BUG: Enable language translation in MRML classes

vtkMRMLI18N singleton class is responsible for internationalization related features in MRML.
It currently only stores a language translator.

A translator that uses Qt for translation is specified in qSlicerCoreApplication.

Enables fixing of these issues:
Slicer/SlicerLanguagePacks#12
Slicer#6647
Slicer#6177

Co-authored-by: Mouhamed DIOP <mouhamed.diop@esp.sn>

Base/QTCore/qSlicerCoreApplication.cxx

@@ -103,7 +103,9 @@
 #ifdef Slicer_BUILD_CLI_SUPPORT
 # include <vtkMRMLCommandLineModuleNode.h>
 #endif
+#include <vtkMRMLI18N.h>
 #include <vtkMRMLScene.h>
+#include <vtkMRMLTranslator.h>
 
 // CTK includes
 #include <ctkUtils.h>
@@ -153,6 +155,30 @@
 #include <ctkDICOMDatabase.h>
 #endif
 
+//-----------------------------------------------------------------------------
+// Adapter class for translation in MRML classes using Qt translation infrastructure
+
+class vtkQtTranslator: public vtkMRMLTranslator
+{
+public:
+  static vtkQtTranslator* New();
+  vtkTypeMacro(vtkQtTranslator, vtkMRMLTranslator);
+
+  /// Translation function for logic classes
+  std::string Translate(const char *context, const char *sourceText, const char *disambiguation = nullptr, int n = -1) override
+    {
+    return QCoreApplication::translate(context, sourceText, disambiguation, n).toStdString();
+    }
+
+protected:
+  vtkQtTranslator() = default;
+  ~vtkQtTranslator() override = default;
+  vtkQtTranslator(const vtkQtTranslator&) = delete;
+  void operator=(const vtkQtTranslator&) = delete;
+};
+
+vtkStandardNewMacro(vtkQtTranslator);
+
 //-----------------------------------------------------------------------------
 // Helper function
 
@@ -353,6 +379,10 @@ void qSlicerCoreApplicationPrivate::init()
     vtkEventBroker::GetInstance()->SetRequestModifiedCallback(modifiedRequestCallback);
   }
 
+  // Set up translation in MRML classes using Qt translator
+  vtkNew<vtkQtTranslator> mrmlTranslator;
+  vtkMRMLI18N::GetInstance()->SetTranslator(mrmlTranslator);
+
   // Ensure that temporary folder is writable
   {
     // QTemporaryFile is deleted automatically when leaving this scope

Libs/MRML/Core/CMakeLists.txt

@@ -139,6 +139,8 @@ set(MRMLCore_SRCS
   vtkCodedEntry.cxx
   vtkEventBroker.cxx
   vtkDataFileFormatHelper.cxx
+  vtkMRMLI18N.cxx
+  vtkMRMLI18N.h
   vtkMRMLMeasurement.cxx
   vtkMRMLStaticMeasurement.cxx
   vtkMRMLLogic.cxx
@@ -221,6 +223,7 @@ set(MRMLCore_SRCS
   vtkMRMLTransformStorageNode.cxx
   vtkMRMLTransformDisplayNode.cxx
   vtkMRMLTransformableNode.cxx
+  vtkMRMLTranslator.h
   vtkMRMLUnitNode.cxx
   vtkMRMLVectorVolumeDisplayNode.cxx
   vtkMRMLViewNode.cxx

Libs/MRML/Core/Testing/CMakeLists.txt

@@ -31,6 +31,7 @@ create_test_sourcelist(Tests ${KIT}CxxTests.cxx
   vtkMRMLGridTransformNodeTest1.cxx
   vtkMRMLHierarchyNodeTest1.cxx
   vtkMRMLHierarchyNodeTest3.cxx
+  vtkMRMLI18NTest1.cxx
   vtkMRMLInteractionNodeTest1.cxx
   vtkMRMLLabelMapVolumeDisplayNodeTest1.cxx
   vtkMRMLLayoutNodeTest1.cxx

Libs/MRML/Core/Testing/vtkMRMLI18NTest1.cxx

@@ -0,0 +1,61 @@
+/*=auto=========================================================================
+
+  Portions (c) Copyright 2005 Brigham and Women's Hospital (BWH)
+  All Rights Reserved.
+
+  See COPYRIGHT.txt
+  or http://www.slicer.org/copyright/copyright.txt for details.
+
+  Program:   3D Slicer
+
+=========================================================================auto=*/
+
+// MRML includes
+#include "vtkMRMLCoreTestingMacros.h"
+#include "vtkMRMLScene.h"
+
+// VTK includes
+#include <vtkMRMLI18N.h>
+#include <vtkMRMLTranslator.h>
+
+namespace
+{
+
+  class vtkTestTranslator : public vtkMRMLTranslator
+  {
+  public:
+    static vtkTestTranslator * New();
+    vtkTypeMacro(vtkTestTranslator, vtkMRMLTranslator);
+
+    /// Translation method for testing that returns "translated-(context)(sourceText)" as translation
+    std::string Translate(const char* context, const char* sourceText, const char* disambiguation = nullptr, int n = -1) override
+      {
+      return std::string("translated-") + context + sourceText;
+      }
+
+  protected:
+    vtkTestTranslator () = default;
+    ~vtkTestTranslator () override = default;
+    vtkTestTranslator (const vtkTestTranslator &) = delete;
+    void operator=(const vtkTestTranslator &) = delete;
+  };
+
+  vtkStandardNewMacro(vtkTestTranslator );
+}
+
+int vtkMRMLI18NTest1(int, char*[])
+{
+  // Check default translation (simply sourcetext is returned)
+  CHECK_STD_STRING(vtkMRMLI18N::Translate("SomeContext", "SomeMessage"), "SomeMessage");
+
+  // Set custom translator
+  vtkNew<vtkTestTranslator> translator;
+  vtkMRMLI18N::GetInstance()->SetTranslator(translator);
+
+  // Check translation with custom translator
+  CHECK_STD_STRING(vtkMRMLI18N::Translate("SomeContext", "SomeMessage"), "translated-SomeContextSomeMessage");
+  // Use translation convenience function
+  CHECK_STD_STRING(vtkMRMLTr("SomeContext", "SomeMessage"), "translated-SomeContextSomeMessage");
+
+  return EXIT_SUCCESS;
+}

Libs/MRML/Core/vtkMRMLI18N.cxx

@@ -0,0 +1,149 @@
+/*==============================================================================
+
+  Program: 3D Slicer
+
+  Copyright(c) Kitware Inc.
+
+  See COPYRIGHT.txt
+  or http://www.slicer.org/copyright/copyright.txt for details.
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+==============================================================================*/
+
+// MRML includes
+#include "vtkMRMLI18N.h"
+#include "vtkMRMLTranslator.h"
+
+// VTK includes
+#include <vtkObjectFactory.h>
+
+vtkCxxSetObjectMacro(vtkMRMLI18N, Translator, vtkMRMLTranslator);
+
+//----------------------------------------------------------------------------
+// The i18n manager singleton.
+// This MUST be default initialized to zero by the compiler and is
+// therefore not initialized here.  The ClassInitialize and
+// ClassFinalize methods handle this instance.
+static vtkMRMLI18N* vtkMRMLI18NInstance;
+
+//----------------------------------------------------------------------------
+// Must NOT be initialized.  Default initialization to zero is necessary.
+unsigned int vtkMRMLI18NInitialize::Count;
+
+//----------------------------------------------------------------------------
+// Implementation of vtkMRMLI18NInitialize class.
+//----------------------------------------------------------------------------
+vtkMRMLI18NInitialize::vtkMRMLI18NInitialize()
+{
+  if(++Self::Count == 1)
+    {
+    vtkMRMLI18N::classInitialize();
+    }
+}
+
+//----------------------------------------------------------------------------
+vtkMRMLI18NInitialize::~vtkMRMLI18NInitialize()
+{
+  if(--Self::Count == 0)
+    {
+    vtkMRMLI18N::classFinalize();
+    }
+}
+
+//----------------------------------------------------------------------------
+
+//----------------------------------------------------------------------------
+// Up the reference count so it behaves like New
+vtkMRMLI18N* vtkMRMLI18N::New()
+{
+  vtkMRMLI18N* ret = vtkMRMLI18N::GetInstance();
+  ret->Register(nullptr);
+  return ret;
+}
+
+//----------------------------------------------------------------------------
+// Return the single instance of the vtkMRMLI18N
+vtkMRMLI18N* vtkMRMLI18N::GetInstance()
+{
+  if(!vtkMRMLI18NInstance)
+    {
+    // Try the factory first
+    vtkMRMLI18NInstance = (vtkMRMLI18N*)vtkObjectFactory::CreateInstance("vtkMRMLI18N");
+    // if the factory did not provide one, then create it here
+    if(!vtkMRMLI18NInstance)
+      {
+      vtkMRMLI18NInstance = new vtkMRMLI18N;
+#ifdef VTK_HAS_INITIALIZE_OBJECT_BASE
+      vtkMRMLI18NInstance->InitializeObjectBase();
+#endif
+      }
+    }
+  // return the instance
+  return vtkMRMLI18NInstance;
+}
+
+//----------------------------------------------------------------------------
+vtkMRMLI18N::vtkMRMLI18N()
+{
+  this->Translator = nullptr;
+}
+
+//----------------------------------------------------------------------------
+vtkMRMLI18N::~vtkMRMLI18N()
+{
+  if (this->Translator)
+    {
+    this->Translator->Delete();
+    }
+  this->Translator = nullptr;
+}
+
+//----------------------------------------------------------------------------
+void vtkMRMLI18N::PrintSelf(ostream& os, vtkIndent indent)
+{
+  this->vtkObject::PrintSelf(os, indent);
+
+  os << indent << "Translator:";
+  if (this->GetTranslator())
+    {
+    this->GetTranslator()->PrintSelf(os, indent.GetNextIndent());
+    }
+  else
+    {
+    os << " (none)" << "\n";
+    }
+}
+
+//----------------------------------------------------------------------------
+void vtkMRMLI18N::classInitialize()
+{
+  // Allocate the singleton
+  vtkMRMLI18NInstance = vtkMRMLI18N::GetInstance();
+}
+
+//----------------------------------------------------------------------------
+void vtkMRMLI18N::classFinalize()
+{
+  vtkMRMLI18NInstance->Delete();
+  vtkMRMLI18NInstance = nullptr;
+}
+
+//----------------------------------------------------------------------------
+std::string vtkMRMLI18N::Translate(const char *context, const char *sourceText, const char *disambiguation/*=nullptr*/, int n/*=-1*/)
+{
+  vtkMRMLI18N* i18n = vtkMRMLI18N::GetInstance();
+  vtkMRMLTranslator* translator = i18n ? i18n->GetTranslator() : nullptr;
+  if (translator)
+    {
+    return translator->Translate(context, sourceText, disambiguation, n);
+    }
+  else
+    {
+    return sourceText ? sourceText : "";
+    }
+}

Libs/MRML/Core/vtkMRMLI18N.h

@@ -0,0 +1,98 @@
+/*==============================================================================
+
+  Program: 3D Slicer
+
+  Copyright(c) Kitware Inc.
+
+  See COPYRIGHT.txt
+  or http://www.slicer.org/copyright/copyright.txt for details.
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+==============================================================================*/
+
+#ifndef __vtkMRMLI18N_h
+#define __vtkMRMLI18N_h
+
+// MRML includes
+#include "vtkMRML.h"
+
+// VTK includes
+#include <vtkObject.h>
+
+class vtkMRMLTranslator;
+
+/// \brief Class that provide internationalization (i18n) features,
+/// such as language translation or region-specific units and date formatting.
+///
+class VTK_MRML_EXPORT vtkMRMLI18N : public vtkObject
+{
+public:
+  vtkTypeMacro(vtkMRMLI18N, vtkObject);
+  void PrintSelf(ostream& os, vtkIndent indent) override;
+
+  ///
+  /// Return the singleton instance with no reference counting.
+  static vtkMRMLI18N* GetInstance();
+
+  ///
+  /// This is a singleton pattern New.  There will only be ONE
+  /// reference to a vtkMRMLI18N object per process.  Clients that
+  /// call this must call Delete on the object so that the reference
+  /// counting will work. The single instance will be unreferenced when
+  /// the program exits.
+  static vtkMRMLI18N* New();
+
+  /// Translate message with the current translator
+  static std::string Translate(const char *context, const char *sourceText, const char *disambiguation = nullptr, int n = -1);
+
+  /// Set translator object. This class takes ownership of the translator
+  /// and it releases it when the process quits.
+  void SetTranslator(vtkMRMLTranslator* translator);
+
+  /// Get translator object that can translate text that is displayed to the user
+  /// to the currently chosen language.
+  vtkGetObjectMacro (Translator, vtkMRMLTranslator);
+
+protected:
+  vtkMRMLI18N();
+  ~vtkMRMLI18N() override;
+  vtkMRMLI18N(const vtkMRMLI18N&);
+  void operator=(const vtkMRMLI18N&);
+
+  ///
+  /// Singleton management functions.
+  static void classInitialize();
+  static void classFinalize();
+
+  friend class vtkMRMLI18NInitialize;
+  typedef vtkMRMLI18N Self;
+
+  vtkMRMLTranslator* Translator{ nullptr };
+};
+
+/// Utility class to make sure qSlicerModuleManager is initialized before it is used.
+class VTK_MRML_EXPORT vtkMRMLI18NInitialize
+{
+public:
+  typedef vtkMRMLI18NInitialize Self;
+
+  vtkMRMLI18NInitialize();
+  ~vtkMRMLI18NInitialize();
+private:
+  static unsigned int Count;
+};
+
+/// This instance will show up in any translation unit that uses
+/// vtkMRMLI18N.  It will make sure vtkMRMLI18N is initialized
+/// before it is used.
+static vtkMRMLI18NInitialize vtkMRMLI18NInitializer;
+
+/// Translation function used in MRML classes
+#define vtkMRMLTr(context, sourceText) vtkMRMLI18N::Translate(context, sourceText)
+
+#endif