Issue displaying color legend in other slice views

Support
1

I was trying to display a color legend in some custom slice views when I noticed that it was not showing as I expected. Is there a certain set of conditions to make sure the color legend shows in the other non-standard slice views.

I start Slicer 5.2.1 (and latest Slicer Preview 5.3.0-2023-02-10), set layout to Four-Up, close Slicer, restart Slicer then run the below snippet

slicer.app.layoutManager().setLayout(slicer.vtkMRMLLayoutNode.SlicerLayoutThreeOverThreeView)

import SampleData
sampleDataLogic = SampleData.SampleDataLogic()
mrHead = sampleDataLogic.downloadMRHead()

color_legend_display_node = slicer.modules.colors.logic().AddDefaultColorLegendDisplayNode(mrHead)
color_legend_display_node.SetVisibility(True)

I observe the following where the color legend is showing in the Red/Yellow/Green slice views, but not in the Red+/Yellow+/Green+ slice views.

image
image1920×1030 168 KB

Then if I close Slicer so that it remembers the “Three over three” layout, relaunch Slicer and run the same script I observe the following where the color legend is showing in all the slice views as I would expect:

image
image1920×1030 175 KB

2

@Mik, since you did some of the recent color legend rework, do you know what is going on here?

3

Definitely a bug. SliceCompositeNode is invalid for a new slice views in color legend displayable manager.

For a fast fix:

  1. Enable Toggle slice visibility in 3D view in slice controller widget
    or
  2. Python script below
layoutManager = slicer.app.layoutManager()
layoutManager.setLayout(slicer.vtkMRMLLayoutNode.SlicerLayoutThreeOverThreeView)
import SampleData
sampleDataLogic = SampleData.SampleDataLogic()
mrHead = sampleDataLogic.downloadMRHead()

for sliceViewName in layoutManager.sliceViewNames():
  view = layoutManager.sliceWidget(sliceViewName).sliceView()
  sliceNode = view.mrmlSliceNode()
  sliceLogic = slicer.app.applicationLogic().GetSliceLogic(sliceNode)
  sliceLogic.StartSliceNodeInteraction(slicer.vtkMRMLSliceNode.SliceVisibleFlag)
  sliceNode.SetSliceVisible(True)
  sliceLogic.EndSliceNodeInteraction()

color_legend_display_node = slicer.modules.colors.logic().AddDefaultColorLegendDisplayNode(mrHead)
color_legend_display_node.SetVisibility(True)

After that the color legends are visible and available for editing.
I hope it helps.

4

I assume then that this commit is likely the culprit for requiring slice visibility to be on?

5

Quite possible. I haven’t tested color legends with nonstandard slice views.

6

Issue now being tracked at:

7

@Mik It would be great if you could try to fix this. I’ve added a comment to the issue about potential approaches.

8

Fix is ready to review and tests.