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<title>Programming With SANE</title>
<h2><a name="s5">5 Programming With SANE</a></h2>
<p>By definition, SANE is only as good as the programs that use
it. This means the more applications and the more devices that use SANE,
the merrier. The SANE distribution comes with a detailed document
that explains the SANE API; however, the interface is quite simple.
The six main functions are listed below:
<p><blockquote>
<dl>
<p><dt><i>handle</i> &lt;- <tt>sane_open</tt> (<i>device-name</i>):<dd>
allows you to open a SANE device by name (e.g., pnm:0).
<p><dt><tt>sane_close</tt> (<i>handle</i>):<dd> allows you to close a SANE
device.
<p><dt><tt>sane_get_option_descriptor</tt> (<i>handle</i>,
<i>option-number</i>):<dd> is used to query the controls available to
the device (such as the brightness control in the PNM pseudo-device
driver).
<p><dt><tt>sane_control_option</tt> (<i>handle</i>, <i>option-number</i>,
<i>action</i>, <i>value</i>):<dd> is used to get or set the value of an
option. For example, it can be used to set the value of the
brightness option to 50 percent. In addition, some options support
an auto-mode where the driver picks a reasonable value. For such
options, <tt>sane_control_option()</tt> can also be used to turn
auto-mode on or off.
<p><dt><tt>sane_start</tt> (<i>handle</i>):<dd> is used to start the
acquisition of an image.
<p><dt><i>bytes-read</i> &lt;- <tt>sane_read</tt> (<i>handle</i>,
<i>buffer</i>, <i>buffer-size</i>):<dd> is used to read the actual image
data until the entire image has been acquired.
<p></dl>
</blockquote>
<p>The SANE API is simple by design. The goal was to make it possible to
accomplish a simple task in a small amount of time while still
providing enough functionality to enable sophisticated drivers and
applications. The simplicity is best evidenced by the fact that it
took just two evening sessions to convert the <tt>hpscanpbm</tt> program
into a SANE driver for HP scanners. On the other end of the spectrum,
the Mustek driver and xscanimage are fairly complicated programs and
SANE had no problems accommodating them.
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