Deprecating vtkCellTypes

`vtkCellTypes` currently holds an attribute `LocationArray` which is not
needed anymore. this commit deprecates all methods that are related to
this attribute.

Common/DataModel/Testing/Cxx/otherCellTypes.cxx

@@ -33,20 +33,15 @@ void TestOCT()
   ct->InsertNextCell(VTK_PIXEL, 1);
 
   vtkUnsignedCharArray* cellTypes = vtkUnsignedCharArray::New();
-  vtkIntArray* cellLocations = vtkIntArray::New();
 
-  cellLocations->InsertNextValue(0);
   cellTypes->InsertNextValue(VTK_QUAD);
 
-  cellLocations->InsertNextValue(1);
   cellTypes->InsertNextValue(VTK_PIXEL);
 
-  cellLocations->InsertNextValue(2);
   cellTypes->InsertNextValue(VTK_TETRA);
 
-  ct->SetCellTypes(3, cellTypes, cellLocations);
+  ct->SetCellTypes(3, cellTypes);
 
-  ct->GetCellLocation(1);
   ct->DeleteCell(1);
 
   ct->GetNumberOfTypes();
@@ -69,7 +64,6 @@ void TestOCT()
 
   ct1->Delete();
   ct->Delete();
-  cellLocations->Delete();
   cellTypes->Delete();
 }
 

Common/DataModel/vtkCellTypes.cxx

@@ -13,6 +13,9 @@
 
 =========================================================================*/
 
+// Hide VTK_DEPRECATED_IN_9_2_0() warnings for this class.
+#define VTK_DEPRECATION_LEVEL 0
+
 #include "vtkCellTypes.h"
 #include "vtkIdTypeArray.h"
 #include "vtkIntArray.h"
@@ -148,6 +151,7 @@ vtkIdType vtkCellTypes::InsertNextCell(unsigned char type, vtkIdType loc)
 void vtkCellTypes::SetCellTypes(
   vtkIdType ncells, vtkUnsignedCharArray* cellTypes, vtkIntArray* cellLocations)
 {
+  VTK_LEGACY_BODY(vtkCellTypes::SetCellTypes, "VTK 9.2");
   this->TypeArray = cellTypes;
   if (!this->LocationArray)
   {
@@ -157,11 +161,20 @@ void vtkCellTypes::SetCellTypes(
   this->MaxId = ncells - 1;
 }
 
+//------------------------------------------------------------------------------
+// Specify a group of cell types.
+void vtkCellTypes::SetCellTypes(vtkIdType ncells, vtkUnsignedCharArray* cellTypes)
+{
+  this->TypeArray = cellTypes;
+  this->MaxId = ncells - 1;
+}
+
 //------------------------------------------------------------------------------
 // Specify a group of cell types.
 void vtkCellTypes::SetCellTypes(
   vtkIdType ncells, vtkUnsignedCharArray* cellTypes, vtkIdTypeArray* cellLocations)
 {
+  VTK_LEGACY_BODY(vtkCellTypes::SetCellTypes, "VTK 9.2");
   this->TypeArray = cellTypes;
   this->LocationArray = cellLocations;
   this->MaxId = ncells - 1;

Common/DataModel/vtkCellTypes.h

@@ -40,6 +40,7 @@
 #include "vtkObject.h"
 
 #include "vtkCellType.h"          // Needed for inline methods
+#include "vtkDeprecation.h"       // Needed for deprecation
 #include "vtkIdTypeArray.h"       // Needed for inline methods
 #include "vtkSmartPointer.h"      // Needed for internals
 #include "vtkUnsignedCharArray.h" // Needed for inline methods
@@ -70,19 +71,28 @@ class VTKCOMMONDATAMODEL_EXPORT vtkCellTypes : public vtkObject
 
   /**
    * Specify a group of cell types.
+   *
+   * \deprecated Please use method version that doesn't use `cellLocations` instead.
    */
+  VTK_DEPRECATED_IN_9_2_0("Please use version without cellLocations.")
   void SetCellTypes(
     vtkIdType ncells, vtkUnsignedCharArray* cellTypes, vtkIdTypeArray* cellLocations);
 
   /**
-   * Specify a group of cell types. This version is provided to maintain
-   * backwards compatibility and does a copy of the cellLocations
+   * Specify a group of cell types.
    */
+  void SetCellTypes(vtkIdType ncells, vtkUnsignedCharArray* cellTypes);
+
+  VTK_DEPRECATED_IN_9_2_0("Please use version without cellLocations.")
   void SetCellTypes(vtkIdType ncells, vtkUnsignedCharArray* cellTypes, vtkIntArray* cellLocations);
 
   /**
    * Return the location of the cell in the associated vtkCellArray.
+   *
+   * \deprecated This method will go away in future releases. Please do not realy on `CellLocation`
+   * in this class.
    */
+  VTK_DEPRECATED_IN_9_2_0("The Location API will disappear.")
   vtkIdType GetCellLocation(vtkIdType cellId) { return this->LocationArray->GetValue(cellId); }
 
   /**
@@ -169,8 +179,13 @@ class VTKCOMMONDATAMODEL_EXPORT vtkCellTypes : public vtkObject
   ~vtkCellTypes() override = default;
 
   vtkSmartPointer<vtkUnsignedCharArray> TypeArray; // pointer to types array
-  vtkSmartPointer<vtkIdTypeArray> LocationArray;   // pointer to array of offsets
-  vtkIdType MaxId;                                 // maximum index inserted thus far
+
+  // DEPRECATION_IN_9_2_0 Note for whoever is in deprecation duties:
+  // The attribute LocationArray needs to be deleted, and any code in this class that would fail
+  // compiling because of its removal deleted as well.
+  vtkSmartPointer<vtkIdTypeArray> LocationArray; // pointer to array of offsets
+
+  vtkIdType MaxId; // maximum index inserted thus far
 
 private:
   vtkCellTypes(const vtkCellTypes&) = delete;

Documentation/dev/deprecation-vtkCellTypes.md

@@ -0,0 +1,10 @@
+# Deprecation in vtkCellTypes
+
+Usage of `LocationArray` in `vtkCellTypes` is deprecated. This is an old legacy feature that was
+used by `vtkUnstructuredGrid`. Currently, this class is used to store a list of distinct cell types
+present in a `vtkUnstructuredGrid`, making `LocationArray` irrelevant.
+In the long run, `vtkCellTypes` will become a static method only class. So it is advised to not use
+instances of this class anymore. Using static methods is fine.
+
+A new more direct interface to the array listing distinct cell types is implemented
+in `vtkUnstructuredGrid` (see release notes about deprecation in `vtkUnstructuredGrid`).