ENH: Add ScriptedFileReader for implementing file readers in Python

Also fixed workarounds of adding dummy file writers to scripted modules to avoid logging error messages.

Base/QTCore/CMakeLists.txt

@@ -119,6 +119,8 @@ endif()
 
 if(Slicer_USE_PYTHONQT)
   list(APPEND KIT_SRCS
+    qSlicerScriptedFileReader.cxx
+    qSlicerScriptedFileReader.h
     qSlicerScriptedFileWriter.cxx
     qSlicerScriptedFileWriter.h
     qSlicerScriptedUtils.cxx
@@ -160,6 +162,7 @@ endif()
 
 if(Slicer_USE_PYTHONQT)
   list(APPEND KIT_MOC_SRCS
+    qSlicerScriptedFileReader.h
     qSlicerScriptedFileWriter.h
     )
 endif()

Base/QTCore/qSlicerScriptedFileReader.cxx

@@ -0,0 +1,260 @@
+/*==============================================================================
+
+  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.
+
+  This file was originally developed by Julien Finet, Kitware Inc.
+  and was partially funded by NIH grant 3P41RR013218-12S1
+
+==============================================================================*/
+
+// Qt includes
+#include <QFileInfo>
+
+// PythonQt includes
+#include <PythonQt.h>
+#include <PythonQtConversion.h>
+
+// Slicer includes
+#include "qSlicerScriptedFileReader.h"
+#include "qSlicerScriptedUtils_p.h"
+
+// VTK includes
+#include <vtkObject.h>
+#include <vtkPythonUtil.h>
+
+//-----------------------------------------------------------------------------
+class qSlicerScriptedFileReaderPrivate
+{
+public:
+  typedef qSlicerScriptedFileReaderPrivate Self;
+  qSlicerScriptedFileReaderPrivate();
+  virtual ~qSlicerScriptedFileReaderPrivate();
+
+  enum {
+    DescriptionMethod = 0,
+    FileTypeMethod,
+    ExtensionsMethod,
+    LoadMethod,
+    };
+
+  mutable qSlicerPythonCppAPI PythonCppAPI;
+
+  QString    PythonSource;
+  QString    PythonClassName;
+};
+
+//-----------------------------------------------------------------------------
+// qSlicerScriptedFileReaderPrivate methods
+
+//-----------------------------------------------------------------------------
+qSlicerScriptedFileReaderPrivate::qSlicerScriptedFileReaderPrivate()
+{
+  this->PythonCppAPI.declareMethod(Self::DescriptionMethod, "description");
+  this->PythonCppAPI.declareMethod(Self::FileTypeMethod, "fileType");
+  this->PythonCppAPI.declareMethod(Self::ExtensionsMethod, "extensions");
+  this->PythonCppAPI.declareMethod(Self::LoadMethod, "load");
+}
+
+//-----------------------------------------------------------------------------
+qSlicerScriptedFileReaderPrivate::~qSlicerScriptedFileReaderPrivate() = default;
+
+//-----------------------------------------------------------------------------
+// qSlicerScriptedFileReader methods
+
+//-----------------------------------------------------------------------------
+qSlicerScriptedFileReader::qSlicerScriptedFileReader(QObject* parent)
+  : Superclass(parent)
+  , d_ptr(new qSlicerScriptedFileReaderPrivate)
+{
+}
+
+//-----------------------------------------------------------------------------
+qSlicerScriptedFileReader::~qSlicerScriptedFileReader() = default;
+
+//-----------------------------------------------------------------------------
+QString qSlicerScriptedFileReader::pythonSource()const
+{
+  Q_D(const qSlicerScriptedFileReader);
+  return d->PythonSource;
+}
+
+//-----------------------------------------------------------------------------
+bool qSlicerScriptedFileReader::setPythonSource(const QString& newPythonSource, const QString& _className, bool missingClassIsExpected)
+{
+  Q_D(qSlicerScriptedFileReader);
+
+  if (!Py_IsInitialized())
+    {
+    return false;
+    }
+
+  if(!newPythonSource.endsWith(".py") && !newPythonSource.endsWith(".pyc"))
+    {
+    return false;
+    }
+
+  // Extract moduleName from the provided filename
+  QString moduleName = QFileInfo(newPythonSource).baseName();
+
+  QString className = _className;
+  if (className.isEmpty())
+    {
+    className = moduleName;
+    if (!moduleName.endsWith("FileReader"))
+      {
+      className.append("FileReader");
+      }
+    }
+  d->PythonClassName = className;
+
+  d->PythonCppAPI.setObjectName(className);
+
+  // Get a reference (or create if needed) the <moduleName> python module
+  PyObject * module = PyImport_AddModule(moduleName.toUtf8());
+
+  // Get a reference to the python module class to instantiate
+  PythonQtObjectPtr classToInstantiate;
+  if (PyObject_HasAttrString(module, className.toUtf8()))
+    {
+    classToInstantiate.setNewRef(PyObject_GetAttrString(module, className.toUtf8()));
+    }
+  else if (missingClassIsExpected)
+    {
+    // Class is not defined for this object, but this is expected, not an error
+    return false;
+    }
+  if (!classToInstantiate)
+    {
+    PythonQt::self()->handleError();
+    PyErr_SetString(PyExc_RuntimeError,
+                    QString("qSlicerScriptedFileReader::setPythonSource - "
+                            "Failed to load scripted file Reader: "
+                            "class %1 was not found in file %2").arg(className).arg(newPythonSource).toUtf8());
+    return false;
+    }
+
+  PyObject* self = d->PythonCppAPI.instantiateClass(this, className, classToInstantiate);
+  if (!self)
+    {
+    return false;
+    }
+
+  d->PythonSource = newPythonSource;
+
+  return true;
+}
+
+//-----------------------------------------------------------------------------
+PyObject* qSlicerScriptedFileReader::self() const
+{
+  Q_D(const qSlicerScriptedFileReader);
+  return d->PythonCppAPI.pythonSelf();
+}
+
+//-----------------------------------------------------------------------------
+QString qSlicerScriptedFileReader::description()const
+{
+  Q_D(const qSlicerScriptedFileReader);
+
+  PyObject * result = d->PythonCppAPI.callMethod(d->DescriptionMethod);
+  if (!result)
+    {
+    return QString();
+    }
+  if (!PyString_Check(result))
+    {
+    qWarning() << d->PythonSource
+               << " - In" << d->PythonClassName << "class, function 'description' "
+               << "is expected to return a string !";
+    return QString();
+    }
+  QString fileType = QString(PyString_AsString(result));
+  return fileType;
+}
+
+//-----------------------------------------------------------------------------
+qSlicerIO::IOFileType qSlicerScriptedFileReader::fileType()const
+{
+  Q_D(const qSlicerScriptedFileReader);
+
+  PyObject * result = d->PythonCppAPI.callMethod(d->FileTypeMethod);
+  if (!result)
+    {
+    return IOFileType();
+    }
+  if (!PyString_Check(result))
+    {
+    qWarning() << d->PythonSource
+               << " - In" << d->PythonClassName << "class, function 'fileType' "
+               << "is expected to return a string !";
+    return IOFileType();
+    }
+  return IOFileType(PyString_AsString(result));
+}
+
+//-----------------------------------------------------------------------------
+QStringList qSlicerScriptedFileReader::extensions()const
+{
+  Q_D(const qSlicerScriptedFileReader);
+  PyObject * result = d->PythonCppAPI.callMethod(d->ExtensionsMethod);
+  if (!result)
+    {
+    return QStringList();
+    }
+  if (!PyList_Check(result))
+    {
+    qWarning() << d->PythonSource
+               << " - In" << d->PythonClassName << "class, function 'extensions' "
+               << "is expected to return a string list !";
+    return QStringList();
+    }
+  PyObject* resultAsTuple = PyList_AsTuple(result);
+  QStringList extensionList;
+  Py_ssize_t size = PyTuple_Size(resultAsTuple);
+  for (Py_ssize_t i = 0; i < size; ++i)
+    {
+    if (!PyString_Check(PyTuple_GetItem(resultAsTuple, i)))
+      {
+      qWarning() << d->PythonSource
+                 << " - In" << d->PythonClassName << "class, function 'extensions' "
+                 << "is expected to return a string list !";
+      break;
+      }
+    extensionList << PyString_AsString(PyTuple_GetItem(resultAsTuple, i));
+    }
+  Py_DECREF(resultAsTuple);
+  return extensionList;
+}
+
+//-----------------------------------------------------------------------------
+bool qSlicerScriptedFileReader::load(const qSlicerIO::IOProperties& properties)
+{
+  Q_D(qSlicerScriptedFileReader);
+  PyObject * arguments = PyTuple_New(1);
+  PyTuple_SET_ITEM(arguments, 0, PythonQtConv::QVariantMapToPyObject(properties));
+  PyObject * result = d->PythonCppAPI.callMethod(d->LoadMethod, arguments);
+  Py_DECREF(arguments);
+  if (!result)
+    {
+    return false;
+    }
+  if (!PyBool_Check(result))
+    {
+    qWarning() << d->PythonSource
+               << " - In" << d->PythonClassName << "class, function 'write' "
+               << "is expected to return a string boolean !";
+    return false;
+    }
+  return result == Py_True;
+}

Base/QTCore/qSlicerScriptedFileReader.h

@@ -0,0 +1,79 @@
+/*==============================================================================
+
+  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.
+
+  This file was originally developed by Jean-Christophe Fillion-Robin, Kitware Inc.
+  and was partially funded by NIH grant 3P41RR013218-12S1
+
+==============================================================================*/
+
+#ifndef __qSlicerScriptedFileReader_h
+#define __qSlicerScriptedFileReader_h
+
+// Slicer includes
+#include "qSlicerFileReader.h"
+#include "qSlicerBaseQTCoreExport.h"
+
+// Forward Declare PyObject*
+#ifndef PyObject_HEAD
+struct _object;
+typedef _object PyObject;
+#endif
+class qSlicerScriptedFileReaderPrivate;
+class vtkObject;
+
+class Q_SLICER_BASE_QTCORE_EXPORT qSlicerScriptedFileReader
+  : public qSlicerFileReader
+{
+  Q_OBJECT
+
+public:
+  typedef qSlicerFileReader Superclass;
+  qSlicerScriptedFileReader(QObject* parent = nullptr);
+  ~qSlicerScriptedFileReader() override;
+
+  QString pythonSource()const;
+
+  /// \warning Setting the source is a no-op. See detailed comment in the source code.
+  /// If missingClassIsExpected is true (default) then missing class is expected and not treated as an error.
+  bool setPythonSource(const QString& newPythonSource, const QString& className = QLatin1String(""), bool missingClassIsExpected = true);
+
+  /// Convenience method allowing to retrieve the associated scripted instance
+  Q_INVOKABLE PyObject* self() const;
+
+  /// Reimplemented to propagate to python methods
+  /// \sa qSlicerIO::description()
+  QString description()const override;
+
+  /// Reimplemented to propagate to python methods
+  /// \sa qSlicerIO::fileType()
+  IOFileType fileType()const override;
+
+  /// Reimplemented to propagate to python methods
+  /// \sa qSlicerFileReader::extensions()
+  QStringList extensions()const override;
+
+  /// Reimplemented to propagate to python methods
+  /// \sa qSlicerFileReader::write()
+  bool load(const qSlicerIO::IOProperties& properties) override;
+
+protected:
+  QScopedPointer<qSlicerScriptedFileReaderPrivate> d_ptr;
+
+private:
+  Q_DECLARE_PRIVATE(qSlicerScriptedFileReader);
+  Q_DISABLE_COPY(qSlicerScriptedFileReader);
+};
+
+#endif

Base/QTCore/qSlicerScriptedFileWriter.cxx

@@ -92,7 +92,7 @@ QString qSlicerScriptedFileWriter::pythonSource()const
 }
 
 //-----------------------------------------------------------------------------
-bool qSlicerScriptedFileWriter::setPythonSource(const QString& newPythonSource, const QString& _className)
+bool qSlicerScriptedFileWriter::setPythonSource(const QString& newPythonSource, const QString& _className, bool missingClassIsExpected)
 {
   Q_D(qSlicerScriptedFileWriter);
 
@@ -131,6 +131,11 @@ bool qSlicerScriptedFileWriter::setPythonSource(const QString& newPythonSource,
     {
     classToInstantiate.setNewRef(PyObject_GetAttrString(module, className.toUtf8()));
     }
+  else if (missingClassIsExpected)
+    {
+    // Class is not defined for this object, but this is expected, not an error
+    return false;
+    }
   if (!classToInstantiate)
     {
     PythonQt::self()->handleError();

Base/QTCore/qSlicerScriptedFileWriter.h

@@ -45,7 +45,8 @@ class Q_SLICER_BASE_QTCORE_EXPORT qSlicerScriptedFileWriter
   QString pythonSource()const;
 
   /// \warning Setting the source is a no-op. See detailed comment in the source code.
-  bool setPythonSource(const QString& newPythonSource, const QString& className = QLatin1String(""));
+  /// If missingClassIsExpected is true (default) then missing class is expected and not treated as an error.
+  bool setPythonSource(const QString& newPythonSource, const QString& className = QLatin1String(""), bool missingClassIsExpected = true);
 
   /// Convenience method allowing to retrieve the associated scripted instance
   Q_INVOKABLE PyObject* self() const;