Add manual drawing reference annotation operator

Adds operator to place manual elevation/section drawing reference
tags that survive drawing regeneration. Includes core function,
tool methods, type-selection dialog, default horizontal rotation
for elevation tags, and SVG null guard for unassigned references.

Generated with the assistance of an AI coding tool.

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

@@ -895,6 +895,8 @@ class SvgWriter:
         reference_id = "-"
         sheet_id = "-"
         drawing = tool.Drawing.get_annotation_element(element)
+        if not drawing:
+            return ("-", "-")
         reference = tool.Drawing.get_drawing_reference(drawing)
         if reference:
             for sheet_reference in tool.Ifc.get().by_type("IfcDocumentReference"):

src/bonsai/bonsai/core/drawing.py

@@ -550,6 +550,28 @@ def add_annotation(
     return obj
 
 
+def add_manual_drawing_reference(
+    ifc: type[tool.Ifc],
+    collector: type[tool.Collector],
+    drawing_tool: type[tool.Drawing],
+    drawing: ifcopenshell.entity_instance,
+    annotation_type: str,
+) -> bpy.types.Object:
+    if annotation_type == "ELEVATION":
+        element = drawing_tool.create_manual_elevation_reference(drawing)
+    else:  # SECTION
+        target_view = drawing_tool.get_drawing_target_view(drawing)
+        context = drawing_tool.get_annotation_context(target_view)
+        if not context:
+            context = drawing_tool.create_annotation_context(target_view, annotation_type)
+        element = drawing_tool.create_manual_section_reference(drawing, context)
+    drawing_tool.set_manual_drawing_reference(element)
+    ifc.run("group.assign_group", group=drawing_tool.get_drawing_group(drawing), products=[element])
+    obj = ifc.get_object(element)
+    collector.assign(obj)
+    return obj
+
+
 def build_schedule(drawing: type[tool.Drawing], schedule: ifcopenshell.entity_instance) -> None:
     drawing.create_svg_schedule(schedule)
     drawing.open_svg(drawing.get_path_with_ext(drawing.get_document_uri(schedule), "svg"))

src/bonsai/bonsai/tool/drawing.py

@@ -1979,6 +1979,48 @@ class Drawing(bonsai.core.tool.Drawing):
             element.Name = elevation.Name or "Unnamed"
             return element
 
+    @classmethod
+    def create_manual_elevation_reference(cls, drawing: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance:
+        cursor_location = bpy.context.scene.cursor.location.copy()
+        obj = bpy.data.objects.new("Unnamed", None)
+        obj.empty_display_size = 0.1
+        obj.matrix_world = Matrix.Translation(cursor_location) @ Matrix.Rotation(math.radians(90), 4, "X")
+        element = cls.run_root_assign_class(
+            obj=obj, ifc_class="IfcAnnotation", predefined_type="ELEVATION", should_add_representation=False
+        )
+        element.Name = "Unnamed"
+        return element
+
+    @classmethod
+    def create_manual_section_reference(
+        cls, drawing: ifcopenshell.entity_instance, context: ifcopenshell.entity_instance
+    ) -> ifcopenshell.entity_instance:
+        cursor_location = bpy.context.scene.cursor.location.copy()
+        mesh = bpy.data.meshes.new("Mesh")
+        obj = bpy.data.objects.new("Unnamed", mesh)
+        obj.matrix_world = Matrix.Translation(cursor_location)
+        element = cls.run_root_assign_class(
+            obj=obj, ifc_class="IfcAnnotation", predefined_type="SECTION", should_add_representation=False
+        )
+        element.Name = "Unnamed"
+        builder = ShapeBuilder(tool.Ifc.get())
+        unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
+        p1 = cursor_location + Vector((-0.5, 0, 0))
+        p2 = cursor_location + Vector((0.5, 0, 0))
+        points = [p1 / unit_scale, p2 / unit_scale]
+        representation = builder.get_representation(context, [builder.polyline(points)])
+        ifcopenshell.api.geometry.assign_representation(tool.Ifc.get(), element, representation)
+        bonsai.core.geometry.switch_representation(tool.Ifc, tool.Geometry, obj=obj, representation=representation)
+        return element
+
+    @classmethod
+    def set_manual_drawing_reference(cls, element: ifcopenshell.entity_instance) -> None:
+        ifc_file = tool.Ifc.get()
+        pset = tool.Pset.get_element_pset(element, "EPset_Annotation")
+        if not pset:
+            pset = ifcopenshell.api.pset.add_pset(ifc_file, product=element, name="EPset_Annotation")
+        ifcopenshell.api.pset.edit_pset(ifc_file, pset=pset, properties={"IsManualDrawingReference": True})
+
     @classmethod
     def regenerate_elevation_reference_annotation(
         cls,