BUG: Fix segment disappearing when sharing segment editor node between widgets

Modules/Loadable/Segmentations/EditorEffects/Python/SegmentEditorEffects/SegmentEditorThresholdEffect.py

@@ -27,6 +27,7 @@ def __init__(self, scriptedEffect):
 
         self.segment2DFillOpacity = None
         self.segment2DOutlineOpacity = None
+        self.previewedSegmentationDisplayNode = None
         self.previewedSegmentID = None
 
         # Effect-specific members
@@ -42,7 +43,6 @@ def __init__(self, scriptedEffect):
 
         self.previewPipelines = {}
         self.histogramPipeline = None
-        self.setupPreviewDisplay()
 
         # Histogram stencil setup
         self.stencil = vtk.vtkPolyDataToImageStencil()
@@ -84,24 +84,24 @@ def helpText(self):
 </ul><p>""")
 
     def activate(self):
-        self.setCurrentSegmentTransparent()
-
         # Update intensity range
         self.sourceVolumeNodeChanged()
 
-        # Setup and start preview pulse
-        self.setupPreviewDisplay()
+        # Start preview pulse
         self.timer.start(200)
 
     def deactivate(self):
+        # Stop preview pulse
+        self.timer.stop()
+
         self.restorePreviewedSegmentTransparency()
 
-        # Clear preview pipeline and stop timer
-        self.clearPreviewDisplay()
+        # Clear preview pipeline
+        self.clearPreviewDisplayPipelines()
         self.clearHistogramDisplay()
-        self.timer.stop()
 
-    def setCurrentSegmentTransparent(self):
+
+    def updatePreviewedSegmentTransparency(self):
         """Save current segment opacity and set it to zero
         to temporarily hide the segment so that threshold preview
         can be seen better.
@@ -110,44 +110,53 @@ def setCurrentSegmentTransparent(self):
         opacity.
         """
         segmentationNode = self.scriptedEffect.parameterSetNode().GetSegmentationNode()
-        if not segmentationNode:
-            return
-        displayNode = segmentationNode.GetDisplayNode()
-        if not displayNode:
-            return
+        displayNode = segmentationNode.GetDisplayNode() if segmentationNode else None
         segmentID = self.scriptedEffect.parameterSetNode().GetSelectedSegmentID()
 
-        if segmentID == self.previewedSegmentID:
+        if (self.previewedSegmentationDisplayNode == displayNode) and (segmentID == self.previewedSegmentID):
             # already previewing the current segment
             return
 
         # If an other segment was previewed before, restore that.
         if self.previewedSegmentID:
             self.restorePreviewedSegmentTransparency()
 
+        if not segmentID:
+            # No segment selected, no need to make any segment transparent
+            return
+
+        # To allow previewing results, temporarily change opacity of the edited segment by modifying the display node.
+        # There may be multiple segment editor widgets that edit the same segmentation display node, therefore
+        # before we modify it we need to check if it is not used by any other segment editor effect.
+        currentEffectHash = str(self.__hash__())
+        previewingEffectHash = displayNode.GetAttribute("SegmentEditor.PreviewingEffect")
+        if previewingEffectHash and (previewingEffectHash != currentEffectHash):
+            # Another effect is already using this display node for preview
+            return
+
+        # Indicate in the display node that other segment editor effects should not tart preview now
+        displayNode.SetAttribute("SegmentEditor.PreviewingEffect", currentEffectHash)
+
         # Make current segment fully transparent
-        if segmentID:
-            self.segment2DFillOpacity = displayNode.GetSegmentOpacity2DFill(segmentID)
-            self.segment2DOutlineOpacity = displayNode.GetSegmentOpacity2DOutline(segmentID)
-            self.previewedSegmentID = segmentID
-            displayNode.SetSegmentOpacity2DFill(segmentID, 0)
-            displayNode.SetSegmentOpacity2DOutline(segmentID, 0)
+        self.segment2DFillOpacity = displayNode.GetSegmentOpacity2DFill(segmentID)
+        self.segment2DOutlineOpacity = displayNode.GetSegmentOpacity2DOutline(segmentID)
+        self.previewedSegmentID = segmentID
+        self.previewedSegmentationDisplayNode = displayNode
+        displayNode.SetSegmentOpacity2DFill(segmentID, 0)
+        displayNode.SetSegmentOpacity2DOutline(segmentID, 0)
 
     def restorePreviewedSegmentTransparency(self):
         """Restore previewed segment's opacity that was temporarily
-        made transparen by calling setCurrentSegmentTransparent().
+        made transparent by calling updatePreviewedSegmentTransparency().
         """
-        segmentationNode = self.scriptedEffect.parameterSetNode().GetSegmentationNode()
-        if not segmentationNode:
-            return
-        displayNode = segmentationNode.GetDisplayNode()
+        displayNode = self.previewedSegmentationDisplayNode
         if not displayNode:
             return
-        if not self.previewedSegmentID:
-            # already previewing the current segment
-            return
-        displayNode.SetSegmentOpacity2DFill(self.previewedSegmentID, self.segment2DFillOpacity)
-        displayNode.SetSegmentOpacity2DOutline(self.previewedSegmentID, self.segment2DOutlineOpacity)
+        if self.previewedSegmentID:
+            displayNode.SetSegmentOpacity2DFill(self.previewedSegmentID, self.segment2DFillOpacity)
+            displayNode.SetSegmentOpacity2DOutline(self.previewedSegmentID, self.segment2DOutlineOpacity)
+        displayNode.RemoveAttribute("SegmentEditor.PreviewingEffect")
+        self.previewedSegmentationDisplayNode = None
         self.previewedSegmentID = None
 
     def setupOptionsFrame(self):
@@ -413,7 +422,7 @@ def sourceVolumeNodeChanged(self):
                 self.scriptedEffect.setParameter("MaximumThreshold", hi)
 
     def layoutChanged(self):
-        self.setupPreviewDisplay()
+        self.updatePreviewDisplayPipelines()
 
     def setMRMLDefaults(self):
         self.scriptedEffect.setParameterDefault("MinimumThreshold", 0.0)
@@ -630,7 +639,7 @@ def onApply(self):
         # De-select effect
         self.scriptedEffect.selectEffect("")
 
-    def clearPreviewDisplay(self):
+    def clearPreviewDisplayPipelines(self):
         for sliceWidget, pipeline in self.previewPipelines.items():
             self.scriptedEffect.removeActor2D(sliceWidget, pipeline.actor)
         self.previewPipelines = {}
@@ -641,52 +650,64 @@ def clearHistogramDisplay(self):
         self.histogramPipeline.removeActors()
         self.histogramPipeline = None
 
-    def setupPreviewDisplay(self):
+    def updatePreviewDisplayPipelines(self):
         # Clear previous pipelines before setting up the new ones
-        self.clearPreviewDisplay()
-
         layoutManager = slicer.app.layoutManager()
-        if layoutManager is None:
-            return
+        sliceViewNames = layoutManager.sliceViewNames() if self.previewedSegmentationDisplayNode and layoutManager else []
 
         # Add a pipeline for each 2D slice view
-        for sliceViewName in layoutManager.sliceViewNames():
+        sliceWidgetPipelinesToKeep = []
+        for sliceViewName in sliceViewNames:
+
             sliceWidget = layoutManager.sliceWidget(sliceViewName)
             if not self.scriptedEffect.segmentationDisplayableInView(sliceWidget.mrmlSliceNode()):
+                # No need to add pipeline in this widget
+                continue
+
+            sliceWidgetPipelinesToKeep.append(sliceWidget)
+            pipeline = self.previewPipelines.get(sliceWidget)
+            if pipeline:
+                # Pipeline is already present
                 continue
+
+            # Add pipeline
             renderer = self.scriptedEffect.renderer(sliceWidget)
             if renderer is None:
-                logging.error("setupPreviewDisplay: Failed to get renderer!")
+                logging.error("updatePreviewDisplayPipelines: Failed to get renderer!")
                 continue
-
-            # Create pipeline
             pipeline = PreviewPipeline()
             self.previewPipelines[sliceWidget] = pipeline
-
-            # Add actor
             self.scriptedEffect.addActor2D(sliceWidget, pipeline.actor)
 
+        # Removed unused pipelines
+        for sliceWidget, pipeline in self.previewPipelines.items():
+            if sliceWidget in sliceWidgetPipelinesToKeep:
+                continue
+            self.scriptedEffect.removeActor2D(sliceWidget, pipeline.actor)
+            self.previewPipelines.pop(sliceWidget)
+
     def preview(self):
+        # Make sure we keep the currently selected segment hidden
+        # (the user may have changed selected segmentation or segment)
+        self.updatePreviewedSegmentTransparency()
+
+        # Update preview display pipelines
+        if self.previewedSegmentationDisplayNode and not self.previewPipelines:
+            self.updatePreviewDisplayPipelines()
+        elif not self.previewedSegmentationDisplayNode and self.previewPipelines:
+            self.clearPreviewDisplayPipelines()
+
+        if not self.previewedSegmentationDisplayNode:
+            return
+
         opacity = 0.5 + self.previewState / (2.0 * self.previewSteps)
         min = self.scriptedEffect.doubleParameter("MinimumThreshold")
         max = self.scriptedEffect.doubleParameter("MaximumThreshold")
 
         # Get color of edited segment
-        segmentationNode = self.scriptedEffect.parameterSetNode().GetSegmentationNode()
-        if not segmentationNode:
-            # scene was closed while preview was active
-            return
-        displayNode = segmentationNode.GetDisplayNode()
-        if displayNode is None:
-            logging.error("preview: Invalid segmentation display node!")
-            color = [0.5, 0.5, 0.5]
         segmentID = self.scriptedEffect.parameterSetNode().GetSelectedSegmentID()
 
-        # Make sure we keep the currently selected segment hidden (the user may have changed selection)
-        if segmentID != self.previewedSegmentID:
-            self.setCurrentSegmentTransparent()
-
-        r, g, b = segmentationNode.GetSegmentation().GetSegment(segmentID).GetColor()
+        r, g, b = self.previewedSegmentationDisplayNode.GetSegmentColor(segmentID)
 
         # Set values to pipelines
         for sliceWidget in self.previewPipelines:
@@ -707,6 +728,16 @@ def preview(self):
     def processInteractionEvents(self, callerInteractor, eventId, viewWidget):
         abortEvent = False
 
+        if viewWidget not in self.previewPipelines:
+            # In this view, this effect instance does not display threshold preview pipeline,
+            # therefore prevent it from displaying the local histogram pipeline, too.
+            return abortEvent
+
+        # Note that if multiple segment editor widgets are active then only one (the first that gets the interaction events)
+        # will be notified. In all the other segment editor widgets the local histogram will not be updated.
+        # The behavior could be made more deterministic by storing a preferred segment editor node in the selection node
+        # and not using the same segment editor node in multiple segment editor widgets.
+
         masterImageData = self.scriptedEffect.sourceVolumeImageData()
         if masterImageData is None:
             return abortEvent