NAME

       Cairo driver - driver for bitmap or vector output using the Cairo graphics library.
       (drivers)

DESCRIPTION

       The  Cairo  driver  generates PNG, BMP, PPM, PS, PDF or SVG images from GRASS display commands, using the
       Cairo graphics library.  The image format is selected from the extension of the output file.

       It is started as 'pseudo' monitor (output to an image file) and when stopped, all output from  previously
       used display commands are written to the output file.

USAGE

   Environment variables
       Several environment variables affect the operation of the Cairo driver:
              GRASS_WIDTH=xxx
              the width of the image.  GRASS_HEIGHT=yyy
              the height of the image.  GRASS_CAIROFILE=filename
              the name and format of the resulting image file, default is map.png.
              The image format is determined from the file extension.
              Supported bitmap formats:
                     .png  -  Portable Network Graphics (PNG) .bmp - Windows Bitmap (BMP, 32-bpp) (these are not
                     readable by some older viewers) .ppm - Portable Pixmap (PPM + PGM for alpha channel)
              Supported vector formats:
                     .pdf - Portable Document Format (PDF) .ps - PostScript (PS) .svg - Scalable Vector Graphics
                     (SVG)
              (Note: Some formats may not be available, depending on your platform and the  Cairo  library  that
              GRASS was built with.)  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).  GRASS_AUTO_WRITE=[TRUE|FALSE]
              if set to TRUE, the image file will be written  after  each  operation  (i.e.  whenever  a  client
              disconnects), rather than only being written out when the driver terminates.
              (Note:  This only applies to bitmap formats - vector formats are always written directly to file).
              GRASS_CAIRO_READ
              if TRUE, the Cairo driver will initialize the image from the contents of GRASS_CAIROFILE.
              (Note: This is only supported for bitmap formats) GRASS_CAIRO_MAPPED
              if TRUE, the Cairo driver will map GRASS_CAIROFILE as its framebuffer, rather than  using  memory.
              This only works with BMP files.

   Examples
       Example using the driver directly (bash-syntax):
       export GRASS_CAIROFILE=spearfish.png
       export GRASS_WIDTH=800
       export GRASS_HEIGHT=800
       d.mon start=cairo
       d.rast map=elevation.10m
       d.vect map=streams width=1 color=blue fcolor=aqua type=area,line
       d.vect map=roads width=2
       d.mon stop=cairo
        Example using d.out.file:
       d.mon x0
       d.rast map=elevation.10m
       d.vect map=streams width=1 color=blue fcolor=aqua type=area,line
       d.vect map=roads width=2
       d.out.file -c sf_cairo format=png size=800,800

       A more complicated example using d.out.file:
       r.shaded.relief map=elevation.dem
       r.watershed elev=elevation.dem basin=watershed.basin thresh=10000
       d.mon x1
       d.shadedmap rel=elevation.dem.shade drape=watershed.basin bright=30
       d.vect streams color=aqua fcolor=aqua type=area,line
       d.vect roads where="label ~ 'light-duty road'" color=grey
       d.vect roads where="label ~ 'unimproved'" color=orange
       d.vect roads where="label ~ 'secondary highway'" color=100:100:100 width=2
       d.vect roads where="label ~ 'primary highway'" color=50:50:50 width=2
       d.vect railroads col=red width=2
       d.vect roads where="label = 'interstate'" color=black width=3
       d.vect archsites icon=basic/star size=25 fcolor=yellow
       d.font Andale_Mono
       echo "Spearfish, SD" | d.text color=black at=28,53 -b
       d.out.file -c sf_cairo2 format=png

NOTES

       The  driver  is  still  in development. Enable it by specifying --with-cairo when configuring GRASS. This
       requires a reasonably recent version of the Cairo libraries and a working pkg-config.

       Antialiasing is enabled by default for bitmap formats. There is currently no way of disabling this.

       Cairo supports true vector format output whenever possible.  However,  if  the  selected  format  doesn't
       support  a  necessary  feature,  Cairo  may  fall  back on rendering a bitmap representation of the image
       wrapped in the selected vector format.

       Cairo driver output via d.out.file is supported via the -c flag.

SEE ALSO

        HTMLMAP driver, PNG driver, PostScript driver, XDRIVER
       d.frame, d.mon, d.rast, d.vect d.out.file

AUTHOR

       Lars Ahlzen
       and the GRASS Development Team.

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                  cairodriver(1grass)