Re: Dynamic imagemaps

David Perrell (
Fri, 7 Mar 1997 12:30:23 -0800

Message-Id: <>
From: "David Perrell" <>
To: <>
Subject: Re: Dynamic imagemaps
Date: Fri, 7 Mar 1997 12:30:23 -0800

Neil St.Laurent wrote:
> When/If this happens it would be nice to see very clear precise 
> details of how the relative values are to work

1. size the image as specified for display.

2. determine the map coordinates in pixels by applying the percentages
to the displayed image size, rounding downward for minimal processing

The maximum error would be less than a pixel, wouldn't it? Not likely
to be discernible by a user with a mouse.

The greater concern is sizing the image for display. Any image with
size specified in points or ems may need to be resized at a percentage
unknown to the author. Again, it's faster to round down. But when
anti-aliasing is supported, placement on sub-pixel boundaries is
possible. In this case, 100% in the imagemap would correspond to the
first pixel fully occupied by the image.

David Perrell