GeListHead Manual
A GeListHead object is the root of a list or tree of GeListNode elements. See also GeListNode Manual .
GeListHead
objects are an instance of
ID_LISTHEAD
.
GeListHead objects can be created with the usual tools:
The creation of GeListHead objects is typically only needed in custom NodeData based plugin classes that internally store custom objects (see also Heads and Branches ).
It is possible to get the root GeListHead from every member of that list or tree:
// loop through all elements of the selection for ( Int32 i = 0; i < selection-> GetCount (); ++i) { C4DAtom * const atom = selection-> GetIndex (i); if (atom == nullptr ) return maxon::UnexpectedError( MAXON_SOURCE_LOCATION );
// check if the C4DAtom is a GeListNode if (atom-> IsInstanceOf ( Tgelistnode ) == false ) continue ;
// check if the list head can be accessed if (head != nullptr ) { GeListNode * const child = head-> GetFirst ();
// check if the child is a BaseList2D object if (child && child-> IsInstanceOf ( Tbaselist2d )) { const BaseList2D * const child2D = static_cast< BaseList2D * > (child); ApplicationOutput ( "First Child Element: " + child2D-> GetName ()); } } }
GeListHead objects can also be obtained using GeListNode::GetBranchInfo() :
// This example loops through all branches of a given BaseDocument. // If possible the name of the first branch child object is printed. BranchInfo info[20]; // 20 is just an arbitrary number, that should be enough to catch all branches const Int32 branchCount = doc-> GetBranchInfo (info, 20, GETBRANCHINFO::NONE ); for ( Int32 i = 0; i < branchCount; ++i) { ApplicationOutput ( "Branch " + String::IntToString (i)); const String branchName = info[i]. name ; ApplicationOutput ( " - Name: " + branchName); GeListHead * const branchHead = info[i]. head ; if (branchHead != nullptr ) { GeListNode * const child = branchHead-> GetFirst ();// check if the child is a BaseList2D object if (child && child-> IsInstanceOf ( Tbaselist2d )) { BaseList2D * const child2D = static_cast< BaseList2D * > (child); ApplicationOutput ( " - First Child Element: " + child2D-> GetName ()); } } }
另请参阅 GeListNode Heads and Branches and BaseList2D::GetMain() at BaseList2D Read-Only Properties .
GeListHead itself is based on GeListNode . So instances of GeListHead can be organized in a list or tree:
The parent of a GeListHead instance is typically the object that owns that instance/branch.
GeListHead::SetParent() is normally used directly after the creation of a GeListHead instance.
// This example allocates a new GeListHead in a custom object's "Init" function. // The "node" argument of "Init" is used as the parent object. _branchHead = GeListHead::Alloc (); if (_branchHead == nullptr ) return false ; _branchHead->SetParent(node); _branchName = ::String { "My Branch" };A GeListHead is a root of a list of GeListNode elements. These elements can be obtained with:
New elements can be added to the list with:
All elements of a list can easily be deleted with:
