More complete fix for breaking styles ui e85043ae3

Now it also doesn't break if user will undo style rename.

src/bonsai/bonsai/bim/module/style/data.py

@@ -36,24 +36,12 @@ class StylesData:
     @classmethod
     def load(cls):
         cls.data = {
-            "styles_to_blender_material_names": cls.styles_to_blender_material_names(),
             "style_types": cls.style_types(),
             "total_styles": cls.total_styles(),
             "reflectance_methods": cls.reflectance_methods(),
         }
         cls.is_loaded = True
 
-    @classmethod
-    def styles_to_blender_material_names(cls) -> list[Union[str, None]]:
-        ifc_file = tool.Ifc.get()
-        props = bpy.context.scene.BIMStylesProperties
-        materials: list[Union[str, None]] = []
-        for style in props.styles:
-            material = tool.Ifc.get_object(ifc_file.by_id(style.ifc_definition_id))
-            # Material will be None if it's not IfcSurfaceStyle.
-            materials.append(material.name if material is not None else None)
-        return materials
-
     @classmethod
     def reflectance_methods(cls):
         declaration = tool.Ifc.schema().declaration_by_name("IfcReflectanceMethodEnum")

src/bonsai/bonsai/bim/module/style/operator.py

@@ -141,6 +141,13 @@ class UnlinkStyle(bpy.types.Operator, tool.Ifc.Operator):
             core.remove_style(tool.Ifc, tool.Style, style)
         else:
             material_copy.use_fake_user = True
+            # Need to reload Styles UI since it's item is now pointing to wrong Blender material.
+            if (
+                tool.Style.is_editing_styles()
+                and (style_type := tool.Style.get_active_style_type())
+                and style_type == style.is_a()
+            ):
+                tool.Style.import_presentation_styles(style_type)
 
         # Ensure there won't be any style sync on project save:
         # bim.update_representation would create new IfcSurfaceStyle

src/bonsai/bonsai/bim/module/style/prop.py

@@ -69,6 +69,13 @@ class Style(PropertyGroup):
     diffuse_colour: bpy.props.FloatVectorProperty(
         name="Diffuse Colour", subtype="COLOR", default=(1, 1, 1), min=0.0, max=1.0, size=3
     )
+    blender_material: PointerProperty(
+        description=(
+            "Needed for UI to have style->blender material link that won't break on undo. "
+            "Can be None if it's not a surface style"
+        ),
+        type=bpy.types.Material,
+    )
 
 
 STYLE_TYPES = [

src/bonsai/bonsai/bim/module/style/ui.py

@@ -52,7 +52,7 @@ class BIM_PT_styles(Panel):
             row.operator("bim.load_styles", text="", icon="IMPORT").style_type = style_type
             return
 
-        active_style = self.props.styles and self.props.active_style_index < len(self.props.styles)
+        active_style = bool(self.props.styles and self.props.active_style_index < len(self.props.styles))
         row = self.layout.row(align=True)
         row.label(text="{} {}s".format(len(self.props.styles), self.props.style_type), icon="SHADING_RENDERED")
         row.operator("bim.disable_editing_styles", text="", icon="CANCEL")
@@ -95,9 +95,7 @@ class BIM_PT_styles(Panel):
         # style ui tools
         if active_style:
             row = self.layout.row(align=True)
-            material_name = StylesData.data["styles_to_blender_material_names"][self.props.active_style_index]
+            if material := style.blender_material:
-            if material_name:  # The user may have unlinked the style, so the material may not exist
-                material = bpy.data.materials[material_name]
                 row.prop(material.BIMStyleProperties, "active_style_type", icon="SHADING_RENDERED", text="")
                 op = row.operator("bim.update_current_style", icon="FILE_REFRESH", text="")
                 op.style_id = style.ifc_definition_id
@@ -268,9 +266,8 @@ class BIM_UL_styles(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
         if item:
             row = layout.row(align=True)
-            material_name: Union[str, None] = StylesData.data["styles_to_blender_material_names"][index]
             material_icon = 0
-            if material_name and (material := bpy.data.materials.get(material_name)):
+            if material := item.blender_material:
                 preview = material.preview_ensure()
                 material_icon = preview.icon_id
             row.prop(item, "name", text="", emboss=False, icon_value=material_icon)

src/bonsai/bonsai/tool/style.py

@@ -521,6 +521,7 @@ class Style(bonsai.core.tool.Style):
         for style in styles:
             new = props.styles.add()
             new.ifc_definition_id = style.id()
+            new.blender_material = tool.Ifc.get_object(style)
             new["name"] = style.Name or "Unnamed"  # Avoid writing to IFC through callback.
             new.ifc_class = style.is_a()
             for surface_style in getattr(style, "Styles", []) or []: