Fix Pierre's issue in Asana by copying metrics

Metrics are now copied from the monospace font into the newly created
font. This may not be the cleanest solution, but it ensures that the
monospacified font does not cause the line height to change. A manual
fix for Asana Math (the font this was originally reported for) is to
copy the Typographic OS/2 metrics into the HHEA metrics. Following
FontForge's recommendations (setting the HHEA metrics to the Win Ascent
and Descent) does not work (it makes the line height huge, which isn't
visible in Emacs 25+ (it ignores it following a bug report of a few
months ago, but it is visible and annoying in Emacs ≤ 24, and LibreOffice)

Makefile

@@ -3,7 +3,7 @@ CONSOLAS=/home/clement/.fonts/Microsoft/Consolas-Fixed.ttf
 
 XITS=/home/clement/.fonts/maths/xits-math.otf
 STIX=/home/clement/.fonts/maths/STIXMath-Regular.otf
-ASANA=/home/clement/.fonts/maths/Asana-Math-Tr.otf
+ASANA=/usr/share/fonts/truetype/asana-math/Asana-Math.otf
 SYMBOLA=/usr/share/fonts/truetype/ttf-ancient-scripts/Symbola605.ttf
 LATINMODERN=/home/clement/.fonts/maths/latinmodern-math.otf
 TEXGYRESCHOLA=/home/clement/.fonts/maths/texgyreschola-math.otf
@@ -19,13 +19,15 @@ ttf: monospacifier.py
 	./monospacifier.py \
 		--references ./sources/references/* \
 		--inputs ./sources/inputs/* \
-		--save-to ./fonts 2>&1 # --merge
+		--save-to ./fonts --copy-metrics # 2>&1 # --merge
 
 prepare:
 	echo "References"
+	rm ./sources/references/*
 	cp $(CONSOLAS)				./sources/references/Consolas.ttf
 	cp $(DEJAVU)				./sources/references/DejaVuSansMono.ttf
 	echo "Inputs"
+	rm ./sources/inputs/*
 	cp $(XITS)					./sources/inputs/XITSMath.otf
 	cp $(STIX)					./sources/inputs/STIXMath.otf
 	cp $(ASANA)					./sources/inputs/AsanaMath.otf

README.md

@@ -1,14 +1,10 @@
 # monospacifier.py
 
-A great way to increase the Unicode coverage of your favorite programming font.
+*A great way to increase the Unicode coverage of your favorite programming font.*
 
-![default vs monospacified](demo/symbola-loop.gif)
-
-## Details
+`monospacifier.py` adjusts every character of your favorite variable-width font to match a reference monospace font. The result is a good fallback font for characters not covered by the reference: the result is a font setup with good Unicode coverage, without breaking indentation.
 
-`monospacifier.py` adjusts every character of your favourite variable-pitch font to match the width of a reference monospace font. The result is an good fallback font to use for characters not covered by the reference font. The final combination (original monospace font + monospacified font as fallback) has good Unicode coverage, and does not break indentation.
-
-`monospacifier.py` includes multiple scaling algorithms. They are all pretty basic; this approach won't work well for anything but a fallback font. The most advanced one (demoed) sets the bounding box of each glyph appropriately, and slightly compresses wide characters to not spill too much from that bounding box. This preserves ratios (so ↦ and ⟼ are still distinguishable), while ensuring that each character occupies one "screen cell". Of course, two consecutive wide symbols will overlap.
+![default vs monospacified](demo/symbola-loop.gif)
 
 ## Pre-monospacified fonts (monospace fonts with good Unicode coverage)
 
@@ -56,3 +52,14 @@ Please submit recipes for other editors or operating systems!
 ![inconsistent fallbacks](demo/original.png) ![consistent fallback](demo/symbola.png) ![monospacified fallback](demo/symbola-monospacified.png)
 
 Monospace font + default fallbacks — Monospace font + original Symbola — Monospace font + Monospacified Symbola
+
+## Usage
+
+## Details
+
+* For help, run `./monospacifier.py -h`
+* For examples of use, see the Makefile (I use it to generate the files listed here)
+
+`monospacifier.py` includes multiple scaling algorithms (only one is exposed on the CLI). They are all rather basic, so don;t expect this program to create anything except a decent fallback font.
+
+The most advanced algorithm (demoed) sets the bounding box of each glyph appropriately (to match the most common width in the monospace font), and slightly compresses wide characters to reduce bleeding (wide glyphs will overlap with neighboring characters), while preserving distinctions between long and short glyphs (so ↦ and ⟼ are still distinguishable). Then (conditional on the `--copy-metrics` flag), `monospacifier.py` adjusts the metrics of the newly created font to match those of the reference (this fixes a number of issues that I don't understand well, in particular with `hhea_descent` and `os2_typodescent` metrics; if you have a clue about this, please do get in touch by opening an issue).

metrics

@@ -0,0 +1,122 @@
+# activeLayer
+# bitmapSizes
+# changed
+# cidcopyright
+# cidfamilyname
+# cidfontname
+# cidfullname
+# cidordering
+# cidregistry
+# cidsubfont
+# cidsubfontcnt
+# cidsubfontnames
+# cidsupplement
+# cidversion
+# cidweight
+# comment
+# copyright
+# cvt
+# default_base_filename
+# design_size
+# em
+# encoding
+# familyname
+# fondname
+# fontlog
+# fontname
+# fullname
+# gasp
+# gasp_version
+# gpos_lookups
+# gsub_lookups
+# guide
+# hasvmetrics
+# head_optimized_for_cleartype
+# horizontalBaseline
+# is_cid
+# is_quadratic
+# iscid
+# isnew
+# italicangle
+# layer_cnt
+# layers
+# loadState
+# macstyle
+# markClasses
+# math
+# maxp_FDEFs
+# maxp_IDEFs
+# maxp_maxStackDepth
+# maxp_storageCnt
+# maxp_twilightPtCnt
+# maxp_zones
+# multilayer
+# onlybitmaps
+# os2_codepages
+# os2_family_class
+# os2_fstype
+# os2_panose
+# os2_unicoderanges
+# os2_use_typo_metrics
+# os2_vendor
+# os2_version
+# os2_weight
+# os2_weight_width_slope_only
+# path
+# persistant
+# persistent
+# private
+# privateState
+# selection
+# sfd_path
+# sfntRevision
+# sfnt_names
+# size_feature
+# strokedfont
+# strokewidth
+# temporary
+# texparameters
+# uniqueid
+# upos
+# userdata
+# uwidth
+# version
+# verticalBaseline
+# vertical_origin
+# weight
+# woffMajor
+# woffMetadata
+# woffMinor
+# xuid
+ascent
+capHeight
+descent
+hhea_ascent
+hhea_ascent_add
+hhea_descent
+hhea_descent_add
+hhea_linegap
+os2_capheight
+os2_strikeypos
+os2_strikeysize
+os2_subxoff
+os2_subxsize
+os2_subyoff
+os2_subysize
+os2_supxoff
+os2_supxsize
+os2_supyoff
+os2_supysize
+os2_typoascent
+os2_typoascent_add
+os2_typodescent
+os2_typodescent_add
+os2_typolinegap
+os2_width
+os2_winascent
+os2_winascent_add
+os2_windescent
+os2_windescent_add
+os2_xheight
+vhea_linegap
+xHeight

monospacifier.py

@@ -115,6 +115,23 @@ def scale(self, glyph):
             GlyphScaler.set_width(glyph, self.cell_width)
 
 class FontScaler(object):
+    # METRICS = ["ascent", "capHeight", "descent", "hhea_ascent", "hhea_ascent_add",
+    #            "hhea_descent", "hhea_descent_add", "hhea_linegap", "os2_capheight",
+    #            "os2_strikeypos", "os2_strikeysize", "os2_subxoff", "os2_subxsize",
+    #            "os2_subyoff", "os2_subysize", "os2_supxoff", "os2_supxsize", "os2_supyoff",
+    #            "os2_supysize", "os2_typoascent", "os2_typoascent_add", "os2_typodescent",
+    #            "os2_typodescent_add", "os2_typolinegap", "os2_width", "os2_winascent",
+    #            "os2_winascent_add", "os2_windescent", "os2_windescent_add", "os2_xheight",
+    #            "vhea_linegap", "xHeight"]
+    METRICS = ["ascent", "descent", "hhea_ascent", "hhea_ascent_add",
+               "hhea_descent", "hhea_descent_add", "hhea_linegap", "os2_capheight",
+               "os2_strikeypos", "os2_strikeysize", "os2_subxoff", "os2_subxsize",
+               "os2_subyoff", "os2_subysize", "os2_supxoff", "os2_supxsize", "os2_supyoff",
+               "os2_supysize", "os2_typoascent", "os2_typoascent_add", "os2_typodescent",
+               "os2_typodescent_add", "os2_typolinegap", "os2_width", "os2_winascent",
+               "os2_winascent_add", "os2_windescent", "os2_windescent_add", "os2_xheight",
+               "vhea_linegap"]
+
     def __init__(self, path):
         self.font = fontforge.open(path) # Prints a few warnings
         self.renamed = False
@@ -155,6 +172,10 @@ def scale_glyphs(self, scaler):
             # counter[glyph.width] += 1
         # print("> Final width distribution: {}".format(", ".join(map(str, counter.most_common(10)))))
 
+    def copy_metrics(self, reference):
+        for metric in FontScaler.METRICS:
+            setattr(self.font, metric, getattr(reference, metric))
+
     def write(self, name):
         """
         Save font to NAME.
@@ -174,7 +195,7 @@ def plot_widths(glyphs):
 def fname(path):
     return os.path.splitext(os.path.basename(path))[0]
 
-def make_monospace(reference, fallback, gscaler, save_to):
+def make_monospace(reference, fallback, gscaler, save_to, copy_metrics):
     fontname = "{}_monospacified_for_{}".format(cleanup_font_name(fallback.fontname), cleanup_font_name(reference.fontname))
     familyname = "{} monospacified for {}".format(cleanup_font_name(fallback.familyname), cleanup_font_name(reference.familyname))
     fullname = "{} monospacified for {}".format(cleanup_font_name(fallback.fullname), cleanup_font_name(reference.fullname))
@@ -189,6 +210,8 @@ def make_monospace(reference, fallback, gscaler, save_to):
 
     fscaler.font.em = reference.em # Adjust em size (number of internal units per em)
     fscaler.scale_glyphs(gscaler)
+    if copy_metrics:
+        fscaler.copy_metrics(reference)
     fscaler.write(destination)
 
     return destination
@@ -228,9 +251,11 @@ def parse_arguments():
                         help="Where to save the newly generated monospace fonts. Defaults to current directory.")
     parser.add_argument('--merge', action='store_const', const=True, default=False,
                         help="Whether to create copies of the reference font, extended with monospacified glyphs of the inputs.")
+    parser.add_argument('--copy-metrics', action='store_const', const=True, default=False,
+                        help="Whether to apply the metrics of the reference font to the new font.")
     return parser.parse_args()
 
-def process_fonts(ref_paths, fnt_paths, save_to, merge):
+def process_fonts(ref_paths, fnt_paths, save_to, merge, copy_metrics):
     for ref in ref_paths:
         reference = fontforge.open(ref)
         ref_width = FontScaler.most_common_width(reference)
@@ -239,7 +264,7 @@ def process_fonts(ref_paths, fnt_paths, save_to, merge):
             fallback = fontforge.open(fnt)
             print(">>> - Monospacifying {}".format(fallback.familyname))
             gscaler = StretchingGlyphScaler(ref_width, FontScaler.average_width(fallback))
-            path = make_monospace(reference, fallback, gscaler, save_to)
+            path = make_monospace(reference, fallback, gscaler, save_to, copy_metrics)
             if merge:
                 monospacified = fontforge.open(path)
                 print(">>> - Merging with {}".format(monospacified.familyname))
@@ -250,7 +275,7 @@ def main():
     args = parse_arguments()
     # del args.inputs[1:]
     # del args.references[1:]
-    results = list(process_fonts(args.references, args.inputs, args.save_to, args.merge))
+    results = list(process_fonts(args.references, args.inputs, args.save_to, args.merge, args.copy_metrics))
 
     tabdata = {}
     for ref, fnt, ttf in results: