undoRedoMsgCmd.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.
// ==========================================================================
//+

/* 

        file : undoRedoMsgCmd.cpp
        class: undoRedoMsg
        ----------------------
        This is an example to demonstrate  how to listen to undo and redo
        message events.  
        
        The syntax of the command is:
                undoRedoMsg add;        
                undoRedoMsg remove;
        The add argument causes listening to undo/redo to be turned on.
        The remove argument causes undo/redo listening to be removed.
*/

#include <maya/MFnPlugin.h>
#include <maya/MStatus.h>
#include <maya/MPxCommand.h>
#include <maya/MMessage.h>
#include <maya/MEventMessage.h>
#include <maya/MGlobal.h>
#include <maya/MArgList.h>
#include <maya/MCallbackIdArray.h>

#define UndoString "Undo"
#define RedoString "Redo"

// Static array to track the callback ids used
static MCallbackIdArray callbackIds;

//
// The command which adds and removes the
// callback listening
//
class undoRedoMsg : public MPxCommand
{
        public:
                virtual MStatus doIt( const MArgList& );
                void runTests();

                static void *creator();
};

//
// Two callbacks - undo/redo
//              These callbacks should not change
//              the state of the scene.  You can
//              update UI for modify local variables
//              etc. in these callbacks.
//
static void undoCB( void *clientData )
{
        MString info = "undoCallback : clientData = ";
        if ( clientData )
                info += (unsigned)(MUintPtrSz)clientData;
        else
                info += "NULL"; 
        MGlobal::displayInfo( info );
}

static void redoCB( void *clientData )
{
        MString info = "redoCallback : clientData ";
        if ( clientData )
                info += (unsigned)(MUintPtrSz) clientData;
        else
                info += "NULL"; 
        MGlobal::displayInfo( info );
}

MStatus undoRedoMsg::doIt( const MArgList& args )
{
        MStatus result = MS::kSuccess;
        
        if ( args.length() > 0 )
        {
                MString argStr;

                unsigned last = args.length();
                for ( unsigned i = 0; i < last; i++ ) 
                {
                        args.get( i, argStr );

                        if ( argStr == "add" )
                        {
                                MCallbackId undoId = MEventMessage::addEventCallback( UndoString, undoCB, NULL, &result );
                                if ( MS::kSuccess != result )
                                        return MS::kFailure;
                                callbackIds.append( undoId );
                                
                                MCallbackId redoId = MEventMessage::addEventCallback( RedoString, redoCB, NULL, &result );
                                if ( MS::kSuccess != result )
                                        return MS::kFailure;    
                                callbackIds.append( redoId );
                        }
                        else if ( argStr == "remove" )
                        {
                                if ( MS::kSuccess != MMessage::removeCallbacks( callbackIds ) )
                                        return MS::kFailure;
                        }
                        else
                        {
                                MGlobal::displayInfo("Failure condition");
                                return MS::kFailure;
                        } 
                }
        }

        return result;
}

//
// Creator for the command
//
void* undoRedoMsg::creator() 
{       
        return new undoRedoMsg;
}

// standard initialize and uninitialize functions

MStatus initializePlugin(MObject obj)
{
        // Version number may need to change in the future
        //
        MFnPlugin pluginFn(obj, PLUGIN_COMPANY, "6.0");

        MStatus status;
        status = pluginFn.registerCommand("undoRedoMsg", undoRedoMsg::creator);

        if( !status)
                status.perror("register Command failed");

        return status;
}

MStatus uninitializePlugin ( MObject obj )
{
        MFnPlugin pluginFn(obj);
        MStatus status = MS::kSuccess;
        
        // Remove the callbacks in case the command for doing
        // this has not been done.
        MMessage::removeCallbacks( callbackIds );
        
        status = pluginFn.deregisterCommand("undoRedoMsg");
        
        return status;
}