Summary of bug description

• actual behaviour

Properties with specializations of mitk::GenericLookupTable can not be compared for equality, because the current implementation will only compare pointers to the lookup table objects, not the objects themselves

• expected behaviour

the == operator should compare the objects, as it does with all other properties

Cause of the bug

The current implementation is this:

  mitkSpecializeGenericProperty(FloatLookupTableProperty,
  FloatLookupTable::Pointer , FloatLookupTable::New());

mitk::GenericProperty is used with a smartpointer to a lookup table as data type. The == operator of GenericProperty is calling == of the smartpointer class, which only checks if the pointer are equal, not if the objects that the pointers point at are equal.

Proposed solution

Therefore another solution is needed: We can not use a (smart)pointer to a lookup table as template paramter, we have to use the lookup table itself:

• mitkSpecializeGenericProperty(FloatLookupTableProperty, FloatLookupTable , FloatLookupTable());

To allow this, mitk::GenericLookupTable may not derive from itk::Object. It must define =, ==, != operators and must define a global ostream& << operator. Because the ostream& << operator has to be a global function, it must be defined in a cpp file. Therefore the mitkSpecializeGenericLookupTable must be splitted into one that declares the new lookup table and is called in a header file (mitkLookupTables.h), and a second macro mitkSpecializeGenericLookupTableOperator that is called for each specialized lookup table in a cpp file (mitkLookupTables.cpp) and defines the << operator function

Affected classes

• mitkGenericLookupTable.h mitk::GenericLookupTable: not derived from itk::Object, define =, ==, != operators and define a global ostream& << operator

• mitkGenericLookupTable.cpp: add calls to mitkSpecializeGenericLookupTableOperator for all lookup tables
• mitkProperties.h: change the declaration of the the properties that hold the lookup tables to use the lookup tables directly instead of a smartpointer
• mitkProperties.cpp: change template instantiation of the properties that hold the lookup tables to use the lookup tables directly instead of a smartpointer

• mitkPropertyList.cpp: add template instantiations for mitk::PropertyList::GetPropertyValue<>() method for the new properties.

• other classes outside mitkCore need to be adapted for the interface changes.

How will the bugfix get tested?

• a unit test will be written for the generic lookup tables and the respective properties.

• The lookup tables and their properties are used in SceneSerialization. The PropertyListSerialization unit test uses them too.