Closes #7877:Add scale to reference view-title from SVG class

When a reference drawing is added to a sheet, the sheet
builder now reads the `scale-X` CSS class from the reference
SVG content and uses it to populate the {{Scale}} field in
the view-title. The scale denominator is resolved to a
human-readable string (e.g. "scale-4" → '3"=1\'-0"') using
the Blender scene unit system to pick imperial vs. metric.

Generated with the assistance of an AI coding tool.

src/bonsai/bonsai/bim/module/drawing/sheeter.py

@@ -486,11 +486,29 @@ class SheetBuilder:
                 data.update({"Sheet" + k: v for k, v in sheet.get_info().items()})
                 if not data["Name"]:
                     data["Name"] = document.Name or "Unnamed"
+                if view.attrib.get("data-type") == "reference":
+                    human_scale = self.get_scale_from_svg(os.path.join(self.layout_dir, path))
+                    if human_scale:
+                        data["Scale"] = human_scale
                 view.append(self.parse_embedded_svg(view_title, data))
 
             for image in images:
                 view.remove(image)
 
+    def get_scale_from_svg(self, svg_path: str) -> str:
+        try:
+            tree = ET.parse(svg_path)
+            root = tree.getroot()
+            for g in root.iter(f"{SVG}g"):
+                for cls in g.attrib.get("class", "").split():
+                    if cls.startswith("scale-"):
+                        denominator = cls[6:]
+                        if denominator.isdigit():
+                            return tool.Drawing.get_human_scale_from_scale_denominator(denominator)
+        except Exception:
+            pass
+        return ""
+
     def get_href(self, element: ET.Element) -> str:
         return urllib.parse.unquote(element.attrib[f"{XLINK}href"]).replace("\\", "/")
 

src/bonsai/bonsai/tool/drawing.py

@@ -2227,6 +2227,63 @@ class Drawing(bonsai.core.tool.Drawing):
         pset = ifcopenshell.util.element.get_pset(drawing, "EPset_Drawing") or {}
         return "NTS" if pset.get("IsNTS", False) else pset.get("HumanScale", "NTS")
 
+    @classmethod
+    def get_human_scale_from_scale_denominator(cls, denominator: str) -> str:
+        """Return the human-readable scale string for a scale CSS class denominator.
+
+        E.g. denominator '4' returns '3"=1\'-0"' (imperial) or '' if not found.
+        """
+        IMPERIAL_SCALES = {
+            "1": "1'=1'-0\"",
+            "2": '6"=1\'-0"',
+            "4": '3"=1\'-0"',
+            "8": '1-1/2"=1\'-0"',
+            "12": '1"=1\'-0"',
+            "16": '3/4"=1\'-0"',
+            "24": '1/2"=1\'-0"',
+            "32": '3/8"=1\'-0"',
+            "48": '1/4"=1\'-0"',
+            "64": '3/16"=1\'-0"',
+            "96": '1/8"=1\'-0"',
+            "128": '3/32"=1\'-0"',
+            "192": '1/16"=1\'-0"',
+            "384": '1/32"=1\'-0"',
+            "768": '1/64"=1\'-0"',
+            "1536": '1/128"=1\'-0"',
+            "120": "1\"=10'",
+            "240": "1\"=20'",
+            "360": "1\"=30'",
+            "480": "1\"=40'",
+            "600": "1\"=50'",
+            "720": "1\"=60'",
+            "840": "1\"=70'",
+            "960": "1\"=80'",
+            "1080": "1\"=90'",
+            "1200": "1\"=100'",
+            "1800": "1\"=150'",
+            "2400": "1\"=200'",
+            "3600": "1\"=300'",
+            "4800": "1\"=400'",
+            "6000": "1\"=500'",
+        }
+        METRIC_SCALES = {
+            "5000": "1:5000",
+            "2000": "1:2000",
+            "1000": "1:1000",
+            "500": "1:500",
+            "200": "1:200",
+            "100": "1:100",
+            "50": "1:50",
+            "20": "1:20",
+            "10": "1:10",
+            "5": "1:5",
+            "2": "1:2",
+            "1": "1:1",
+        }
+        import bpy
+        is_imperial = bpy.context.scene.unit_settings.system == "IMPERIAL"
+        return (IMPERIAL_SCALES if is_imperial else METRIC_SCALES).get(denominator, "")
+
     @classmethod
     def get_drawing_metadata(cls, drawing: ifcopenshell.entity_instance) -> list[str]:
         pset_data = ifcopenshell.util.element.get_pset(drawing, "EPset_Drawing")