[family_and_style_max_length] Modernize check

CHANGELOG.md

@@ -5,6 +5,9 @@ A more detailed list of changes is available in the corresponding milestones for
   - Replace deprecated `pkg_resources` by `importlib.resources` (issue #5028)
   - ...
 
+### Changes to existing checks
+### On the Universal profile
+  - **[name/family_and_style_max_length]:** Update to account for STAT table, along with recent testing and observations contributed to issue #2179
 
 ## 1.0.1 (2025-Jul-04)
 ### Bugfixes

Lib/fontbakery/checks/name/family_and_style_max_length.py

@@ -1,10 +1,9 @@
 import re
+from collections import defaultdict
+from itertools import product
 
-from fontbakery.constants import (
-    RIBBI_STYLE_NAMES,
-    NameID,
-)
-from fontbakery.prelude import check, Message, FAIL, WARN
+from fontbakery.constants import RIBBI_STYLE_NAMES, NameID
+from fontbakery.prelude import FAIL, WARN, Message, check
 from fontbakery.utils import get_name_entry_strings
 
 
@@ -13,38 +12,51 @@
     rationale="""
         This check ensures that the length of name table entries is not
         too long, as this causes problems in some environments.
+
+        Background on length limit (credit to Aaron Bell at google/fonts/issues/9185):
+
+        The font dropdown in Microsoft Office on PC is driven by the older
+        GDI font enumeration and rendering technology. GDI uses LOGFONTA
+        (https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-logfonta)
+        to define the attributes of a font, and CHAR lfFaceName[LF_FACESIZE];
+        to define the font name. The problem, though, is that the string lfFaceName
+        is restricted to 32 characters, including the terminating NULL.
+
+        In a variable font where the master location is at a location with a
+        significant number of characters, say, “ExtraLight”, name ID 1 can become
+        quite long (eg: “Chiron Hei HK ExtraLight”). However, in determining the
+        font name, Microsoft will prioritize name ID 16 over name ID 1. So this
+        lets one reduce the character count back to the standard font name
+        (eg: “Chiron Hei HK”).
     """,
     proposal=[
         "https://github.com/fonttools/fontbakery/issues/1488",
         "https://github.com/fonttools/fontbakery/issues/2179",
     ],
 )
 def check_name_family_and_style_max_length(ttFont):
-    """Combined length of family and style must not exceed 32 characters."""
+    """Combined length of family and style must not exceed 31 characters."""
 
     def strip_ribbi(x):
         ribbi_re = " (" + "|".join(RIBBI_STYLE_NAMES) + ")$"
         return re.sub(ribbi_re, "", x)
+
+    # constants for name length limits
+    NAME_LENGTH_LIMIT = 31
+    PSNAME_LENGTH_LIMIT = 27
+    ELIDABLE_FLAG = 2
 
     checks = [
         [
             FAIL,
-            NameID.FULL_FONT_NAME,
-            32,
-            (
-                "with the dropdown menu in old versions of Microsoft Word"
-                " as well as shaping issues for some accented letters in"
-                " Microsoft Word on Windows 10 and 11"
-            ),
+            NameID.FONT_FAMILY_NAME,
+            NAME_LENGTH_LIMIT,
+            "cause a fallback font to appear for some accented letters, as well"
+            " as in some scripts such as Thai, in"
+            " Microsoft Word on Windows 10 and 11. It can also lead to names"
+            " which are truncated in the Microsoft Word font menu.\n\n",
             strip_ribbi,
         ],
-        [
-            WARN,
-            NameID.POSTSCRIPT_NAME,
-            27,
-            "with PostScript printers, especially on Mac platforms",
-            lambda x: x,
-        ],
     ]
     for loglevel, nameid, maxlen, reason, transform in checks:
         for the_name in get_name_entry_strings(ttFont, nameid):
@@ -57,36 +69,92 @@ def strip_ribbi(x):
                     f" cause problems {reason}.",
                 )
 
-    # name ID 1/16 + fvar instance name > 32 : FAIL : problems with Windows
-    if "fvar" in ttFont:
+    # check variable font name lengths
+    if "fvar" in ttFont and "STAT" in ttFont:
+        # Get the family name from the name table (prefer ID 16)
+        if ttFont["name"].getName(NameID.TYPOGRAPHIC_FAMILY_NAME, 3, 1, 0x409):
+            family_name = (
+                ttFont["name"]
+                .getName(NameID.TYPOGRAPHIC_FAMILY_NAME, 3, 1, 0x409)
+                .toUnicode()
+            )
+            family_name_id = NameID.TYPOGRAPHIC_FAMILY_NAME
+        else:
+            family_name = (
+                ttFont["name"].getName(NameID.FONT_FAMILY_NAME, 3, 1, 0x409).toUnicode()
+            )
+            family_name_id = NameID.FONT_FAMILY_NAME
+
+        styles_per_axis = defaultdict(list)
+        for value in ttFont["STAT"].table.AxisValueArray.AxisValue:
+            # if the value is marked as elidable, don’t count it
+            if value.Flags & ELIDABLE_FLAG:
+                continue
+            # skip "Regular" and "Italic" style names, which do not count towards MS Word limit
+            if ttFont["name"].getName(value.ValueNameID, 3, 1, 0x409).toUnicode() in [
+                "Regular",
+                "Italic",
+            ]:
+                continue
+            # otherwise, get the STAT style particle name and add it to the list
+            styles_per_axis[value.AxisIndex].append(
+                ttFont["name"].getName(value.ValueNameID, 3, 1, 0x409).toUnicode()
+            )
+
+        # make list of combined family & STAT style names
+        names = [
+            f'{family_name} {" ".join(combination)}'
+            for combination in product(*styles_per_axis.values())
+        ]
+
+        for name in names:
+            if len(name) > NAME_LENGTH_LIMIT:
+                stat_style_combination = name.replace(f"{family_name} ", "")
+                yield FAIL, Message(
+                    "familyname-plus-stat-entries-too-long",
+                    f"Name ID {family_name_id} '{family_name}' plus"
+                    f" STAT table style combination '{stat_style_combination}'"
+                    f" exceeds 31 characters (the combination is {len(name)} characters).\n\n"
+                    f" This has been found to"
+                    f" cause a fallback font to appear for some accented letters, as well"
+                    f" as in some scripts such as Thai, in"
+                    f" Microsoft Word on Windows 10 and 11. It can also lead to names"
+                    f" which are truncated in the Microsoft Word font menu.\n\n",
+                )
+
+    # if STAT not in font, assume that "fvar" instance names are used
+    if "fvar" in ttFont and "STAT" not in ttFont:
         for instance in ttFont["fvar"].instances:
             for instance_name in get_name_entry_strings(
                 ttFont, instance.subfamilyNameID
             ):
                 typo_family_names = {
                     (r.platformID, r.platEncID, r.langID): r
                     for r in ttFont["name"].names
-                    if r.nameID == 16
+                    if r.nameID == NameID.TYPOGRAPHIC_FAMILY_NAME
                 }
                 family_names = {
                     (r.platformID, r.platEncID, r.langID): r
                     for r in ttFont["name"].names
-                    if r.nameID == 1
+                    if r.nameID == NameID.FONT_FAMILY_NAME
                 }
                 for platform in family_names:
                     if platform in typo_family_names:
                         family_name = typo_family_names[platform].toUnicode()
                     else:
                         family_name = family_names[platform].toUnicode()
                     full_instance_name = family_name + " " + instance_name
-                    if len(full_instance_name) > 32:
+                    if len(full_instance_name) > NAME_LENGTH_LIMIT:
                         yield FAIL, Message(
-                            "instance-too-long",
+                            "fvar-instance-too-long",
                             f"Variable font instance name '{full_instance_name}'"
                             f" formed by space-separated concatenation of"
                             f" font family name (nameID {NameID.FONT_FAMILY_NAME})"
                             f" and instance subfamily nameID {instance.subfamilyNameID}"
-                            f" exceeds 32 characters.\n\n"
-                            f"This has been found to cause shaping issues for some"
-                            f" accented letters in Microsoft Word on Windows 10 and 11.",
+                            f" exceeds {NAME_LENGTH_LIMIT} characters.\n\n"
+                            f" This has been found to"
+                            f" cause a fallback font to appear for some accented letters, as well"
+                            f" as in some scripts such as Thai, in"
+                            f" Microsoft Word on Windows 10 and 11. It can also lead to names"
+                            f" which are truncated in the Microsoft Word font menu.\n\n",
                         )

tests/test_checks_name.py

@@ -216,8 +216,8 @@ def test_check_name_char_restrictions(check):
 def test_check_name_family_and_style_max_length(check):
     """Name table entries should not be too long."""
 
-    # Our reference Cabin Regular is known to be good
-    ttFont = TTFont(TEST_FILE("cabinvf/Cabin[wdth,wght].ttf"))
+    # Our static reference Merriweather Regular is known to be good
+    ttFont = TTFont(TEST_FILE("merriweather/Merriweather-Regular.ttf"))
 
     # So it must PASS the check:
     assert_PASS(check(ttFont), "with a good font...")
@@ -227,8 +227,8 @@ def test_check_name_family_and_style_max_length(check):
     # a discussion of the requirements
 
     for index, name in enumerate(ttFont["name"].names):
-        if name.nameID == NameID.FULL_FONT_NAME:
-            # This has 33 chars, while the max currently allowed is 32
+        if name.nameID == NameID.FONT_FAMILY_NAME:
+            # This has 33 chars, while the max currently allowed is 31
             bad = "An Absurdly Long Family Name Font"
             assert len(bad) == 33
             ttFont["name"].names[index].string = bad.encode(name.getEncoding())
@@ -238,12 +238,45 @@ def test_check_name_family_and_style_max_length(check):
             ttFont["name"].names[index].string = bad.encode(name.getEncoding())
 
     results = check(ttFont)
-    assert_results_contain(results, FAIL, "nameid4-too-long", "with a bad font...")
+    assert_results_contain(results, FAIL, "nameid1-too-long", "with a bad font...")
     assert_results_contain(results, WARN, "nameid6-too-long", "with a bad font...")
 
-    # Restore the original VF
+    # Now get a variable font reference
     ttFont = TTFont(TEST_FILE("cabinvf/Cabin[wdth,wght].ttf"))
 
+    # set long STAT style name, then check for a FAIL
+    for index, name in enumerate(ttFont["name"].names):
+        # verify that "Cabin" length, plus 27 chars, exceeds limit of 31
+        if name.nameID == NameID.TYPOGRAPHIC_FAMILY_NAME:
+            assert len(ttFont["name"].names[index].string) + 27 > 31
+
+    # find the first instance nameID from the STAT table, then make it long
+    # and check for a FAIL
+    for value in ttFont["STAT"].table.AxisValueArray.AxisValue:
+        # if the value is marked as elidable, don’t count it
+        if value.Flags & 2:
+            continue
+        # otherwise, get the STAT style name entry and make it long
+        bad = "Absurdly Long Name Particle"
+        assert len(bad) == 27
+
+        # edit the name table entry for the STAT style name
+        for index, name in enumerate(ttFont["name"].names):
+            if name.nameID == value.ValueNameID:
+                ttFont["name"].names[index].string = bad.encode(name.getEncoding())
+
+        # stop after the first applicable STAT value
+        break
+
+    results = check(ttFont)
+    assert_results_contain(
+        results, FAIL, "familyname-plus-stat-entries-too-long", "with a bad font..."
+    )
+
+    # remove STAT table, then check for a FAIL if the STAT table is not present
+    ttFont = TTFont(TEST_FILE("cabinvf/Cabin[wdth,wght].ttf"))
+    del ttFont["STAT"]
+
     # ...and break the check again with a bad fvar instance name:
     nameid_to_break = ttFont["fvar"].instances[0].subfamilyNameID
     for index, name in enumerate(ttFont["name"].names):
@@ -254,8 +287,10 @@ def test_check_name_family_and_style_max_length(check):
             assert len(bad) == 28
             ttFont["name"].names[index].string = bad.encode(name.getEncoding())
             break
+
+    results = check(ttFont)
     assert_results_contain(
-        check(ttFont), FAIL, "instance-too-long", "with a bad font..."
+        results, FAIL, "fvar-instance-too-long", "with a bad font..."
     )