Re: link areas within images

Dave_Raggett (
Mon, 21 Jun 93 16:28:53 BST

Kevin Altis says:

> I propose using the top left corner of the image as 0,0 (top,left) and
> specifying the rectangular areas within the image as top,left,bottom,right
> relative to the top left corner of the image, which fits with many of the
> existing image models. top,left,bottom,right will be specified as positive
> integers (you can't have a link area off the image). If a link area
> overlaps another, then the first link area specified in the HTML for the
> document would take precedence. Link areas within images should have
> several highlighting types, much like Bold, Italics, and Underline for
> text, so that link areas on the image can appear transparent to the user (a
> rectangular highlight would distract from the rest of the image), some
> highlight such as color or brightness change, or have a state showing the
> link has been visited. Supporting arbitrary closed polygons as link areas
> would require a little more work, but would be a good idea in the long run.

Kevin, you make like to look at HTML+ and how it supports figures using an
element specifying rectangular regions within the image and a URL to
traverse when the user clicks on this part of the image. The image data
is specified as either a URL or via embedded data on a non-HTML+ format (e.g.
for Adobe Illustrator drawings). This work is based on Pei Wei's experimental
DTD "HMML" and provides an alternative to making the server do all the work.

The coordinate scheme is (0,0) for the upper left corner to (1,1) for the
lower right. Scaled coordinates are used because pixel based coordinates are
inappropriate for drawings.

Dave Raggett

p.s. the HTML+ DTD is at