[PATCH] improvements to client-side imagemap support

[mapserver@…]

The existing support for generating client-side imagemaps using mapserver is
sloppily-coded in places, generates HTML which is inconsistent with the latest
W3C guidelines, and is rather inflexible.  Attached is a patch to clean up the
code and output a bit and allow customization of the href, onMouseOver,
onMouseOut, and name attributes generated.

[mapserver@…]

Patch to improve imagemap support.

[mapserver@…]

The source file patch includes better comments describing the (improved)
functionality of the imagemap output format; if the patch is accepted I plan on
updating the wiki (http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?ImageMap) to add
this documentation, too.

[sdlime]

Probably should consult the original author before applying. I've cc'd him. 
Have you compared the imagemap output format with the [shpxy...] tag that was 
recently added? I was after SVG output but several folks have been using it for 
imagemap production as well.

Steve

[mapserver@…]

Some documentation on the patch, extracted from the patched source file for
reader's convenience.  The defaults for the new options were all chosen for
backward-compatibility; .map files without any of the new options produce output
identical to that produced by the current code.

---

Client-side imagemap support was originally written by
Attila Csipa (http://prometheus.org.yu/me.php).  C. Scott Ananian
(http://cscott.net) cleaned up the code somewhat and made it more flexible:
you can now customize the generated HREFs and create mouseover and
mouseout attributes.

Use
   IMAGETYPE imagemap
to select this driver.

The following FORMATOPTIONs are available. If any are set to the empty
string the associated attribute will be suppressed.
   POLYHREF   the href string to use for the <area> elements.
              use a %s to interpolate the area title.
              default:   "javascript:Clicked('%s');"
   POLYMOUSEOVER the onMouseOver string to use for the <area> elements.
              use a %s to interpolate the area title.
              default:   "" (ie the attribute is suppressed)
   POLYMOUSEOUT the onMouseOut string to use for the <area> elements.
              use a %s to interpolate the area title.
              default:   "" (ie the attribute is suppressed)
   SYMBOLMOUSEOVER and SYMBOLMOUSEOUT are equivalent properties for
              <area> tags representing symbols, with the same defaults.
   MAPNAME    the string which will be used in the name attribute
              of the <map> tag.  There is no %s interpolation.
              default: "map1"
   SUPPRESS   if "yes", then we will suppress area declarations with
              no title.
              default: "NO"

For example, http://vevo.verifiedvoting.org/verifier contains this
.map file fragment:
        OUTPUTFORMAT
             NAME imagemap
             DRIVER imagemap
             FORMATOPTION "POLYHREF=/verifier/map.php?state=%s"
             FORMATOPTION "SYMBOLHREF=#"
             FORMATOPTION "SUPPRESS=YES"
             FORMATOPTION "MAPNAME=map-48"
             FORMATOPTION "POLYMOUSEOUT=return nd();"
             FORMATOPTION "POLYMOUSEOVER=return overlib('%s');"
        END

[mapserver@…]

Where can I find documentation on [shpxy...]?

For the record, I'm not using template files at all in my application; all the
HTML is generated by a separate set of PHP scripts and mapserver is just used as
a backend to generate images and client-side imagemap fragments on demand.

This is a valuable use which the [shpxy] technique (if I'm guessing at it
correctly) does not allow.  [Also, as far as I know, PHP/MapScript is still
unsupported on Debian systems due to the system regex library issue.
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=138971 ;
http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=156 ) ]

[sdlime]

You're correct that [shpxy...] requires using templates. However, it imposes no 
structural limitations on output so is useful in a broad range of applications, 
plus you get access to any attribute present in a feature. It's not clear how 
that is addressed with the output filter since they are not layer specific. 
I'll need to read up more... 

You can retrieve imagemap fragments on demand using [shp...] and templates. 
There's nothing that prevents you from using MODE=NQUERY as part of a URL and 
limiting the templates to producing just an imagemap.

I plan to add support for inline templates so there will be no need for 
external files which should make maintenance even easier (and configurable on-
the-fly).

Steve

[sdlime]

Ok, I've applied the patch in 4.3. Looks like there are still a number of unused
functions, and I get a few warnings about unused variables. Just in case someone
wants to really clean up that source file... ;-)

Steve

[vilson.farias@…]

We still detected a bug in this implementation. The new code inserts an
undesired comma in the beginning of the "coords" item everytime our map polygon
has too many vertices.
Following there is an exemple : 

<area onMouseOver="eval(getValor('47000'));" onMouseOut="return nd();"
title="47000" shape="poly" coords=" 496,169, 495,170, 495,169, 496,169" />
<area onMouseOver="eval(getValor('47000'));" onMouseOut="return nd();"
title="47000" shape="poly" coords=", 485,159, 486,160, 484,162, 483" />

This problem has no effect in Internet Explorer but Mozilla Firefox can't show
it properly.

I'm attaching a patch for it.

[vilson.farias@…]

Patch for undesired comma bug in coords element (see Additional Comment #8)

[sdlime]

Looks simple enough to get into 4.10...

Steve

[sdlime]

Vilson, please verify the supplied patch works ok. Marking as fixed unless I
hear otherwise.

Steve