ENH: Load DICOM files using DICOM module by default (#7077)

Drag-and-dropping a DICOM file made Slicer use ITK DICOM reader, which often did not load the data correctly.

This commit adds a new "DICOM import" reader type, which is selected by default for DICOM files. This reader imports the files into the Slicer DICOM database and switches to the DICOM module.

The workaround of interpreting all files as DICOM by default while in DICOM module has now been removed. "Add data" window is brought up when loading a file, regardless of what is the active module. The workaround surprised users when they could not load non-DICOM data while they were in DICOM module.

If a user wants to read the DICOM file using ITK reader, it is possible by changing "Description" in the "Add data" module to "Volume".

fixes #5726

Base/QTCore/qSlicerScriptedFileReader.cxx

@@ -278,7 +278,7 @@ double qSlicerScriptedFileReader::canLoadFileConfidence(const QString& file)cons
     return this->Superclass::canLoadFileConfidence(file);
     }
 
-  if (PyFloat_Check(result))
+  if (!PyFloat_Check(result))
     {
     qWarning() << d->PythonSource
                << " - In" << d->PythonClassName << "class, function 'canLoadFileConfidence' "

Docs/user_guide/modules/dicom.md

@@ -62,7 +62,7 @@ Since DICOM files are often located in several folders, they can cross-reference
 
 :::{note}
 
-When a folder is drag-and-dropped to the Slicer application while not the DICOM module is active, Slicer displays a popup, asking what to do - click OK ("Load directory in DICOM database"). After import is completed, go to DICOM module.
+When a folder is drag-and-dropped to the Slicer application, Slicer displays a popup, asking what to do - click OK ("Load directory in DICOM database"). After import is completed, go to DICOM module.
 
 :::
 

Modules/Scripted/DICOM/DICOM.py

@@ -531,57 +531,6 @@ def dropEvent(self):
         self.directoriesToAdd = []
 
 
-class DICOMLoadingByDragAndDropEventFilter(qt.QWidget):
-    """This event filter is used for overriding drag-and-drop behavior while
-    the DICOM module is active. To simplify DICOM import, while DICOM module is active
-    then files or folders that are drag-and-dropped to the application window
-    are always interpreted as DICOM data.
-    """
-
-    def eventFilter(self, object, event):
-        """
-        Custom event filter for Slicer Main Window.
-
-        Inputs: Object (QObject), Event (QEvent)
-        """
-        if event.type() == qt.QEvent.DragEnter:
-            self.dragEnterEvent(event)
-            return True
-        if event.type() == qt.QEvent.Drop:
-            self.dropEvent(event)
-            return True
-        return False
-
-    def dragEnterEvent(self, event):
-        """
-        Actions to do when a drag enter event occurs in the Main Window.
-
-        Read up on https://doc.qt.io/qt-5.12/dnd.html#dropping
-        Input: Event (QEvent)
-        """
-        self.directoriesToAdd, self.filesToAdd = DICOMFileDialog.pathsFromMimeData(event.mimeData())
-        if self.directoriesToAdd or self.filesToAdd:
-            event.acceptProposedAction()  # allows drop event to proceed
-        else:
-            event.ignore()
-
-    def dropEvent(self, event):
-        if not DICOMFileDialog.createDefaultDatabase():
-            return
-
-        if not DICOMFileDialog.validDirectories(self.directoriesToAdd) or not DICOMFileDialog.validDirectories(self.filesToAdd):
-            confirmMessage = _(
-                "Import from folders with special (non-ASCII) characters in the name is not supported."
-                " It is recommended to move files into a different folder and retry."
-                " Try to import from current location anyway?")
-            if not slicer.util.confirmYesNoDisplay(confirmMessage):
-                self.directoriesToAdd = []
-                return
-
-        slicer.modules.DICOMInstance.browserWidget.dicomBrowser.importDirectories(self.directoriesToAdd)
-        slicer.modules.DICOMInstance.browserWidget.dicomBrowser.importFiles(self.filesToAdd)
-
-
 #
 # DICOM widget
 #
@@ -605,8 +554,6 @@ def setup(self):
         if hasattr(self, "reloadCollapsibleButton"):
             self.reloadCollapsibleButton.collapsed = True
 
-        self.dragAndDropEventFilter = DICOMLoadingByDragAndDropEventFilter()
-
         globals()['d'] = self
 
         self.testingServer = None
@@ -746,15 +693,8 @@ def enter(self):
         self.onOpenBrowserWidget()
         self.addListenerObservers()
         self.onListenerStateChanged()
-        # While DICOM module is active, drag-and-drop always performs DICOM import
-        mw = slicer.util.mainWindow()
-        if mw:
-            mw.installEventFilter(self.dragAndDropEventFilter)
 
     def exit(self):
-        mw = slicer.util.mainWindow()
-        if mw:
-            mw.removeEventFilter(self.dragAndDropEventFilter)
         self.removeListenerObservers()
         self.browserWidget.close()
 
@@ -948,3 +888,41 @@ def onClearDatabase(self):
         slicer.app.setOverrideCursor(qt.Qt.WaitCursor)
         DICOMLib.clearDatabase(slicer.dicomDatabase)
         slicer.app.restoreOverrideCursor()
+
+
+class DICOMFileReader:
+    """This reader claims DICOM files with higher-than default confidence
+    """
+
+    def __init__(self, parent):
+        self.parent = parent
+
+    def description(self):
+        return 'DICOM import'
+
+    def fileType(self):
+        return 'DICOMFileImport'
+
+    def extensions(self):
+        return ['DICOM (*.dcm)', 'DICOM (*)']
+
+    def canLoadFileConfidence(self, filePath):
+        import pydicom
+        if pydicom.misc.is_dicom(filePath):
+            # This is a DICOM file, so we return higher confidence than the default 0.5
+            # to import DICOM files using DICOM module.
+            return 0.6
+        else:
+            return 0.0
+
+    def load(self, properties):
+
+        filePath = properties['fileName']
+        dicomFilesDirectory = os.path.dirname(os.path.abspath(filePath))
+
+        # instantiate a new DICOM browser (and create DICOM database if not created yet)
+        slicer.util.selectModule("DICOM")
+        dicomBrowser = slicer.modules.DICOMWidget.browserWidget.dicomBrowser
+        dicomBrowser.importDirectory(dicomFilesDirectory, dicomBrowser.ImportDirectoryMode)
+
+        return True