HTML5 Guidelines for Web Developers

322 Pages·2013·7.24 MB·English

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HTML5 Guidelines
for Web Developers
Klaus Förster
Bernd Öggl
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Library of Congress Cataloging-in-Publication Data
Förster, Klaus, 1964-
[HTML 5. English]
HTML5 guidelines for Web developers / Klaus Förster, Bernd Öggl.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-321-77274-9 (pbk. : alk. paper)
1. HTML (Document markup language) 2. Internet programming. 3.
Web site development. I. Öggl, Bernd. II. Title. III. Title: HTML 5
guidelines for Web developers.
QA76.625.F6713 2012
006.7’4—dc23
2011014135
Copyright © 2011 Pearson Education, Inc.
All rights reserved. Printed in the United States of America. This publication is protected by
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write to:
Pearson Education, Inc.
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Fax: [phone]
ISBN-13: 978-0-321-77274-9
ISBN-10: 0-321-77274-1
Text printed in the United States on recycled paper at RR Donnelley in Crawfordsville, Indiana.
First printing, June 2011
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Thanks to Andrea and Sabine—you are wonderful!
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Contents
Preface .............................................................................................................. xi
About the Authors ........................................................................................... xiii
1 Overview of the New Web Standard ...........................................................1
1.1 How It All Started ......................................................................................1
1.2 Time Travel through Historic Events .......................................................7
1.3 In Medias Res .............................................................................................9
1.3.1 What Is New? ..................................................................................9
1.3.2 What Has Become Obsolete? ......................................................13
1.3.3 And What About XHTML? ...........................................................15
1.4 Can I Start Using HTML5 Now? .............................................................16
Summary ...........................................................................................................18
2 Structure and Semantics for Documents .................................................19
2.1 Header with “header” and “hgroup” .....................................................21
2.2 Content with “article” .............................................................................22
2.3 Footer with “footer” and “nav” ..............................................................24
2.4 Sidebar with “aside” and “section” ........................................................25
2.5 The Outline Algorithm ............................................................................27
2.6 Figures with “figure” and “figcaption” ..................................................28
2.7 Text-Level Semantics—More New Tags ................................................29
2.7.1 The Elements “ruby,” “rt,” and “rp” ..........................................30
2.7.2 The “time” Element .....................................................................31
2.7.3 The “mark” Element ....................................................................32
2.7.4 The “wbr” Element ......................................................................32
2.7.5 Elements with Marginal Changes ..............................................33
Summary ...........................................................................................................35
3 Intelligent Forms .........................................................................................37
3.1 New Input Types .....................................................................................38
3.1.1 The Input Types “tel” and “search” ...........................................39
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vi Contents
3.1.2 The Input Types “url” and “email” ............................................40
3.1.3 Date and Time with “datetime”, “date”, “month”,
“week”, “time”, and “datetime-local” .......................................40
3.1.4 The Input Types “number” and “range” ...................................40
3.1.5 The Input Type “color” ...............................................................41
3.1.6 The New Input Types in Action ..................................................41
3.2 Useful Attributes for Forms ....................................................................43
3.2.1 Focusing with “autofocus”..........................................................43
3.2.2 Placeholder Text with “placeholder” .........................................44
3.2.3 Compulsory Fields with “required” ...........................................44
3.2.4 Even More Attributes for the “input” Element .........................45
3.3 New Elements ..........................................................................................47
3.3.1 Displaying Measurements with “meter” ...................................47
3.3.2 Displaying the Progress of a Task with “progress” ...................50
3.3.3 Lists of Options with “datalist” ...................................................51
3.3.4 Cryptographic Keys with “keygen” ............................................53
3.3.5 Calculations with “output” .........................................................55
3.4 Client-Side Form Validation ...................................................................57
3.4.1 The “invalid” Event ......................................................................59
3.4.2 The “checkValidity” Function ....................................................59
3.4.3 Error Handling with “setCustomValidity()” ..............................61
3.4.4 Summary of Validity Checks .......................................................63
3.4.5 Or Perhaps Better Not to Validate? “formnovalidate” ..............63
3.5 Example: A Support Form ......................................................................64
Summary ...........................................................................................................68
4 Video and Audio ..........................................................................................69
4.1 A First Example ........................................................................................70
4.2 The “video” Element and Its Attributes ................................................71
4.3 Video Codecs ...........................................................................................73
4.3.1 Ogg: Theora and Vorbis...............................................................75
4.3.2 MPEG-4: H.264 and AAC .............................................................75
4.3.3 WebM: VP8 and Vorbis ................................................................76
4.4 Tools for Video Conversion ....................................................................76
4.4.1 FFmpeg .........................................................................................76
4.4.2 VLC ................................................................................................78
4.4.3 Firefogg .........................................................................................79
4.4.4 Miro Video Converter ..................................................................81
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Contents vii
4.5 Which Format for Which Browser? ........................................................82
4.6 Interim Solutions for Older Browsers ....................................................83
4.6.1 mwEmbed ....................................................................................83
4.6.2 html5media ..................................................................................85
4.7 Video and Scripting—A Simple Video Player ........................................86
4.7.1 Integrating the Video ...................................................................87
4.7.2 Starting and Stopping the Video ................................................88
4.7.3 Displaying and Setting the Playback Position ..........................89
4.7.4 Fast Forward and Backward .......................................................91
4.7.5 Selecting Specific Scenes in the Film .........................................93
4.7.6 Set Volume to High, Low, or Mute .............................................93
4.7.8 Other Attributes and Methods of the
“HTMLMediaElement” Interface ...............................................94
4.7.9 The Long List of Media Events ...................................................98
4.8 And What About Audio? ..........................................................................99
Summary .........................................................................................................105
5 Canvas .......................................................................................................107
5.1 A First Example ......................................................................................108
5.2 Rectangles ..............................................................................................111
5.3 Colors and Shadows ..............................................................................113
5.4 Gradients ................................................................................................114
5.5 Paths .......................................................................................................117
5.5.1 Lines ............................................................................................119
5.5.2 Bézier Curves .............................................................................120
5.5.3 Arcs..............................................................................................121
5.5.4 Rectangles ..................................................................................126
5.5.5 Outlines, Fills, and Clipping Masks..........................................127
5.6 Text .........................................................................................................130
5.6.1 Fonts ...........................................................................................130
5.6.2 Horizontal Anchor Point ...........................................................132
5.6.3 Vertical Anchor Point ................................................................133
5.6.4 Drawing and Measuring Text ...................................................134
5.7 Embedding Images ................................................................................135
5.8 Pixel Manipulation ................................................................................141
5.8.1 Working with the “ImageData” Object ....................................141
5.8.2 Color Manipulation with “getImageData()”,
“createImageData()”, and “putImageData()” .........................145
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5.9 Compositing ...........................................................................................149
5.10 Patterns ..................................................................................................152
5.11 Transformations ....................................................................................156
5.12 Base64 Encoding with “canvas.toDataURL()” ....................................163
5.13 “save()” and “restore()” .........................................................................165
5.14 Animations .............................................................................................166
5.14.1 Animation with Multicolored Spheres ..................................166
5.14.2 Playing a Video with “drawImage()” ......................................169
5.15 Anything Still Missing? ..........................................................................173
5.15.1 “isPointInPath(x, y)” ................................................................173
5.15.2 Accessibility in Canvas? ...........................................................174
5.15.3 Security Aspects .......................................................................175
5.15.4 Browser Support ......................................................................176
5.15.5 Further Links ............................................................................176
Summary .........................................................................................................177
6 SVG and MathML ......................................................................................179
6.1 MathML ..................................................................................................180
6.2 SVG .........................................................................................................182
Summary .........................................................................................................183
7 Geolocation ...............................................................................................185
7.1 Introduction to Geolocation .................................................................186
7.1.1 About Geographical Data ..........................................................186
7.1.2 Online Map Services ..................................................................186
7.2 A First Experiment: Geolocation in the Browser ................................190
7.3 Technical Background of Determining Position ................................193
7.4 Display of Current Position on OpenStreetMap ................................194
7.5 Location Tracking with Google Maps ..................................................196
7.6 Example: Geonotes ................................................................................197
7.6.1 Operation ...................................................................................198
7.6.2 Important Code Fragments ......................................................199
7.7 Browser Support ....................................................................................202
Summary .........................................................................................................203
8 Web Storage and Offline Web Applications ...........................................205
8.1 Storage ....................................................................................................206
8.1.1 The “Storage” Interface .............................................................206
8.1.2 “sessionStorage” ........................................................................208
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Contents ix
8.1.3 “localStorage” ............................................................................209
8.1.4 The “storage” Event ...................................................................210
8.1.5 Debugging ..................................................................................210
8.2 Offline Web Applications ......................................................................212
8.2.1 The Cache Manifest File ............................................................213
8.2.2 Offline Status and Events ..........................................................214
8.2.3 Debugging ..................................................................................217
8.3 Browser Support ....................................................................................220
8.4 Example: Click to tick! ...........................................................................220
8.4.1 Using the Application: As a Player ...........................................221
8.4.2 Using the Application: As an Administrator ...........................222
8.4.3 Important Code Fragments ......................................................223
8.4.4 Expansion Options ....................................................................229
Summary .........................................................................................................230
9 WebSockets ..............................................................................................231
9.1 The WebSocket Server ..........................................................................233
9.2 Example: A Broadcast Server ................................................................234
9.2.1 The Broadcast Client .................................................................235
9.2.2 The Broadcast Server .................................................................237
9.3 Example: Battleships! ............................................................................239
Summary .........................................................................................................248
10 Web Workers .............................................................................................249
10.1 Introduction to Web Workers...............................................................249
10.2 Search for Leap Years ............................................................................251
10.3 Calculate Altitude Profiles with Canvas ..............................................253
10.3.1 Important Code Fragments ....................................................255
Summary .........................................................................................................259
11 Microdata ...................................................................................................261
11.1 The Syntax of Microdata .......................................................................263
11.1.1 The Attributes “itemscope” and ”itemprop” ........................263
11.1.2 The “itemtype” Attribute ........................................................266
11.1.3 The “itemid” Attribute.............................................................268
11.1.4 The “itemref” Attribute ...........................................................268
11.2 The Microdata DOM API ......................................................................269
Summary .........................................................................................................271
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