Merge pull request #58 from source-foundry/cvar-removal-vf

Remove cvar tables from variable fonts

Author: chrissimpkins

Makefile

@@ -3,6 +3,11 @@ all: install
 black:
 	black lib/dehinter/*.py
 
+import-sort:
+	isort lib/dehinter/*.py
+
+format: import-sort black
+
 clean:
 	- rm dist/*.whl dist/*.tar.gz dist/*.zip
 

lib/dehinter/__main__.py

@@ -21,28 +21,30 @@
 from fontTools.ttLib import TTFont  # type: ignore
 
 from dehinter import __version__
-from dehinter.font import is_truetype_font
 from dehinter.font import (
+    has_cvar_table,
     has_cvt_table,
     has_fpgm_table,
-    has_gasp_table,
     has_hdmx_table,
     has_ltsh_table,
     has_prep_table,
     has_ttfa_table,
     has_vdmx_table,
-)
-from dehinter.font import (
+    is_truetype_font,
+    is_variable_font,
+    remove_cvar_table,
     remove_cvt_table,
     remove_fpgm_table,
+    remove_glyf_instructions,
     remove_hdmx_table,
     remove_ltsh_table,
     remove_prep_table,
     remove_ttfa_table,
     remove_vdmx_table,
-    remove_glyf_instructions,
+    update_gasp_table,
+    update_head_table_flags,
+    update_maxp_table,
 )
-from dehinter.font import update_gasp_table, update_head_table_flags, update_maxp_table
 from dehinter.paths import filepath_exists, get_default_out_path
 from dehinter.system import get_filesize
 
@@ -65,6 +67,7 @@ def run(argv: List[str]) -> None:
         "--version", action="version", version="dehinter v{}".format(__version__)
     )
     parser.add_argument("-o", "--out", help="out file path (dehinted font)")
+    parser.add_argument("--keep-cvar", help="keep cvar table", action="store_true")
     parser.add_argument("--keep-cvt", help="keep cvt table", action="store_true")
     parser.add_argument("--keep-fpgm", help="keep fpgm table", action="store_true")
     parser.add_argument("--keep-hdmx", help="keep hdmx table", action="store_true")
@@ -129,61 +132,85 @@ def run(argv: List[str]) -> None:
         )
         sys.exit(1)
 
+    if is_variable_font(tt) and not args.keep_cvar:
+        if has_cvar_table(tt):
+            remove_cvar_table(tt)
+            if not has_cvar_table(tt):
+                print("[-] Removed cvar table")
+            else:  # pragma: no cover
+                sys.stderr.write(
+                    f"[!] Error: failed to remove cvar table from font{os.linesep}"
+                )
+
     if not args.keep_cvt:
         if has_cvt_table(tt):
             remove_cvt_table(tt)
             if not has_cvt_table(tt):
                 print("[-] Removed cvt table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove cvt table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove cvt table from font{os.linesep}"
+                )
 
     if not args.keep_fpgm:
         if has_fpgm_table(tt):
             remove_fpgm_table(tt)
             if not has_fpgm_table(tt):
                 print("[-] Removed fpgm table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove fpgm table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove fpgm table from font{os.linesep}"
+                )
 
     if not args.keep_hdmx:
         if has_hdmx_table(tt):
             remove_hdmx_table(tt)
             if not has_hdmx_table(tt):
                 print("[-] Removed hdmx table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove hdmx table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove hdmx table from font{os.linesep}"
+                )
 
     if not args.keep_ltsh:
         if has_ltsh_table(tt):
             remove_ltsh_table(tt)
             if not has_ltsh_table(tt):
                 print("[-] Removed LTSH table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove LTSH table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove LTSH table from font{os.linesep}"
+                )
 
     if not args.keep_prep:
         if has_prep_table(tt):
             remove_prep_table(tt)
             if not has_prep_table(tt):
                 print("[-] Removed prep table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove prep table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove prep table from font{os.linesep}"
+                )
 
     if not args.keep_ttfa:
         if has_ttfa_table(tt):
             remove_ttfa_table(tt)
             if not has_ttfa_table(tt):
                 print("[-] Removed TTFA table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove TTFA table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove TTFA table from font{os.linesep}"
+                )
 
     if not args.keep_vdmx:
         if has_vdmx_table(tt):
             remove_vdmx_table(tt)
             if not has_vdmx_table(tt):
                 print("[-] Removed VDMX table")
             else:  # pragma: no cover
-                sys.stderr.write("[!] Error: failed to remove VDMX table from font")
+                sys.stderr.write(
+                    f"[!] Error: failed to remove VDMX table from font{os.linesep}"
+                )
 
     #  (2) Remove glyf table instruction set bytecode
     if not args.keep_glyf:
@@ -196,10 +223,9 @@ def run(argv: List[str]) -> None:
 
     #  (3) Edit gasp table
     if not args.keep_gasp:
-        if has_gasp_table(tt):
-            if update_gasp_table(tt):
-                gasp_string = pp.pformat(tt["gasp"].__dict__)
-                print(f"[Δ] New gasp table values:{os.linesep}    {gasp_string}")
+        if update_gasp_table(tt):
+            gasp_string = pp.pformat(tt["gasp"].__dict__)
+            print(f"[Δ] New gasp table values:{os.linesep}    {gasp_string}")
 
     #  (4) Edit maxp table
     if not args.keep_maxp:
@@ -224,9 +250,11 @@ def run(argv: List[str]) -> None:
 
     try:
         tt.save(outpath)
-        print("{os.linesep}[+] Saved dehinted font as '{outpath}'")
+        print(f"{os.linesep}[+] Saved dehinted font as '{outpath}'")
     except Exception as e:  # pragma: no cover
-        sys.stderr.write(f"[!] Error: Unable to save dehinted font file: {str(e)}")
+        sys.stderr.write(
+            f"[!] Error: Unable to save dehinted font file: {str(e)}{os.linesep}"
+        )
 
     # File size comparison
     # --------------------

lib/dehinter/font.py

@@ -16,12 +16,19 @@
 import os
 from typing import Union
 
-from dehinter.bitops import is_bit_k_set, clear_bit_k
+from fontTools import ttLib  # type: ignore
+
+from dehinter.bitops import clear_bit_k, is_bit_k_set
 
 
 # ========================================================
 # Utilities
 # ========================================================
+def has_cvar_table(tt) -> bool:
+    """Tests for the presence of a cvat table in a TrueType variable font."""
+    return "cvar" in tt
+
+
 def has_cvt_table(tt) -> bool:
     """Tests for the presence of a cvt table in a TrueType font."""
     return "cvt " in tt
@@ -72,9 +79,24 @@ def is_truetype_font(filepath: Union[bytes, str, "os.PathLike[str]"]) -> bool:
         return file_signature in (b"\x00\x01\x00\x00", b"\x74\x72\x75\x65")
 
 
+def is_variable_font(tt) -> bool:
+    """Tests for the presence of a fvar table to confirm that a file is
+    a variable font."""
+    return "fvar" in tt
+
+
 # ========================================================
 # OpenType table removal
 # ========================================================
+def remove_cvar_table(tt) -> None:
+    """Removes cvt table from a fontTools.ttLib.TTFont object"""
+    try:
+        del tt["cvar"]
+    except KeyError:
+        # do nothing if table is not present in the font
+        pass
+
+
 def remove_cvt_table(tt) -> None:
     """Removes cvt table from a fontTools.ttLib.TTFont object"""
     try:
@@ -163,6 +185,9 @@ def update_gasp_table(tt) -> bool:
     """Modifies the following gasp table fields:
     1) rangeMaxPPEM changed to 65535
     2) rangeGaspBehavior changed to 0x000a (symmetric grayscale, no gridfit)"""
+    if "gasp" not in tt:
+        tt["gasp"] = ttLib.newTable("gasp")
+        tt["gasp"].gaspRange = {}
     if tt["gasp"].gaspRange != {65535: 0x000A}:
         tt["gasp"].gaspRange = {65535: 0x000A}
         return True

tests/test_files/fonts/OpenSans-VF.ttf

@@ -2,16 +2,19 @@
 
 The fonts used in the testing of this project include the following:
 
-1. Roboto-Regular.ttf
-2. Roboto-Regular-dehinted.ttf (ttfautohint dehinted derivative of Roboto-Regular.ttf)
-3. NotoSans-Regular.ttf
-4. NotoSans-Regular-dehinted.ttf (ttfautohint dehinted derivative of NotoSans-Regular.ttf)
-5. Ubuntu-Regular.ttf
+1. OpenSans-VF.ttf
+2. Roboto-Regular.ttf
+3. Roboto-Regular-dehinted.ttf (ttfautohint dehinted derivative of Roboto-Regular.ttf)
+4. NotoSans-Regular.ttf
+5. NotoSans-Regular-dehinted.ttf (ttfautohint dehinted derivative of NotoSans-Regular.ttf)
+6. Ubuntu-Regular.ttf
+
+Open Sans is licensed under the [SIL Open Font License 1.1](https://github.com/googlefonts/opensans/blob/main/OFL.txt)
 
 Roboto is licensed under the [Apache License v2.0](https://github.com/google/roboto/blob/master/LICENSE).
 
 Noto Sans is licensed under the [SIL Open Font License 1.1](https://github.com/googlefonts/noto-fonts/blob/master/LICENSE).
 
 Ubuntu is licensed under the [Ubuntu Font License](https://ubuntu.com/legal/font-licence).
 
-You may find the full text of these licenses in the `licenses` subdirectory.
+You may find the full text of these licenses in the `licenses` subdirectory.

tests/test_files/fonts/README.md

@@ -0,0 +1,88 @@
+Copyright 2020 The Open Sans Project Authors (https://github.com/googlefonts/opensans)
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to
+provide a free and open framework in which fonts may be shared and
+improved in partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply to
+any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software
+components as distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to,
+deleting, or substituting -- in part or in whole -- any of the
+components of the Original Version, by changing formats or by porting
+the Font Software to a new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed,
+modify, redistribute, and sell modified and unmodified copies of the
+Font Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components, in
+Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the
+corresponding Copyright Holder. This restriction only applies to the
+primary font name as presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created using
+the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.