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<refentry id="cairo-Version-Information">
<refmeta>
<refentrytitle role="top_of_page" id="cairo-Version-Information.top_of_page">Version Information</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>
  CAIRO Library
</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Version Information</refname>
<refpurpose>Compile-time and run-time version checks.</refpurpose>
</refnamediv>

<refsynopsisdiv id="cairo-Version-Information.synopsis" role="synopsis">
<title role="synopsis.title">Synopsis</title>

<synopsis>#define             <link linkend="CAIRO-VERSION:CAPS">CAIRO_VERSION</link>
#define             <link linkend="CAIRO-VERSION-MAJOR:CAPS">CAIRO_VERSION_MAJOR</link>
#define             <link linkend="CAIRO-VERSION-MINOR:CAPS">CAIRO_VERSION_MINOR</link>
#define             <link linkend="CAIRO-VERSION-MICRO:CAPS">CAIRO_VERSION_MICRO</link>
#define             <link linkend="CAIRO-VERSION-STRING:CAPS">CAIRO_VERSION_STRING</link>
#define             <link linkend="CAIRO-VERSION-ENCODE:CAPS">CAIRO_VERSION_ENCODE</link>                (major,
                                                         minor,
                                                         micro)
#define             <link linkend="CAIRO-VERSION-STRINGIZE:CAPS">CAIRO_VERSION_STRINGIZE</link>             (major,
                                                         minor,
                                                         micro)
<link linkend="int"><returnvalue>int</returnvalue></link>                 <link linkend="cairo-version">cairo_version</link>                       (<parameter><type>void</type></parameter>);
const <link linkend="char"><returnvalue>char</returnvalue></link> *        <link linkend="cairo-version-string">cairo_version_string</link>                (<parameter><type>void</type></parameter>);
</synopsis>
</refsynopsisdiv>

<refsect1 id="cairo-Version-Information.description" role="desc">
<title role="desc.title">Description</title>
<para>
Cairo has a three-part version number scheme. In this scheme, we use
even vs. odd numbers to distinguish fixed points in the software
vs. in-progress development, (such as from git instead of a tar file,
or as a "snapshot" tar file as opposed to a "release" tar file).
</para>
<para>
<informalexample><programlisting>
 _____ Major. Always 1, until we invent a new scheme.
/  ___ Minor. Even/Odd = Release/Snapshot (tar files) or Branch/Head (git)
| /  _ Micro. Even/Odd = Tar-file/git
| | /
1.0.0
</programlisting></informalexample>
</para>
<para>
Here are a few examples of versions that one might see.
<informalexample><programlisting>
Releases
--------
1.0.0 - A major release
1.0.2 - A subsequent maintenance release
1.2.0 - Another major release

Snapshots
---------
1.1.2 - A snapshot (working toward the 1.2.0 release)

In-progress development (eg. from git)
--------------------------------------
1.0.1 - Development on a maintenance branch (toward 1.0.2 release)
1.1.1 - Development on head (toward 1.1.2 snapshot and 1.2.0 release)
</programlisting></informalexample>
</para>
<refsect2>
<title>Compatibility</title>
<para>
The API/ABI compatibility guarantees for various versions are as
follows. First, let's assume some cairo-using application code that is
successfully using the API/ABI "from" one version of cairo. Then let's
ask the question whether this same code can be moved "to" the API/ABI
of another version of cairo.
</para>
<para>
Moving from a release to any later version (release, snapshot,
development) is always guaranteed to provide compatibility.
</para>
<para>
Moving from a snapshot to any later version is not guaranteed to
provide compatibility, since snapshots may introduce new API that ends
up being removed before the next release.
</para>
<para>
Moving from an in-development version (odd micro component) to any
later version is not guaranteed to provide compatibility. In fact,
there's not even a guarantee that the code will even continue to work
with the same in-development version number. This is because these
numbers don't correspond to any fixed state of the software, but
rather the many states between snapshots and releases.
</para>
</refsect2>
<refsect2>
<title>Examining the version</title>
<para>
Cairo provides the ability to examine the version at either
compile-time or run-time and in both a human-readable form as well as
an encoded form suitable for direct comparison. Cairo also provides the
macro <link linkend="CAIRO-VERSION-ENCODE:CAPS"><function>CAIRO_VERSION_ENCODE()</function></link> to perform the encoding.
</para>
<para>
<informalexample><programlisting>
Compile-time
------------
CAIRO_VERSION_STRING    Human-readable
CAIRO_VERSION           Encoded, suitable for comparison

Run-time
--------
cairo_version_string()  Human-readable
cairo_version()         Encoded, suitable for comparison
</programlisting></informalexample>
</para>
<para>
For example, checking that the cairo version is greater than or equal
to 1.0.0 could be achieved at compile-time or run-time as follows:
</para>
<para>
<informalexample><programlisting>
##if CAIRO_VERSION &gt;= CAIRO_VERSION_ENCODE(1, 0, 0)
printf ("Compiling with suitable cairo version: %s\n", %CAIRO_VERSION_STRING);
##endif

if (cairo_version() &gt;= CAIRO_VERSION_ENCODE(1, 0, 0))
    printf ("Running with suitable cairo version: %s\n", cairo_version_string ());
</programlisting></informalexample>
</para>
</refsect2>
</refsect1>
<refsect1 id="cairo-Version-Information.details" role="details">
<title role="details.title">Details</title>
<refsect2 id="CAIRO-VERSION:CAPS" role="macro">
<title>CAIRO_VERSION</title>
<indexterm zone="CAIRO-VERSION:CAPS"><primary sortas="VERSION">CAIRO_VERSION</primary></indexterm>
<programlisting>#define             CAIRO_VERSION</programlisting>
<para>
The version of cairo available at compile-time, encoded using
<link linkend="CAIRO-VERSION-ENCODE:CAPS"><function>CAIRO_VERSION_ENCODE()</function></link>.
</para></refsect2>
<refsect2 id="CAIRO-VERSION-MAJOR:CAPS" role="macro">
<title>CAIRO_VERSION_MAJOR</title>
<indexterm zone="CAIRO-VERSION-MAJOR:CAPS"><primary sortas="VERSION_MAJOR">CAIRO_VERSION_MAJOR</primary></indexterm>
<programlisting>#define CAIRO_VERSION_MAJOR USE_cairo_version_OR_cairo_version_string_INSTEAD
</programlisting>
<para>
The major component of the version of cairo available at compile-time.
</para></refsect2>
<refsect2 id="CAIRO-VERSION-MINOR:CAPS" role="macro">
<title>CAIRO_VERSION_MINOR</title>
<indexterm zone="CAIRO-VERSION-MINOR:CAPS"><primary sortas="VERSION_MINOR">CAIRO_VERSION_MINOR</primary></indexterm>
<programlisting>#define CAIRO_VERSION_MINOR USE_cairo_version_OR_cairo_version_string_INSTEAD
</programlisting>
<para>
The minor component of the version of cairo available at compile-time.
</para></refsect2>
<refsect2 id="CAIRO-VERSION-MICRO:CAPS" role="macro">
<title>CAIRO_VERSION_MICRO</title>
<indexterm zone="CAIRO-VERSION-MICRO:CAPS"><primary sortas="VERSION_MICRO">CAIRO_VERSION_MICRO</primary></indexterm>
<programlisting>#define CAIRO_VERSION_MICRO USE_cairo_version_OR_cairo_version_string_INSTEAD
</programlisting>
<para>
The micro component of the version of cairo available at compile-time.
</para></refsect2>
<refsect2 id="CAIRO-VERSION-STRING:CAPS" role="macro">
<title>CAIRO_VERSION_STRING</title>
<indexterm zone="CAIRO-VERSION-STRING:CAPS"><primary sortas="VERSION_STRING">CAIRO_VERSION_STRING</primary></indexterm>
<programlisting>#define             CAIRO_VERSION_STRING</programlisting>
<para>
A human-readable string literal containing the version of cairo available
at compile-time, in the form of "X.Y.Z".
</para></refsect2>
<refsect2 id="CAIRO-VERSION-ENCODE:CAPS" role="macro">
<title>CAIRO_VERSION_ENCODE()</title>
<indexterm zone="CAIRO-VERSION-ENCODE:CAPS"><primary sortas="VERSION_ENCODE">CAIRO_VERSION_ENCODE</primary></indexterm>
<programlisting>#define             CAIRO_VERSION_ENCODE(major, minor, micro)</programlisting>
<para>
This macro encodes the given cairo version into an integer.  The numbers
returned by <link linkend="CAIRO-VERSION:CAPS"><literal>CAIRO_VERSION</literal></link> and <link linkend="cairo-version"><function>cairo_version()</function></link> are encoded using this macro.
Two encoded version numbers can be compared as integers.  The encoding ensures
that later versions compare greater than earlier versions.
</para>
<para>
<parameter>Returns</parameter>: the encoded version.
</para><variablelist role="params">
<varlistentry><term><parameter>major</parameter>&#160;:</term>
<listitem><simpara>the major component of the version number
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>minor</parameter>&#160;:</term>
<listitem><simpara>the minor component of the version number
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>micro</parameter>&#160;:</term>
<listitem><simpara>the micro component of the version number
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="CAIRO-VERSION-STRINGIZE:CAPS" role="macro">
<title>CAIRO_VERSION_STRINGIZE()</title>
<indexterm zone="CAIRO-VERSION-STRINGIZE:CAPS"><primary sortas="VERSION_STRINGIZE">CAIRO_VERSION_STRINGIZE</primary></indexterm>
<programlisting>#define             CAIRO_VERSION_STRINGIZE(major, minor, micro)</programlisting>
<para>
This macro encodes the given cairo version into an string.  The numbers
returned by <link linkend="CAIRO-VERSION-STRING:CAPS"><literal>CAIRO_VERSION_STRING</literal></link> and <link linkend="cairo-version-string"><function>cairo_version_string()</function></link> are encoded using this macro.
The parameters to this macro must expand to numerical literals.
</para>
<para>
<parameter>Returns</parameter>: a string literal containing the version.
</para>
<para>
<parameter>Since</parameter>: 1.8
</para><variablelist role="params">
<varlistentry><term><parameter>major</parameter>&#160;:</term>
<listitem><simpara>the major component of the version number
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>minor</parameter>&#160;:</term>
<listitem><simpara>the minor component of the version number
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>micro</parameter>&#160;:</term>
<listitem><simpara>the micro component of the version number
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-version" role="function">
<title>cairo_version ()</title>
<indexterm zone="cairo-version"><primary sortas="version">cairo_version</primary></indexterm>
<programlisting><link linkend="int"><returnvalue>int</returnvalue></link>                 cairo_version                       (<parameter><type>void</type></parameter>);</programlisting>
<para>
Returns the version of the cairo library encoded in a single
integer as per <link linkend="CAIRO-VERSION-ENCODE:CAPS"><literal>CAIRO_VERSION_ENCODE</literal></link>. The encoding ensures that
later versions compare greater than earlier versions.
</para>
<para>
A run-time comparison to check that cairo's version is greater than
or equal to version X.Y.Z could be performed as follows:
</para>
<para>
<informalexample><programlisting>
if (cairo_version() &gt;= CAIRO_VERSION_ENCODE(X,Y,Z)) {...}
</programlisting></informalexample>
</para>
<para>
See also <link linkend="cairo-version-string"><function>cairo_version_string()</function></link> as well as the compile-time
equivalents <link linkend="CAIRO-VERSION:CAPS"><literal>CAIRO_VERSION</literal></link> and <link linkend="CAIRO-VERSION-STRING:CAPS"><literal>CAIRO_VERSION_STRING</literal></link>.
</para><variablelist role="params">
<varlistentry><term><emphasis>Returns</emphasis>&#160;:</term><listitem><simpara> the encoded version.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-version-string" role="function">
<title>cairo_version_string ()</title>
<indexterm zone="cairo-version-string"><primary sortas="version_string">cairo_version_string</primary></indexterm>
<programlisting>const <link linkend="char"><returnvalue>char</returnvalue></link> *        cairo_version_string                (<parameter><type>void</type></parameter>);</programlisting>
<para>
Returns the version of the cairo library as a human-readable string
of the form "X.Y.Z".
</para>
<para>
See also <link linkend="cairo-version"><function>cairo_version()</function></link> as well as the compile-time equivalents
<link linkend="CAIRO-VERSION-STRING:CAPS"><literal>CAIRO_VERSION_STRING</literal></link> and <link linkend="CAIRO-VERSION:CAPS"><literal>CAIRO_VERSION</literal></link>.
</para><variablelist role="params">
<varlistentry><term><emphasis>Returns</emphasis>&#160;:</term><listitem><simpara> a string containing the version.
</simpara></listitem></varlistentry>
</variablelist></refsect2>

</refsect1>

</refentry>
