PNG driver

NAME

PNGdriver - driver to create PNG images
(drivers)

DESCRIPTION

The PNG driver generates PNG pictures from GRASS display commands.

USAGE

Environment variables

Several environment variables effect the operation of the PNG driver.

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_PNGFILE=filename
the filename to put the resulting image in, default is map.png.
GRASS_BACKGROUNDCOLOR=RRGGBB
specifies the background color to use in RGB notation (hex values). Default is FFFFFF (white).
GRASS_TRANSPARENT=[TRUE|FALSE]
sets transparent background on (TRUE) or off (FALSE, default).

Example

Start up the driver

         d.mon start=PNG
         d.mon select=PNG

Display text strings (HREF's) and polygons

         d.area map=someareamap fillcolor=green linecolor=black
         d.vect map=somevectormap color=red

Stop the driver when all polygon have been displayed. This will cause a file named map.png to be created in your current directory.
```
         d.mon stop=PNG
```

NOTES

The PNG driver uses the Gd library (http://www.boutell.com/gd/) developed by Boutell.Com, Inc. The Gd library in turn relies on libpng (see the libpng home page) and zlib (see the info-zip home page), all which needs to be installed for the PNG driver to work (it's worth it).

Note that the PNG driver is limited to 8bit colors (due to libgd1.x limitations).

AUTHOR

Per Henrik Johansen
phj@norgit.no
NORGIT AS