I have a similar question.
My working client-side image map has several hundred AREAs defining a
MAP on a multi-megapixel image. Now, I would like to modify my code so
that each AREA gets highlighted when the mouse hovers over it.
A technique I've seen involves swapping the entire image with another
(one for each area) that is identical except for the highlighting. This
is practical for a small image and just a few areas. However it is
impractical to pre-store and download several hundred slightly-differing
copies of my multi-megapixel image.
I would prefer to draw each area directly on the image when the mouse
hovers, then restore the original image when the mouse leaves. That way
only two images are needed: the unmodified original, and the scratch
version onto which each highlighted AREA is drawn. What I'm missing is
I tried Walter Zorn's JSGraphics package
but have been unable to make it modify a displayed image.
Surely what I'm trying to do can't be all that unusual. Can anyone
point me to a working example?