About

NodeData based classic plugin classes can implement NodeData::Read() and NodeData::Write(). This allows to store internal data that is not stored in the BaseContainer when the scene is saved to a *.c4d file.

Note: If NodeData::Read() and NodeData::Write() are implemented typically also NodeData::CopyTo() should be implemented.

NodeData::Read() corresponds to C4DAtom::Read(), NodeData::Write() corresponds to C4DAtom::Write().

Usage

NodeData::Read() is called when a *.c4d file is loaded, NodeData::Write() is called when the element is saved to a *.c4d file. The given HyperFile object represents this *.c4d file.

  // This example stores an internal list and an integer value with the actual object.
 
  Bool Read(GeListNode* node, HyperFile* hf, Int32 level)
  {
    if (level >= 0) // checks the plugin level
    {
      // read a GeListHead
      _branchHead->ReadObject(hf, true);
      // read an integer value
      hf->ReadInt32(&_value);
    }
 
    return true;
  }
 
  Bool Write(GeListNode* node, HyperFile* hf)
  {
    // store a GeListHead
    _branchHead->WriteObject(hf);
    // store an integer value
    hf->WriteInt32(_value);
 
    return true;
  }

The arguments of the functions are:

The node itself.
The HyperFile to read from or write to. See HyperFile Manual.
The element level: This is the plugin version defined with the "Register" function. See Registration.

Note: The order of operations needs to be the same in both function implementations.; When NodeData::Read() is called the element is not yet part of a BaseDocument.; To check if a message dialog can be shown in the context of NodeData::Read(), use HyperFile::GetFilterFlags() to check if SCENEFILTER::DIALOGSALLOWED is set.

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