Ubuntu: Fix wrong Condensed classification

src/unpatched-fonts/Ubuntu/Condensed/make_condensed.py

@@ -0,0 +1,149 @@
+#!/usr/bin/env python
+# coding=utf8
+# Nerd Fonts Version: 3.0.0
+
+import sys
+
+class TableHEADWriter:
+    """ Access to the HEAD table without external dependencies """
+    def getlong(self, pos = None):
+        """ Get four bytes from the font file as integer number """
+        if pos:
+            self.goto(pos)
+        return (ord(self.f.read(1)) << 24) + (ord(self.f.read(1)) << 16) + (ord(self.f.read(1)) << 8) + ord(self.f.read(1))
+
+    def getshort(self, pos = None):
+        """ Get two bytes from the font file as integer number """
+        if pos:
+            self.goto(pos)
+        return (ord(self.f.read(1)) << 8) + ord(self.f.read(1))
+
+    def putlong(self, num, pos = None):
+        """ Put number as four bytes into font file """
+        if pos:
+            self.goto(pos)
+        self.f.write(bytearray([(num >> 24) & 0xFF, (num >> 16) & 0xFF ,(num >> 8) & 0xFF, num & 0xFF]))
+        self.modified = True
+
+    def putshort(self, num, pos = None):
+        """ Put number as two bytes into font file """
+        if pos:
+            self.goto(pos)
+        self.f.write(bytearray([(num >> 8) & 0xFF, num & 0xFF]))
+        self.modified = True
+
+    def calc_checksum(self, start, end, checksum = 0):
+        """ Calculate a font table checksum, optionally ignoring another embedded checksum value (for table 'head') """
+        self.f.seek(start)
+        for i in range(start, end - 4, 4):
+            checksum += self.getlong()
+            checksum &= 0xFFFFFFFF
+        i += 4
+        extra = 0
+        for j in range(4):
+            extra = extra << 8
+            if i + j <= end:
+                extra += ord(self.f.read(1))
+        checksum = (checksum + extra) & 0xFFFFFFFF
+        return checksum
+
+    def find_table(self, tablenames, idx):
+        """ Search all tables for one of the tables in tablenames and store its metadata """
+        # Use font with index idx if this is a font collection file
+        self.f.seek(0, 0)
+        tag = self.f.read(4)
+        if tag == b'ttcf':
+            self.f.seek(2*2, 1)
+            self.num_fonts = self.getlong()
+            if (idx >= self.num_fonts):
+                raise Exception('Trying to access subfont index {} but have only {} fonts'.format(idx, num_fonts))
+            for _ in range(idx + 1):
+                offset = self.getlong()
+            self.f.seek(offset, 0)
+        elif idx != 0:
+            raise Exception('Trying to access subfont but file is no collection')
+        else:
+            self.f.seek(0, 0)
+            self.num_fonts = 1
+
+        self.f.seek(4, 1)
+        numtables = self.getshort()
+        self.f.seek(3*2, 1)
+
+        for i in range(numtables):
+            tab_name = self.f.read(4)
+            self.tab_check_offset = self.f.tell()
+            self.tab_check = self.getlong()
+            self.tab_offset = self.getlong()
+            self.tab_length = self.getlong()
+            if tab_name in tablenames:
+                return True
+        return False
+
+    def find_head_table(self, idx):
+        """ Search all tables for the HEAD table and store its metadata """
+        # Use font with index idx if this is a font collection file
+        found = self.find_table([ b'head' ], idx)
+        if not found:
+            raise Exception('No HEAD table found in font idx {}'.format(idx))
+
+
+    def goto(self, where):
+        """ Go to a named location in the file or to the specified index """
+        if isinstance(where, str):
+            positions = {'checksumAdjustment': 2+2+4,
+                         'flags': 2+2+4+4+4,
+                         'lowestRecPPEM': 2+2+4+4+4+2+2+8+8+2+2+2+2+2,
+                         'avgWidth': 2,
+                         'widthClass': 2+2+2,
+                }
+            where = self.tab_offset + positions[where]
+        self.f.seek(where)
+
+
+    def calc_full_checksum(self, check = False):
+        """ Calculate the whole file's checksum """
+        self.f.seek(0, 2)
+        self.end = self.f.tell()
+        full_check = self.calc_checksum(0, self.end, (-self.checksum_adj) & 0xFFFFFFFF)
+        if check and (0xB1B0AFBA - full_check) & 0xFFFFFFFF != self.checksum_adj:
+            sys.exit("Checksum of whole font is bad")
+        return full_check
+
+    def calc_table_checksum(self, check = False):
+        tab_check_new = self.calc_checksum(self.tab_offset, self.tab_offset + self.tab_length - 1, (-self.checksum_adj) & 0xFFFFFFFF)
+        if check and tab_check_new != self.tab_check:
+            sys.exit("Checksum of 'head' in font is bad")
+        return tab_check_new
+
+    def reset_table_checksum(self):
+        new_check = self.calc_table_checksum()
+        self.putlong(new_check, self.tab_check_offset)
+
+    def reset_full_checksum(self):
+        new_adj = (0xB1B0AFBA - self.calc_full_checksum()) & 0xFFFFFFFF
+        self.putlong(new_adj, 'checksumAdjustment')
+
+    def close(self):
+        self.f.close()
+
+
+    def __init__(self, filename):
+        self.modified = False
+        self.f = open(filename, 'r+b')
+
+        self.find_head_table(0)
+
+        self.flags = self.getshort('flags')
+        self.lowppem = self.getshort('lowestRecPPEM')
+        self.checksum_adj = self.getlong('checksumAdjustment')
+
+
+print('Tweaking {}'.format(sys.argv[1]))
+font = TableHEADWriter(sys.argv[1])
+font.find_table([b'OS/2'], 0)
+width = font.getshort('widthClass')
+font.putshort(3, 'widthClass') # 3 == Condensed
+font.reset_table_checksum()
+font.reset_full_checksum()
+font.close()

src/unpatched-fonts/Ubuntu/README.md

@@ -14,3 +14,10 @@ you are expressly encouraged to experiment, modify, share and improve.
 http://font.ubuntu.com/
 
 Version: 0.83
+
+## Preprocessed Source Font
+
+For the _Ubuntu Condensed_ font Nerd Fonts corrected the `OS/2` `usWidthClass` to
+Condensed (3) by direct patching.
+
+The script used is in the `Condensed/` directory.