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).
Here are a few examples of versions that one might see.
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 macro CAIRO_VERSION_ENCODE() to perform the encoding.
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:
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
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.