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