Autocenter coords on viewer if data present

jdaviz/configs/default/plugins/virtual_observatory/vo_plugin.py

@@ -9,15 +9,15 @@
 from requests.exceptions import ConnectionError as RequestConnectionError
 from traitlets import Dict, Bool, Unicode, Any, List, Int
 
-from jdaviz.core.events import SnackbarMessage
+from jdaviz.core.events import SnackbarMessage, AddDataMessage, RemoveDataMessage
 from jdaviz.core.registries import tray_registry
-from jdaviz.core.template_mixin import PluginTemplateMixin, AddResultsMixin, TableMixin
+from jdaviz.core.template_mixin import PluginTemplateMixin, AddResultsMixin, TableMixin, ViewerSelectMixin
 
 __all__ = ['VoPlugin']
 
 
 @tray_registry('VoPlugin', label="Virtual Observatory")
-class VoPlugin(PluginTemplateMixin, AddResultsMixin, TableMixin):
+class VoPlugin(PluginTemplateMixin, AddResultsMixin, TableMixin, ViewerSelectMixin):
     """ Plugin to query the Virtual Observatory and load data into Imviz """
     template_file = __file__, "vo_plugin.vue"
 
@@ -52,6 +52,46 @@ def __init__(self, *args, **kwargs):
         self.table.show_rowselect = True
         self.table.item_key = "URL"
 
+        self.hub.subscribe(self, AddDataMessage, handler=self._center_on_data)
+        self.hub.subscribe(self, RemoveDataMessage, handler=self._center_on_data)
+
+        self.previous_autogen_source = None
+
+
+    def _center_on_data(self, _):
+        """
+        If data is present in the default viewer, center the plugin's coordinates on
+        the viewer's center WCS coordinates. 
+        """
+        # This plugin should not overwrite existing user input.
+        # Immediately exit if the user has entered a value
+        if self.source not in ('', self.previous_autogen_source):
+            return
+
+        # gets the current viewer
+        viewer = self.viewer.selected_obj
+
+        # nothing happens in the case there is no image in the viewer
+        # additionally if the data does not have WCS
+        if viewer.state.reference_data is None or viewer.state.reference_data.coords is None:
+            return
+
+        # obtains the center point of the current image and converts the point into sky coordinates
+        x_center = (viewer.state.x_min + viewer.state.x_max) * 0.5
+        y_center = (viewer.state.y_min + viewer.state.y_max) * 0.5
+        skycoord_center = viewer.state.reference_data.coords.pixel_to_world(x_center, y_center)
+
+        # Extract SkyCoord values as strings for plugin display
+        ra_deg = skycoord_center.ra.deg
+        dec_deg = skycoord_center.dec.deg
+        frame = skycoord_center.frame.name.lower()
+
+        # Show center value in plugin
+        self.source = f"{ra_deg} {dec_deg}"
+        self.coordframe_selected = frame
+        self.previous_autogen_source = self.source
+
+
     def vue_waveband_selected(self,event):
         """ Sync waveband selected
 

jdaviz/configs/default/plugins/virtual_observatory/vo_plugin.vue

@@ -4,6 +4,14 @@
     :link="'https://www.ivoa.net/astronomers/index.html'"
     :popout_button="popout_button">
 
+    <plugin-viewer-select
+       :items="viewer_items"
+       :selected.sync="viewer_selected"
+       label="Viewer"
+       :show_if_single_entry="false"
+       hint="Select a viewer to search."
+    />
+
     <j-plugin-section-header>Survey Collections</j-plugin-section-header>
       <v-row>
         <v-select