ENH: adds hook for loading directory archetypes

When a directory is added via the Add Data dialog,
it may contain a collection of files that should be
treated as a single MRML data type, such as a series
of image files that get loaded as a volume.

This change allows a qSlicerFileReader subclass to define
a method that can examine the contents of a directory and
filter out any files that should be loaded as a group.  One
of these files then serves as the archetype and the io properties
can be configured such that the files are loaded correctly.

Base/QTCore/qSlicerCoreIOManager.cxx

@@ -781,3 +781,18 @@ void qSlicerCoreIOManager::setDefaultSceneFileType(QString fileType)
   Q_D(qSlicerCoreIOManager);
   d->DefaultSceneFileType = fileType;
 }
+
+//-----------------------------------------------------------------------------
+bool qSlicerCoreIOManager::examineFileInfoList(QFileInfoList &fileInfoList, QFileInfo &archetypeFileInfo, qSlicerIO::IOProperties &ioProperties)const
+{
+  Q_D(const qSlicerCoreIOManager);
+  QList<qSlicerFileReader*> res;
+  foreach(qSlicerFileReader* reader, d->Readers)
+    {
+    if (reader->examineFileInfoList(fileInfoList, archetypeFileInfo, ioProperties))
+      {
+      return (true);
+      }
+    }
+  return (false);
+}

Base/QTCore/qSlicerCoreIOManager.h

@@ -22,8 +22,9 @@
 #define __qSlicerCoreIOManager_h
 
 // Qt includes
-#include <QList>
+#include <QFileInfo>
 #include <QImage>
+#include <QList>
 #include <QMap>
 #include <QObject>
 #include <QVariantMap>
@@ -170,6 +171,21 @@ class Q_SLICER_BASE_QTCORE_EXPORT qSlicerCoreIOManager:public QObject
   /// Defines the file format that should be offered by default when the scene is saved.
   Q_INVOKABLE QString defaultSceneFileType()const;
 
+  /// Iterates through readers looking at the fileInfoList to see if there is an entry that can serve as
+  /// an archetype for loading multiple fileInfos.  If so, the reader removes the recognized
+  /// fileInfos from the list and sets the ioProperties so that the corresponding
+  /// loader will read these files. The archetypeEntry will contain the fileInfo
+  /// for the archetype and the method returns true.  If no pattern is recognized
+  /// the method returns false.
+  /// The specific motivating use case is when the file
+  /// list contains a set of related files, such as a list of image files that
+  /// are recognized as a volume. But other cases could also make sense, such as when
+  /// a file format has a set or related files such as textures or material files
+  /// for a surface model.
+  /// \sa qSlicerDataDialog
+  /// \sa qSlicerFileReader
+  Q_INVOKABLE bool examineFileInfoList(QFileInfoList &fileInfoList, QFileInfo &archetypeEntry, qSlicerIO::IOProperties &ioProperties)const;
+
 public slots:
 
   /// Defines the file format that should be offered by default when the scene is saved.

Base/QTCore/qSlicerFileReader.cxx

@@ -119,3 +119,9 @@ QStringList qSlicerFileReader::loadedNodes()const
   Q_D(const qSlicerFileReader);
   return d->LoadedNodes;
 }
+
+//----------------------------------------------------------------------------
+bool qSlicerFileReader::examineFileInfoList(QFileInfoList &fileInfoList, QFileInfo archetypeEntry, qSlicerIO::IOProperties &ioProperties)const
+{
+  return(false);
+}

Base/QTCore/qSlicerFileReader.h

@@ -21,6 +21,9 @@
 #ifndef __qSlicerFileReader_h
 #define __qSlicerFileReader_h
 
+// Qt includes
+#include <QFileInfo>
+
 // QtCore includes
 #include "qSlicerIO.h"
 #include "qSlicerBaseQTCoreExport.h"
@@ -64,6 +67,11 @@ class Q_SLICER_BASE_QTCORE_EXPORT qSlicerFileReader
   /// \sa setLoadedNodes(), load()
   QStringList loadedNodes()const;
 
+  /// Implements the file list examination for the corresponding method in the core
+  /// IO manager.
+  /// \sa qSlicerCoreIOManager
+  virtual bool examineFileInfoList(QFileInfoList &fileInfoList, QFileInfo archetypeEntry, qSlicerIO::IOProperties &ioProperties)const;
+
 protected:
   /// Must be called in load() on success with the list of nodes added into the
   /// scene.

Base/QTGUI/qSlicerDataDialog.cxx

@@ -163,6 +163,38 @@ void qSlicerDataDialogPrivate::addDirectory(const QDir& directory)
   bool recursive = true;
   QDir::Filters filters =
     QDir::AllDirs | QDir::Files | QDir::Readable | QDir::NoDotAndDotDot;
+  QFileInfoList fileInfoList = directory.entryInfoList(filters);
+
+  //
+  // check to see if any readers recognize the directory contents
+  // and provide an archetype.
+  //
+  qSlicerCoreIOManager* coreIOManager =
+    qSlicerCoreApplication::application()->coreIOManager();
+  qSlicerIO::IOProperties ioProperties;
+  QFileInfo archetypeEntry;
+  if (coreIOManager->examineFileInfoList(fileInfoList, archetypeEntry, ioProperties))
+    {
+    this->addFile(archetypeEntry);
+    QString filePath = archetypeEntry.absoluteFilePath();
+    QList<QTableWidgetItem *> items = this->FileWidget->findItems(filePath, Qt::MatchExactly);
+    if (items.isEmpty())
+      {
+      qWarning() << "Couldn't add archetype widget for file: " << filePath;
+      }
+    else
+      {
+      QTableWidgetItem *item = items[0];
+      QWidget *cellWidget = this->FileWidget->cellWidget(item->row(), OptionsColumn);
+      qSlicerIOOptionsWidget *ioOptionsWidget = dynamic_cast<qSlicerIOOptionsWidget *> (cellWidget);
+      ioOptionsWidget->updateGUI(ioProperties);
+      }
+    }
+
+  //
+  // now add any files and directories that weren't filtered
+  // out by the ioManager
+  //
   foreach(QFileInfo entry, directory.entryInfoList(filters))
     {
     if (entry.isFile())