Add remap_layout script (#826)

* Add remap layout script

* Install remap_layout script

* Sort --list-subcommands output

Lib/gftools/scripts/__init__.py

@@ -90,7 +90,7 @@ def main(args=None):
         mod = import_module(f".{module}", package)
         mod.main(args[2:])
     elif "--list-subcommands" in sys.argv:
-        print(' '.join(list(subcommands.keys())))
+        print(' '.join(list(sorted(subcommands.keys()))))
     else:
         # shows menu and help if no args
         print_menu()

Lib/gftools/scripts/remap_layout.py

@@ -0,0 +1,172 @@
+#!/usr/bin/env python3
+"""
+Rearrange the features in a font file: drop features
+or move lookups into another feature or language system.
+"""
+from argparse import ArgumentParser, RawTextHelpFormatter
+from fontTools.ttLib import TTFont
+import re
+import logging
+
+logging.basicConfig(level=logging.INFO)
+
+parser = ArgumentParser(description=__doc__)
+parser.add_argument("font", help="Font file")
+parser.add_argument("-o", help="Output font file")
+parser.add_argument(
+    "commands",
+    nargs="+",
+    help="""\
+Commands to rearrange the features in the font file.
+
+Features and lookups are specified like so:
+    <feature> = [script/][lang/]<feature>
+
+If lookup id is not given, then all lookups in the feature are affected.
+If script or lang are not given, then DFLT and dflt are assumed.
+(The script and lang tags do not need to be padded to four characters.)
+
+Commands may be:
+
+* `!<feature>` to drop a feature.
+* `<feature> -> <feature2>` to add the lookups to the end of feature2.
+* `<feature> => |<feature2>` to move the lookups to the start of feature2.
+* `<feature> -> <feature2>` to add the lookups to the end of feature2.
+* `<feature> => |<feature2>` to move the lookups to the start of feature2.
+""",
+)
+args = parser.parse_args()
+ttfont = TTFont(args.font)
+LAYOUT_TABLES = ["GSUB", "GPOS"]
+tables = [ttfont[table].table for table in LAYOUT_TABLES if table in ttfont]
+
+KEY_RE = r"(?:(\w+)/)?(?:(\w+)/)?(\w+)"
+
+
+def parse_key(key):
+    match = re.match(KEY_RE, key)
+    if match is None:
+        raise ValueError(f"Invalid feature or lookup: {key}")
+    script, lang, feature = match.groups()
+    script = (script or "DFLT").ljust(4)
+    lang = (lang or "dflt").ljust(4)
+    return script, lang, feature
+
+
+def find_langsys(table, script, lang):
+    tag = type(table).__name__
+    scripts = [
+        sr.Script for sr in table.ScriptList.ScriptRecord if sr.ScriptTag == script
+    ]
+    if not scripts:
+        logging.info(f"[{tag}] Script not found: {script}")
+        return
+    if lang == "dflt":
+        langsys = scripts[0].DefaultLangSys
+    else:
+        langsys = [
+            ls.LangSys for ls in scripts[0].LangSysRecord if ls.LangSysTag == lang
+        ]
+        if not langsys:
+            logging.info(f"[{tag}] Language system not found: {lang}")
+            return
+        langsys = langsys[0]
+    return langsys
+
+def delete_feature(table, script, lang, feature):
+    tag = type(table).__name__
+    langsys = find_langsys(table, script, lang)
+    featurelist = table.FeatureList.FeatureRecord
+    logging.info(f"[{tag}] Feature indices were: {langsys.FeatureIndex}")
+    langsys.FeatureIndex = [
+        i for i in langsys.FeatureIndex if featurelist[i].FeatureTag != feature
+    ]
+    logging.info(f"[{tag}] Feature indices are now: {langsys.FeatureIndex}")
+
+def delete_lookup(table, script, lang, feature, lookup):
+    tag = type(table).__name__
+    langsys = find_langsys(table, script, lang)
+    featurelist = table.FeatureList.FeatureRecord
+    done = False
+    for i in langsys.FeatureIndex:
+        if featurelist[i].FeatureTag != feature:
+            continue
+        lookups = featurelist[i].Feature.LookupListIndex
+        if lookup in lookups:
+            lookups.remove(lookup)
+            logging.info(f"[{tag}] Removed lookup {lookup} from {feature}")
+            done = True
+    if not done:
+        logging.info(f"[{tag}] Lookup {lookup} not found in {feature}")    
+
+def remap_lookups(table, src, dst, operation="copy", start=False):
+    tag = type(table).__name__
+    src_script, src_lang, src_feature = src
+    dst_script, dst_lang, dst_feature = dst
+    src_langsys = find_langsys(table, src_script, src_lang)
+    dst_langsys = find_langsys(table, dst_script, dst_lang)
+    if not src_langsys:
+        logging.error(f"[{tag}] Languagesystem {src_script}/{src_lang} not found")
+        return
+    if not dst_langsys:
+        logging.error(f"[{tag}] Languagesystem {dst_script}/{dst_lang} not found")
+        return
+    src_features = src_langsys.FeatureIndex
+    dst_features = dst_langsys.FeatureIndex
+    src_lookups = []
+    featurelist = table.FeatureList.FeatureRecord
+    for src_feature_index in src_features:
+        if featurelist[src_feature_index].FeatureTag == src_feature:
+            src_lookups.extend(featurelist[src_feature_index].Feature.LookupListIndex)
+            if operation == "move":
+                featurelist[src_feature_index].Feature.LookupListIndex = []
+    if not src_lookups:
+        logging.info(f"[{tag}] No lookups found")
+        return
+
+    for dst_feature_index in dst_features:
+        if featurelist[dst_feature_index].FeatureTag == dst_feature:
+            dst_feature = featurelist[dst_feature_index].Feature
+            if start:
+                dst_feature.LookupListIndex = src_lookups + dst_feature.LookupListIndex
+            else:
+                dst_feature.LookupListIndex.extend(src_lookups)
+            logging.info(f"[{tag}] {operation} lookups {src_lookups} to {featurelist[dst_feature_index].FeatureTag}")
+            return
+    logging.error(f"[{tag}] destination feature {dst_script}/{dst_lang}/{dst_feature} not found")
+
+
+for cmd in args.commands:
+    if cmd.startswith("!"):
+        script, lang, feature = parse_key(cmd[1:])
+        for table in tables:
+            delete_feature(table, script, lang, feature)
+        continue
+    src = re.match(KEY_RE, cmd)
+    if src is None:
+        raise ValueError(f"Could not parse source: {cmd}")
+    cmd = cmd[len(src.group(0)):]
+
+    remap = None
+    if re.match(r"^\s*->\s*", cmd):
+        remap = "copy"
+    elif re.match(r"^\s*=>\s*", cmd):
+        remap = "move"
+    else:
+        raise ValueError(f"Could not parse operation: {cmd}")
+    dst = re.sub(r"^\s*->\s*|\s*=>\s*", "", cmd).strip()
+
+    start = False
+    if dst.startswith("|"):
+        dst = dst[1:]
+        start = True
+    dst = re.match(KEY_RE, dst)
+    if dst is None:
+        raise ValueError(f"Could not parse destination: {cmd}")
+    for table in tables:
+        remap_lookups(
+            table, parse_key(src[0]), parse_key(dst[0]), operation=remap, start=start
+        )
+
+if args.o:
+    ttfont.save(args.o)

pyproject.toml

@@ -139,6 +139,7 @@ gftools-rangify = "gftools.scripts.rangify:main"
 gftools-rename-font = "gftools.scripts.rename_font:main"
 gftools-rename-glyphs = "gftools.scripts.rename_glyphs:main"
 gftools-remap-font = "gftools.scripts.remap_font:main"
+gftools-remap-layout = "gftools.scripts.remap_layout:main"
 gftools-sanity-check = "gftools.scripts.sanity_check:main"
 gftools-set-primary-script = "gftools.scripts.set_primary_script:main"
 gftools-space-check = "gftools.scripts.space_check:main"