C
HAPTER
1: Overview
Plug-in entry point and messages
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your plug-in implements a preferences suite that other plug-ins use, they may call you in their shut-down
handlers after you already shut down.
Notifiers
Some message actions also are referred to as
notifiers
, indicating something in Illustrator was changed by
the user; for example, when the user selects an object.
Plug-ins must register for the notifiers in which they are interested. The Notifier suite is used to register and
remove notification requests (see
AINotifierSuite
).
Plug-ins also can create their own notifiers, which can be used to broadcast changes to other plug-ins.
Handling callers and selectors
Your plug-in’s organization is based largely on the messages it receives. The main routine of your plug-in
must first determine the message action, using the caller and selector parameters. For example:
extern "C" ASAPI ASErr PluginMain(char* caller, char* selector, void* message)
{
ASErr error = kNoErr;
if ( strcmp( caller, kSPAccessCaller ) == 0 ) {
// Handle Reload and Unload
if ( strcmp( selector, kSPAccessReloadSelector ) == 0 )
error = MyRestoreGlobals( message );
else if ( strcmp( selector, kSPAccessUnloadSelector ) == 0 )
error = MySaveGlobals( message );
} else if ( strcmp( caller, kSPInterfaceCaller ) == 0 ) {
// Handle Startup and Shutdown
if ( strcmp( selector, kSPInterfaceStartupSelector ) == 0 )
error = MyStartupPlugin( message );
else if ( strcmp( selector, kSPInterfaceShutdownSelector ) == 0 )
error = MyShutdownPlugin( message );
} else if ( strcmp( caller, kCallerAIMenu ) == 0 &&
strcmp( selector, kSelectorAIGoMenuItem ) == 0 ) ){
// Handle menu message
error = MyHandleMenu( message );
}
return error;
}
Message data
The last argument passed to your plug-in entry point is a pointer to a message data structure, which
contains information appropriate to the message action. For example, when a mouse-clicked message
action is received, the message data structure contains the mouse position.
The contents of the message data structure depend on the message action and are not completely known
until your plug-in identifies this. While the contents of the message data vary, by convention all message
data structures begin with the common fields that are grouped into the
SPMessageData
structure:
typedef struct SPMessageData {
long SPCheck;
struct SPPlugin *self;
void *globals;