#ifndef _MPxData
#define _MPxData
//-
// ==========================================================================
// Copyright (C) 1995 - 2006 Autodesk, Inc., and/or its licensors.  All
// rights reserved.
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// The coded instructions, statements, computer programs, and/or related
// material (collectively the "Data") in these files contain unpublished
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// and by international treaties.
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// The Data may not be disclosed or distributed to third parties or be
// copied or duplicated, in whole or in part, without the prior written
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//+
//
// CLASS:    MPxData
//
// ****************************************************************************

#if defined __cplusplus

// ****************************************************************************
// INCLUDED HEADER FILES


#include <maya/MStatus.h>
#include <maya/MTypes.h>
#include <maya/MIOStreamFwd.h>

// ****************************************************************************
// DECLARATIONS

class MString;
class MObject;
class MTypeId;
class MPlug;
class MArgList;

// ****************************************************************************
// CLASS DECLARATION (MPxData)

//! \ingroup OpenMaya MPx
//! \brief  Base Class for User-defined Dependency Graph Data Types. 
/*!
In Maya, both intrinsic and user-defined Maya Objects are registered
and recognized by their type identifier (MTypeId).  Data which flows in
the Dependency Graph (DG) is implemented as Maya objects, therefore,
the type characteristics of DG Data are specified by the type id
(MTypeId).  The type id is used to at run-time to determine how to
create and destroy Maya Objects, and how they are to be input/output
from/to files.

User-defined Data has two parts.  One part is an internal Maya Data
object of neutral type which is common to all user-defined types.  This
common Data object implements the interface and behaviour
characteristics required for user-defined Data to act as Data within
Maya.  The second part is unique to each user-defined type and
implements the type-specific behaviour.

The Proxy Data (MPxData) class is the base class for user-defined Data
types.  All user-defined Data that is to be passed between Nodes in the
DG must be derived from MPxData.  MPxData transparently incorporates
the common behaviour and defines the common interface required for DG
Data.  When initialized with a unique type id, Data objects of classes
derived from MPxData are recognized by Maya the same as built-in DG
Data types, but are be able to implement user-specified behaviour.

The MPxData class defines the interface for methods to read, write and
assign Data objects of the the user-defined type.  User-defined types
must override these methods to provide type-specific behaviour.

MPxData also provides common methods for querying the type id and type
name of the Data object.

All user-defined DG Data types require an associated static creator
function that returns a void pointer to a new instance of the data
class.  This function is usually a static function within the user
defined data type class.

The registration of the new data type is performed by the
MFnPlugin::registerData() which is invoked in the initializePlugin()
function during Plug-in loading.  One of the most important thing that
the registration does is it associates the type id with the data.

Once a user-defined Data type based on MPxData has been defined and
registered, use the Typed Attribute Function Set (MFnTypedAttribute) to
create an Attribute of the user-defined type.  The Attribute may also
be an multi-Attribute (array).  Use the DG Node Function Set
(MFnDependencyNode) to add the Attribute to a user- defined Node.  This
is usually done in the initialize() method of the Node creator.

Data of a user-defined type on a Node is accessed in the same way as
intrinsic Data types.  The Data is actually held in an Data Block
(MDataBlock).  Use a Data Handle (MDataHandle) or Array Data Handle
(MArrayDataHandle) to access the Data within a Data Block.  Use a Data
Block to obtain a Data Handle or Array Data Handle for either an
Attribute or the associated Plug on the Attribute.  The Data Handle or
Array data handle can then be queried for the underlying Data object.
The underlying Data object is a generic Maya Object (MObject) with a
type id of the user-defined type.

Use the Plug-in Data Function Set (MFnPluginData) to obtain an MPxData
pointer which can be safely cast to a pointer of the user-defined type.
*/
class OPENMAYA_EXPORT MPxData
{
public:
	//! Type of the data. Used when registering the custom data
	//! type with MFnPlugin::registerData.
	enum Type {
		kData,		//!< \nop
		kGeometryData,	//!< \nop
		kLast		//!< \nop
	};

	MPxData();
	virtual ~MPxData();
	virtual MStatus			readASCII( const MArgList& argList,
									   unsigned int& endOfTheLastParsedElement );
	virtual MStatus			readBinary( std::istream& in, unsigned int length );
	virtual MStatus			writeASCII( std::ostream& out );
	virtual MStatus			writeBinary( std::ostream& out );
	virtual	void			copy( const MPxData& src) = 0;
	virtual MTypeId         typeId() const = 0;
	virtual MString         name() const = 0;

protected:
	friend class            MDataHandle;
	void*					instance;

private:
// No private members
};

#endif /* __cplusplus */
#endif /* _MPxData */