Fix autoscaling logic in BaseCrossSectionPlot: streamline handling of autoscale and lockscales, ensuring consistent scaling behavior across methods.

Author: PierreRaybaut

CHANGELOG.md

@@ -71,6 +71,11 @@
 
 🛠️ Bug fixes:
 
+* Cross-section panels: Fixed autoscaling logic in `BaseCrossSectionPlot`
+  * Streamlined handling of `autoscale_mode` and `lockscales` options for consistent scaling behavior across all code paths
+  * The `update_plot()` method now delegates all scaling logic to `plot_axis_changed()` to avoid code duplication and ensure consistency
+  * Fixed issue where Y cross-section plots for rectangular images with non-uniform axes (e.g., Y = f(X)) were not properly scaled on initial display
+  * The lockscales mode now correctly syncs the cross-section axis (CS_AXIS) to the image plot while autoscaling the intensity axis (Z_AXIS)
 * [Issue #49](https://github.com/PlotPyStack/PlotPy/issues/49) - Fixed multiple coordinate handling bugs in `XYImageItem`:
   * **Root cause**: `XYImageItem` internally stores bin edges (length n+1) but several methods were incorrectly treating them as pixel centers (length n)
   * Fixed `get_x_values()` and `get_y_values()` to correctly compute and return pixel centers from stored bin edges: `(edge[i] + edge[i+1]) / 2`

plotpy/panels/csection/csplot.py

@@ -227,7 +227,9 @@ def plot_axis_changed(self, plot: BasePlot) -> None:
         Args:
             plot: Plot containing the image items to be used for cross section
         """
-        if self.lockscales:
+        if self.autoscale_mode:
+            self.do_autoscale(replot=True)
+        elif self.lockscales:
             self.do_autoscale(replot=False, axis_id=self.Z_AXIS)
             vmin, vmax = plot.get_axis_limits(self.CS_AXIS)
             self.set_axis_limits(self.CS_AXIS, vmin, vmax)
@@ -278,7 +280,8 @@ def update_plot(self, obj: Any = None, refresh: bool = True) -> None:
                 return
         else:
             self.last_obj = weakref.ref(obj)
-        if obj.plot() is None:
+        plot = obj.plot()
+        if plot is None:
             self.unregister_shape(obj)
             return
         if self.label.isVisible():
@@ -294,10 +297,9 @@ def update_plot(self, obj: Any = None, refresh: bool = True) -> None:
                 curve.apply_lut = self.apply_lut
                 if refresh:
                     curve.update_item(obj)
-        if self.autoscale_mode:
-            self.do_autoscale(replot=True)
-        elif self.lockscales:
-            self.do_autoscale(replot=True, axis_id=self.Z_AXIS)
+
+        # Delegate all scaling logic to plot_axis_changed for consistency
+        self.plot_axis_changed(plot)
 
     def toggle_perimage_mode(self, state: bool) -> None:
         """Toggle the per item mode