LIBRARY ""

EXPORTS
NP_GetEntryPoints @1
NP_Initialize @2
NP_Shutdown @3

外掛介面

NPError OSCALL NP_GetEntryPoints(NPPluginFuncs* aNPPFuncs)
{
return fillPluginFunctionTable(aNPPFuncs);
}

其呼叫的fillPluginFunctionTable為：

static NPError fillPluginFunctionTable(NPPluginFuncs* aNPPFuncs)
{
if (!aNPPFuncs)
return NPERR_INVALID_FUNCTABLE_ERROR;

// Set up the plugin function table that Netscape will use to call us.
aNPPFuncs->version = (NP_VERSION_MAJOR << 8) | NP_VERSION_MINOR;
aNPPFuncs->newp = NPP_New;
aNPPFuncs->destroy = NPP_Destroy;
aNPPFuncs->setwindow = NPP_SetWindow;
aNPPFuncs->newstream = NPP_NewStream;
aNPPFuncs->destroystream = NPP_DestroyStream;
aNPPFuncs->asfile = NPP_StreamAsFile;
aNPPFuncs->writeready = NPP_WriteReady;
aNPPFuncs->write = NPP_Write;
aNPPFuncs->print = NPP_Print;
aNPPFuncs->event = NPP_HandleEvent;
aNPPFuncs->urlnotify = NPP_URLNotify;
aNPPFuncs->getvalue = NPP_GetValue;
aNPPFuncs->setvalue = NPP_SetValue;

return NPERR_NO_ERROR;
}
 

fillPluginFunctionTable函式設定了一系列的函式入口，都是很熟悉的在mozilla的開發文件中經常提到的以NPP開頭的函式。這些函式是需要在外掛中加以實現的。

NPError OSCALL NP_Initialize(NPNetscapeFuncs* aNPNFuncs)
{
NPError rv = fillNetscapeFunctionTable(aNPNFuncs);
if (rv != NPERR_NO_ERROR)
return rv;

return NS_PluginInitialize();
}

其呼叫的fillNetscapeFunctionTable為：

static NPError fillNetscapeFunctionTable(NPNetscapeFuncs* aNPNFuncs)
{
if (!aNPNFuncs)
return NPERR_INVALID_FUNCTABLE_ERROR;

if (HIBYTE(aNPNFuncs->version) > NP_VERSION_MAJOR)
return NPERR_INCOMPATIBLE_VERSION_ERROR;

if (aNPNFuncs->size < sizeof(NPNetscapeFuncs))
return NPERR_INVALID_FUNCTABLE_ERROR;

NPNFuncs.size = aNPNFuncs->size;
NPNFuncs.version = aNPNFuncs->version;
NPNFuncs.geturlnotify = aNPNFuncs->geturlnotify;
NPNFuncs.geturl = aNPNFuncs->geturl;
NPNFuncs.posturlnotify = aNPNFuncs->posturlnotify;
NPNFuncs.posturl = aNPNFuncs->posturl;
NPNFuncs.requestread = aNPNFuncs->requestread;
NPNFuncs.newstream = aNPNFuncs->newstream;
NPNFuncs.write = aNPNFuncs->write;
NPNFuncs.destroystream = aNPNFuncs->destroystream;
NPNFuncs.status = aNPNFuncs->status;
NPNFuncs.uagent = aNPNFuncs->uagent;
NPNFuncs.memalloc = aNPNFuncs->memalloc;
NPNFuncs.memfree = aNPNFuncs->memfree;
NPNFuncs.memflush = aNPNFuncs->memflush;
NPNFuncs.reloadplugins = aNPNFuncs->reloadplugins;
NPNFuncs.getvalue = aNPNFuncs->getvalue;
NPNFuncs.setvalue = aNPNFuncs->setvalue;
NPNFuncs.invalidaterect = aNPNFuncs->invalidaterect;
NPNFuncs.invalidateregion = aNPNFuncs->invalidateregion;
NPNFuncs.forceredraw = aNPNFuncs->forceredraw;

return NPERR_NO_ERROR;
}

這裡獲取一系列函式的入口，這些函式是瀏覽器中實現的。

#ifndef npplat_h_
#define npplat_h_

#include "npapi.h"
#include "npfunctions.h"

#ifdef XP_WIN
#include "windows.h"
#endif

#ifdef XP_UNIX
#include <stdio.h>
#endif

#ifdef XP_MAC
#include <Carbon/Carbon.h>
#endif

#ifndef HIBYTE
#define HIBYTE(i) (i >> 8)
#endif

#ifndef LOBYTE
#define LOBYTE(i) (i & 0xff)
#endif

#endif

另外看看pluginbase.h，該檔案定義了nsPluginInstanceBase類並聲明瞭四個全域性函式： NS_NewPluginInstance(nsPluginCreateData * aCreateDataStruct)

NPN函式

NPError NPN_GetURL(NPP instance, const char *url, const char *target)
{
return (*NPNFuncs.geturl)(instance, url, target);
}

這個一看咱就明白了，NPN_GetURL確實可以說是瀏覽器實現的，因為這個函式直接呼叫了NPNetscapeFuncs的一個函式地址處的函式。

NPP函式

瀏覽器對外掛介面的呼叫