Add instances_name_length_req check

khaledhosny · khaledhosny · commit 8d4e7668bc80 · 2025-06-30T02:42:28.000+03:00
Similar to name_length_req, but checks the family and subfamily names of
the instances, computed from STAT table.

Add the new check to Microsoft profile.

Also add failing test case for the new check as well as name_length_req.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -9,6 +9,10 @@ A more detailed list of changes is available in the corresponding milestones for
 ### On the opentype profile
 - **[check_monospace]:** Check CFF fonts as well: remove conditions "is_ttf" + remove "glyf" from required tables (issue #5030)
 
+### New checks
+### On micorosoft profile
+- **[instances_name_length_req]:** Check family and subfamily name length, similar to **name_length_req** but for "fvar" instances, using names computed from "STAT" table. (PR #5035)
+
 
 ## 1.0.0 (2025-May-07)
   - See also: https://github.com/fonttools/fontspector
diff --git a/Lib/fontbakery/checks/name_length_req.py b/Lib/fontbakery/checks/name_length_req.py
@@ -1,7 +1,28 @@
-from fontbakery.prelude import check, FAIL
+from fontbakery.constants import NameID
+from fontbakery.prelude import check, FAIL, Message
 from fontbakery.utils import get_family_name, get_subfamily_name
 
 
+def _check_name_length_req(family_name, subfamily_name):
+    if family_name is None:
+        yield FAIL, Message("missing-name-id", "Name ID 1 (family) missing")
+    if subfamily_name is None:
+        yield FAIL, Message("missing-name-id", "Name ID 2 (sub family) missing")
+
+    logfont = (
+        family_name
+        if subfamily_name in ("Regular", "Bold", "Italic", "Bold Italic")
+        else " ".join([family_name, subfamily_name])
+    )
+
+    if len(logfont) > 31:
+        yield FAIL, Message(
+            "long-name",
+            f"Family + subfamily name, '{logfont}', is too long: "
+            f"{len(logfont)} characters; must be 31 or less",
+        )
+
+
 @check(
     id="name_length_req",
     rationale="""
@@ -14,19 +35,112 @@ def check_name_length_req(ttFont):
     """Maximum allowed length for family and subfamily names."""
     family_name = get_family_name(ttFont)
     subfamily_name = get_subfamily_name(ttFont)
-    if family_name is None:
-        yield FAIL, "Name ID 1 (family) missing"
-    if subfamily_name is None:
-        yield FAIL, "Name ID 2 (sub family) missing"
+    yield from _check_name_length_req(family_name, subfamily_name)
 
-    logfont = (
-        family_name
-        if subfamily_name in ("Regular", "Bold", "Italic", "Bold Italic")
-        else " ".join([family_name, subfamily_name])
+
+def resolve_stat_names(vf, coordinates):
+    """
+    Returns a dictionary of names & axis order, indexed by axis tag, for an
+    instance in the given font at the given coordinates.
+
+    e.g. result['wght']: ('Regular', 0)
+    """
+    stat_table = vf["STAT"].table
+    result = {}
+
+    for avr in stat_table.AxisValueArray.AxisValue:
+        axis_tag = stat_table.DesignAxisRecord.Axis[avr.AxisIndex].AxisTag
+        if (
+            axis_tag in coordinates
+            and (
+                (
+                    avr.Format == 2
+                    and avr.RangeMinValue <= coordinates[axis_tag] <= avr.RangeMaxValue
+                )
+                or (avr.Format in (1, 3) and avr.Value == coordinates[axis_tag])
+            )
+        ) or (axis_tag not in coordinates):
+            if avr.Flags & 0x2 == 0:
+                name = vf["name"].getDebugName(avr.ValueNameID)
+                axis_order = stat_table.DesignAxisRecord.Axis[
+                    avr.AxisIndex
+                ].AxisOrdering
+                result[axis_tag] = (name, axis_order)
+
+    return result
+
+
+RBIZ_AXES = ["wght", "ital"]
+
+
+def compute_rbiz_names(family, stat_names, rbiz_axes):
+    # Name IDs 1 & 2 in a RBIZ model
+    rbiz_family_names = [
+        n
+        for axis, (n, _) in sorted(stat_names.items(), key=lambda x: x[1][1])
+        if axis not in rbiz_axes
+    ]
+    rbiz_family = " ".join([f"{family}", *rbiz_family_names])
+    rbiz_subfamily_names = [
+        stat_names[axis] for axis in rbiz_axes if axis in stat_names
+    ]
+    rbiz_subfamily = " ".join(
+        [n for n, _ in sorted(rbiz_subfamily_names, key=lambda x: x[1])]
     )
+    if rbiz_subfamily == "":
+        rbiz_subfamily = "Regular"
+    return (rbiz_family, rbiz_subfamily)
 
-    if len(logfont) > 31:
-        yield FAIL, (
-            f"Family + subfamily name, '{logfont}', is too long: "
-            f"{len(logfont)} characters; must be 31 or less"
-        )
+
+def names_from_stat(vf, coordinates):
+    """
+    Returns family and subfamily names generated from the STAT and name tables, for an instance
+    at the given coordinates.
+    """
+    stat_names = resolve_stat_names(vf, coordinates)
+
+    # Find any implicit style names in ID 1 by removing ID 16 and any of the
+    # default instance style names. E.g. if ID 1 is "Bahnschrift Rounded Light",
+    # and ID 16 is "Bahnschrift", find "Rounded".
+    id1 = vf["name"].getDebugName(NameID.FONT_FAMILY_NAME)
+    id16 = vf["name"].getDebugName(NameID.TYPOGRAPHIC_FAMILY_NAME)
+    if id1 and id16 and id1.startswith(id16) and id1 != id16:
+        id1_names = id1[len(id16) + 1 :].split(" ")
+        default_inst_coords = {
+            axis.axisTag: axis.defaultValue for axis in vf["fvar"].axes
+        }
+        default_stat_names = resolve_stat_names(vf, default_inst_coords)
+        default_stat_names = [n for n, _ in sorted(default_stat_names.values())]
+        remaining_names = [n for n in id1_names if n not in default_stat_names]
+        # Update axis ordering in stat_names
+        for axis_tag, (name, ordering) in stat_names.items():
+            stat_names[axis_tag] = (name, ordering + len(remaining_names))
+        # Add the names from ID 1
+        stat_names.update({f"X{i:<3}": (n, i) for i, n in enumerate(remaining_names)})
+
+    family = vf["name"].getDebugName(NameID.TYPOGRAPHIC_FAMILY_NAME)
+    if family is None:
+        family = vf["name"].getDebugName(NameID.FONT_FAMILY_NAME)
+
+    rbiz_axes = list(RBIZ_AXES)
+    if "wght" in coordinates and coordinates["wght"] not in (400, 700):
+        rbiz_axes = [x for x in rbiz_axes if x != "wght"]
+
+    rbiz_family, rbiz_subfamily = compute_rbiz_names(family, stat_names, rbiz_axes)
+    return rbiz_family, rbiz_subfamily
+
+
+@check(
+    id="instances_name_length_req",
+    conditions=["is_variable_font"],
+    rationale="""
+        For Office, instance family and subfamily names must be 31 characters or less total
+        to fit in a LOGFONT.
+    """,
+)
+def instances_name_length_req(ttFont):
+    """Maximum allowed length for instance family and subfamily names."""
+    fvar = ttFont["fvar"]
+    for instance in fvar.instances:
+        family_name, subfamily_name = names_from_stat(ttFont, instance.coordinates)
+        yield from _check_name_length_req(family_name, subfamily_name)
diff --git a/Lib/fontbakery/profiles/microsoft.py b/Lib/fontbakery/profiles/microsoft.py
@@ -70,6 +70,7 @@
             "name_id_1",  # TODO: These name id 1 & 2 checks are too simple. Maybe they could be merged.
             "name_id_2",  # TODO: Also, they could be included in some other name table check on the universal profile.
             "name_length_req",  # TODO: Maybe the same applies to this one.
+            "instances_name_length_req",
         ],
         "Metrics Checks": [
             "microsoft/vertical_metrics",
diff --git a/tests/test_checks_name.py b/tests/test_checks_name.py
@@ -1,3 +1,4 @@
+import copy
 import pytest
 from fontTools.ttLib import TTFont
 
@@ -82,7 +83,24 @@ def test_check_name_length_req(check, test_ttFont):
 
     assert_PASS(check(test_ttFont), "with a good font...")
 
-    # TODO: test a FAIL case
+    test_ttFont_bad = copy.deepcopy(test_ttFont)
+    for rec in test_ttFont_bad["name"].names:
+        if rec.nameID in (NameID.FONT_FAMILY_NAME, NameID.TYPOGRAPHIC_FAMILY_NAME):
+            rec.string = "A" * 32
+    assert_results_contain(check(test_ttFont_bad), FAIL, "long-name")
+
+
+@check_id("instances_name_length_req")
+def test_check_instances_name_length_req(check, test_ttFont):
+    """Maximum allowed length for family and subfamily names."""
+
+    assert_PASS(check(test_ttFont), "with a good font...")
+
+    test_ttFont_bad = copy.deepcopy(test_ttFont)
+    for rec in test_ttFont_bad["name"].names:
+        if rec.nameID in (NameID.FONT_FAMILY_NAME, NameID.TYPOGRAPHIC_FAMILY_NAME):
+            rec.string = "A" * 32
+    assert_results_contain(check(test_ttFont_bad), FAIL, "long-name")
 
 
 @check_id("typographic_family_name")
