Improve live-collapsed spectrum contrast in cubeviz

CHANGES.rst

@@ -30,6 +30,8 @@ Mosviz
 Specviz
 ^^^^^^^
 
+- Improve visibility of live-collapsed spectra from spatial regions in Cubeviz [#2387]
+
 Specviz2d
 ^^^^^^^^^
 

jdaviz/configs/cubeviz/plugins/viewers.py

@@ -1,6 +1,7 @@
 from glue.core import BaseData
 
 from glue.core.subset_group import GroupedSubset
+from bqplot import Lines
 from glue_jupyter.bqplot.image import BqplotImageView
 
 from jdaviz.core.registries import viewer_registry
@@ -229,6 +230,21 @@ def _is_unique(m):
                 if _is_unique(new_shadow):
                     new_marks.append(new_shadow)
 
+            # change opacity for live-collapsed spectra from spatial subsets in Cubeviz:
+            spatial_layers = [sub_layer for sub_layer in
+                              self._get_spatial_subset_layers(layer_state.layer.data.label)]
+            spatial_marks = self._get_marks_for_layers(spatial_layers)
+            for layer, mark in zip(spatial_layers, spatial_marks):
+                # update profile opacities for spatial subset:
+                if isinstance(mark, Lines):
+                    mark.set_trait(
+                        'opacities',
+                        # set the alpha for the spectrum in the profile viewer
+                        # to be 50% more opaque than the alpha for the spatial subset
+                        # in the flux-viewer
+                        [min(1.5 * layer.alpha, 1)]
+                    )
+
         elif subset_type == 'spectral':
             # need to add marks for every intersection between THIS spectral subset and ALL spatial
             # subset marks corresponding to this data

jdaviz/configs/default/plugins/plot_options/plot_options.py

@@ -4,6 +4,7 @@
 from astropy.visualization import PercentileInterval
 from traitlets import Any, Dict, Float, Bool, Int, List, Unicode, observe
 
+from glue.core.subset_group import GroupedSubset
 from glue.viewers.scatter.state import ScatterViewerState
 from glue.viewers.profile.state import ProfileViewerState, ProfileLayerState
 from glue.viewers.image.state import ImageSubsetLayerState
@@ -535,7 +536,7 @@ def _update_stretch_histogram(self, msg={}):
             # no (image) viewer with stretch function options
             return
 
-        if (not self.viewer.selected or not self.layer.selected):  # pragma: no cover
+        if not self.viewer.selected or not self.layer.selected:  # pragma: no cover
             # nothing to plot
             self.stretch_histogram.clear_all_marks()
             return
@@ -579,6 +580,10 @@ def _update_stretch_histogram(self, msg={}):
             # skip further updates if no data are available:
             return
 
+        if isinstance(data, GroupedSubset):
+            # don't update histogram for subsets:
+            return
+
         comp = data.get_component(data.main_components[0])
 
         # TODO: further optimization could be done by caching sub_data