GABC_OProperty.h

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#ifndef __GABC_OProperty__
#define __GABC_OProperty__

#include "GABC_API.h"
#include "GABC_OError.h"
#include "GABC_LayerOptions.h"
#include <Alembic/AbcGeom/All.h>
#include <GT/GT_Handles.h>
#include <GT/GT_Types.h>

namespace GABC_NAMESPACE
{

class GABC_OOptions;

/// Base class for exporting attribute and user property data from a
/// GT_DataArray to Alembic.
///
/// The Alembic equivalent of attributes are Alembic arbitrary geometry
/// parameters (arbGeomParams). In addition, Alembic geometry can have user
/// properties which have no direct equivalent in Houdini. We store user
/// properties as a JSON dictionary exposed to users through a special
/// attribute (see: GABC_Util::theUserPropsValsAttrib).
///
/// User properties are stored using OScalarProperty and OArrayProperty
/// objects, while arbGeomParams are stored using OGeomParam objects which
/// contain an underlying OArrayProperty.
///
/// The children derived from this base class write data representing
/// attributes and user properties from GT_DataArray objects to the appropriate
/// type of OProperty.
///
class GABC_API GABC_OProperty
{
public:
    typedef Alembic::Abc::OCompoundProperty OCompoundProperty;
    typedef Alembic::Util::PlainOldDataType PlainOldDataType;

                    GABC_OProperty(GABC_LayerOptions::LayerType ltype)
                        : myLayerType(ltype) {}
    virtual        ~GABC_OProperty() {}

    /// Creates the appropriate child object, based on the array's storage
    /// type, tuple size, and interpretation, and the Alembic POD (if provided)
    virtual bool    start(OCompoundProperty &parent,
                            const char *name,
                            const GT_DataArrayHandle &array,
                            GABC_OError &err,
                            const GABC_OOptions &options,
                            const PlainOldDataType pod
                                = Alembic::Abc::kUnknownPOD) = 0;

    /// Write GT_DataArray conents as samples to the property.
    virtual bool    update(const GT_DataArrayHandle &array,
                            GABC_OError &err,
                            const GABC_OOptions &options,
                            const PlainOldDataType pod
                                = Alembic::Abc::kUnknownPOD) = 0;

    /// Reuse the previous sample .
    virtual bool    updateFromPrevious() = 0;

    /// Get number of samples written to property so far.
    virtual exint   getNumSamples() const = 0;

    /// Returns true if storage only differs by precision.
    bool compatibleStorage(GT_Storage storage)
    {
        if(myStorage == storage)
            return true;
        if(GTisFloat(myStorage))
            return GTisFloat(storage);
        if(GTisInteger(myStorage))
            return GTisInteger(storage);
        return false;
    }

protected:
    GT_DataArrayHandle           myCache;
    GT_Size                      myTupleSize;
    GT_Storage                   myStorage;
    GT_Type                      myType;
    PlainOldDataType             myPOD;
    void                        *myBuffer;
    GABC_LayerOptions::LayerType myLayerType;
};

} // GABC_NAMESPACE

#endif