NodeData::Read() / NodeData::Write() Manual

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About

NodeData based Cinema API 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(const GeListNode* node, HyperFile* hf) const
{
// store a GeListHead
_branchHead->WriteObject(hf);
// store an integer value
hf->WriteInt32(_value);
return true;
}
level
PyObject PyObject PyObject int level
Definition: import.h:58
cinema::Bool
maxon::Bool Bool
Definition: ge_sys_math.h:46
cinema::Int32
maxon::Int32 Int32
Definition: ge_sys_math.h:51
_node
Definition: node.h:10

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.

Further Reading