reading
    8. 6. You Are Here (And So Is Everybody Else)
      1. Diving In
      2. The Geolocation API
      3. Show Me the Code
      4. Handling Errors
      5. Choices! I Demand Choices!
      6. What About IE?
      7. geo.js to the Rescue
      8. A Complete Example
      9. Further Reading
    9. 7. The Past, Present, and Future of Local Storage for Web Applications
      1. Diving In
      2. A Brief History of Local Storage Hacks Before HTML5
      3. Introducing HTML5 Storage
      4. Using HTML5 Storage
      5. HTML5 Storage in Action
      6. Beyond Named Key/Value Pairs: Competing Visions
      7. Further Reading
    10. 8. Let’s Take This Offline
      1. Diving In
      2. The Cache Manifest
      3. The Flow of Events
      4. The Fine Art of Debugging, a.k.a. “Kill Me! Kill Me Now!”
      5. Let’s Build One!
      6. Further Reading
    11. 9. A Form of Madness
      1. Diving In
      2. Placeholder Text
      3. Autofocus Fields
      4. Email Addresses
      5. Web Addresses
      6. Numbers As Spinboxes
      7. Numbers As Sliders
      8. Date Pickers
      9. Search Boxes
      10. Color Pickers
      11. And One More Thing...
      12. Further Reading
    12. 10. “Distributed,” “Extensibility,” and Other Fancy Words
      1. Diving In
      2. What Is Microdata?
      3. The Microdata Data Model
      4. Marking Up People
      5. Marking Up Organizations
      6. Marking Up Events
      7. Marking Up Reviews
      8. Further Reading
    13. A. The All-in-One Almost-Alphabetical Guide to Detecting Everything
      1. List of Elements
      2. Further Reading
    14. Index
    15. About the Author
    16. Colophon
    17. SPECIAL OFFER: Upgrade this ebook with O’Reilly

Choices! I Demand Choices!

Some popular mobile devices—like the iPhone and Android phones—support two methods of figuring out where you are. The first method triangulates your position based on your relative proximity to different cellular towers operated by your phone carrier. This method is fast and doesn’t require any dedicated GPS hardware, but it only gives you a rough idea of where you are. Depending on how many cell towers are in your area, this “rough idea” could be accurate to as little as one city block or as much as a kilometer in every direction.

The second method actually uses dedicated GPS hardware on your device to talk to dedicated GPS positioning satellites that are orbiting the Earth. GPS can usually pinpoint your location to within a few meters. The downside is that the dedicated GPS chip on your device draws a lot of power, so phones and other general-purpose mobile devices usually turn off the chip until it’s needed. That means there will be a startup delay while the chip initializes its connection with the GPS satellites in the sky. If you’ve ever used Google Maps on an iPhone or other smartphone, you’ve seen both methods in action. First you see a large circle that approximates your position (finding the nearest cell tower), then a smaller circle (triangulating with other cell towers), then a single dot with an exaction position (given by GPS satellites).

The reason I mention this is that, depending on your web application, you may not need high accuracy. For ...

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