GT_DAConstant.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        GT_DAConstant.h ( GT Library, C++)
 *
 * COMMENTS:
 */

#ifndef __GT_DAConstant__
#define __GT_DAConstant__

#include "GT_API.h"
#include "GT_DAInherit.h"

#include <UT/UT_StringArray.h> // required by GT_IMPL_INHERIT_ARRAY()
#include <UT/UT_ValArray.h>

/// @brief Extend a single element from a source array to emulate a larger array
///
/// Given a source data array, this class will emulate a larger array by
/// extending a single element from the source array over a given size.
/// For example: @code
///     GT_DataArray    &src;
///     GT_DAConstant    varying;
///     varying.init(32, 100);
/// @endcode
/// Creates an array of 100 entries referencing element 32 from the source
/// array.
class GT_API GT_DAConstant : public GT_DAInherit
{
public:
    /// Default constructor
    GT_DAConstant()
        : mySize(0)
        , myOffset(0)
        , GT_DAInherit()
    {
    }
    /// Useful constructor
    GT_DAConstant(const GT_DataArrayHandle &data,
                    GT_Offset offset, GT_Size size)
        : myOffset(offset)
        , mySize(size)
        , GT_DAInherit(data)
    {
    }
    /// Copy constructor
    GT_DAConstant(const GT_DAConstant &src)
        : myOffset(src.myOffset),
          mySize(src.mySize),
          GT_DAInherit(src)
    {
    }
    ~GT_DAConstant() override;

    const char         *className() const override { return "GT_DAConstant"; }
    
    GT_Size             itemSize(GT_Offset) const override
                            { return GT_DAInherit::itemSize(myOffset); }
    GT_Size             getTotalArrayEntries() const override
                            { return mySize * itemSize(myOffset); }

    /// Create a constant data array from the existing data array.
    static const GT_DataArrayHandle     createConstant(
                                                const GT_DataArrayHandle &h,
                                                GT_Offset offset,
                                                GT_Size size);

    /// Initialize with given data
    void                init(const GT_DataArrayHandle &data,
                            GT_Offset offset, GT_Size size)
                        {
                            GT_DAInherit::init(data);
                            myOffset = offset;
                            mySize = size;
                        }

    GT_IMPL_INHERIT_ARRAY(getIndirect, mySize)

private:
    /// Map the requested offset to the offset in my data
    inline GT_Offset    getIndirect(GT_Offset) const
                            { return myOffset; }

    GT_Offset           myOffset;
    GT_Size             mySize;
};

#endif