Re: New <AREA> syntax proposal

Jeff de la Beaujardiere (
Wed, 11 Jun 1997 17:41:31 -0400

Date: Wed, 11 Jun 1997 17:41:31 -0400
Message-Id: <>
From: Jeff de la Beaujardiere <>
In-reply-to: <199706111647.JAA05275@Comps.COM> (message from Dan Miser on Wed,
Subject: Re: New <AREA> syntax proposal

Dan Miser writes:
> One last point, as far as the UA not knowing the color, it is a simple
> matter to figure out the color of the point clicked. After all, the UA
> already returns the coordinates of the point clicked!

I wonder whether it is that simple.  The color shown on the screen may be
different than that in the original image due to colormap issues, so the UA
would probably need to read the image file to determine the color.  Doing so
dynamically (i.e., while the mouse is wandering over some large image) might
be a problem.

Something simpler to implement might be mathematical equations and relations
to specify regions and shapes.  Recalling that y=0 is the top of the image,
and assuming that angle brackets are permitted within quoted CDATA, one
could select regions like:

   The quadrant above a horizontal line and to the right of a vertical one:
   <area eqn="y < 50, x > 100" href="foo.html">

   Everything below a diagonal line:
   <area eqn="y > 3*x + 40" href="bar.html">

   The inside of an parabola:
   <area eqn="y > x**2 + 4*x + 10" href="bletch.html">

   The _perimeter_ of a circle with radius 20 pixels:
   <area eqn="x**2 + y**2 = 400" href="bletch.html">

   The region above a logarithmic curve:
   <area eqn="y < log(x)" href="metabletch.html">

Of course, this can all be done on the server side, but doing so defeats the
utility of client-side maps.


  = J-F Pitot de La Beaujardiere