SlideShare a Scribd company logo
Copyright © Terry Felke-Morris http://terrymorris.net
Web Development & Design
Foundations with HTML5
8th
Edition
CHAPTER 11
KEY CONCEPTS
1
Copyright © Terry Felke-Morris http://terrymorris.net
Learning Outcomes
In this chapter, you will learn how to ...
◦ Describe the purpose of plug-ins, helper applications, media containers, and codecs
◦ Describe types of multimedia files used on the Web
◦ Configure hyperlinks to multimedia files
◦ Configure audio and video on a web page with HTML5 elements
◦ Describe features and common uses of Adobe Flash, JavaScript,
Java applets, Ajax, and jQuery
◦ Configure a Flash animation on a web page
◦ Configure a Java applet on a web page
◦ Create an interactive image gallery with CSS
◦ Configure the CSS3 transform and transition properties
◦ Describe the purpose of geolocation, web storage, offline web applications, and canvas
HTML5 APIs.
2
Copyright © Terry Felke-Morris http://terrymorris.net
Helper Applications & Plug-ins
Helper Application
◦A program that can be designated to handle a particular file type
(such as .wav or .mpg) to allow the user to view or otherwise
utilize the special file.
◦The helper application runs in a separate window from the
browser.
Plug-In
◦A newer and more common method
◦Plug-ins run right in the browser window so that media objects
can be integrated directly into the web page.
3
Copyright © Terry Felke-Morris http://terrymorris.net
Containers & Codecs
Container
◦Designated by the file extension – contains the media and
metadata
Codec
◦The algorithm used to compress the media
HTML5 audio & video
◦Native to the browser
◦ISSUE: Browsers do not all support the same codecs
◦http://www.longtailvideo.com/html5/
4
Copyright © Terry Felke-Morris http://terrymorris.net
Commonly Used Plug-ins
Adobe Flash Player
Adobe Reader
Windows Media Player
Apple Quicktime
5
Copyright © Terry Felke-Morris http://terrymorris.net
Common Audio File Types
.wav Wave File
.aiff Audio Interchange File Format
.mid Musical Instrument Digital Interface (MIDI)
.au Sun UNIX sound file
.mp3 MPEG-1 Audio Layer-3
.ogg Ogg Vorbis (open-source)
. m4a MPEG 4 Audio.
This audio-only MPEG-4 format is
supported by Quicktime, iTunes, and iPods.
6
Copyright © Terry Felke-Morris http://terrymorris.net
Common Video File Types
.mov Quicktime
.avi Microsoft Audio Video Interleaved
.wmv Windows Media File
.flv Flash Video File
.mpg MPEG (Motion Picture Experts Group)
.m4v .mp4 (MPEG-4)
.ogv Ogg Theora (open-source)
.webm VP8 codec (open video format, free)
7
Copyright © Terry Felke-Morris http://terrymorris.net
Copyright Issues
•Only publish web pages, images, and other media that you
have personally created or have obtained the rights or
license to use.
•Ask permission to use media created by another person
instead of simply “grabbing” it.
•All work (including web pages) are automatically
copyrighted even if there is not copyright mark or date.
•Fair Use Clause of the Copyright Act
•Creative Commons – A new approach to copyright
8
Copyright © Terry Felke-Morris http://terrymorris.net
Configure Audio & Video
Most basic method to provide audio or video files:
Hyperlink
<a href="wdfpodcast.mp3" title="Web Design Podcast">Web
Design Podcast</a>
9
Copyright © Terry Felke-Morris http://terrymorris.net
Multimedia & Accessibility
Provide alternate content
◦Transcript (for audio)
◦Captions (for video)
◦Text format
10
Copyright © Terry Felke-Morris http://terrymorris.net
What is Adobe Flash?
•A popular multimedia application
•Create multimedia which adds visual interest and
interactivity to web pages
•Flash movies are saved in “.swf” files
•Perception of speedy display
•.swf files play as they download
•Flash Player
• Free browser plug-in
• Widely installed on desktop browsers but not well-supported
by mobile devices
11
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Embed Element
<embed type="application/x-shockwave-flash"
src="fall5.swf"
width="640"
height="100"
quality="high”
title="Fall Nature Hikes">
12
Copyright © Terry Felke-Morris http://terrymorris.net
Checkpoint
1. List three common web browser plug-ins and
describe their use.
2. Describe issues involved with adding media such
as audio or video to a web page.
3. Describe a disadvantage of using Flash on a web
page.
13
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Audio & Source
Elements
<audio controls="controls">
<source src="soundloop.mp3" type="audio/mpeg">
<source src="soundloop.ogg" type="audio/ogg">
<a href="soundloop.mp3">Download the Audio File</a> (MP3)
</audio>
14
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Video &
Source Elements
<video controls="controls" poster="sparky.jpg"
width="160" height="150">
<source src="sparky.m4v" type="video/mp4">
<source src="sparky.ogv" type="video/ogg">
<a href="sparky.mov">Sparky the Dog</a> (.mov)
</video>
15
Copyright © Terry Felke-Morris http://terrymorris.net
CSS Drop Down Menu
•Configure nav container with position relative
•Code submenu (drop down menu) ul element with the
parent li element
•Configure submenu ul element to initially not display
•Configure submenu ul element with absolute positioning
16
Copyright © Terry Felke-Morris http://terrymorris.net
CSS3 Transform Property
Allows you to rotate, scale, skew, or move an element
Example:
transform: rotate(3deg);
17
Copyright © Terry Felke-Morris http://terrymorris.net
CSS3 Transition Property
Provides for changes in property values to display in a smoother
manner over a specified time.
Example:
nav a:hover { color: #869dc7; background-color: #eaeaea;
transition: background-color 2s linear; }
18
Copyright © Terry Felke-Morris http://terrymorris.net
CSS Image Gallery
Configure each thumbnail image:
<li><a href="photo1.jpg"><img src="photo1thumb.jpg" width="100" height="75"
alt="Golden Gate Bridge">
<span><img src="photo1.jpg" width="400" height="300“
alt="Golden Gate Bridge"><br>Golden Gate Bridge </span></a>
</li>
The key CSS:
#gallery span { position: absolute;
opacity: 0;
transition: opacity 3s ease-in-out;
left: -1000px; }
#gallery a:hover span {
position: absolute;
top: 16px; left: 320px;
text-align: center; }
19
Copyright © Terry Felke-Morris http://terrymorris.net
What is Java?
•Object Oriented Programming (OOP)
•Developed by Sun Microsystems
•Java is not the same language as JavaScript.
•Java is more powerful and much more flexible
than JavaScript.
•Java can be used to:
• develop stand-alone executable applications
• applets that are invoked by Web pages
20
Copyright © Terry Felke-Morris http://terrymorris.net
Java Applets
Compiled -- translated from the
English-like Java statements to an encoded
form called Byte Code.
Use the “.class” file extension
Java Virtual Machine (JVM)
◦interprets the byte code into the proper machine
language for the operating system
◦After translation, the applet is executed and
appears on the Web page.
21
Copyright © Terry Felke-Morris http://terrymorris.net
Adding a Java Applet to a Web
Page
OBSOLETE: the applet element
HTML5: the object element
<object type="application/x-java-applet" width="610" height="30"
title="This Java Applet displays a message">
<param name="code" value="example.class">
<param name="textColor" value="#FF0000">
<param name="message" value="This is a Java Applet">
<param name="backColor" value="#FFFFFF">
Java Applets can be used to display text, manipulate graphics, play
games, and more.
Visit <a href="http://download.oracle.com/javase/tutorial/">Oracle</a>
for more information.
</object>
22
Copyright © Terry Felke-Morris http://terrymorris.net
Checkpoint
1. Describe a benefit of using the new
HTML5 video and audio elements.
2. Describe the purpose of the transform
property.
3. Describe a disadvantage of using Java
applets on web pages.
23
Copyright © Terry Felke-Morris http://terrymorris.net
What is JavaScript?
•Object-based client-side scripting language
•Originally developed by Brendan Eich at
Netscape
• JavaScript is NOT Java
•Manipulates the objects associated with a
web page document:
◦the window
◦the document
◦the elements such as forms, images, hyperlinks, and so on
24
Copyright © Terry Felke-Morris http://terrymorris.net
Common Uses of
JavaScript
Display a message box
Select list navigation
Edit and validate form information
Create a new window with a specified size and
screen position
Image Rollovers
Status Messages
Display Current Date
Calculations
25
Copyright © Terry Felke-Morris http://terrymorris.net
Document Object Model
(DOM)
A portion of the DOM is
shown at the left.
Defines every object
and element on a Web
page
Hierarchical structure
Accesses page elements
and apply styles to page
elements
26
Copyright © Terry Felke-Morris http://terrymorris.net
What is Ajax?
Asynchronous JavaScript and XML
“Ajax” – Jesse James Garrett at Adaptive Path
Existing technologies used in a new way
 Standards-based XHTML and CSS
 Document Object Model
 XML (and the related XSLT technology)
 Asynchronous data retrieval using XMLHttpRequest
 JavaScript
Very Basic Example:
◦ http://webdevfoundations.net/css
27
Copyright © Terry Felke-Morris http://terrymorris.net
Exploring JQueryA JavaScript library intended
to simplify client-side scripting
Example: http://webdevfoundations.net/jquery
API – Application Programming Interface
◦A protocol that allows software components to
communicate – interacting and sharing data.
The jQuery API can be used to configure many
interactive features, including:
◦image slideshows
◦animation (moving, hiding, fading)
◦event handling (mouse movements and mouse clicking)
◦document manipulation
◦Ajax
28
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 APIs
API – a protocol that allows software components to
communicate – interacting and sharing data
A variety of APIs that are intended to work with
HTML5, CSS, and JavaScript are currently under
development and in the W3C approval process,
including:
◦geolocation
◦web storage
◦offline web applications
◦canvas
29
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Geolocation
Allows your web page visitors to share their geographic
location
Their location may be determined by the IP address,
wireless network connection, local cell tower, or GPS
hardware depending on the type of device and browser.
JavaScript is used to work with the latitude and longitude
coordinates provided by the browser.
Examples:
◦http://webdevfoundations.net/geo and
http://html5demos.com/geo
30
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Web Storage
Traditionally, the JavaScript cookie object has been used to store
information in key-value pairs on the client (the website visitor’s
computer).
NEW FOR HTML5: Web Storage API
◦ provides two new ways to store information on the client side:
local storage and session storage.
◦ Advantage: increase in the amount of data that can be stored (5MB per domain).
◦ The localStorage object stores data without an expiration date.
◦ The sessionStorage object stores data only for the duration of the current browser
◦ JavaScript is used to work with the values stored in the localStorage and sessionStorage
objects.
Examples:
◦ http://webdevfoundations.net/storage and http://html5demos.com/storage
31
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Offline Web
Applications
An offline web application enables website visitors to view
documents and access web applications even when they are not
connected to the Internet.
A web application (app) can be written with HTML, CSS and
JavaScript and can run in any browser – as long as you are online.
An offline web application takes this one step further and stores the
HTML, CSS, and JavaScript files on the visitor’s device for use offline,
even when the device is not connected to the Internet.
Examples:
◦ http://html5demos.com/offlineapp
◦ http://www.w3schools.com/html/html5_app_cache.asp
32
Copyright © Terry Felke-Morris http://terrymorris.net
HTML5 Canvas ElementConfigures dynamic graphics
◦ Draw lines, shapes, text, image
◦ Interact with actions taken by the user
Canvas API (application programming interface)
JavaScript – client-side scripting language
33
<script type="text/javascript">
function drawMe() {
var canvas = document.getElementById("myCanvas");
if (canvas.getContext) {
var ctx = canvas.getContext("2d");
ctx.fillStyle = "rgb(255, 0, 0)";
ctx.font = "bold 3em Georgia";
ctx.fillText("My Canvas", 70, 100);
ctx.fillStyle = "rgba(0, 0, 200, 0.50)";
ctx.fillRect (57, 54, 100, 65);
}
}
</script>
Copyright © Terry Felke-Morris http://terrymorris.net
Checkpoint
1. Describe two uses of JavaScript.
2. Describe two technologies used in Ajax.
3. Describe the purpose of the HTML5
canvas element.
34
Copyright © Terry Felke-Morris http://terrymorris.net
Multimedia & Accessibility
•Provide links to plug-ins
•Provide text descriptions and captions
•Verify keyboard access
•Check for screen flickering
•Verify functionality if JavaScript is disabled
•If media is used for main navigation, provide plain text links
35
Copyright © Terry Felke-Morris http://terrymorris.net
Summary
This chapter introduced the HTML & CSS
techniques and technologies used to configure
sound, video, and interactivity on web pages.
Issues related to accessibility and copyright were
also discussed.
The number one reason for visitors to leave web
pages is too long of a download time. When
using multimedia, be careful to minimize this
issue.
36

More Related Content

Chapter11

  • 1. Copyright © Terry Felke-Morris http://terrymorris.net Web Development & Design Foundations with HTML5 8th Edition CHAPTER 11 KEY CONCEPTS 1
  • 2. Copyright © Terry Felke-Morris http://terrymorris.net Learning Outcomes In this chapter, you will learn how to ... ◦ Describe the purpose of plug-ins, helper applications, media containers, and codecs ◦ Describe types of multimedia files used on the Web ◦ Configure hyperlinks to multimedia files ◦ Configure audio and video on a web page with HTML5 elements ◦ Describe features and common uses of Adobe Flash, JavaScript, Java applets, Ajax, and jQuery ◦ Configure a Flash animation on a web page ◦ Configure a Java applet on a web page ◦ Create an interactive image gallery with CSS ◦ Configure the CSS3 transform and transition properties ◦ Describe the purpose of geolocation, web storage, offline web applications, and canvas HTML5 APIs. 2
  • 3. Copyright © Terry Felke-Morris http://terrymorris.net Helper Applications & Plug-ins Helper Application ◦A program that can be designated to handle a particular file type (such as .wav or .mpg) to allow the user to view or otherwise utilize the special file. ◦The helper application runs in a separate window from the browser. Plug-In ◦A newer and more common method ◦Plug-ins run right in the browser window so that media objects can be integrated directly into the web page. 3
  • 4. Copyright © Terry Felke-Morris http://terrymorris.net Containers & Codecs Container ◦Designated by the file extension – contains the media and metadata Codec ◦The algorithm used to compress the media HTML5 audio & video ◦Native to the browser ◦ISSUE: Browsers do not all support the same codecs ◦http://www.longtailvideo.com/html5/ 4
  • 5. Copyright © Terry Felke-Morris http://terrymorris.net Commonly Used Plug-ins Adobe Flash Player Adobe Reader Windows Media Player Apple Quicktime 5
  • 6. Copyright © Terry Felke-Morris http://terrymorris.net Common Audio File Types .wav Wave File .aiff Audio Interchange File Format .mid Musical Instrument Digital Interface (MIDI) .au Sun UNIX sound file .mp3 MPEG-1 Audio Layer-3 .ogg Ogg Vorbis (open-source) . m4a MPEG 4 Audio. This audio-only MPEG-4 format is supported by Quicktime, iTunes, and iPods. 6
  • 7. Copyright © Terry Felke-Morris http://terrymorris.net Common Video File Types .mov Quicktime .avi Microsoft Audio Video Interleaved .wmv Windows Media File .flv Flash Video File .mpg MPEG (Motion Picture Experts Group) .m4v .mp4 (MPEG-4) .ogv Ogg Theora (open-source) .webm VP8 codec (open video format, free) 7
  • 8. Copyright © Terry Felke-Morris http://terrymorris.net Copyright Issues •Only publish web pages, images, and other media that you have personally created or have obtained the rights or license to use. •Ask permission to use media created by another person instead of simply “grabbing” it. •All work (including web pages) are automatically copyrighted even if there is not copyright mark or date. •Fair Use Clause of the Copyright Act •Creative Commons – A new approach to copyright 8
  • 9. Copyright © Terry Felke-Morris http://terrymorris.net Configure Audio & Video Most basic method to provide audio or video files: Hyperlink <a href="wdfpodcast.mp3" title="Web Design Podcast">Web Design Podcast</a> 9
  • 10. Copyright © Terry Felke-Morris http://terrymorris.net Multimedia & Accessibility Provide alternate content ◦Transcript (for audio) ◦Captions (for video) ◦Text format 10
  • 11. Copyright © Terry Felke-Morris http://terrymorris.net What is Adobe Flash? •A popular multimedia application •Create multimedia which adds visual interest and interactivity to web pages •Flash movies are saved in “.swf” files •Perception of speedy display •.swf files play as they download •Flash Player • Free browser plug-in • Widely installed on desktop browsers but not well-supported by mobile devices 11
  • 12. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Embed Element <embed type="application/x-shockwave-flash" src="fall5.swf" width="640" height="100" quality="high” title="Fall Nature Hikes"> 12
  • 13. Copyright © Terry Felke-Morris http://terrymorris.net Checkpoint 1. List three common web browser plug-ins and describe their use. 2. Describe issues involved with adding media such as audio or video to a web page. 3. Describe a disadvantage of using Flash on a web page. 13
  • 14. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Audio & Source Elements <audio controls="controls"> <source src="soundloop.mp3" type="audio/mpeg"> <source src="soundloop.ogg" type="audio/ogg"> <a href="soundloop.mp3">Download the Audio File</a> (MP3) </audio> 14
  • 15. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Video & Source Elements <video controls="controls" poster="sparky.jpg" width="160" height="150"> <source src="sparky.m4v" type="video/mp4"> <source src="sparky.ogv" type="video/ogg"> <a href="sparky.mov">Sparky the Dog</a> (.mov) </video> 15
  • 16. Copyright © Terry Felke-Morris http://terrymorris.net CSS Drop Down Menu •Configure nav container with position relative •Code submenu (drop down menu) ul element with the parent li element •Configure submenu ul element to initially not display •Configure submenu ul element with absolute positioning 16
  • 17. Copyright © Terry Felke-Morris http://terrymorris.net CSS3 Transform Property Allows you to rotate, scale, skew, or move an element Example: transform: rotate(3deg); 17
  • 18. Copyright © Terry Felke-Morris http://terrymorris.net CSS3 Transition Property Provides for changes in property values to display in a smoother manner over a specified time. Example: nav a:hover { color: #869dc7; background-color: #eaeaea; transition: background-color 2s linear; } 18
  • 19. Copyright © Terry Felke-Morris http://terrymorris.net CSS Image Gallery Configure each thumbnail image: <li><a href="photo1.jpg"><img src="photo1thumb.jpg" width="100" height="75" alt="Golden Gate Bridge"> <span><img src="photo1.jpg" width="400" height="300“ alt="Golden Gate Bridge"><br>Golden Gate Bridge </span></a> </li> The key CSS: #gallery span { position: absolute; opacity: 0; transition: opacity 3s ease-in-out; left: -1000px; } #gallery a:hover span { position: absolute; top: 16px; left: 320px; text-align: center; } 19
  • 20. Copyright © Terry Felke-Morris http://terrymorris.net What is Java? •Object Oriented Programming (OOP) •Developed by Sun Microsystems •Java is not the same language as JavaScript. •Java is more powerful and much more flexible than JavaScript. •Java can be used to: • develop stand-alone executable applications • applets that are invoked by Web pages 20
  • 21. Copyright © Terry Felke-Morris http://terrymorris.net Java Applets Compiled -- translated from the English-like Java statements to an encoded form called Byte Code. Use the “.class” file extension Java Virtual Machine (JVM) ◦interprets the byte code into the proper machine language for the operating system ◦After translation, the applet is executed and appears on the Web page. 21
  • 22. Copyright © Terry Felke-Morris http://terrymorris.net Adding a Java Applet to a Web Page OBSOLETE: the applet element HTML5: the object element <object type="application/x-java-applet" width="610" height="30" title="This Java Applet displays a message"> <param name="code" value="example.class"> <param name="textColor" value="#FF0000"> <param name="message" value="This is a Java Applet"> <param name="backColor" value="#FFFFFF"> Java Applets can be used to display text, manipulate graphics, play games, and more. Visit <a href="http://download.oracle.com/javase/tutorial/">Oracle</a> for more information. </object> 22
  • 23. Copyright © Terry Felke-Morris http://terrymorris.net Checkpoint 1. Describe a benefit of using the new HTML5 video and audio elements. 2. Describe the purpose of the transform property. 3. Describe a disadvantage of using Java applets on web pages. 23
  • 24. Copyright © Terry Felke-Morris http://terrymorris.net What is JavaScript? •Object-based client-side scripting language •Originally developed by Brendan Eich at Netscape • JavaScript is NOT Java •Manipulates the objects associated with a web page document: ◦the window ◦the document ◦the elements such as forms, images, hyperlinks, and so on 24
  • 25. Copyright © Terry Felke-Morris http://terrymorris.net Common Uses of JavaScript Display a message box Select list navigation Edit and validate form information Create a new window with a specified size and screen position Image Rollovers Status Messages Display Current Date Calculations 25
  • 26. Copyright © Terry Felke-Morris http://terrymorris.net Document Object Model (DOM) A portion of the DOM is shown at the left. Defines every object and element on a Web page Hierarchical structure Accesses page elements and apply styles to page elements 26
  • 27. Copyright © Terry Felke-Morris http://terrymorris.net What is Ajax? Asynchronous JavaScript and XML “Ajax” – Jesse James Garrett at Adaptive Path Existing technologies used in a new way  Standards-based XHTML and CSS  Document Object Model  XML (and the related XSLT technology)  Asynchronous data retrieval using XMLHttpRequest  JavaScript Very Basic Example: ◦ http://webdevfoundations.net/css 27
  • 28. Copyright © Terry Felke-Morris http://terrymorris.net Exploring JQueryA JavaScript library intended to simplify client-side scripting Example: http://webdevfoundations.net/jquery API – Application Programming Interface ◦A protocol that allows software components to communicate – interacting and sharing data. The jQuery API can be used to configure many interactive features, including: ◦image slideshows ◦animation (moving, hiding, fading) ◦event handling (mouse movements and mouse clicking) ◦document manipulation ◦Ajax 28
  • 29. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 APIs API – a protocol that allows software components to communicate – interacting and sharing data A variety of APIs that are intended to work with HTML5, CSS, and JavaScript are currently under development and in the W3C approval process, including: ◦geolocation ◦web storage ◦offline web applications ◦canvas 29
  • 30. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Geolocation Allows your web page visitors to share their geographic location Their location may be determined by the IP address, wireless network connection, local cell tower, or GPS hardware depending on the type of device and browser. JavaScript is used to work with the latitude and longitude coordinates provided by the browser. Examples: ◦http://webdevfoundations.net/geo and http://html5demos.com/geo 30
  • 31. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Web Storage Traditionally, the JavaScript cookie object has been used to store information in key-value pairs on the client (the website visitor’s computer). NEW FOR HTML5: Web Storage API ◦ provides two new ways to store information on the client side: local storage and session storage. ◦ Advantage: increase in the amount of data that can be stored (5MB per domain). ◦ The localStorage object stores data without an expiration date. ◦ The sessionStorage object stores data only for the duration of the current browser ◦ JavaScript is used to work with the values stored in the localStorage and sessionStorage objects. Examples: ◦ http://webdevfoundations.net/storage and http://html5demos.com/storage 31
  • 32. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Offline Web Applications An offline web application enables website visitors to view documents and access web applications even when they are not connected to the Internet. A web application (app) can be written with HTML, CSS and JavaScript and can run in any browser – as long as you are online. An offline web application takes this one step further and stores the HTML, CSS, and JavaScript files on the visitor’s device for use offline, even when the device is not connected to the Internet. Examples: ◦ http://html5demos.com/offlineapp ◦ http://www.w3schools.com/html/html5_app_cache.asp 32
  • 33. Copyright © Terry Felke-Morris http://terrymorris.net HTML5 Canvas ElementConfigures dynamic graphics ◦ Draw lines, shapes, text, image ◦ Interact with actions taken by the user Canvas API (application programming interface) JavaScript – client-side scripting language 33 <script type="text/javascript"> function drawMe() { var canvas = document.getElementById("myCanvas"); if (canvas.getContext) { var ctx = canvas.getContext("2d"); ctx.fillStyle = "rgb(255, 0, 0)"; ctx.font = "bold 3em Georgia"; ctx.fillText("My Canvas", 70, 100); ctx.fillStyle = "rgba(0, 0, 200, 0.50)"; ctx.fillRect (57, 54, 100, 65); } } </script>
  • 34. Copyright © Terry Felke-Morris http://terrymorris.net Checkpoint 1. Describe two uses of JavaScript. 2. Describe two technologies used in Ajax. 3. Describe the purpose of the HTML5 canvas element. 34
  • 35. Copyright © Terry Felke-Morris http://terrymorris.net Multimedia & Accessibility •Provide links to plug-ins •Provide text descriptions and captions •Verify keyboard access •Check for screen flickering •Verify functionality if JavaScript is disabled •If media is used for main navigation, provide plain text links 35
  • 36. Copyright © Terry Felke-Morris http://terrymorris.net Summary This chapter introduced the HTML & CSS techniques and technologies used to configure sound, video, and interactivity on web pages. Issues related to accessibility and copyright were also discussed. The number one reason for visitors to leave web pages is too long of a download time. When using multimedia, be careful to minimize this issue. 36