文章目录
1.入口点函数2.作者答疑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 __cplusplusSPMessageData(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 faileddelete 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elseerror = kNoErr;}if (error == kUnhandledMsgErr){error = kNoErr;#ifndef NDEBUG#ifdef MAC_ENVfprintf(stderr, "Warning: Unhandled plugin message: caller \"%s\" selector \"%s\"\n", caller, selector);#elsechar 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elsePlugin::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 SuitesThis 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 aplug-in that loads a suite, provides valid pointers when the suite isacquired. When a suite is not available, the pointers are set to theaddress 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 unavailableduring these load and unload operations.You can acquire all the suites you will need when your plug-in is firstloaded, as long as you release them before your plug-in is unloaded.At shutdown, however, it is most efficient to acquire only thosesuites explicitly needed to shut down; for example, to free memoryand save preferences.The \c SPBasicSuite itself is a part of the message data passedto your plug-in with any call. To access it from the message data structure:@codeSPBasicSuite 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:@codeSPErr 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 thereference 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 measureagainst other plug-ins that may mistakenly use the suite after they havereleased it.A plug-in that exports a suite should unload the suite's procedure pointerswhen it is unloaded, and restore them when the plug-in is reloaded.\li On unload, replace the suite's procedure pointerswith the address of this function.\li On reload, restore the suite's procedurepointers with the updated addresses of their functions.For example:@codeSPErr 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
如有疑问，请留言。
