HUSD_ObjectHandle.h

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/*
 * Copyright 2019 Side Effects Software Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef __HUSD_ObjectHandle_h__
#define __HUSD_ObjectHandle_h__

#include "HUSD_API.h"
#include "HUSD_DataHandle.h"
#include "HUSD_PostLayers.h"
#include "HUSD_Overrides.h"
#include "HUSD_Path.h"
#include <UT/UT_StringHolder.h>

// This class is a standalone wrapper around a specific object in a USD
// stage wrapped in an HUSD_DataHandle. It's purpose is to serve as the data
// accessor for tree nodes in the Scene Graph Tree. It should not be used for
// any other purpose, as it is extremely inefficient. Each function call locks
// the HUSD_DataHandle, queries its information, then unlocks it again. This
// is a matter of convenience for the calling pattern of the scene graph tree.
// Because it is inefficient the scene graph tree caches any information that
// comes out of this object.
//
// Anyone else tempted to use this object should use HUSD_Info instead.
class HUSD_API HUSD_ObjectHandle
{
public:
    enum OverridesHandling {
        OVERRIDES_COMPOSE,
        OVERRIDES_INSPECT,
        OVERRIDES_IGNORE
    };

                                 HUSD_ObjectHandle(
                                        OverridesHandling overrides_handling
                                            = OVERRIDES_IGNORE);
                                 HUSD_ObjectHandle(const HUSD_Path &path,
                                        OverridesHandling overrides_handling
                                            = OVERRIDES_IGNORE);
    virtual                     ~HUSD_ObjectHandle();

    virtual const HUSD_DataHandle           &dataHandle() const = 0;
    virtual const HUSD_ConstOverridesPtr    &overrides() const = 0;
    virtual const HUSD_ConstPostLayersPtr   &postLayers() const = 0;

    OverridesHandling            overridesHandling() const
                                 { return myOverridesHandling; }
    const HUSD_Path             &path() const
                                 { return myPath; }
    bool                         isValid() const
                                 { return !myPath.isEmpty(); }

private:
    HUSD_Path                    myPath;
    OverridesHandling            myOverridesHandling;
};

#endif