script_user_object.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

//=============================================================================
//
// ScriptUserObject is a dynamic (managed) struct manager.
//
//=============================================================================

#ifndef AGS_ENGINE_DYNOBJ__SCRIPTUSERSTRUCT_H
#define AGS_ENGINE_DYNOBJ__SCRIPTUSERSTRUCT_H

#include "ags/engine/ac/dynobj/cc_ags_dynamic_object.h"
#include "ags/shared/util/stream.h"

namespace AGS3 {

struct ScriptUserObject final : AGSCCDynamicObject {
public:
    static const char *TypeName;

    struct Header {
        uint32_t Size = 0u;
        // NOTE: we use signed int for Size at the moment, because the managed
        // object interface's Serialize() function requires the object to return
        // negative value of size in case the provided buffer was not large
        // enough. Since this interface is also a part of Plugin API, we would
        // need more significant change to program before we could use different
        // approach.
    };

    ScriptUserObject() = default;
    ~ScriptUserObject() = default;

    inline static const Header &GetHeader(const void *address) {
        return reinterpret_cast<const Header &>(*(static_cast<const uint8_t *>(address) - MemHeaderSz));
    }

    // Create managed struct object and return a pointer to the beginning of a buffer
    static DynObjectRef Create(size_t size);

    // return the type name of the object
    const char *GetType() override;
    int  Dispose(void *address, bool force) override;
    void Unserialize(int index, AGS::Shared::Stream *in, size_t data_sz) override;

private:
    // The size of the array's header in memory, prepended to the element data
    static const size_t MemHeaderSz = sizeof(Header);
    // The size of the serialized header
    static const size_t FileHeaderSz = sizeof(uint32_t) * 0; // no header serialized

    // Savegame serialization
    // Calculate and return required space for serialization, in bytes
    size_t CalcSerializeSize(const void *address) override;
    // Write object data into the provided stream
    void Serialize(const void *address, AGS::Shared::Stream *out) override;
};

// Helper functions for setting up custom managed structs based on ScriptUserObject.
namespace ScriptStructHelpers {
// Creates a managed Point object, represented as a pair of X and Y coordinates.
ScriptUserObject *CreatePoint(int x, int y);
} // namespace ScriptStructHelpers

} // namespace AGS3

#endif