refactor nodes into standalone file

backend/nodes/mask_morphology.py

@@ -0,0 +1,71 @@
+from __future__ import annotations
+import numpy as np
+from backend.node_registry import register_node
+from backend.data_types import DataField, encode_preview
+from backend.nodes.helpers import _mask_overlay, _mask_structure
+
+
+@register_node(display_name="Mask Morphology")
+class MaskMorphology:
+    """Morphological operations on binary masks.
+
+    Equivalent to Gwyddion's mask_morph.c (erode, dilate, open, close).
+    """
+    _CUSTOM_PREVIEW = True
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "mask": ("IMAGE",),
+                "operation": (["dilate", "erode", "open", "close"],),
+                "radius": ("INT", {"default": 1, "min": 1, "max": 50, "step": 1}),
+                "shape": (["disk", "square"],),
+            },
+            "optional": {
+                "field": ("DATA_FIELD",),
+            }
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    RETURN_NAMES = ("mask",)
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Apply morphological operations to a binary mask. "
+        "Dilate expands regions, erode shrinks them, "
+        "open (erode then dilate) removes small spots, "
+        "close (dilate then erode) fills small holes. "
+        "Equivalent to Gwyddion mask_morph."
+    )
+
+    _broadcast_fn = None
+    _current_node_id: str = ""
+
+    def process(self, mask: np.ndarray, operation: str, radius: int, shape: str,
+                field: DataField | None = None) -> tuple:
+        from scipy.ndimage import binary_closing, binary_dilation, binary_erosion, binary_opening
+
+        binary = mask > 127
+        struct = _mask_structure(radius, shape)
+
+        if operation == "dilate":
+            result = binary_dilation(binary, structure=struct)
+        elif operation == "erode":
+            result = binary_erosion(binary, structure=struct)
+        elif operation == "open":
+            result = binary_opening(binary, structure=struct)
+        elif operation == "close":
+            result = binary_closing(binary, structure=struct)
+        else:
+            raise ValueError(f"Unknown morphological operation: {operation}")
+
+        out = result.astype(np.uint8) * 255
+
+        if field is not None and MaskMorphology._broadcast_fn is not None:
+            overlay = _mask_overlay(field, out)
+            MaskMorphology._broadcast_fn(
+                MaskMorphology._current_node_id, encode_preview(overlay),
+            )
+
+        return (out,)