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Rewrite font height calculation #1060

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merged 4 commits into from
Jan 22, 2023
Merged

Rewrite font height calculation #1060

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5cc911e
font-patcher: Use format for output
Finii Jan 20, 2023
ce6c161
font-patcher: Handle -l option in all metrics
Finii Jan 20, 2023
04c682f
font-patcher: Rewrite font height calculation
Finii Jan 20, 2023
6210087
font-patcher: Use WIN metrics in all conflicting cases
Finii Jan 22, 2023
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118 changes: 74 additions & 44 deletions font-patcher
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
from __future__ import absolute_import, print_function, unicode_literals

# Change the script version when you edit this script:
script_version = "3.4.5"
script_version = "3.5.0"

version = "2.3.0"
projectName = "Nerd Fonts"
Expand Down Expand Up @@ -271,8 +271,8 @@ class font_patcher:
self.assert_monospace()
self.remove_ligatures()
self.setup_patch_set()
self.setup_line_dimensions()
self.get_sourcefont_dimensions()
self.improve_line_dimensions()
self.sourceFont.encoding = 'UnicodeFull' # Update the font encoding to ensure that the Unicode glyphs are available
self.onlybitmaps = self.sourceFont.onlybitmaps # Fetch this property before adding outlines. NOTE self.onlybitmaps initialized and never used

Expand Down Expand Up @@ -902,23 +902,16 @@ class font_patcher:
{'Enabled': self.args.custom, 'Name': "Custom", 'Filename': self.args.custom, 'Exact': True, 'SymStart': 0x0000, 'SymEnd': 0x0000, 'SrcStart': None, 'ScaleRules': None, 'Attributes': CUSTOM_ATTR}
]

def setup_line_dimensions(self):
# win_ascent and win_descent are used to set the line height for windows fonts.
# hhead_ascent and hhead_descent are used to set the line height for mac fonts.
#
def improve_line_dimensions(self):
# Make the total line size even. This seems to make the powerline separators
# center more evenly.
if self.args.adjustLineHeight:
if (self.sourceFont.os2_winascent + self.sourceFont.os2_windescent) % 2 != 0:
# All three are equal before due to get_sourcefont_dimensions()
self.sourceFont.hhea_ascent += 1
self.sourceFont.os2_typoascent += 1
self.sourceFont.os2_winascent += 1

# Make the line size identical for windows and mac
# ! This is broken because hhea* is changed but os2_typo* is not
# ! On the other hand we need intact (i.e. original) typo values
# ! in get_sourcefont_dimensions() @TODO FIXME
self.sourceFont.hhea_ascent = self.sourceFont.os2_winascent
self.sourceFont.hhea_descent = -self.sourceFont.os2_windescent

def get_essential_references(self):
"""Find glyphs that are needed for the basic glyphs"""
# Sometimes basic glyphs are constructed from multiple other glyphs.
Expand All @@ -932,18 +925,46 @@ class font_patcher:
self.essential.add(self.sourceFont[r[0]].unicode)

def get_sourcefont_dimensions(self):
# Initial font dimensions
self.font_dim = {
'xmin' : 0,
'ymin' : -self.sourceFont.os2_windescent,
'xmax' : 0,
'ymax' : self.sourceFont.os2_winascent,
'width' : 0,
'height': 0,
}
if self.sourceFont.os2_use_typo_metrics:
self.font_dim['ymin'] = self.sourceFont.os2_typodescent
self.font_dim['ymax'] = self.sourceFont.os2_typoascent
""" This gets the font dimensions (cell width and height), and makes them equal on all platforms """
# Step 1
# There are three ways to discribe the baseline to baseline distance
# (a.k.a. line spacing) of a font. That is all a kuddelmuddel
# and we try to sort this out here
# See also https://glyphsapp.com/learn/vertical-metrics
# See also https://github.com/source-foundry/font-line
hhea_height = self.sourceFont.hhea_ascent - self.sourceFont.hhea_descent
typo_height = self.sourceFont.os2_typoascent - self.sourceFont.os2_typodescent
win_height = self.sourceFont.os2_winascent + self.sourceFont.os2_windescent
win_gap = max(0, self.sourceFont.hhea_linegap - win_height + hhea_height)
hhea_btb = hhea_height + self.sourceFont.hhea_linegap
typo_btb = typo_height + self.sourceFont.os2_typolinegap
win_btb = win_height + win_gap
use_typo = self.sourceFont.os2_use_typo_metrics != 0

# We use either TYPO (1) or WIN (2) and compare with HHEA
# and use HHEA (0) if the fonts seems broken
our_btb = typo_btb if use_typo else win_btb
if our_btb == hhea_btb:
metrics = 1 if use_typo else 2 # conforming font
else:
# We trust the WIN metric more, see experiments in #1056
print("{}: WARNING Font vertical metrics inconsistent (HHEA {} / TYPO {} / WIN {}), using WIN".format(projectName, hhea_btb, typo_btb, win_btb))
our_btb = win_btb
metrics = 1

# print("FINI hhea {} typo {} win {} use {} {} {}".format(hhea_btb, typo_btb, win_btb, use_typo, our_btb != hhea_btb, self.sourceFont.fontname))

self.font_dim = {'xmin': 0, 'ymin': 0, 'xmax': 0, 'ymax': 0, 'width' : 0, 'height': 0}

if metrics == 0:
self.font_dim['ymin'] = self.sourceFont.hhea_descent + half_gap(self.sourceFont.hhea_linegap, False)
self.font_dim['ymax'] = self.sourceFont.hhea_ascent + half_gap(self.sourceFont.hhea_linegap, True)
elif metrics == 1:
self.font_dim['ymin'] = self.sourceFont.os2_typodescent + half_gap(self.sourceFont.os2_typolinegap, False)
self.font_dim['ymax'] = self.sourceFont.os2_typoascent + half_gap(self.sourceFont.os2_typolinegap, True)
else:
self.font_dim['ymin'] = -self.sourceFont.os2_windescent + half_gap(win_gap, False)
self.font_dim['ymax'] = self.sourceFont.os2_winascent + half_gap(win_gap, True)

# Calculate font height
self.font_dim['height'] = -self.font_dim['ymin'] + self.font_dim['ymax']
Expand All @@ -958,26 +979,21 @@ class font_patcher:
'width' : self.sourceFont.em,
'height': self.sourceFont.descent + self.sourceFont.ascent,
}
elif self.font_dim['height'] < 0:
sys.exit("{}: Can not detect sane font height".format(projectName))

# Line gap add extra space on the bottom of the line which
# doesn't allow the powerline glyphs to fill the entire line.
# Put half of the gap into the 'cell', each top and bottom
gap = max(self.sourceFont.hhea_linegap, self.sourceFont.os2_typolinegap) # TODO probably wrong
if self.sourceFont.os2_use_typo_metrics:
gap = self.sourceFont.os2_typolinegap
self.sourceFont.hhea_linegap = 0
# Make all metrics equal
self.sourceFont.os2_typolinegap = 0
if gap > 0:
gap_top = int(gap / 2)
gap_bottom = gap - gap_top
print("Redistributing line gap of {} ({} top and {} bottom)".format(gap, gap_top, gap_bottom))
self.font_dim['ymin'] -= gap_bottom
self.font_dim['ymax'] += gap_top
self.font_dim['height'] = -self.font_dim['ymin'] + self.font_dim['ymax']
self.sourceFont.os2_typoascent = self.sourceFont.os2_typoascent + gap_top
self.sourceFont.os2_typodescent = self.sourceFont.os2_typodescent - gap_bottom
# TODO Check what to do with win and hhea values

self.sourceFont.os2_typoascent = self.font_dim['ymax']
self.sourceFont.os2_typodescent = self.font_dim['ymin']
self.sourceFont.os2_winascent = self.sourceFont.os2_typoascent
self.sourceFont.os2_windescent = -self.sourceFont.os2_typodescent
self.sourceFont.hhea_ascent = self.sourceFont.os2_typoascent
self.sourceFont.hhea_descent = self.sourceFont.os2_typodescent
self.sourceFont.hhea_linegap = self.sourceFont.os2_typolinegap
self.sourceFont.os2_use_typo_metrics = 1

# Step 2
# Find the biggest char width and advance width
# 0x00-0x17f is the Latin Extended-A range
warned = self.args.quiet or self.args.nonmono # Do not warn if quiet or proportional target
Expand Down Expand Up @@ -1387,6 +1403,20 @@ class font_patcher:
return None


def half_gap(gap, top):
""" Divides integer value into two new integers """
# Line gap add extra space on the bottom of the line which
# doesn't allow the powerline glyphs to fill the entire line.
# Put half of the gap into the 'cell', each top and bottom
if gap <= 0:
return 0
gap_top = int(gap / 2)
gap_bottom = gap - gap_top
if top:
print("Redistributing line gap of {} ({} top and {} bottom)".format(gap, gap_top, gap_bottom))
return gap_top
return gap_bottom

def replace_font_name(font_name, replacement_dict):
""" Replaces all keys with vals from replacement_dict in font_name. """
for key, val in replacement_dict.items():
Expand Down Expand Up @@ -1566,7 +1596,7 @@ def setup_arguments():
args = parser.parse_args()

if args.makegroups and not FontnameParserOK:
sys.exit(projectName + ": FontnameParser module missing (bin/scripts/name_parser/Fontname*), can not --makegroups".format(projectName))
sys.exit("{}: FontnameParser module missing (bin/scripts/name_parser/Fontname*), can not --makegroups".format(projectName))

# if you add a new font, set it to True here inside the if condition
if args.complete:
Expand Down