Version Information

Version Information — Compile-time and run-time version checks.

Synopsis




#define     CAIRO_VERSION
#define     CAIRO_VERSION_MAJOR
#define     CAIRO_VERSION_MINOR
#define     CAIRO_VERSION_MICRO
#define     CAIRO_VERSION_STRING
#define     CAIRO_VERSION_ENCODE            (major, minor, micro)
int         cairo_version                   (void);
const char* cairo_version_string            (void);

Description

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 CVS instead of a tar file, or as a "snapshot" tar file as opposed to a "release" tar file). 

 _____ Major. Always 1, until we invent a new scheme.
/  ___ Minor. Even/Odd = Release/Snapshot (tar files) or Branch/Head (CVS)
| /  _ Micro. Even/Odd = Tar-file/CVS
| | /
1.0.0

Here are a few examples of versions that one might see. 

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 CVS)
--------------------------------------
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)

Compatibility

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.

Moving from a release to any later version (release, snapshot, development) is always guaranteed to provide compatibility.

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.

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.

Examining the version

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 a macro (CAIRO_VERSION_ENCODE) to perform the encoding. 

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

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: 

#if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 0, 0)
printf ("Compiling with suitable cairo version: %s\n", CAIRO_VERSION_STRING);
#endif

if (cairo_version() >= CAIRO_VERSION_ENCODE(1, 0, 0))
    printf ("Running with suitable cairo version: %s\n", cairo_version_string());

Details

CAIRO_VERSION

#define     CAIRO_VERSION

CAIRO_VERSION_MAJOR

#define CAIRO_VERSION_MAJOR 1

CAIRO_VERSION_MINOR

#define CAIRO_VERSION_MINOR 2

CAIRO_VERSION_MICRO

#define CAIRO_VERSION_MICRO 6

CAIRO_VERSION_STRING

#define CAIRO_VERSION_STRING "1.2.6"

CAIRO_VERSION_ENCODE()

#define     CAIRO_VERSION_ENCODE(major, minor, micro)

major :
minor :
micro :

cairo_version ()

int         cairo_version                   (void);

Returns the version of the cairo library encoded in a single integer as per CAIRO_VERSION_ENCODE. The encoding ensures that later versions compare greater than earlier versions.

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: 

if (cairo_version() >= CAIRO_VERSION_ENCODE(X,Y,Z)) {...}

See also cairo_version_string() as well as the compile-time equivalents CAIRO_VERSION and CAIRO_VERSION_STRING.

Returns : the encoded version.

cairo_version_string ()

const char* cairo_version_string            (void);

Returns the version of the cairo library as a human-readable string of the form "X.Y.Z".

See also cairo_version() as well as the compile-time equivalents CAIRO_VERSION_STRING and CAIRO_VERSION.

Returns : a string containing the version.