refactor nodes into standalone file

backend/nodes/colormap_adjust.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+import numpy as np
+from backend.node_registry import register_node
+from backend.data_types import DataField
+
+
+@register_node(display_name="Colormap Adjust")
+class ColormapAdjust:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "offset": ("FLOAT", {"default": 0.0, "min": -1.0, "max": 1.0, "step": 0.01}),
+                "scale": ("FLOAT", {"default": 1.0, "min": 0.05, "max": 4.0, "step": 0.01}),
+                "auto": ("BUTTON", {"label": "Auto", "set_widgets": {"offset": 0.0, "scale": 1.0}}),
+            }
+        }
+
+    RETURN_TYPES = ("DATA_FIELD",)
+    RETURN_NAMES = ("field",)
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Adjust how a DATA_FIELD maps into its colormap without changing the underlying data. "
+        "offset and scale operate in normalized display coordinates; Auto resets to the full data range."
+    )
+
+    def process(self, field: DataField, offset: float, scale: float) -> tuple:
+        scale = float(scale)
+        if not np.isfinite(scale) or scale <= 0.0:
+            raise ValueError("Scale must be a positive number.")
+        return (field.replace(display_offset=float(offset), display_scale=scale),)