Lecture 1c - HTML5

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10 déc. 2013 (il y a 3 années et 10 mois)

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HTML5

Kevin Curran

HTML5

~= HTML + CSS3 + JavaScript APIs


Internet Explorer 9 Online Test Site

http://ie.microsoft.com/testdrive/


HTML


Draft Specification of the next iteration of HTML


HTML 4 (1997) and XHTML 1 (2000)


Clearer separation of data and layout/style


Makes what you would already do in HTML easier


New Content Tags


<
nav
>, <section>, <header>, <article>, <aside>, <summary>


New Media Tags


<video>, <audio>, <figure>


New Dynamic drawing
<canvas>
graphic tag


A tag that allows programmatic drawing via JavaScript


Inline metadata to help search engines identify content


<span
itemprop
=“agency”>Moxie Interactive</span>

CSS3


Specification currently under active development since 2005


Improved selectors for determining which content to effect


(good support across modern browsers)


Embeddable font support (TTF, OTF)


Improved text layout with column support


Rounded corners, Reflections (WebKit)


Multiple backgrounds, transforms (rotation, scale, etc), animations (WebKit)

JavaScript APIs


Local data storage


Application Cache (offline access)


Multitasking (Worker processes)


Sockets (real
-
time server communication: chat, games, etc.)


Native Drag and Drop events


GeoLocation


Lots of active 3
rd

party libraries (Prototype, jQuery, etc)

The Good News!


Good support on modern mobile devices (iOS, Android)


Simpler, more intuitive syntax


Video and Audio without requiring a plugin


Incremental improvements to previous HTML challenges


Much needed next step in HTML evolution


Creative enhancements: Rounded corners, gradients, text layout


Emergence of more advanced technologies such as O3D (WebGL)


Easier SEO than plugin technologies


Promising Mobile JS Frameworks (Sencha, jQTouch)

The Bad News


The HTML5 spec is DRAFT and is in ongoing development (change)


Video support is not standardized


Not currently a single codec that all browsers will support


Google WebM (VP 8) (open sourced by Google)


Ogg Theora (open source)


h.264/MP4 (potential licensing issues)


No supported DRM for video or audio


Currently no support for cue points or alpha (transparent) video

The Bad News…Continued


Limited desktop browser support


Only the newest and best have reasonable support


Internet Explorer will not have decent support until IE9


Challenges getting consistent page display across browsers


Graceful page degradation is potentially complex


Currently no designer tools for creating HTML5 animation or interactivity
(all must be implemented by a developer)


Limited developer debugging tools

Introduction



The web is constantly evolving. New and innovative websites are being created
every day, pushing the boundaries of HTML in every direction.




HTML 4 has been around for nearly a decade now, and publishers seeking new
techniques to provide enhanced functionality are being held back by the constraints
of the language and browsers.




To give authors more flexibility and interoperability, and enable more interactive and
exciting websites and applications, HTML 5 introduces and enhances a wide range
of features including form controls, APIs, multimedia, structure, and semantics


Introduction



Work on HTML 5, which commenced in 2004, is currently being carried out in a
joint effort between the W3C HTML WG and the WHATWG.




Many key players are participating in the W3C effort including representatives
from the four major browser vendors: Apple, Mozilla, Opera, and Microsoft; and a
range of other organisations and individuals with many diverse interests and
expertise.




Note that the specification is still a
work in progress

and quite a long way from
completion.




As such, it is possible that any feature discussed in this lecture may change in
the future.

Good Example of the Power of HTML5

http://thewildernessdowntown.com/

HTML5 Demos

http://html5demos.com/

Structure


HTML 5 introduces a whole set of new elements that make it much easier to
structure pages. Most HTML 4 pages include a variety of common structures, such
as headers, footers and columns and today, it is fairly common to mark them up
using div elements, giving each a descriptive id or class.

Diagram illustrates a typical
two
-
column layout marked up
using divs with id and class
attributes. It contains a
header, footer, and horizontal
navigation bar below the
header. The main content
contains an article and
sidebar on the right.

Structure

The use of div elements is largely because current versions of HTML 4 lack the
necessary semantics for describing these parts more specifically. HTML 5 addresses this
issue by introducing new elements for representing each of these different sections.

The div elements can be replaced with the new elements: header, nav, section, article, aside, & footer.

Markup

The markup for that document could look like the following:


<body>


<header>...</header>


<nav>...</nav>


<article>


<section>


...


</section>


</article>


<aside>...</aside>


<footer>...</footer>

</body>

Markup


There are several advantages to using these elements. When used in conjunction
with the heading elements (h1 to h6), all of these provide a way to mark up nested
sections with heading levels, beyond the six levels possible with previous versions
of HTML.


The specification includes a detailed algorithm for generating an outline that takes
the structure of these elements into account and remains backwards compatible
with previous versions.



This can be used by both authoring tools and browsers to generate tables of
contents to assist users with navigating the document.

Markup


For example, the following markup structure marked up with nested section and h1
elements:


<section>


<h1>Level 1</h1>


<section>


<h1>Level 2</h1>


<section>


<h1>Level 3</h1>


</section>


</section>

</section>



Note that for better compatibility with current browsers, it is also possible to make use of the other
heading elements (h2 to h6) appropriately in place of the h1 elements

Sections


By identifying the purpose of sections in the page using specific sectioning
elements, assistive technology can help the user to more easily navigate the page.



For example, they can easily skip over the navigation section or quickly jump from
one article to the next without the need for authors to provide skip links.


Authors also benefit because replacing many of the divs in the document with one
of several distinct elements can help make the source code clearer and easier to
author.

Header Section


The header element represents the header of a section. Headers may contain
more than just the section’s heading

for example it would be reasonable for the
header to include sub headings, version history information or bylines.


<header>


<h1>A Preview of HTML 5</h1>


<p class="byline">By Lachlan Hunt</p>

</header>


<header>


<h1>Example Blog</h1>


<h2>Insert tag line here.</h2>

</header>

Footer Section

The footer element represents the footer for the section it applies to.


A footer typically contains information about its section such as who wrote it,
links to related documents, copyright data, and the like.


<footer>© 2007 Example Inc.</footer>

Nav Element


The nav element represents a section of navigation links. It is suitable for either
site navigation or a table of contents.


<nav>


<ul>


<li><a href="/">Home</a></li>


<li><a href="/products">Products</a></li>


<li><a href="/services">Services</a></li>


<li><a href="/about">About</a></li>


</ul>

</nav>

Aside Element


The aside element is for content that is tangentially related to the content around it,
and is typically useful for marking up sidebars.


<aside>


<h1>Archives</h1>


<ul>


<li><a href="/2007/09/">September 2007</a></li>


<li><a href="/2007/08/">August 2007</a></li>


<li><a href="/2007/07/">July 2007</a></li>


</ul>


</aside>

Section Element


The section element represents a generic section of a document or application,
such as a chapter, for example.


<section>


<h1>Chapter 1: The Period</h1>


<p>It was the best of times, it was the worst of times,


it was the age of wisdom, it was the age of foolishness,


it was the epoch of belief, it was the epoch of incredulity,


it was the season of Light, it was the season of Darkness,


...</p>


</section>

Article Element


The article element represents an independent section of a document, page or
site. It is suitable for content like news or blog articles, forum posts or individual
comments.


<article id="comment
-
2">


<header>


<h4><a href="#comment
-
2" rel="bookmark">Comment #2</a>


by <a href="http://example.com/">Jack O'Niell</a></h4>


<p><time datetime="2007
-
08
-
29T13:58Z">August 29th, 2007 at 13:58</time>


</header>


<p>That's another great article!</p>

</article>

Video and Audio


In recent years, video and audio on the web has become increasingly viable and
sites like
YouTube
,
Viddler
,
Revver
,
MySpace
, and dozens of others are making it
easy for anyone to publish video and audio.


However, since HTML currently lacks the necessary means to successfully embed
and control multimedia itself, many sites are relying on Flash to provide that
functionality.


Although it is possible to embed multimedia using various plug
-
ins (such as
QuickTime, Windows Media, etc.), Flash is currently the only widely deployed
plugin that provides a cross
-
browser compatible solution with the desired APIs for
developers.

Video and Audio

As evidenced by the various Flash
-
based media players, authors are interested in
providing their own custom
-
designed user interfaces, which generally allow users to
play, pause, stop, seek, and adjust volume.


The plan is to provide this functionality in browsers by adding native support for
embedding video and audio and providing DOM APIs for scripts to control the
playback.


The new video and audio elements make this really easy.


Most of the APIs are shared between the two elements, with the only differences
being related to the inherent differences between visual and non
-
visual media.


Video and Audio

Both Opera and WebKit have released builds with partial support for the video
element.


You may download the experimental build of Opera or a recent nightly build of
WebKit to try out these examples. Opera includes support for Ogg Theora and
WebKit supports all the formats that are supported by QuickTime, including third
party codecs.


The simplest way to embed a video is to use a video element and allow the browser
to provide a default user interface. The controls attribute is a boolean attribute that
indicates whether or not the author wants this UI on or off by default.


<video src="video.ogv" controls poster="poster.jpg" width="320" height="240"> <a
href="video.ogv">Download movie</a> </video>

Video and Audio

The optional poster attribute can be used to specify an image which will be displayed
in place of the video before the video has begun playing.


Although there are some video formats that support their own poster frame feature,
such as MPEG
-
4, this provides an alternative solution that can work independently of
the video format.


It is just as simple to embed audio into a page using the audio element. Most of the
attributes are common between the video and audio elements, although for obvious
reasons, the audio element lacks the width, height, and poster attributes.


<audio src="music.oga" controls> <a href="music.oga">Download song</a> </audio>

Source Element


HTML 5 provides the source element for specifying alternative video and audio
files which the browser may choose from based on its media type or codec
support.


The media attribute can be used to specify a media query for selection based on
the device limitations and the type attribute for specifying the media type and
codecs.


Note that when using the source elements, the src attribute needs to be omitted
from their parent video or audio element or the alternatives given by the source
elements will be ignored.

Video and Audio

<video poster="poster.jpg">


<source src="video.3gp" type="video/3gpp"


media="handheld">


<source src="video.ogv" type="video/ogg;


codecs=theora, vorbis">


<source src="video.mp4" type="video/mp4">

</video>

<audio>


<source src="music.oga" type="audio/ogg">


<source src="music.mp3" type="audio/mpeg">

</audio>

Video and Audio


For authors who want a little more control over the user interface so that they can
make it fit the overall design of the web page, the extensive API provides several
methods and events to let scripts control the playback of the media. The simplest
methods to use are the play(), pause(), and setting currentTime to rewind to the
beginning. The following example illustrates the use of these.


<video src="video.ogg" id="video"></video>

<script>


var video = document.getElementById("video");

</script>

<p><button type="button" onclick="video.play();">Play</button>


<button type="button" onclick="video.pause();">Pause</button>


<button type="button" onclick="video.currentTime = 0;">

Document Representation


Unlike previous versions of HTML and XHTML, which are defined in terms of
their syntax, HTML 5 is being defined in terms of the Document Object Model
(DOM)

the tree representation used internally by browsers to represent the
document. For example, consider a very simple document consisting of a title,
heading and paragraph. The DOM tree could look something like this:

The DOM tree includes a title element in the head and h1 and p elements in the body.

HTML & XML


The advantage of defining HTML 5 in terms of the DOM is that the language itself
can be defined independently of the syntax.



There are primarily two syntaxes that can be used to represent HTML documents:
the HTML serialisation (known as HTML 5) and the XML serialisation (known as
XHTML 5).



The HTML serialisation refers to the syntax that is inspired by the SGML syntax
from earlier versions of HTML, but defined to be more compatible with the way
browsers actually handle HTML in practice.


HTML

<!DOCTYPE html>

<html>


<head>


<title>An HTML Document</title>


</head>


<body>


<h1>Example</h1>


<p>This is an example HTML document.


</body>

</html>



Note that like previous versions of HTML, some tags are optional and are
automatically implied.


XML Serialisation


The XML serialisation refers to the syntax using XML 1.0 and namespaces, just
like XHTML 1.0.


<html xmlns="http://www.w3.org/1999/xhtml">


<head>


<title>An HTML Document</title>


</head>


<body>


<h1>Example</h1>


<p>This is an example HTML document.</p>


</body>

</html>



Excluding differences in whitespace and the presence of the xmlns attribute, those
two examples are equivalent.

MIME

Browsers use the MIME type to distinguish between the two.


Any document served as text/html must conform to the requirements for the HTML
serialisation and any document served with an XML MIME type such as
application/
xhtml+xml

must conform to the requirements for the XML serialisation.


Authors should make an informed choice about which serialisation to use, which may
be dependent on a number of different factors.


Authors should not be unconditionally forced to use one or the other; each one is
optimised for different situations.


Benefits of Using HTML



Backwards compatible with existing browsers




Authors are already familiar with the syntax




The lenient and forgiving syntax means there will be no user
-
hostile “Yellow Screen
of Death” if a mistake accidentally slips through




Convenient shorthand syntax, e.g. authors can omit some tags and attribute values




(NOTE:
The
Yellow Screen of Death

occurs when an ASP.NET web application
encounters a problem and crashes.

It is also used to refer to an error in the parsing
of an XML document in a web browser.
)

Benefits of Using XHTML



Strict XML syntax encourages authors to write well
-
formed
markup
, which some
authors may find easier to maintain





Integrates directly with other XML vocabularies, such as SVG and
MathML




Allows the use of XML Processing, which some authors use as part of their editing
and/or publishing processes


What HTML5 is
NOT


A magic bullet for all your mobile and desktop
-
to
-
mobile woes


A replacement for technologies such as Flash or Silverlight


Immersive RLP’s would be much more time consuming


Certain functionality would not be possible or cost
-
prohibitive


While HTML5 quickly fixes some small
-
scale HTML issues (video, audio,
layout and fonts), it does not instantly solve architectural needs for large
-
scale immersive cross
-
platform applications

Fluid Ping
-
Pong


http://anirudhjoshi.github.com/fluid_table_tennis/#



Fluid Ping
-
Pong uses a real
-
time fluid dynamics engine.




The extra dynamics are evident from the name: the ball moves in a somewhat
viscous fluid. In addition to moving the paddles PONG
-
style, players can send jets
into the ambient fluid, or "suck" the fluid back.




Because the gameplay is based on real fluid dynamics, the motion of the ball can
be unpredictable,.




Having two players means there could be two competing streams of fluid colliding,
with turbulence at the boundary.

Summary

Good

HTML5 has new standards and features that are long overdue

Allows display of multimedia content without need of a plugin

Good and rapidly progressing mobile support


Bad

Spotty desktop browser support

Complexity creating consistent experiences across platforms

Technical limitations on what can creatively be done

Recommendations


Still consider separate desktop and mobile experiences


For HTML
-
based desktop experiences, consider simplified modular layout for
streamlined restyling on mobile platforms


Don’t expect what has been traditionally executed in Flash or Silverlight to be
cost
-
effective or even possible in HTML


Clearly understand the target
USER

and their needs before recommending a
technology


Design for the chosen technology

BrowserQuest


https://hacks.mozilla.org/2012/03/browserquest/

My Favourite……Sinuous


www.sinuousgame.com

Related Links


http://www.pcworld.com/article/196670/google_announces_webm_video_format_the_future_of_html5_video.html


http://en.wikipedia.org/wiki/HTML5


http://www.deepbluesky.com/blog/
-
/browser
-
support
-
for
-
css3
-
and
-
html5_72/


http://www.html5test.com/


http://newteevee.com/2010/05/13/hulu
-
html5
-
isnt
-
ready
-
for
-
prime
-
time/


http://www.htmlgoodies.com/daily_news/article.php/386914/Is
-
HTML
-
5
-
the
-
Flash
-
Killer
-
Its
-
sure
-
got
-
the
-
potential.htm


http://slides.html5rocks.com/


http://www.deepbluesky.com/blog/
-
/browser
-
support
-
for
-
css3
-
and
-
html5_72/


http://www.sencha.com/products/touch/



HTML5 Online Presentation

http://slides.html5rocks.com/#slide1