1.入口点函数
插件作为illustrator软件的一部分，需要与主体程序进行通信，必然需要约定调用函数。而入口点函数就是其中关键一环，实例代码如下：
/** Basic suite-access information provided with every call. */
struct SPMessageData {
#ifdef __cplusplus
SPMessageData(ai::int32 SPCheck_ = 0, struct SPPlugin *self_ = 0, void *globals_ = 0, struct SPBasicSuite *basic_ = 0)
: SPCheck(SPCheck_), self(self_), globals(globals_), basic(basic_) {}
#endif
/** \c #kSPValidSPMessageData if this is a valid PICA message. */
ai::int32 SPCheck;
/** This plug-in, an \c #SPPluginRef. */
struct SPPlugin *self;
/** An array of application-wide global variables. */
void *globals;
/** A pointer to the basic PICA suite, which you use to obtain all other suites. */
struct SPBasicSuite *basic;
};
extern "C" ASAPI ASErr PluginMain(char* caller, char* selector, void* message)
{
//caller指示消息的发送者(PICA,宿主程序或插件)和动作的通用类型。
//selector指定动作类型的执行动作。所有插件收到至少4类消息动作：reload(重新加载),unload(卸载),startup(启动)和shutdown(关系)。此外，插件可能收到特定插件类型的附加消息。
//message指针是一个消息数据结构体，它包括这个消息动作的相关信息。如，当一个鼠标点击消息接收到时，消息结构体包括鼠标的位置。消息结构体的内容取决于消息，在你的插件定义这个后，才能知道。由于消息内容不同，按照约定，所有消息结构体由相同字段组成，组合到SPMessageData结构体中。
ASErr error = kNoErr;
SPMessageData *msgData = (SPMessageData *)message;
Plugin *plugin = (Plugin *)msgData->globals;
sSPBasic = msgData->basic;
/** PICA messaging system caller; see \c #SPInterfaceSuite. */
//#define kSPInterfaceCaller "SP Interface"
if (strcmp(caller, kSPInterfaceCaller) == 0) //是否是消息系统调用
{
/** PICA messaging system startup; see \c #SPInterfaceSuite. */
//#define kSPInterfaceStartupSelector "Startup"
if (strcmp( selector, kSPInterfaceStartupSelector) == 0)//插件启动
{
plugin = AllocatePlugin(msgData->self);//全局插件
if (plugin)
{
msgData->globals = (void *)plugin;
error = plugin->StartupPlugin((SPInterfaceMessage *)message);//插件启动
if (error != kNoErr)
{
// Make sure to delete in case startup failed
delete plugin;
plugin = nil;
msgData->globals = nil;
}
}
else
{
error = kOutOfMemoryErr;
}
}
else if (strcmp(selector, kSPInterfaceShutdownSelector) == 0)// 插件关闭
{
if (plugin)
{
error = plugin->ShutdownPlugin((SPInterfaceMessage *)message);//关闭函数
delete plugin;
plugin = nil;
msgData->globals = nil;
}
}
}
if (plugin)
{
if (Plugin::IsReloadMsg(caller, selector))//重载插件
{
// Call this before calling any virtual functions (like Message)
FixupReload(plugin);
error = plugin->ReloadPlugin((SPInterfaceMessage *)message);
}
else
{
// If a load or reload failed because the suites could not be acquired, we released
// any partially acquired suites and returned an error. However, SuitePea still might
// call us, so protect against this situation.
if (plugin->SuitesAcquired())
error = plugin->Message(caller, selector, message);//消息路由
else
error = kNoErr;
}
if (error == kUnhandledMsgErr)
{
error = kNoErr;
#ifndef NDEBUG
#ifdef MAC_ENV
fprintf(stderr, "Warning: Unhandled plugin message: caller \"%s\" selector \"%s\"\n", caller, selector);
#else
char buf[1024];
sprintf(buf+1, "Warning: Unhandled plugin message: caller \"%s\" selector \"%s\"\n", caller, selector);
OutputDebugStringA(buf+1);
#endif
#endif
}
}
if (error)
{
if (plugin)
plugin->ReportError(error, caller, selector, message);//错误
else
Plugin::DefaultError(msgData->self, error);
}
return error;
}
功能解析都写在注释里，方便读者阅读，在上述入口函数中，涉及到了两个类一个是SPMessageData，它里面有几个参数，见注释，另一个是SPBasicSuite类，代码如下所示：
/*******************************************************************************
**
** Suite
**
**/
/** @ingroup Suites
This suite provides basic memory management for PICA (the Adobe plug-in manager)
and defines the basic functions for acquiring and releasing other suites.
A suite consists of a list of function pointers. The application, or a
plug-in that loads a suite, provides valid pointers when the suite is
acquired. When a suite is not available, the pointers are set to the
address of the \c #Undefined() function.
Do not attempt to acquire a suite (other than the \c #SPBlocksSuite)
in response to a PICA access (\c #kSPAccessCaller) or property
(\c #kSPPropertiesCaller) message. Most suites are unavailable
during these load and unload operations.
You can acquire all the suites you will need when your plug-in is first
loaded, as long as you release them before your plug-in is unloaded.
At shutdown, however, it is most efficient to acquire only those
suites explicitly needed to shut down; for example, to free memory
and save preferences.
The \c SPBasicSuite itself is a part of the message data passed
to your plug-in with any call. To access it from the message data structure:
@code
SPBasicSuite sBasic = message->d.basic;
sBasic->function( )
@endcode
*/
typedef struct SPBasicSuite {
/** Acquires a function suite. Loads the suite if necessary,
and increments its reference count. For example:
@code
SPErr error;
SPBasicSuite *sBasic = message->d.basic;
AIRandomSuite *sRandom;
sBasic->AcquireSuite( kAIRandomSuite, kAIRandomVersion, &sRandom );
@endcode
@param name The suite name.
@param version The suite version number.
@param suite [out] A buffer in which to return the suite pointer.
@see \c #SPSuitesSuite::AcquireSuite()
*/
SPAPI SPErr (*AcquireSuite)( const char *name, ai::int32 version, const void **suite );
/** Decrements the reference count of a suite and unloads it when the
reference count reaches 0.
@param name The suite name.
@param version The suite version number.
*/
SPAPI SPErr (*ReleaseSuite)( const char *name, ai::int32 version );
/** Compares two strings for equality.
@param token1 The first null-terminated string.
@param token2 The second null-terminated string.
@return True if the strings are the same, false otherwise.
*/
SPAPI SPBoolean (*IsEqual)( const char *token1, const char *token2 );
/** Allocates a block of memory.
@param size The number of bytes.
@param block [out] A buffer in which to return the block pointer.
@see \c #SPBlocksSuite::AllocateBlock()
*/
SPAPI SPErr (*AllocateBlock)( size_t size, void **block );
/** Frees a block of memory allocated with \c #AllocateBlock().
@param block The block pointer.
@see \c #SPBlocksSuite::FreeBlock()
*/
SPAPI SPErr (*FreeBlock)( void *block );
/** Reallocates a block previously allocated with \c #AllocateBlock().
Increases the size without changing the location, if possible.
@param block The block pointer.
@param newSize The new number of bytes.
@param newblock [out] A buffer in which to return the new block pointer.
@see \c #SPBlocksSuite::ReallocateBlock()
*/
SPAPI SPErr (*ReallocateBlock)( void *block, size_t newSize, void **newblock );
/** A function pointer for unloaded suites. This is a protective measure
against other plug-ins that may mistakenly use the suite after they have
released it.
A plug-in that exports a suite should unload the suite's procedure pointers
when it is unloaded, and restore them when the plug-in is reloaded.
\li On unload, replace the suite's procedure pointers
with the address of this function.
\li On reload, restore the suite's procedure
pointers with the updated addresses of their functions.
For example:
@code
SPErr UnloadSuite( MySuite *mySuite, SPAccessMessage *message ) {
mySuite->functionA = (void *) message->d.basic->Undefined;
mySuite->functionB = (void *) message->d.basic->Undefined;
}
SPErr ReloadSuite( MySuite *mySuite, SPAccessMessage *message ) {
mySuite->functionA = functionA;
mySuite->functionB = functionB;
}
@endcode
*/
SPAPI SPErr (*Undefined)( void );
} SPBasicSuite;
这是一个加载模块，它实现了模块的加载和卸载，还有内存分配、释放和重新分配功能。
2.作者答疑
代码长度过长，如需全部项目或有疑问，请留言。
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