View spectrum from single spaxel on hover

CHANGES.rst

@@ -17,6 +17,8 @@ Cubeviz
 
 - Moment map plugin now supports linear per-spaxel continuum subtraction. [#2587]
 
+- Single-pixel subset tool now shows spectrum-at-spaxel on hover. [#2647]
+
 Imviz
 ^^^^^
 

docs/cubeviz/displaycubes.rst

@@ -99,9 +99,10 @@ the bottom of the UI.
 Spectrum At Spaxel
 ==================
 
-This tool allows the user to create a one spaxel subset in an image viewer. This subset will then be
+This tool allows the user to create a single-spaxel subset in an image viewer. This subset will then be
 visualized in the spectrum viewer by showing the spectrum at that spaxel.
-Activate this tool and then left-click to create the new region.
+While this tool is active, hovering over a pixel in the image viewer will show a preview of the spectrum
+at that spaxel in the spectrum viewer, and left-clicking will create a new subset at that spaxel.
 Click again to move the region to a new location under the cursor. Holding down the
 alt key (Alt key on Windows, Option key on Mac) while clicking on a spaxel creates a new subset at
 that point instead of moving the previously created region.
@@ -110,6 +111,11 @@ You can also use the subset modes that are explained in the
 :ref:`Spatial Regions <imviz_defining_spatial_regions>`
 section above in the same way you would with the other subset selection tools.
 
+Note that moving the cursor outside of the image viewer or deactivating the spectrum-at-spaxel tool
+will revert the spectrum viewer zoom limits from the zoomed-in preview view to the limits set prior
+to using the tool. Thus it may be necessary to reset the zoom to see any single-spaxel subset spectra
+created using the tool.
+
 .. _cubeviz-display-settings:
 
 Display Settings

jdaviz/configs/cubeviz/plugins/tests/test_tools.py

@@ -18,6 +18,12 @@ def test_spectrum_at_spaxel(cubeviz_helper, spectrum1d_cube):
     assert len(flux_viewer.native_marks) == 2
     assert len(spectrum_viewer.data()) == 1
 
+    # Move to spaxel location
+    flux_viewer.toolbar.active_tool.on_mouse_move(
+        {'event': 'mousemove', 'domain': {'x': x, 'y': y}, 'altKey': False})
+    assert flux_viewer.toolbar.active_tool._mark in spectrum_viewer.figure.marks
+    assert flux_viewer.toolbar.active_tool._mark.visible is True
+
     # Click on spaxel location
     flux_viewer.toolbar.active_tool.on_mouse_event(
         {'event': 'click', 'domain': {'x': x, 'y': y}, 'altKey': False})
@@ -30,6 +36,11 @@ def test_spectrum_at_spaxel(cubeviz_helper, spectrum1d_cube):
     assert len(subsets) == 1
     assert isinstance(reg, RectanglePixelRegion)
 
+    # Mouse leave event
+    flux_viewer.toolbar.active_tool.on_mouse_move(
+        {'event': 'mouseleave', 'domain': {'x': x, 'y': y}, 'altKey': False})
+    assert flux_viewer.toolbar.active_tool._mark.visible is False
+
     # Deselect tool
     flux_viewer.toolbar.active_tool = None
     assert len(flux_viewer.native_marks) == 3

jdaviz/configs/cubeviz/plugins/tools.py

@@ -3,11 +3,15 @@
 
 from glue.config import viewer_tool
 from glue_jupyter.bqplot.image import BqplotImageView
+from glue_jupyter.bqplot.image.layer_artist import BqplotImageSubsetLayerArtist
 from glue.viewers.common.tool import CheckableTool
+import numpy as np
+from specutils import Spectrum1D
 
 from jdaviz.configs.imviz.plugins.tools import _MatchedZoomMixin
 from jdaviz.core.events import SliceToolStateMessage
 from jdaviz.core.tools import PanZoom, BoxZoom, SinglePixelRegion
+from jdaviz.core.marks import PluginLine
 
 __all__ = []
 
@@ -83,3 +87,86 @@ class SpectrumPerSpaxel(SinglePixelRegion):
     tool_id = 'jdaviz:spectrumperspaxel'
     action_text = 'See spectrum at a single spaxel'
     tool_tip = 'Click on the viewer and see the spectrum at that spaxel in the spectrum viewer'
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._spectrum_viewer = None
+        self._previous_bounds = None
+        self._mark = None
+        self._data = None
+
+    def _reset_spectrum_viewer_bounds(self):
+        sv_state = self._spectrum_viewer.state
+        sv_state.x_min = self._previous_bounds[0]
+        sv_state.x_max = self._previous_bounds[1]
+        sv_state.y_min = self._previous_bounds[2]
+        sv_state.y_max = self._previous_bounds[3]
+
+    def activate(self):
+        self.viewer.add_event_callback(self.on_mouse_move, events=['mousemove', 'mouseleave'])
+        if self._spectrum_viewer is None:
+            self._spectrum_viewer = self.viewer.jdaviz_helper.app.get_viewer('spectrum-viewer')
+        if self._mark is None:
+            self._mark = PluginLine(self._spectrum_viewer, visible=False)
+            self._spectrum_viewer.figure.marks = self._spectrum_viewer.figure.marks + [self._mark,]
+        # Store these so we can revert to previous user-set zoom after preview view
+        sv_state = self._spectrum_viewer.state
+        self._previous_bounds = [sv_state.x_min, sv_state.x_max, sv_state.y_min, sv_state.y_max]
+        super().activate()
+
+    def deactivate(self):
+        self.viewer.remove_event_callback(self.on_mouse_move)
+        self._reset_spectrum_viewer_bounds()
+        super().deactivate()
+
+    def on_mouse_move(self, data):
+        if data['event'] == 'mouseleave':
+            self._mark.visible = False
+            self._reset_spectrum_viewer_bounds()
+            return
+
+        x = int(np.round(data['domain']['x']))
+        y = int(np.round(data['domain']['y']))
+
+        # Use the selected layer from coords_info as long as it's 3D
+        coords_info_dataset = self.viewer.session.application._tools['g-coords-info'].dataset.selected
+        if coords_info_dataset == 'auto':
+            cube_data = self.viewer.active_image_layer.layer
+        elif coords_info_dataset == 'none':
+            cube_data = self.viewer.layers[0].layer
+        else:
+            for layer in self.viewer.layers:
+                if layer.layer.label == coords_info_dataset and layer.visible:
+                    if isinstance(layer, BqplotImageSubsetLayerArtist):
+                        # cannot expose info for spatial subset layers
+                        continue
+                    cube_data = layer.layer
+                    break
+            else:
+                return
+
+        if cube_data.ndim != 3:
+            cube_data = [layer.layer for layer in self.viewer.layers if layer.state.visible
+                        and layer.layer.ndim == 3]
+            if len(cube_data) == 0:
+                return
+            cube_data = cube_data[0]
+
+        spectrum = cube_data.get_object(statistic=None)
+        # Note: change this when Spectrum1D.with_spectral_axis is fixed.
+        if spectrum.spectral_axis.unit != self._spectrum_viewer.state.x_display_unit:
+            new_spectral_axis = spectrum.spectral_axis.to(self._spectrum_viewer.state.x_display_unit)
+            spectrum = Spectrum1D(spectrum.flux, new_spectral_axis)
+
+        if x >= spectrum.flux.shape[0] or x < 0 or y >= spectrum.flux.shape[1] or y < 0:
+            self._reset_spectrum_viewer_bounds()
+            self._mark.visible = False
+        else:
+            y_values = spectrum.flux[x, y, :]
+            if np.all(np.isnan(y_values)):
+                self._mark.visible = False
+                return
+            self._mark.update_xy(spectrum.spectral_axis.value, y_values)
+            self._mark.visible = True
+            self._spectrum_viewer.state.y_max = np.nanmax(y_values.value) * 1.2
+            self._spectrum_viewer.state.y_min = np.nanmin(y_values.value) * 0.8