IfcText - different text sizes in viewport

src/blenderbim/blenderbim/bim/module/drawing/data.py

@@ -182,3 +182,36 @@ class DecoratorData:
 
         cls.data[obj.name] = display_data
         return display_data
+
+    @classmethod
+    def get_ifc_text_font_size(cls, obj):        
+        """returns font size in mm for current ifc text object"""
+        result = cls.data.get(obj.name, None)
+        if result is not None:
+            return result
+        
+        element = tool.Ifc.get_entity(obj)
+        if not element:
+            return
+        
+        classes = ifcopenshell.util.element.get_pset(element, "EPset_Annotation", "Classes")
+        
+        font_sizes = {
+            'small':   1.8,
+            'regular': 2.5,
+            'large':   3.5,
+            'header':  5,
+            'title':   7,
+        }
+
+        # use `regular` as default
+        if classes:        
+            tags = classes.split()
+            # prioritize smaller font sizes just like in svg
+            font_size_type = next((font_size_type for font_size_type in font_sizes if font_size_type in tags), 'regular')
+        else:
+            font_size_type = 'regular'
+
+        font_size = font_sizes[font_size_type]
+        cls.data[obj.name] = font_size
+        return font_size

src/blenderbim/blenderbim/bim/module/drawing/decoration.py

@@ -2072,7 +2072,7 @@ class TextDecorator(BaseDecorator):
         # TODO: support text rotation
         dir = Vector((1, 0))
         pos = location_3d_to_region_2d(region, region3d, obj.matrix_world.translation)
-        font_size = 2.5
+        font_size = DecoratorData.get_ifc_text_font_size(obj)
         for line_i, line in enumerate(obj.BIMTextProperties.value.split("\\n")):
             self.draw_label(
                 context, line, pos, dir, gap=0, center=False, vcenter=False, font_size=font_size, line_no=line_i