Detailed 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 git 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 (git)
| / _ Micro. Even/Odd = Tar-file/git
| | /
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 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)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 the
function cairoVersionEncode() 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 ());