Propagate project crs change to widget

Author: lachlangrose

loopstructural/gui/modelling/model_definition/bounding_box.py

@@ -2,6 +2,7 @@
 
 import numpy as np
 from PyQt5.QtWidgets import QWidget
+from qgis.core import QgsProject
 from qgis.PyQt import uic
 
 from loopstructural.main.data_manager import default_bounding_box
@@ -13,7 +14,7 @@ def __init__(self, parent=None, data_manager=None):
         super().__init__(parent)
         ui_path = os.path.join(os.path.dirname(__file__), "bounding_box.ui")
         uic.loadUi(ui_path, self)
-        
+
         # Connect bounding box spinbox signals
         self.originXSpinBox.valueChanged.connect(lambda x: self.onChangeExtent({'xmin': x}))
         self.maxXSpinBox.valueChanged.connect(lambda x: self.onChangeExtent({'xmax': x}))
@@ -23,20 +24,28 @@ def __init__(self, parent=None, data_manager=None):
         self.maxZSpinBox.valueChanged.connect(lambda z: self.onChangeExtent({'zmax': z}))
         self.useCurrentViewExtentButton.clicked.connect(self.useCurrentViewExtent)
         self.selectFromCurrentLayerButton.clicked.connect(self.selectFromCurrentLayer)
-        
+
         # Connect CRS control signals
         self.useProjectCrsRadioButton.toggled.connect(self.onCrsSourceChanged)
         self.useCustomCrsRadioButton.toggled.connect(self.onCrsSourceChanged)
         self.crsSelector.crsChanged.connect(self.onCrsChanged)
-        
+
         # Set up callbacks
         self.data_manager.set_bounding_box_update_callback(self.set_bounding_box)
         self.data_manager.set_model_crs_callback(self.update_crs_ui)
-        
+
         # Initialize CRS UI
         self.initialize_crs_ui()
         self._update_bounding_box_styles()
 
+        # Connect to project CRS changes so the widget updates when the project's CRS changes
+        try:
+            project = getattr(self.data_manager, 'project', None) or QgsProject.instance()
+            project.crsChanged.connect(self._onProjectCrsChanged)
+        except Exception:
+            # If the signal isn't available or connection fails, ignore to keep widget functional
+            pass
+
     def initialize_crs_ui(self):
         """Initialize CRS controls with current settings."""
         # Set initial CRS selector value
@@ -46,28 +55,28 @@ def initialize_crs_ui(self):
         else:
             # Default to project CRS
             self.crsSelector.setCrs(self.data_manager.project.crs())
-        
+
         # Set radio button based on use_project_crs setting
         if self.data_manager._use_project_crs:
             self.useProjectCrsRadioButton.setChecked(True)
         else:
             self.useCustomCrsRadioButton.setChecked(True)
-        
+
         self.validate_crs()
 
     def onCrsSourceChanged(self):
         """Handle change in CRS source (project vs custom)."""
         use_project_crs = self.useProjectCrsRadioButton.isChecked()
         self.crsSelector.setEnabled(not use_project_crs)
-        
+
         if use_project_crs:
             # Use project CRS
             success, msg = self.data_manager.set_model_crs(None, use_project_crs=True)
         else:
             # Use custom CRS
             crs = self.crsSelector.crs()
             success, msg = self.data_manager.set_model_crs(crs, use_project_crs=False)
-        
+
         self.validate_crs()
 
     def onCrsChanged(self):
@@ -79,7 +88,7 @@ def onCrsChanged(self):
 
     def update_crs_ui(self, crs, use_project_crs):
         """Update UI when model CRS changes externally.
-        
+
         Parameters
         ----------
         crs : QgsCoordinateReferenceSystem or None
@@ -91,45 +100,68 @@ def update_crs_ui(self, crs, use_project_crs):
         self.useProjectCrsRadioButton.blockSignals(True)
         self.useCustomCrsRadioButton.blockSignals(True)
         self.crsSelector.blockSignals(True)
-        
+
         try:
             if use_project_crs:
                 self.useProjectCrsRadioButton.setChecked(True)
                 self.crsSelector.setEnabled(False)
+                self.crsSelector.setCrs(crs)
+
             else:
                 self.useCustomCrsRadioButton.setChecked(True)
                 self.crsSelector.setEnabled(True)
                 if crs is not None and crs.isValid():
                     self.crsSelector.setCrs(crs)
-            
+
             self.validate_crs()
         finally:
             # Unblock signals
             self.useProjectCrsRadioButton.blockSignals(False)
             self.useCustomCrsRadioButton.blockSignals(False)
             self.crsSelector.blockSignals(False)
 
+    def _onProjectCrsChanged(self, crs=None):
+        """Handle project CRS changes and update UI when the widget is using the project CRS.
+
+        Accept an optional `crs` argument because different QGIS versions may emit the
+        new CRS or emit no arguments when the project's CRS changes.
+        """
+        # If the signal didn't provide a CRS, try to obtain it from the project's current CRS
+        if crs is None:
+            try:
+                project = getattr(self.data_manager, 'project', None) or QgsProject.instance()
+                crs = project.crs()
+            except Exception:
+                crs = None
+
+        # Only update the UI if the model is configured to use the project CRS
+        try:
+            if getattr(self.data_manager, '_use_project_crs', False):
+                # Update the UI to reflect the new project CRS
+                self.update_crs_ui(crs, use_project_crs=True)
+        except Exception:
+            pass
+
     def validate_crs(self):
         """Validate the selected CRS and update warning label."""
         crs = self.data_manager.get_model_crs()
-        
+
         if crs is None or not crs.isValid():
             self.crsWarningLabel.setText("⚠ Invalid CRS selected. Model cannot be initialized.")
             return False
-        
+
         if crs.isGeographic():
             # Safely get CRS description
             try:
                 crs_desc = crs.description() or crs.authid() or "Unknown"
             except Exception:
                 crs_desc = crs.authid() if hasattr(crs, 'authid') else "Unknown"
-            
+
             self.crsWarningLabel.setText(
-                f"⚠ CRS must be projected (in meters), not geographic.\n"
-                f"Selected: {crs_desc}"
+                f"⚠ CRS must be projected (in meters), not geographic.\n" f"Selected: {crs_desc}"
             )
             return False
-        
+
         # CRS is valid and projected
         self.crsWarningLabel.setText("")
         return True