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 ());

CAIRO_VERSION

#define             CAIRO_VERSION

The version of cairo available at compile-time, encoded using CAIRO_VERSION_ENCODE().

CAIRO_VERSION_MAJOR

#define CAIRO_VERSION_MAJOR 1

The major component of the version of cairo available at compile-time.

CAIRO_VERSION_MINOR

#define CAIRO_VERSION_MINOR 6

The minor component of the version of cairo available at compile-time.

CAIRO_VERSION_MICRO

#define CAIRO_VERSION_MICRO 4

The micro component of the version of cairo available at compile-time.

CAIRO_VERSION_STRING

#define CAIRO_VERSION_STRING "1.6.4"

A human-readable string literal containing the version of cairo available at compile-time, in the form of "X.Y.Z".

CAIRO_VERSION_ENCODE()

#define             CAIRO_VERSION_ENCODE(major, minor, micro)

This macro encodes the given cairo version into an integer. The numbers returned by CAIRO_VERSION and cairo_version() 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.

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.

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.