Using imagemap for your home page on IOHK
Web Server
IOHK Web Server provides "Internal Imagemap Support"
that can handle imagemap queries without launching the external
imagemap script. This not only provides faster mechanism for
handling imagemap queries but also decreases server load.
1.) Creating an image
2.) Creating an imagemap map file
3.) Referencing your imagemap in your HTML file
4.) Testing your imagemap
1.) Creating an image
Use your image creation and editing program to create your image.
2.) Creating an imagemap map file
Create your imagemap file with an extension .map.
The lines in the imagemap file can have one of several formats:-
directive value [x,y ...]
directive value "Menu text" [x,y ...]
directive value x,y ... "Menu text"
The directive is one of base, default, poly,
circle, rect, or point. The value is an absolute
or relative URL, or one of the special values listed below. The
coordinates are x,y pairs separated by whitespace. The quoted
text is used as the text of the link if a imagemap menu is generated.
Lines beginning with '#' are comments.
Imagemap File Directives
There are six directives allowed in the imagemap file. The directives
can come in any order, but are processed in the order they are found
in the imagemap file.
- base Directive
- Has the effect of <BASE href="value">. The
non-absolute URLs of the map-file are taken relative to this value.
The base directive overrides ImapBase as set in a
.htaccess file or in the server configuration files. In the absence
of an ImapBase configuration directive, base defaults to
http://server_name/.
base_uri is synonymous with base. Note that
a trailing slash on the URL is significant.
- default Directive
- The action taken if the coordinates given do not fit any of the
poly, circle or rect
directives, and there are no point directives. Defaults
to nocontent in the absence of an ImapDefault
configuration setting, causing a status code of 204 No
Content to be returned. The client should keep the same
page displayed.
- poly Directive
- Takes three to one-hundred points, and is obeyed if the user selected
coordinates fall within the polygon defined by these points.
- circle Directive
- Takes the center coordinates of a circle and a point on the circle. Is
obeyed if the user selected point is with the circle.
- rect Directive
- Takes the coordinates of two opposing corners of a rectangle. Obeyed
if the point selected is within this rectangle.
- point Directive
- Takes a single point. The point directive closest to the user
selected point is obeyed if no other directives are satisfied.
Note that default will not be followed if a
point directive is present and valid coordinates are
given.
Values
The values for each of the directives can any of the following:
- a URL
- The URL can be relative or absolute URL. Relative URLs can
contain '..' syntax and will be resolved relative to the
base value.
base itself will not resolved according to the current
value. A statement base mailto: will work properly, though.
- map
- Equivalent to the URL of the imagemap file itself. No
coordinates are sent with this, so a menu will be generated
unless ImapMenu is set to 'none'.
- menu
- Synonymous with map.
- referer
- Equivalent to the URL of the referring document.
Defaults to http://servername/ if no Referer:
header was present.
- nocontent
- Sends a status code of 204 No Content,
telling the client to keep the same page displayed. Valid for
all but base.
- error
- Fails with a 500 Server Error. Valid for all but
base, but sort of silly for anything but
default.
Coordinates
- 0,0 200,200
- A coordinate consists of an x and a y value
separated by a comma. The coordinates are separated from each other
by whitespace. To accommodate the way Lynx handles imagemaps, should a
user select the coordinate 0,0, it is as if
no coordinate had been selected.
Quoted Text
- "Menu Text"
- After the value or after the coordinates, the line optionally may
contain text within double quotes. This string is used as the
text for the link if a menu is generated:
<a href="http://www.iohk.com/">Menu text</a>
If no quoted text is present, the name of the link will be used
as the text:
<a href="http://www.iohk.com/">http://www.iohk.com</a>
It is impossible to escape double quotes within this text.
3.) Referencing your imagemap in your HTML file
You can reference your imagemap in your HTML file using either relative
or absolute URL. For example, if your imagemap file 'sample.map' is in the
same directory of your HTML file and uses the image 'sample.gif' for the
map, then includes the following tags in your HTML file
<A HREF="sample.map">
<IMG SRC="sample.gif" ISMAP>
</A>
To use absolute URL, if the imagemap file 'sample.map' is in your home
directory
<A HREF="http://www.iohk.com/UserPages/login_id/sample.map">
<IMG SRC="sample.gif" ISMAP>
</A>
4.) Testing your imagemap
Upload your HTML file, image file and imagemap file to IOHK Web Server,
click somewhere on the image, and see what happens.
An example
Click here for a demo of imagemap
on IOHK Web Server.
- Internet Online Hong Kong Limited, March 1997.
