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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().

See also BaseDocument Disc I/O.

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:

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.

Further Reading

HyperFile::WriteInt32
Bool WriteInt32(Int32 v)
GeListNode
Represents a C4DAtom that resides in a 4D list.
Definition: c4d_baselist.h:1797
HyperFile::ReadInt32
Bool ReadInt32(Int32 *v)
Int32
maxon::Int32 Int32
Definition: ge_sys_math.h:60
HyperFile
Definition: c4d_file.h:1069
Bool
maxon::Bool Bool
Definition: ge_sys_math.h:55