Ubuntu Manpage: HTMLMAP driver - driver to create HTML image maps.

NAME

       HTMLMAP driver - driver to create HTML image maps.
       (drivers)

DESCRIPTION

       The  HTMLMAP  driver  allows  the generation of HTML image maps for area vector data. HTML
       image maps are used in conjunction with images to provide unique URL targets for different
       portions  of  an image. The HTMLMAP driver can create both client-side image maps embedded
       into HTML files, or server-side image maps used by web server software.

       Note that GRASS display commands that require the MOUSE will not  work  correctly  (or  at
       all!)

       Polygons  can at most have 100 vertices (this limit imposed by HTML image map formats, see
       GRASS_HTMLMAXPOINTS below.) The driver will attempt to trim polygons that have  more  that
       100  vertices  by  removing  vertices  with the least amount of angle to the next vertice.
       Also, any polygon that is entirely bounded by another polygon will be discarded.

       Text written to the driver before polygons are used as the HREF  tag  for  all  subsequent
       polygons written. All polygons that exist in a vector map will have the same HREF tag.

       The only GRASS display commands that should be used with this driver are:
              d.text  -  pass  href information for resulting image maps.  d.vect - draw polygons
              from a vector map.

USAGE

Environment variablesSeveral environment variables affect the operation
of HTMLMAP.
GRASS_WIDTH=xxx
the width of the image map (default is 640). GRASS_HEIGHT=yyy
the height of the image map (default is 480). GRASS_HTMLTYPE=type
the type of image mape to create (default is CLIENT):
CLIENT Netscape/IE client-side image map. (NAME="map")
APACHE Apache/NCSA server-side image map.
RAW Raw url and polygon vertices ( url x1 y1 x2 y2 format with user
supplied conversion program.

GRASS_HTMLFILE=filename
specifies the resulting file to store the html image map, default is htmlmap. Files
without absolute path names are written in the current directory where the driver
was started.
Any existing file of the same name is overwritten without warning.
GRASS_HTMLMINDIST=n
specifies the minimum distance in pixels that a point must change from the previous
point to keep in the list of vertices for a polygon. The default is 2, which means
that a point's x and y difference from the previous point must change by a number
of pixels greater than this value. This parameter helps to eliminate closely
spaced points. GRASS_HTMLMINBBOX=n
specifies the minimum bounding box dimensions to record a polygon as a clickable
area. The default is 2, which means that a polygon with a bounding box of less
than this value is not included. This parameter helps to eliminate polygons than
are a point or line. GRASS_HTMLMAXPOINTS=n
specifies the maximum number of vertices included in a polygon's clickable area.
The default is 99. Some browsers can only accommodate polygons of 100 vertices or
less. The HTMLMAP driver automatically ensures that a polygon is closed by making
the last point the same as the first point.

Typical usage
Start up the driver
d.mon start=HTMLMAP
Display text strings (HREF's) and polygons
echo "http://www.no-such-place.net/area51/" | d.text
d.vect map=area51
echo "http://www.roswell-nm.net/little/green/men.html" | d.text
d.vect map=roswell
Stop the driver when all polygon have been displayed. This will cause a file named
'htmlmap' to be created in your current directory.
d.mon stop=HTMLMAP
You will also want to create an image for your image map. Use the PNG driver and
other utilities to create .gif or .jpg files. The following example is somewhat
out of date and refers to options available in GRASS 5.
# using previous GRASS_WIDTH & GRASS_HEIGHT
d.mon start=PNG
d.mon select=PNG
d.rast map=terrain
d.vect map=area51 fillcolor=white linecolor=blue
d.vect map=roswell fillcolor=yellow linecolor=blue
d.vect map=states color=green
d.vect map=roads color=black
d.mon stop=PNG
# make the region the same as the newly created cell for ppm export
g.region save=saved.reg
g.region raster=D_cell
r.out.ppm -q input=D_cell output=alien.ppm
# use the netpbm utilities to create a gif (quantize if needed)
ppmquant 128 <alien.ppm | ppmtogif >alien.gif
# assemble some html with the image and the image map
cat htmlmap >>alien.html

# don't forget to reset your region
g.region region=saved.reg
# take a look and test it out
netscape file:`pwd`/alien.html &

NOTES

       HTMLMAP  was  adapted  from  the CELL driver in GRASS 4.3.  Point-in-polygon test code was
       lifted from Randolph Franklin's web page, see
              http://www.ecse.rpi.edu/Homepages/wrf/
              http://www.ecse.rpi.edu/Homepages/wrf/research/geom/pnpoly.html

       If  you  create an HTML file with two or more images and image maps, you will need to edit
       the map names. The HTMLMAP driver creates its map with the name map. A  small  sed  script
       can easily change the map name:
         sed -e 's/NAME="map"/NAME="foomap"/' < htmlmap > foomap.html

NAME

DESCRIPTION

USAGE

NOTES

SEE ALSO