generally improve the clarity and appearance of the maps.  The scale factor
buttons numbered 1-5 actually correspond to scale factors of 1, 1.5, 2, 2.5,
and 3.

Notice that the floorimages table in the database now has an integer "scale"
column to distinguish the cached zoomed-in images with a suffix "-[1-5].jpg" .

I use jpeg files instead of the png files that were used before.  They look as
good or better, and are a third the size.  Panning around at a given zoom
factor just involves cropping out a different rectangle of the scaled-up
images.

The 0311X064_[1-4]fl.pdf floor map files we got from Michael Kay started
out life in Adobe Illustrator.  Although GhostScript/gv crash while
trying to draw the pdf files, extracting them into PostScript files in
Acrobat on Coke allows GhostScript to render them flawlessly.

I started out using gs to render jpeg files in the shell, and then
found that ImageMagick uses the same GhostScript renderer, and nicely
handles cropping, drawing and annotations, and format conversion as well.

The PostScript rendering gets slow at higher zoom factors.  So I cache the
zoomed floor images, scaled up by rendering the PostScript files at a finer
dot-pitch (density) in GhostScript, and then cropping out the right rectangle
to register them properly.

For readability, and to avoid having the thin lines and bitmap fonts used in
some parts of the PostScript map from falling between the pixel cracks, I
actually render at twice the pixel density and filter down to the final image
with a gaussian -sharpen option to keep it from looking blurry.

ImageMagick is callable from both the shell and as the Image::Magick package
in Perl.  I converted the Perl logic in floormap.in to use Image::Magick
instead of the GD graphics library, resulting in anti-aliased (smoothed)
drawing of the wireless node dots and labels on floor maps for a better
appearance.  Then I added optional scaling and centering arguments which
select the proper cached zoomed-in image, and drive the logic for cropping and
drawing.

I modified the floormap.php3 file to wrap an input form around a set of zoom
control buttons and the floormap image.  The zoom buttons set the scale
argument to the Perl floormap script called on the server.  The floor map
image itself is wrapped in a graphical submit button, so clicking on it
returns the mouse coordinates within the image, which are then sent to the
centering argument of the Perl script.