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<!-- meta page description: Display drivers -->
<!-- meta page index: display -->
The current command line rendering mechanism is direct rendering into
a file. The driver is selected by setting
the <code>GRASS_RENDER_IMMEDIATE</code> variable or by
running <em><a href="d.mon.html">d.mon</a></em> module.
<p>
<b>List of available display drivers:</b>
<ul>
<li><a href="cairodriver.html">Cairo driver</a></li>
<li><a href="pngdriver.html">PNG driver</a></li>
<li><a href="psdriver.html">PS driver (Postscript)</a></li>
<li><a href="htmldriver.html">HTMLMAP driver</a></li>
</ul>
<h2>NOTES</h2>
<h3>GRASS_RENDER_COMMAND</h3>
If environmental variable GRASS_RENDER_COMMAND is defined,
rendering is redirected by display library to the given external command
defined by this variable. Currently only Python scrips are supported.
<p>
Lets start with simple example of Python script called <i>render.py</i>:
<div class="code"><pre>
#!/usr/bin/env python3
import os
import sys
import grass.script as gs
from grass.script import task as gtask
os.environ['GRASS_RENDER_IMMEDIATE'] = 'default'
os.environ['GRASS_RENDER_FILE'] = 'output.png'
cmd, dcmd = gtask.cmdstring_to_tuple(sys.argv[1])
gs.run_command('d.text', text="Test of GRASS_RENDER_COMMAND redirection")
os.environ['GRASS_RENDER_FILE_READ'] = 'TRUE'
gs.run_command(cmd, **dcmd)
</pre></div>
After defining GRASS_RENDER_COMMAND variable (example for Bash):
<div class="code"><pre>
export GRASS_RENDER_COMMAND=render.py
</pre></div>
Display GRASS modules like <em><a href="d.rast.html">d.rast</a></em>
or <em><a href="d.vect.html">d.vect</a></em> will be executed
by <i>render.py</i> program.
For example the command
<div class="code"><pre>
d.vect roadsmajor
</pre></div>
produces output PNG file <i>output.png</i> which will contain rendered
features from vector map <i>roadsmajor</i> and sample text <i>"Test of
GRASS_RENDER_COMMAND redirection"</i>.
<h2>SEE ALSO</h2>
<em>
<a href="d.mon.html">d.mon</a>,
<a href="variables.html#list-of-selected-grass-environment-variables-for-rendering">variables</a>
</em>
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