From 00d99793ac86934d39c0d26caa1be94b376e5ee4 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Mon, 4 Mar 2019 08:47:18 -0800
Subject: [PATCH] start cff

---
 fontland/fontland/subset.rkt | 57 ++++++++++++++++++++++++++++--------
 1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/fontland/fontland/subset.rkt b/fontland/fontland/subset.rkt
index 42bfe26d..469c2b1f 100644
--- a/fontland/fontland/subset.rkt
+++ b/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.
@@ -84,9 +115,9 @@ https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
   ;; if it is a compound glyph, include its components
   (when (and ttf-glyf-data (negative? (hash-ref ttf-glyf-data 'numberOfContours)))
     (for ([ttf-glyph-component (in-list (hash-ref ttf-glyf-data 'components))])
-      (define gid (subset-add-glyph! ss (ttf-glyph-component-glyph-id ttf-glyph-component)))
-      ;; note: this (ttf-glyph-component-pos component) is correct. It's a field of a Component object, not a port
-      (bytes-copy! glyf-bytes (ttf-glyph-component-pos ttf-glyph-component) (encode uint16be gid #f))))
+         (define gid (subset-add-glyph! ss (ttf-glyph-component-glyph-id ttf-glyph-component)))
+         ;; note: this (ttf-glyph-component-pos component) is correct. It's a field of a Component object, not a port
+         (bytes-copy! glyf-bytes (ttf-glyph-component-pos ttf-glyph-component) (encode uint16be gid #f))))
   
   (set-ttf-subset-glyf! ss (append (ttf-subset-glyf ss) (list glyf-bytes)))
   (hash-update! (ttf-subset-loca ss) 'offsets
@@ -117,8 +148,8 @@ https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
   ;; glyphs to the array as component glyphs are discovered & enqueued
   (for ([idx (in-naturals)]
         #:break (= idx (length (subset-glyphs ss))))
-    (define gid (list-ref (subset-glyphs ss) idx))
-    (ttf-subset-add-glyph ss gid))
+       (define gid (list-ref (subset-glyphs ss) idx))
+       (ttf-subset-add-glyph ss gid))
   
   (define new-maxp-table (clone-deep (get-maxp-table (subset-font ss))))
   (dict-set! new-maxp-table 'numGlyphs (length (ttf-subset-glyf ss)))
@@ -146,7 +177,7 @@ https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
                            'fpgm (get-fpgm-table (subset-font ss))))
       (for ([(k v) (in-dict kvs)]
             #:unless v)
-        (error 'encode (format "missing value for ~a" k)))
+           (error 'encode (format "missing value for ~a" k)))
       (make-hasheq kvs)))
   
   (encode Directory (mhash 'tables new-tables) port)