Fix OpenCV 4.12 cv2.rectangle error due to non-contiguous arrays (#510)

OpenCV 4.12 requires C-contiguous arrays for in-place drawing
operations. The image from rasterio (via np.transpose) and the blended
array from float arithmetic were non-contiguous, causing cv2.rectangle
to fail with "Layout of the output array img is incompatible with
cv::Mat".

- Ensure self.image is C-contiguous after set_image()
- Copy blended array before OpenCV drawing in _render_anns_opencv()

Author: giswqs

samgeo/samgeo3.py

@@ -344,6 +344,10 @@ def set_image(
                 "Input image must be either a path, numpy array, or PIL Image."
             )
 
+        # Ensure the image is C-contiguous for OpenCV compatibility
+        if not self.image.flags["C_CONTIGUOUS"]:
+            self.image = np.ascontiguousarray(self.image)
+
         self.image_height, self.image_width = self.image.shape[:2]
 
         # Reset batch processing attributes so that subsequent calls to
@@ -2821,6 +2825,7 @@ def _render_anns_opencv(
         mask_3d = mask_combined[:, :, np.newaxis]
         blended = frame_np * (1 - mask_3d * alpha) + overlay * (mask_3d * alpha)
         blended = np.clip(blended, 0, 255).astype(np.uint8)
+        blended = blended.copy()
 
         # Draw bounding boxes and labels using OpenCV
         for box, text, color in labels_to_draw: