Fix coordinate alteration issue in XYImageItem: return copies of X/Y values to prevent modification of internal data

Fix #49

Author: PierreRaybaut

CHANGELOG.md

@@ -63,6 +63,7 @@
 
 🛠️ Bug fixes:
 
+* [Issue #49](https://github.com/PlotPyStack/PlotPy/issues/49) - Using cross-section tools on `XYImageItem` images alters the X/Y coordinate arrays
 * Fixed index bounds calculation for image slicing compatibility:
   * Corrected the calculation of maximum indices in `get_plot_coordinates` to ensure proper bounds when using NumPy array slicing
   * Previously, the maximum indices were off by one, which could cause issues when extracting image data using the returned coordinates

plotpy/items/image/standard.py

@@ -703,7 +703,10 @@ def get_x_values(self, i0: int, i1: int) -> np.ndarray:
         Returns:
             X values corresponding to the given pixel indexes
         """
-        return self.x[i0:i1]
+        # Returning a copy to prevent modification of internal data by caller
+        # (Fixes issue #49 - Using cross-section tools on `XYImageItem` images alters
+        # the X/Y coordinate arrays)
+        return self.x[i0:i1].copy()
 
     def get_y_values(self, j0: int, j1: int) -> np.ndarray:
         """Get Y values from pixel indexes
@@ -715,7 +718,7 @@ def get_y_values(self, j0: int, j1: int) -> np.ndarray:
         Returns:
             Y values corresponding to the given pixel indexes
         """
-        return self.y[j0:j1]
+        return self.y[j0:j1].copy()  # (same remark as in `get_x_values`)
 
     def get_closest_coordinates(self, x: float, y: float) -> tuple[float, float]:
         """