start cff

fontland/fontland/subset.rkt

@@ -12,11 +12,24 @@
          xenomorph
          racket/dict)
 
-(provide subset +subset ttf-subset +ttf-subset subset-add-glyph! encode-to-port create-subset)
+(provide subset +subset
+         ttf-subset +ttf-subset
+         cff-subset +cff-subset
+         subset-add-glyph! encode-to-port create-subset)
+
+#|
+from
+https://github.com/mbutterick/fontkit/blob/master/src/TTFFont.js
+|#
+
+(define (create-subset font)
+  ((if (has-table? font #"CFF_")
+       +cff-subset
+       +ttf-subset) font))
 
 #|
 approximates
-https://github.com/devongovett/fontkit/blob/master/src/subset/Subset.js
+https://github.com/mbutterick/fontkit/blob/master/src/subset/Subset.js
 |#
 
 ; glyphs = list of glyph ids in the subset
@@ -33,7 +46,7 @@ https://github.com/devongovett/fontkit/blob/master/src/subset/Subset.js
   (subset-encode ss p)
   p)
 
-(define (subset-add-glyph! ss glyph-or-gid)
+(define (subset-add-glyph! ss glyph-or-gid) ; fka `includeGlyph`
   (define new-gid ((if (glyph? glyph-or-gid) glyph-id values) glyph-or-gid))
   ;; put the new glyph at the end of `glyphs`,
   ;; and put its index in the mapping
@@ -43,6 +56,28 @@ https://github.com/devongovett/fontkit/blob/master/src/subset/Subset.js
                (sub1 (length (subset-glyphs ss))))))  
 
 
+#|
+approximates
+https://github.com/mbutterick/fontkit/blob/master/src/subset/CFFSubset.js
+|#
+
+(struct cff-subset subset (cff strings charstrings gsubrs) #:transparent #:mutable)
+
+(define (+cff-subset font [glyphs empty] [mapping (mhash)]
+                     [cff #f]
+                     [strings #f]
+                     [charstrings #f]
+                     [gsubrs #f])
+  (define ss (cff-subset font glyphs mapping cff strings charstrings gsubrs))
+  (subset-add-glyph! ss 0)
+  ss)
+
+(module+ test
+  (require "font.rkt" "helper.rkt")
+  (define otf (open-font (path->string fira-otf-path)))
+  (define cffss (+cff-subset otf))
+  cffss)
+
 #|
 approximates
 https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
@@ -59,10 +94,6 @@ https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
   (subset-add-glyph! ss 0)
   ss)
 
-(define (create-subset font)
-  ((if (has-table? font #"CFF_")
-       (error 'cff-fonts-unsupported)
-       +ttf-subset) font))
 
 (define (ttf-subset-add-glyph ss gid)
   ;; glyph-decode unpacks the `glyf` table data corresponding to a certin gid.