GeMarker Manual

Table of Contents

• About
• Access
• Allocation/Deallocation
• Functionality
• Read and Write
• Further Reading

About

A GeMarker object contains an unique ID. It is used to identify BaseList2D based objects.

Warning

These markers change when the source object is copied or when the document is re-loaded.

Access

• BaseList2D::GetMarker(): Returns the element's marker.
• BaseList2D::SetMarker(): Sets the element's marker.

  // This example gets the name and the marker of the given BaseObject.
  // The name is used to search for an object with the same name in the document.
  // The marker is used to check if the found object is also the original object.
 
  const String    objectName = object->GetName();
  const GeMarker& marker = object->GetMarker();
 
  // search object with the same name
  const BaseObject* const foundObject = doc->SearchObject(objectName);
  if (foundObject != nullptr)
  {
    // check if it is the same object
    const GeMarker& foundObjectMarker = foundObject->GetMarker();
 
    // compare if the markers are equal
    if (foundObjectMarker.Compare(marker) == 0)
      ApplicationOutput("The found object is the original object"_s);
    else
      ApplicationOutput("The found object is not the original object"_s);
  }

The marker of a copy is different than the marker of the original object:

  // This example copies an object.
  // The copy has a different marker than the original.
 
  const GeMarker& originalMarker = object->GetMarker();
 
  C4DAtom* const    atomClone = object->GetClone(COPYFLAGS::NONE, nullptr);
  BaseObject* const clone = static_cast<BaseObject*>(atomClone);
  if (clone == nullptr)
    return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
  doc->InsertObject(clone, nullptr, nullptr);
 
  const GeMarker& cloneMarker = clone->GetMarker();
 
  // check if the markers are not equal
  if (cloneMarker.IsEqual(originalMarker) == false)
    ApplicationOutput("The markers are not equal"_s);

See also BaseList2D Marker.

Allocation/Deallocation

GeMarker objects can be created with the usual tools:

• GeMarker::Alloc(): Creates a new GeMarker.
• GeMarker::Free(): Deletes the given GeMarker.

  // This example creates two markers and checks if they are not equal.
 
  AutoAlloc<GeMarker> markerA;
  AutoAlloc<GeMarker> markerB;
 
  const Bool invalidMarkerA = markerA == nullptr;
  const Bool invalidMarkerB = markerB == nullptr;
 
  if (invalidMarkerA || invalidMarkerB)
    return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
  // compare
  if (markerA->IsEqual(*markerB) == false)
    ApplicationOutput("Markers not identical"_s);

Functionality

GeMarker objects can be handled with:

• GeMarker::IsPopulated(): Returns true if the GeMarker has been set.
• GeMarker::IsEqual(): Returns true if the given GeMarker is equal.
• GeMarker::Compare(): Compares the GeMarker and returns their relationship.
• GeMarker::Set(): Sets the GeMarker to the value of the given GeMarker.
• GeMarker::GetMemory(): Retrieves the internally stored data. Typically used to calculate a unique hash value based on that internal data.

  // This example iterates through all BaseDocuments in the document list.
  // The active BaseDocument is marked with a star.
 
  const BaseDocument* const activeDocument = GetActiveDocument();
  if (activeDocument == nullptr)
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  BaseDocument* document = GetFirstDocument();
 
  while (document != nullptr)
  {
    const GeMarker& docMarker = document->GetMarker();
    const GeMarker& activeDocMarker = activeDocument->GetMarker();
 
    // use GeMarker to compare identity of the BaseDocuments
    if (docMarker.IsEqual(activeDocMarker))
    {
      ApplicationOutput("Document: " + document->GetDocumentName().GetString() + " *");
    }
    else
    {
      ApplicationOutput("Document: " + document->GetDocumentName().GetString());
    }
 
    document = document->GetNext();
  }

Read and Write

GeMarker objects can be stored in a HyperFile.

• GeMarker::Read(): Reads the GeMarker from the given HyperFile.
• GeMarker::Write(): Stores the GeMarker in the given HyperFile.

Further Reading

• BaseList2D Manual