new check: com.google.fonts/check/STAT/axis_order

INFO-level check to gather stats on usage of the STAT table AxisOrdering field.
May be updated in the future to enforce some ordering scheme yet to be defined.
(issue fonttools#3049)

CHANGELOG.md

@@ -8,6 +8,7 @@ A more detailed list of changes is available in the corresponding milestones for
   - Now Travis is configured to use pinned versions of dependencies as described on requirements.txt (issue #3058)
 
 ### New checks
+  - **[com.google.fonts/check/STAT/axis_order]:** INFO-level check to gather stats on usage of the STAT table AxisOrdering field. May be updated in the future to enforce some ordering scheme yet to be defined. (issue #3049)
   - **[com.google.fonts/check/metadata/consistent_axis_enumeration]:** Validate VF axes on the 'fvar' table match the ones declared on METADATA.pb (issue #3051)
   - **[com.google.fonts/check/metadata/gf-axisregistry_valid_tags]:** VF axis tags are registered on GF Axis Registry (issue #3010)
   - **[com.google.fonts/check/metadata/gf-axisregistry_bounds]:** VF axes have ranges compliant to the bounds specified on the GF Axis Registry (issue #3022)

Lib/fontbakery/profiles/googlefonts.py

@@ -151,7 +151,8 @@
     'com.google.fonts/check/varfont_duplicate_instance_names',
     'com.google.fonts/check/varfont/consistent_axes',
     'com.google.fonts/check/varfont/unsupported_axes',
-    'com.google.fonts/check/STAT/gf-axisregistry'
+    'com.google.fonts/check/STAT/gf-axisregistry',
+    'com.google.fonts/check/STAT/axis_order'
 ]
 
 GOOGLEFONTS_PROFILE_CHECKS = \
@@ -4887,6 +4888,52 @@ def com_google_fonts_check_metadata_consistent_axis_enumeration(family_metadata,
         yield PASS, "OK"
 
 
+@check(
+    id = 'com.google.fonts/check/STAT/axis_order',
+    rationale = """
+        This is (for now) a merely informative check to detect what's the axis ordering declared on the STAT table of fonts in the Google Fonts collection.
+
+        We may later update this to enforce some unified axis ordering scheme, yet to be determined.
+    """,
+    misc_metadata = {
+        'request': 'https://github.com/googlefonts/fontbakery/issues/3049'
+    }
+)
+def com_google_fonts_check_STAT_axis_order(fonts):
+    """ Check axis ordering on the STAT table. """
+    from collections import Counter
+    from fontTools.ttLib import TTFont
+
+    no_stat = 0
+    summary = []
+    for font in fonts:
+        try:
+            ttFont = TTFont(font)
+            if 'STAT' in ttFont:
+                order = {}
+                for axis in ttFont['STAT'].table.DesignAxisRecord.Axis:
+                    order[axis.AxisTag] = axis.AxisOrdering
+
+                summary.append('-'.join(sorted(order.keys(), key=order.get)))
+            else:
+                no_stat += 1
+                yield SKIP,\
+                      Message('missing-STAT',
+                             f"This font does not have a STAT table.")
+        except:
+            yield INFO, f"Something wrong with {font}"
+
+    report = "\n\t".join(map(str, Counter(summary).most_common()))
+    yield INFO,\
+          Message('summary',
+                  f"From a total of {len(fonts)} font files,"
+                  f" {no_stat} of them ({100.0*no_stat/len(fonts):.2f}%)"
+                  f" lack a STAT table.\n"
+                  f"\n"
+                  f"\tAnd these are the most common STAT axis orderings:\n"
+                  f"\t{report}")
+
+
 ###############################################################################
 
 def is_librebarcode(font):