bdbarnett · Nov 6, 2026 · Nov 6, 2026
diff --git a/binding/emit_c_micropython_style.py b/binding/emit_c_micropython_style.py
@@ -73,7 +73,7 @@
     target_banner,
 )
 from .runtime_exports import filter_module_funcs_for_target, filter_registration_module_funcs
-from .util import eprint, memoize
+from .util import eprint, guarded, memoize
 from .context import EmitterResult
 
 
@@ -2929,15 +2929,21 @@ def gen_global(global_name, global_type_ast):
  * {module_name} {global_name} global definitions
  */
 
-static const mp_lv_struct_t mp_{global_name} = {{
-    {{ &mp_{struct_name}_type }},
-    ({cast}*)&{global_name}
-}};
+{definition}
     """.format(
                 module_name=module_name,
                 global_name=global_name,
-                struct_name=global_type,
-                cast=gen.visit(global_type_ast),
+                definition=guarded(
+                    """static const mp_lv_struct_t mp_{global_name} = {{
+    {{ &mp_{struct_name}_type }},
+    ({cast}*)&{global_name}
+}};""".format(
+                        global_name=global_name,
+                        struct_name=global_type,
+                        cast=gen.visit(global_type_ast),
+                    ),
+                    global_name,
+                ),
             )
         )
 
@@ -3157,10 +3163,15 @@ def gen_global(global_name, global_type_ast):
             ),
             blobs="".join(
                 [
-                    "{{ MP_ROM_QSTR(MP_QSTR_{name}), MP_ROM_PTR(&mp_{global_name}) }},\n    ".format(
-                        name=export_name(global_name, "blob"),
-                        global_name=global_name,
+                    guarded(
+                        "{{ MP_ROM_QSTR(MP_QSTR_{name}), MP_ROM_PTR(&mp_{global_name}) }},".format(
+                            name=export_name(global_name, "blob"),
+                            global_name=global_name,
+                        ),
+                        global_name,
+                        indent="    ",
                     )
+                    + "\n    "
                     # _nesting is deliberately kept here even though the
                     # canonical API model marks it private: see the
                     # comment in emit_backend.module_registration_plan and

diff --git a/binding/emit_circuitpython_glue.py b/binding/emit_circuitpython_glue.py
@@ -8,6 +8,7 @@
 import collections
 
 from . import runtime
+from .util import guarded
 from .emit_backend import enum_namespace_plan, module_registration_plan, public_enum_module_names, public_struct_c_names
 
 
@@ -74,9 +75,12 @@ def _module_global_entries(
             )
         for global_name in plan.generated_globals:
             entries.append(
-                "    {{ MP_ROM_QSTR(MP_QSTR_{name}), MP_ROM_PTR(&mp_{global_name}) }}".format(
-                    name=export_name(global_name, "blob"),
-                    global_name=global_name,
+                guarded(
+                    "    {{ MP_ROM_QSTR(MP_QSTR_{name}), MP_ROM_PTR(&mp_{global_name}) }},".format(
+                        name=export_name(global_name, "blob"),
+                        global_name=global_name,
+                    ),
+                    global_name,
                 )
             )
     if plan.enum_names:
@@ -125,6 +129,17 @@ def _module_global_entries(
     return entries
 
 
+def _table(entries):
+    """Join table entries; an entry that already ends in its comma keeps it.
+
+    Entries wrapped in ``#if``/``#endif`` carry their comma inside the guard.
+    """
+    return "\n".join(
+        entry if entry.endswith(",") or entry.endswith("#endif") else entry + ","
+        for entry in entries
+    )
+
+
 def finish_cp_fragment(max_phase):
     """Emit mergeable module entry table for shared-bindings/lvgl/__init__.c."""
     int_constants = runtime.get("int_constants", [])
@@ -192,7 +207,7 @@ def finish_cp_fragment(max_phase):
 
 const size_t lvgl_module_entry_count = sizeof(lvgl_module_entries) / sizeof(lvgl_module_entries[0]);
 """.format(
-            table=",\n".join(all_entries) if all_entries else "    /* no module entries */"
+            table=_table(all_entries) if all_entries else "    /* no module entries */"
         )
     )
 

diff --git a/binding/emit_cpython_glue.py b/binding/emit_cpython_glue.py
@@ -8,6 +8,7 @@
 import collections
 
 from . import runtime
+from .util import guarded
 from .emit_backend import enum_namespace_plan, module_registration_plan, public_enum_module_names, public_struct_c_names
 
 
@@ -424,12 +425,15 @@ def finish_py_module(max_phase):
             )
             py_name = simplify_identifier(global_name)
             print(
-                '    {{ PyObject *obj = lv_to_mp_struct({type_object}, (void *)&{global_name});'
-                ' if (obj == NULL) return NULL;'
-                ' if (PyModule_AddObject(m, "{py_name}", obj) < 0) {{ Py_DECREF(obj); return NULL; }} }}'.format(
-                    type_object=type_object,
-                    global_name=global_name,
-                    py_name=py_name,
+                guarded(
+                    '    {{ PyObject *obj = lv_to_mp_struct({type_object}, (void *)&{global_name});'
+                    ' if (obj == NULL) return NULL;'
+                    ' if (PyModule_AddObject(m, "{py_name}", obj) < 0) {{ Py_DECREF(obj); return NULL; }} }}'.format(
+                        type_object=type_object,
+                        global_name=global_name,
+                        py_name=py_name,
+                    ),
+                    global_name,
                 )
             )
 

diff --git a/binding/util.py b/binding/util.py
@@ -5,6 +5,7 @@
 """Small utilities: memoize and stderr logging for analyze/emit."""
 from __future__ import print_function
 
+import re
 import sys
 from functools import lru_cache
 
@@ -29,3 +30,31 @@ def clear_memoized():
 
 def eprint(*args, **kwargs):
     print(*args, file=sys.stderr, **kwargs)
+
+
+_MONTSERRAT_FONT = re.compile(r"lv_font_montserrat_(\d+)$")
+
+
+def config_guard(global_name):
+    """Return the ``lv_conf.h`` switch a generated global depends on, or None.
+
+    A build can turn a built-in Montserrat size off (``-DLV_FONT_MONTSERRAT_40=0``)
+    without regenerating the binding, so the font's wrapper and its module entry
+    are emitted inside ``#if`` on that switch.
+    """
+    match = _MONTSERRAT_FONT.match(global_name)
+    if match is None:
+        return None
+    return "LV_FONT_MONTSERRAT_%s" % match.group(1)
+
+
+def guarded(text, global_name, indent=""):
+    """Wrap ``text`` in ``#if``/``#endif`` on `config_guard` when it has one.
+
+    ``indent`` goes before ``text`` and ``#endif``, for a line that the caller's
+    template has already indented.
+    """
+    guard = config_guard(global_name)
+    if guard is None:
+        return text
+    return "#if %s\n%s%s\n%s#endif" % (guard, indent, text, indent)
diff --git a/docs/reference/fonts.md b/docs/reference/fonts.md
@@ -19,6 +19,20 @@ loaded font is parsed into the heap (roughly its file size: see the sizes in
 your everyday fonts compiled in; load the occasional large size, or a script
 you only sometimes need, at runtime.
 
+## Leaving a built-in font out
+
+Each `LV_FONT_MONTSERRAT_<n>` in `lv_conf.h` can be set from the build, so a
+firmware short of flash can drop a compiled-in size without editing
+`lv_conf.h` or regenerating the binding:
+
+```bash
+make BOARD=... CFLAGS_EXTRA=-DLV_FONT_MONTSERRAT_40=0
+```
+
+`lv.font_montserrat_40` is then missing from the module, and you can load
+`montserrat_40.bin` at runtime instead. This only turns sizes off: a size that
+`lv_conf.h` leaves out has no wrapper in the generated binding.
+
 ## Getting a font onto the board
 
 ```bash

diff --git a/generated/lvgl_circuitpython.c b/generated/lvgl_circuitpython.c
@@ -27522,50 +27522,60 @@ static const mp_lv_struct_t mp_lv_tree_node_class = {
  * lvgl lv_font_montserrat_14 global definitions
  */
 
+#if LV_FONT_MONTSERRAT_14
 static const mp_lv_struct_t mp_lv_font_montserrat_14 = {
     { &mp_lv_font_t_type },
     (lv_font_t*)&lv_font_montserrat_14
 };
+#endif
 
 
 /*
  * lvgl lv_font_montserrat_16 global definitions
  */
 
+#if LV_FONT_MONTSERRAT_16
 static const mp_lv_struct_t mp_lv_font_montserrat_16 = {
     { &mp_lv_font_t_type },
     (lv_font_t*)&lv_font_montserrat_16
 };
+#endif
 
 
 /*
  * lvgl lv_font_montserrat_24 global definitions
  */
 
+#if LV_FONT_MONTSERRAT_24
 static const mp_lv_struct_t mp_lv_font_montserrat_24 = {
     { &mp_lv_font_t_type },
     (lv_font_t*)&lv_font_montserrat_24
 };
+#endif
 
 
 /*
  * lvgl lv_font_montserrat_32 global definitions
  */
 
+#if LV_FONT_MONTSERRAT_32
 static const mp_lv_struct_t mp_lv_font_montserrat_32 = {
     { &mp_lv_font_t_type },
     (lv_font_t*)&lv_font_montserrat_32
 };
+#endif
 
 
 /*
  * lvgl lv_font_montserrat_40 global definitions
  */
 
+#if LV_FONT_MONTSERRAT_40
 static const mp_lv_struct_t mp_lv_font_montserrat_40 = {
     { &mp_lv_font_t_type },
     (lv_font_t*)&lv_font_montserrat_40
 };
+#endif
 
 /* Global struct wrapper for int */
 
@@ -48882,11 +48892,21 @@ static const mp_rom_map_elem_t lvgl_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_TABLE_CELL_NONE), MP_ROM_PTR(MP_ROM_INT(ENUM_LV_TABLE_CELL_NONE)) },
     { MP_ROM_QSTR(MP_QSTR_color_filter_shade), MP_ROM_PTR(&mp_lv_color_filter_shade) },
     { MP_ROM_QSTR(MP_QSTR_tree_node_class), MP_ROM_PTR(&mp_lv_tree_node_class) },
+#if LV_FONT_MONTSERRAT_14
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_14), MP_ROM_PTR(&mp_lv_font_montserrat_14) },
+#endif
+#if LV_FONT_MONTSERRAT_16
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_16), MP_ROM_PTR(&mp_lv_font_montserrat_16) },
+#endif
+#if LV_FONT_MONTSERRAT_24
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_24), MP_ROM_PTR(&mp_lv_font_montserrat_24) },
+#endif
+#if LV_FONT_MONTSERRAT_32
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_32), MP_ROM_PTR(&mp_lv_font_montserrat_32) },
+#endif
+#if LV_FONT_MONTSERRAT_40
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_40), MP_ROM_PTR(&mp_lv_font_montserrat_40) },
+#endif
     { MP_ROM_QSTR(MP_QSTR_style_const_prop_id_inv), MP_ROM_PTR(&mp_lv_style_const_prop_id_inv) },
     { MP_ROM_QSTR(MP_QSTR_obj_class), MP_ROM_PTR(&mp_lv_obj_class) },
     { MP_ROM_QSTR(MP_QSTR_binfont_font_class), MP_ROM_PTR(&mp_lv_binfont_font_class) },
@@ -49464,7 +49484,7 @@ static const mp_rom_map_elem_t lvgl_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_group_deinit), MP_ROM_PTR(&mp_lv_group_deinit_mpobj) },
     { MP_ROM_QSTR(MP_QSTR_fs_init), MP_ROM_PTR(&mp_lv_fs_init_mpobj) },
     { MP_ROM_QSTR(MP_QSTR_fs_deinit), MP_ROM_PTR(&mp_lv_fs_deinit_mpobj) },
-    { MP_ROM_QSTR(MP_QSTR_event_mark_deleted), MP_ROM_PTR(&mp_lv_event_mark_deleted_mpobj) }
+    { MP_ROM_QSTR(MP_QSTR_event_mark_deleted), MP_ROM_PTR(&mp_lv_event_mark_deleted_mpobj) },
 };
 
 static MP_DEFINE_CONST_DICT(lvgl_module_globals, lvgl_module_globals_table);
@@ -49509,11 +49529,21 @@ const mp_rom_map_elem_t lvgl_module_entries[] = {
     { MP_ROM_QSTR(MP_QSTR_TABLE_CELL_NONE), MP_ROM_PTR(MP_ROM_INT(ENUM_LV_TABLE_CELL_NONE)) },
     { MP_ROM_QSTR(MP_QSTR_color_filter_shade), MP_ROM_PTR(&mp_lv_color_filter_shade) },
     { MP_ROM_QSTR(MP_QSTR_tree_node_class), MP_ROM_PTR(&mp_lv_tree_node_class) },
+#if LV_FONT_MONTSERRAT_14
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_14), MP_ROM_PTR(&mp_lv_font_montserrat_14) },
+#endif
+#if LV_FONT_MONTSERRAT_16
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_16), MP_ROM_PTR(&mp_lv_font_montserrat_16) },
+#endif
+#if LV_FONT_MONTSERRAT_24
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_24), MP_ROM_PTR(&mp_lv_font_montserrat_24) },
+#endif
+#if LV_FONT_MONTSERRAT_32
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_32), MP_ROM_PTR(&mp_lv_font_montserrat_32) },
+#endif
+#if LV_FONT_MONTSERRAT_40
     { MP_ROM_QSTR(MP_QSTR_font_montserrat_40), MP_ROM_PTR(&mp_lv_font_montserrat_40) },
+#endif
     { MP_ROM_QSTR(MP_QSTR_style_const_prop_id_inv), MP_ROM_PTR(&mp_lv_style_const_prop_id_inv) },
     { MP_ROM_QSTR(MP_QSTR_obj_class), MP_ROM_PTR(&mp_lv_obj_class) },
     { MP_ROM_QSTR(MP_QSTR_binfont_font_class), MP_ROM_PTR(&mp_lv_binfont_font_class) },
@@ -50091,7 +50121,7 @@ const mp_rom_map_elem_t lvgl_module_entries[] = {
     { MP_ROM_QSTR(MP_QSTR_group_deinit), MP_ROM_PTR(&mp_lv_group_deinit_mpobj) },
     { MP_ROM_QSTR(MP_QSTR_fs_init), MP_ROM_PTR(&mp_lv_fs_init_mpobj) },
     { MP_ROM_QSTR(MP_QSTR_fs_deinit), MP_ROM_PTR(&mp_lv_fs_deinit_mpobj) },
-    { MP_ROM_QSTR(MP_QSTR_event_mark_deleted), MP_ROM_PTR(&mp_lv_event_mark_deleted_mpobj) }
+    { MP_ROM_QSTR(MP_QSTR_event_mark_deleted), MP_ROM_PTR(&mp_lv_event_mark_deleted_mpobj) },
 };
 
 const size_t lvgl_module_entry_count = sizeof(lvgl_module_entries) / sizeof(lvgl_module_entries[0]);