(e) Redundant text links shall be provided for each active region of a server-side image map.
Image maps incorporate links or script activations into one graphical image, as opposed to using separate free-standing graphical image buttons. When a
user selects an area of a server-side image map, the vertical and horizontal coordinates of the cursor location are transmitted back to the web page's
server, which then calculates in which region of the image the user's cursor is located, and activates the associated URL. The presence of a server-side
image map is more difficult to determine than it is for a client-side, although searching through a page's source code for the presence of the ISMAP attribute
in an <img> tag, or a form input tag specifying a parameter of IMAGE, can help.
For the purposes of image maps, it is a good idea to test this checkpoint with the more simplistic geometric shapes, such as squares, rectangles, circles,
triangles, and some polygons (i.e. shapes that are known to the average person, not a math major). If, as an example, an image map displayed the continental
United States, the area of Colorado could be accommodated by a geometric shape (rectangle), but the area of Maryland could not.
If every link region within an image map can be defined by a simplistic geometric shape, the image map must be converted to client-side. In the above example,
therefore, the image map of the United States could remain as server-side because the vast majority of the states cannot be defined as simplistic geometric
shapes.
Because the server-side image map is essentially a graphical image, it falls under the same jurisdiction as any other graphical image.
The text for the <img> tag's alt attribute should describe the appearance of the image map, and give a general but brief description of what information
can be accessed.
Browsers cannot indicate to a user the URL that will be followed when a region of a server-side image map is activated. Therefore, the redundant text link
is necessary to provide access to the page for anyone not able to see or accurately click on the map.
For every link or script activation that can be accessed via a server-side image map, a text hyperlink must be provided somewhere near the image map.
There might be a case where page layout concerns might not gracefully accommodate alternate links for an image map with ten or more links (e.g. an image
map of the United States would require fifty-one text links). A good alternative is to provide a pick list that allows the user to select the same values
that are contained on the image map. However, create a pick list that requires a submit button; assistive technologies cannot get past the first selection
of a pick list that submits the first value selected.
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