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

name
description
usage
notes
see also

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