Change vertical metrics to make Apple ATS work properly. New ascender value: 2728, new descender value: -680

Includes alternate fix to @thundernixon's PR #146
2019-03-30 17:00:54 -07:00 · 2019-03-30 17:00:54 -07:00 · 1dbc8fd053
commit 1dbc8fd053
parent e1d8712ecd
3 changed files with 1073 additions and 1239 deletions
--- a/misc/glyphs-scripts/fixup-vertical-metrics.py
+++ b/misc/glyphs-scripts/fixup-vertical-metrics.py
@ -0,0 +1,110 @@
+#MenuTitle: Fixup Vertical Metrics
+# -*- coding: utf-8 -*-
+
+font = Glyphs.font
+caps = set(font.classes['Uppercase'].code.strip().split(' '))
+lowercase = set(font.classes['Lowercase'].code.strip().split(' '))
+
+print(font)
+
+mainMaxDescent = 0
+mainMaxDescentGlyph = ""
+maxDescent = 0
+mainMaxAscent = 0
+mainMaxAscentGlyph = ""
+maxAscent = 0
+typoAscender = 0
+typoDescender = 0
+
+for master in font.masters:
+  ta = max(master.ascender, master.capHeight)
+  if typoAscender == 0:
+    typoAscender = ta
+  elif typoAscender != ta:
+    raise Error('ascender or capHeight varies with masters; vertical metrics must be same in all masters')
+
+  td = master.descender
+  if typoDescender == 0:
+    typoDescender = td
+  elif typoDescender != td:
+    raise Error('descender or capHeight varies with masters; vertical metrics must be same in all masters')
+
+  for glyph in font.glyphs:
+    if not glyph.export:
+      continue
+
+    layer = glyph.layers[master.id]
+
+    # get descender of current layer
+    descent = layer.bounds.origin.y
+    
+    # get ascender of current layer
+    ascent = layer.bounds.size.height + descent  
+
+    # if descent/ascent of current layer is greater than previous max descents/ascents, update the max descent/ascent
+    if descent <= maxDescent:
+      maxDescent = descent
+      maxDescentGlyph = glyph.name
+      
+    if ascent >= maxAscent:
+      maxAscent = ascent
+      maxAscentGlyph = glyph.name
+
+    # get descender of current layer
+    descent = layer.bounds.origin.y
+        
+    # get ascender of current layer (total height of layer, subtracting value of descender)
+    ascent = layer.bounds.size.height + descent
+
+    # get maximums of only letters in list vars, for typo and hhea values
+    if glyph.name in caps and ascent >= mainMaxAscent:
+      mainMaxAscent = ascent
+      mainMaxAscentGlyph = glyph.name
+
+    if glyph.name in lowercase and descent <= mainMaxDescent:
+      # if descent/ascent of current layer is greater than previous max descents/ascents, update the max descent/ascent
+      mainMaxDescent = descent
+      mainMaxDescentGlyph = glyph.name
+      
+
+# check values for sanity
+# print(maxDescentGlyph, maxDescent, maxAscentGlyph, maxAscent)
+
+# make lineGap so that the total of `ascent + descent + lineGap` equals 120% of UPM size
+# UPM = font.upm
+# totalSize = maxAscent + abs(maxDescent)
+# lineGap = int((UPM * 1.2)) - totalSize
+# print(UPM, UPM * 1.2, totalSize, lineGap)
+
+## use highest/lowest points to set custom parameters for winAscent and winDescent
+## following vertical metric schema from https://github.com/googlefonts/gf-docs/tree/master/VerticalMetrics
+
+font.customParameters["Use Typo Metrics"] = True
+
+# ascenderDelta = max(abs(typoAscender), abs(mainMaxAscent)) - min(abs(typoAscender), abs(mainMaxAscent))
+descenderDelta = max(typoDescender, mainMaxDescent) - min(typoDescender, mainMaxDescent)
+
+if descenderDelta == 0:
+  print('descenderDelta is zero -- no change')
+else:
+  print('descenderDelta:', descenderDelta)
+
+  for master in font.masters:
+
+    # Win Ascent/Descent = Font bbox yMax/yMin
+    master.customParameters["winAscent"] = maxAscent
+    master.customParameters["winDescent"] = abs(maxDescent)
+
+    # no/zero line gap
+    # if "typoLineGap" in master.customParameters:
+    #   del master.customParameters["typoLineGap"]
+    # if "hheaLineGap" in master.customParameters:
+    #   del master.customParameters["hheaLineGap"]
+    master.customParameters["typoLineGap"] = 0
+    master.customParameters["hheaLineGap"] = 0
+
+    master.customParameters["typoDescender"] = typoDescender - descenderDelta
+    master.customParameters["hheaDescender"] = typoDescender - descenderDelta
+
+    master.customParameters["typoAscender"] = typoAscender + descenderDelta
+    master.customParameters["hheaAscender"] = typoAscender + descenderDelta