fix spectral extraction previews on unit change

CHANGES.rst

@@ -5,7 +5,7 @@ New Features
 ------------
 
 - Added flux/surface brightness translation and surface brightness
-  unit conversion in Cubeviz and Specviz. [#2781, #2940, #3088, #3111, #3113, #3129, #3139, #3155]
+  unit conversion in Cubeviz and Specviz. [#2781, #2940, #3088, #3111, #3113, #3129, #3139, #3155, #3157]
 
 - Plugin tray is now open by default. [#2892]
 

jdaviz/app.py

@@ -1274,7 +1274,12 @@ def merge_func(spectral_region):  # noop
                 return self._get_multi_mask_subset_definition(subset_state)
 
     def _get_display_unit(self, axis):
-        if self._jdaviz_helper is None or self._jdaviz_helper.plugins.get('Unit Conversion') is None:  # noqa
+        if self._jdaviz_helper is None:
+            # cannot access either the plugin or the spectrum viewer.
+            # Plugins that access the unit at this point will need to
+            # detect that they are set to unitless and attempt again later.
+            return ''
+        elif self._jdaviz_helper.plugins.get('Unit Conversion') is None:  # noqa
             # fallback on native units (unit conversion is not enabled)
             if axis == 'spectral':
                 sv = self.get_viewer(self._jdaviz_helper._default_spectrum_viewer_reference_name)

jdaviz/configs/cubeviz/plugins/spectral_extraction/spectral_extraction.py

@@ -26,6 +26,7 @@
 from jdaviz.core.user_api import PluginUserApi
 from jdaviz.configs.cubeviz.plugins.parsers import _return_spectrum_with_correct_units
 from jdaviz.configs.cubeviz.plugins.viewers import WithSliceIndicator
+from jdaviz.utils import _eqv_pixar_sr
 
 
 __all__ = ['SpectralExtraction']
@@ -109,8 +110,8 @@ class SpectralExtraction(PluginTemplateMixin, ApertureSubsetSelectMixin,
 
     results_units = Unicode().tag(sync=True)
     spectrum_y_units = Unicode().tag(sync=True)
-    flux_unit = Unicode().tag(sync=True)
-    sb_unit = Unicode().tag(sync=True)
+    flux_units = Unicode().tag(sync=True)
+    sb_units = Unicode().tag(sync=True)
 
     aperture_method_items = List().tag(sync=True)
     aperture_method_selected = Unicode('Center').tag(sync=True)
@@ -180,7 +181,7 @@ def __init__(self, *args, **kwargs):
         self.session.hub.subscribe(self, SliceValueUpdatedMessage,
                                    handler=self._on_slice_changed)
         self.hub.subscribe(self, GlobalDisplayUnitChanged,
-                           handler=self._on_gloabl_display_unit_changed)
+                           handler=self._on_global_display_unit_changed)
 
         self._update_disabled_msg()
 
@@ -315,31 +316,33 @@ def _update_mark_scale(self, *args):
         else:
             self.background.scale_factor = self.slice_spectral_value/self.reference_spectral_value
 
-    def _on_gloabl_display_unit_changed(self, msg={}):
+    def _on_global_display_unit_changed(self, msg=None):
+        if msg is None:
+            self.flux_units = str(self.app._get_display_unit('flux'))
+            self.sb_units = str(self.app._get_display_unit('sb'))
+            self.spectrum_y_units = str(self.app._get_display_unit('spectral_y'))
 
-        if msg.axis == 'spectral_y':
-            self.spectrum_y_units = str(msg.unit)
-
-        # a 'flux' and 'sb' message should be recieved back to back from
-        # the unit conversion plugin, so don't need to sync them immediatley
-        # within each message recieved
         elif msg.axis == 'flux':
-            self.flux_unit = str(msg.unit)
+            self.flux_units = str(msg.unit)
         elif msg.axis == 'sb':
-            self.sb_unit = str(msg.unit)
+            self.sb_units = str(msg.unit)
+        elif msg.axis == 'spectral_y':
+            self.spectrum_y_units = str(msg.unit)
+            # no need to update results_units
+            return
         else:
+            # ignore
             return
-
-        # and set results_units, which depends on function selected
+        # update results_units based on flux_units, sb_units, and currently selected function
         self._update_units_on_function_selection()
 
     @observe('function_selected')
     def _update_units_on_function_selection(self, *args):
-
         if self.function_selected.lower() == 'sum':
-            self.results_units = self.flux_unit
+            self.results_units = self.flux_units
         else:
-            self.results_units = self.sb_unit
+            self.results_units = self.sb_units
+        # any changes to results_units will trigger _live_update_marks
 
     @observe('function_selected', 'aperture_method_selected')
     def _update_aperture_method_on_function_change(self, *args):
@@ -542,7 +545,9 @@ def _preview_x_from_extracted(self, extracted):
         return extracted.spectral_axis.value
 
     def _preview_y_from_extracted(self, extracted):
-        return extracted.flux.value
+        # TODO: use extracted's PIXAR_SR instead (but for some reason isn't populated here...)
+        return extracted.flux.to_value(self.spectrum_y_units,
+                                       equivalencies=_eqv_pixar_sr(self.dataset.selected_obj.meta.get('PIXAR_SR', 1.0)))  # noqa:
 
     @with_spinner()
     def extract(self, return_bg=False, add_data=True, **kwargs):
@@ -726,8 +731,15 @@ def _clear_marks(self):
              'wavelength_dependent', 'bg_wavelength_dependent', 'reference_spectral_value',
              'function_selected',
              'aperture_method_selected',
+             'spectrum_y_units', 'results_units',
              'previews_temp_disabled')
     def _live_update_marks(self, event={}):
+        if self.spectrum_y_units == '':
+            # ensure that units are populated
+            # which in turn will make a call back here
+            # from the observe on spectrum_y_units
+            self._on_global_display_unit_changed(None)
+            return
         self._update_marks(event)
 
     @skip_if_not_tray_instance()

jdaviz/configs/specviz/plugins/unit_conversion/unit_conversion.py

@@ -175,7 +175,7 @@ def _on_glue_y_display_unit_changed(self, y_unit_str):
         if self.app.data_collection[0]:
             dc_unit = self.app.data_collection[0].get_component("flux").units
             self.angle_unit.choices = create_angle_equivalencies_list(dc_unit)
-            self.angle_unit.selected = self.angle_unit.choices[0]
+            self.angle_unit.select_default()
             self.sb_unit_selected = self._append_angle_correctly(
                 self.flux_unit.selected,
                 self.angle_unit.selected
@@ -217,8 +217,8 @@ def _on_flux_or_sb_selected(self, msg):
         if msg.get('name') == 'flux_or_sb_selected':
             self._translate(self.flux_or_sb_selected)
 
-    @observe('flux_unit_selected')
-    def _on_flux_unit_changed(self, msg):
+    @observe('flux_unit_selected', 'angle_unit_selected')
+    def _on_flux_or_angle_unit_changed(self, msg):
 
         """
         Observes changes in selected flux unit.
@@ -231,13 +231,12 @@ def _on_flux_unit_changed(self, msg):
         SB is read only, so anything observing for changes in surface brightness
         should be looking for a change in 'flux' (as well as angle).
         """
-
-        if msg.get('name') != 'flux_unit_selected':
-            # not sure when this would be encountered but keeping as a safeguard
-            return
         if not hasattr(self, 'flux_unit'):
             return
-        if not self.flux_unit.choices and self.app.config == 'cubeviz':
+        if not self.flux_unit.choices:
+            return
+        if self.flux_unit.selected == '' or self.angle_unit.selected == '':
+            # wait until flux AND angle unit are both populated during init
             return
 
         # various plugins are listening for changes in either flux or sb and