instanceCallbackCmd/instanceCallbackCmd.cpp

//-
// ==========================================================================
// Copyright 1995,2006,2008 Autodesk, Inc. All rights reserved.
//
// Use of this software is subject to the terms of the Autodesk
// license agreement provided at the time of installation or download,
// or which otherwise accompanies this software in either electronic
// or hard copy form.
// ==========================================================================
//+
    
// DESCRIPTION:
//
// class InstanceCallbackCmd
// This plugin demonstrates the functionality added to the MDagMessage class.
// The new functions added allow callbacks to be added for:
//      1) Instance added for a specified node(and its instances)
//      2) Instance removed for a specified node(and its instances)
//      3) Instance added for any node
//      4) Instance removed for any node
//
// This plugin:
//      i.   Draws a circle, 
//      ii.  Gets its dagPath using an iterator
//      iii. Adds callback for the instance added and removed for this circle
//
// The callback functions just display a message indicating the invocation
// of the registered callback function.
//
// To execute this plug-in, do the following: 
//  
//      instCallbackCmd;
//
//

#include <maya/MFnPlugin.h>
#include <maya/MPxCommand.h>
#include <maya/MArgList.h>
#include <maya/MItDependencyNodes.h>
#include <maya/MFnDependencyNode.h>
#include <maya/MString.h>
#include <maya/MGlobal.h>
#include <maya/MLockMessage.h>
#include <maya/MFnAttribute.h>
#include <maya/MFnMesh.h>
#include <maya/MFloatPointArray.h>
#include <maya/MIntArray.h>
#include <maya/MDagPath.h>
#include <maya/MDagMessage.h>
#include <maya/MFnNurbsCurve.h>


// callback function for instance added
void addCallbackFunc (MDagPath &dagPath, MDagPath &otherPath,   
        void *clientData/*, MLockMessage::LockDAGEvent eventType, bool &decision*/ )
{
    MGlobal::displayInfo("CALLBACK-FUNCTION REGISTERED FOR INSTANCE ADDED INVOKED");    
}


// callback function for instance removed
void remCallbackFunc ( MDagPath &dagPath, MDagPath &otherPath, void *clientData)
{
    MGlobal::displayInfo("CALLBACK-FUNCTION REGISTERED FOR INSTANCE REMOVED INVOKED");
}



 
class InstanceCallbackCmd : public MPxCommand
{

public:
        
    MStatus doIt( const MArgList& args ) override;
    static void* creator();
};




void* InstanceCallbackCmd::creator()
{
    return new InstanceCallbackCmd;
}


MStatus InstanceCallbackCmd::doIt( const MArgList& args )
{
    
    MStatus status = MS::kSuccess;

    // Draw a circle and get its dagPath
    // using an iterator
    MGlobal::executeCommand("circle");
    MFnNurbsCurve circle;
        
    
    MDagPath dagPath;
    MItDependencyNodes iter( MFn::kNurbsCurve , &status);

    for(iter.reset(); !iter.isDone() ; iter.next())
    {
        MObject item = iter.thisNode();
        if(item.hasFn(MFn::kNurbsCurve))
        {
            circle.setObject(item);
            circle.getPath(dagPath);
            MGlobal::displayInfo("DAG_PATH is " + dagPath.fullPathName());
            
            if(dagPath.isValid())
            {
                // register callback for instance add AND remove
                //
                MDagMessage::addDagCallback( dagPath, MDagMessage::DagMessage::kInstanceAdded, addCallbackFunc, NULL, &status);
                MDagMessage::addDagCallback( dagPath, MDagMessage::DagMessage::kInstanceRemoved, remCallbackFunc, NULL, &status);

                MGlobal::displayInfo("CALLBACK ADDED FOR INSTANCE ADD/REMOVE");
                
            }
            
        }
    }

    
    if (status != MS::kSuccess)
    {
        MGlobal::displayInfo("STATUS RETURNED IS NOT SUCCESS");
    }
    
    return status;
}




//
//              Init // UnInit
//
MStatus initializePlugin( MObject obj )
{ 
    MStatus   status;
    MFnPlugin plugin( obj, PLUGIN_COMPANY, "6.0", "Any");
    plugin.registerCommand( "instCallbackCmd", InstanceCallbackCmd::creator);
    MGlobal::displayInfo("PLUGIN LOADED");
    return status;
}

MStatus uninitializePlugin( MObject obj )
{
    MStatus   status;
    MFnPlugin plugin( obj );
    plugin.deregisterCommand( "instCallbackCmd" );
    return status;
}