BUG: Fix get_subsets when XOR is involved

[pllim]

Description

This pull request is to fix bug found in https://github.com/spacetelescope/jdaviz/pull/2941#discussion_r1672866076

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[pllim]

Was hoping we could simply hook into glue-astronomy region translator but it didn't work. Maybe the translator is incomplete. I think we wrote a lot of the stuff focused on 2D image region, not spectral region.

from glue.config import subset_state_translator

dc = specviz_helper.app.data_collection
subsets = dc.subset_groups
subset = subsets[0]
handler = subset_state_translator.get_handler_for('astropy-regions')
handler.to_object(subset.subsets[0])  # traceback

I feel like the proper solution is to implement a new spectral region translator in glue-astronomy but that is way more "story points" than we have available.

[pllim]

If this is too controversial, other options:

1. Drop XOR from possible options, as Jesse suggested.
2. Implement proper translation over at glue-astronomy.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.55172% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.78%. Comparing base (31ac58f) to head (6cb9ef3). Report is 126 commits behind head on main.

Files with missing lines	Patch %	Lines
jdaviz/app.py	96.49%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3124      +/-   ##
==========================================
- Coverage   88.81%   88.78%   -0.04%     
==========================================
  Files         112      112              
  Lines       17427    17446      +19     
==========================================
+ Hits        15478    15489      +11     
- Misses       1949     1957       +8     

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[javerbukh]

I was still able to find a bug by doing the following order of spectral subsets (you can use PR #3082 to import the entire dictionary). I would expect a SpectralRegions object with 6 elements but app.get_subsets(simplify_spectral=True) only returns 2. The following is the return from app.get_subsets(simplify_spectral=False):

{'Subset 1': [{'name': 'RangeSubsetState',
   'glue_state': 'AndState',
   'region': Spectral Region, 1 sub-regions:
     (5.667263706861359 um, 6.768955332154135 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fb7719f0>},
  {'name': 'RangeSubsetState',
   'glue_state': 'AndNotState',
   'region': Spectral Region, 1 sub-regions:
     (6.01443541526278 um, 6.495846921545017 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fb7737f0>},
  {'name': 'RangeSubsetState',
   'glue_state': 'XorState',
   'region': Spectral Region, 1 sub-regions:
     (5.491363409920771 um, 6.912452830362193 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fb61d420>},
  {'name': 'RangeSubsetState',
   'glue_state': 'OrState',
   'region': Spectral Region, 1 sub-regions:
     (7.01428986482661 um, 7.24110871431554 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fb61e680>},
  {'name': 'RangeSubsetState',
   'glue_state': 'OrState',
   'region': Spectral Region, 1 sub-regions:
     (5.051612596937036 um, 5.204368130975595 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fb61d060>},
  {'name': 'RangeSubsetState',
   'glue_state': 'XorState',
   'region': Spectral Region, 1 sub-regions:
     (6.06535393249499 um, 6.968000303706421 um) ,
   'sky_region': None,
   'subset_state': <glue.core.subset.RangeSubsetState at 0x245fde88610>}]}

[pllim]

@javerbukh , good catch. I guess I misunderstood how SpectralRegion.invert() behaves in a more complicated situation. I added more tests, including one that is similar to what you pointed out above. I might still have missed something, so please re-review. Thanks!

[pllim]

"Understand" is a strong word...