The OfxHost struct is how a host
provides plug-ins with access to the various suites that make up the
API they implement, as well as a host property set handle which a plug-in can ask
questions of. The setHost
function in the
OfxPlugin struct is passed a pointer to an
OfxHost as the first thing to boot-strapping
plug-in/host communication. The struct looks like...
typedef struct OfxHost { OfxPropertySetHandle host; void *(*fetchSuite)(OfxPropertySetHandle host, const char *suiteName, int suiteVersion); } OfxHost;
The OfxHost contains two elements,
host
- a property set handle that holds a set of properties which describe the host for the plug-in's API fetchSuite
- a function handle used to fetch function suites from the host that implement the plug-in's API
The host
property set handle in the
OfxHost is not global across all plug-ins
defined in the binary. It is only applicable for the plug-in whose
'setHost' function was called. Use this handle to fetch things like
host application names, host capabilities and so on. The set of
properties on an OFX Image Effect host is found in the section Properties on the Image Effect Host
The fetchSuite
function is how a plug-in
gets a suite from the host. It asks for a suite by giving the C string
corresponding to that suite and the version of that suite. The host
will return a pointer to that suite, or NULL if it does not support
it. Please note that a suite cannot be fetched until the very first
action is called on the plug-in, which is the load action.