AREA - Image Map Region

<AREA>

SHAPE=[ rect | circle | poly | default ] (shape of region)
ALT=Text (alternate text)
COORDS=Coords (coordinates of region)
HREF=url (linked resource)
NOHREF (inactive region)
TARGET=FrameTarget (frame to render link in)
TABINDEX=Number (position in tabbing order)
ID=string
CLASS=string
STYLE=string
TITLE=string
LANG=Language (i.e. RU - Russian)
DIR=ltr|rtl
SCRIPTING EVENTS=string
ONFOCUS=Script (region received focus)
ONBLUR=Script (region lost focus)

Nothing

MAP

The AREA element defines a map region in a client-side image map. Each map region is a piece of the image with a different action when clicked.

The SHAPE and COORDS attributes of AREA specify what part of the image is included in the region. The default SHAPE value is rect, which defines a rectangular region using COORDS="left, top, right, bottom". Other SHAPE values are

• default, which specifies the entire image;
• circle, which specifies a circular region using COORDS="center-x, center-y, radius";
• poly, which specifies a polygonal region using COORDS="x₁, y₁, x₂, y₂, ..., x_N, y_N".

Coordinate values are relative to the top left corner of the object and may be expressed as pixels or percentages. A percentage radius value for circular regions is calculated relative to the smaller of the object's width and height. If two or more regions overlap, the earliest specified region takes precedence.

The HREF attribute specifies a link to another resource, such as an HTML document or a JPEG image. The TITLE attribute can be used to briefly describe the contents of the link and is rendered as a "tooltip" by some visual browsers. The boolean NOHREF attribute indicates that the region has no link.

The required ALT attribute provides alternate text for those not loading images. Effective ALT text should generally give the function of the map region rather than a description of the region. For example, ALT="WDG Home" or ALT="Web Design Group" would be more appropriate than ALT="WDG Logo" for a map region whose link went to the WDG home page. Good ALT text is crucial to the document's accessibility for the significant portion of users who do not load images.

The TARGET attribute is used with frames to specify in which frame the link should be rendered. If no frame with such a name exists, the link is rendered in a new window unless overridden by the user. Special frame names begin with an underscore:

• _blank renders the link in a new, unnamed window
• _self renders the link in the current frame (useful for overriding a BASE TARGET)
• _parent renders the link in the immediate FRAMESET parent
• _top renders the link in the full, unframed window

The ACCESSKEY attribute specifies a single Unicode character as a shortcut key for following the link. Entities (e.g. &eacute;) may be used as the ACCESSKEY value.

The ID attribute uniquely identifies an element within a document. No two elements can have the same ID value in a single document. The attribute's value must begin with a letter in the range A-Z or a-z and may be followed by letters (A-Za-z), digits (0-9), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").

The following example uses the ID attribute to identify each of the first two paragraphs of a document:

<P ID=firstp>My first paragraph.</P>
<P ID=secondp>My second paragaph.</P>

The paragraphs in the example could have style rules associated with them through their ID attributes. The following Cascading Style Sheet defines unique colors for the two paragraphs:

P#firstp {
  color: navy;
  background: transparent
}

P#secondp {
  color: black;
  background: transparent
}

The paragraphs in the initial example could also be used as a target anchor for links:

<P>See <A HREF="#firstp">the opening paragraph</A> for more information.</P>

The CLASS attribute specifies the element to be a member of one or more classes. Classes allow authors to define specific kinds of a given element. For example, an author could use <CODE CLASS=Java> when giving Java code and <CODE CLASS=Perl> when giving Perl code.

Unlike with the ID attribute, any number of elements can share the same class. An element may also belong to multiple classes; the CLASS attribute value is a space-separated list of class names.

Note that most current browsers do not support multiple classes. Such browsers typically ignore a CLASS attribute that specifies multiple classes.

The CLASS attribute is particularly useful when combined with style sheets. For example, consider the following navigation bar:

<DIV CLASS=navbar>
<P><A HREF="/">Home</A> | <A HREF="./">Index</A> | <A HREF="/search.html">Search</A></P>
<P><A HREF="/"><IMG SRC="logo.gif" ALT="" TITLE="WDG Logo"></A></P>
</DIV>

This example's use of the CLASS attribute allows style rules to easily be added. The following Cascading Style Sheet suggests a presentation for the preceding example:

.navbar {
  margin-top: 2em;
  padding-top: 1em;
  border-top: solid thin navy
}

.navbar IMG { float: right }

@media print {
  .navbar { display: none }
}

The STYLE attribute allows authors to specify style rules inline for a single occurrence of an element. An example follows:

<P>A popular font for on-screen reading is <SPAN STYLE="font-family: Verdana">Verdana</SPAN>.</P>

When the STYLE attribute is used, a default style sheet language must be specified for the document by setting the Content-Style-Type HTTP header to the media type of the style sheet language. The previous example could use the following META element in the document's HEAD:

<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">

In most cases, use of the CLASS or ID attributes is a better choice than using STYLE since ID and CLASS can be selectively applied to different media and since they provide a separation of content and presentation that often simplifies maintenance.

The TITLE attribute provides a title for an element and is commonly implemented as a "tooltip" on visual browsers, though many browsers lack support for TITLE. The attribute is most useful with A, LINK, IMG, and OBJECT elements, where it provides a title for the linked or embedded resource. Some examples follow:

• <A HREF="mailto:liam@htmlhelp.com" TITLE="Feedback on HTML 4.0 Reference">liam@htmlhelp.com</A>
• <A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html" TITLE="CGI.pm - a Perl5 CGI Library">CGI.pm</A>
• <LINK REL=Alternate HREF="index.fr.html" HREFLANG=fr LANG=fr TITLE="Version française">
• <OBJECT CLASSID="java:Yahtzee.class" CODETYPE="application/java" WIDTH=400 HEIGHT=250 STANDBY="Ready to play Yahtzee?" TITLE="My Yahtzee Game">
<IMG SRC="yahtzee.gif" ALT="" TITLE="A Yahtzee animation">
Yahtzee is my <EM>favorite</EM> game!
</OBJECT>

TITLE is also helpful with the ABBR and ACRONYM elements to provide the long form of the abbreviation. Examples:

• He weighs 180 <ABBR TITLE=pounds>lbs.</ABBR>
• <ABBR TITLE="Parti Québécois" LANG=fr-CA>PQ</ABBR>
• <ACRONYM TITLE="North Atlantic Treaty Organization">NATO</ACRONYM>

The LANG attribute specifies the language of an element's attribute values and its content, including all contained elements that do not specify their own LANG attribute. While the LANG attribute is not widely supported, its use may help search engines index a document by its language while allowing speech synthesizers to use language-dependent pronunciation rules. As well, visual browsers can use the language's proper quotation marks when rendering the Q element.

The attribute value is case-insensitive, and should be specified according to RFC 1766; examples include en for English, en-US for American English, and ja for Japanese. Whitespace is not allowed in the language code.

Use of the LANG attribute also allows authors to easily change the style of text depending on the language. For example, a bilingual document may have one language in italics if rendered visually or a different voice if rendered aurally. The HTML of such a document might be as follows:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
   "http://www.w3.org/TR/REC-html40/strict.dtd">
<TITLE>Welcome - Bienvenue</TITLE>
<H1>
  <SPAN LANG=en>Welcome</SPAN> -
  <SPAN LANG=fr>Bienvenue</SPAN>
</H1>
<P LANG=en>This paragraph is in English.</P>
<P LANG=fr>Ce paragraphe est en français.</P>
...

A document's primary language may be set using the LANG attribute on the HTML element, or, alternatively, by using the Content-Language HTTP header.

A number of attributes that define client-side scripting events are common to most elements. The attribute value is a script--typically a function call or a few short statements--that is executed when the event occurs. The value may contain entities (e.g., &quot;).

The following example features JavaScript code to handle two events of a submit button, giving the user a reminder in the status bar when the mouse moves over the button and clearing the status bar when the mouse moves away. Note that the attribute values are delimited by single quotes since double quotes are used within them.

<INPUT TYPE=submit ONMOUSEOVER='window.status="Did you fill in all required fields?";' ONMOUSEOUT='window.status="";'>

When an event attribute is used, a default scripting language must be specified for the document by setting the Content-Script-Type HTTP header to the media type of the scripting language. The previous example could use the following META element in the document's HEAD:

<META HTTP-EQUIV="Content-Script-Type" CONTENT="text/javascript">

The common event attributes are device-dependent and largely tailored for the graphical user interface. The available events are as follows:

• ONCLICK, when the mouse button is clicked on an element;
• ONDBLCLICK, when the mouse button is double-clicked on an element;
• ONMOUSEDOWN, when the mouse button is pressed over an element;
• ONMOUSEUP, when the mouse button is released over an element;
• ONMOUSEOVER, when the mouse is moved onto an element;
• ONMOUSEMOVE, when the mouse is moved while over an element;
• ONMOUSEOUT, when the mouse is moved away from an element;
• ONKEYPRESS, when a key is pressed and released over an element;
• ONKEYDOWN, when a key is pressed down over an element;
• ONKEYUP, when a key is released over an element.