structify glyphrun

fontland/fontland/font.rkt

@@ -5,7 +5,7 @@
          "subset.rkt"
          "glyph.rkt"
          "bbox.rkt"
-         "glyphrun.rkt"
+         (except-in "glyphrun.rkt" advanceWidth)
          "directory.rkt"
          "db.rkt"
          xenomorph
@@ -275,7 +275,7 @@ https://github.com/mbutterick/fontkit/blob/master/src/TTFFont.js
      (define positions (for/list ([pos (in-list posns)])
                                  (match pos
                                    [(list xad yad xoff yoff _) (+GlyphPosition xad yad xoff yoff)])))
-     (+GlyphRun glyphs positions)]))
+     (glyphrun glyphs positions)]))
 
 
 (define (harfbuzz-layout this codepoints userFeatures script language)

fontland/fontland/glyphrun.rkt

@@ -12,20 +12,26 @@ https://github.com/mbutterick/fontkit/blob/master/src/layout/GlyphRun.js
 
 ;; Represents a run of Glyph and GlyphPosition objects.
 ;; Returned by the font layout method.
-(define-subclass object% (GlyphRun
-                          glyphs ; An array of Glyph objects in the run
-                          positions) ; An array of GlyphPosition objects for each glyph in the run
+#;(define-subclass object% (GlyphRun
+                            glyphs ; An array of Glyph objects in the run
+                            positions) ; An array of GlyphPosition objects for each glyph in the run
 
 
-  (define/public (advanceWidth)
-    (for/sum ([pos (in-list positions)])
-             (· pos xAdvance))))
+    (define/public (advanceWidth)
+      (for/sum ([pos (in-list positions)])
+               (· pos xAdvance))))
 
 
+(struct glyphrun (glyphs positions) #:transparent)
+
+(define (advanceWidth gr)
+  (for/sum ([pos (in-list (glyphrun-positions gr))])
+           (· pos xAdvance)))
+
 (define (append-glyphruns . grs)
   (for/fold ([glyphss null]
              [positionss null]
-             #:result (make-object GlyphRun
+             #:result (make-object glyphrun
                         (apply append (reverse glyphss))
                         (apply append (reverse positionss))))
             ([gr (in-list grs)])

fontland/fontland/main.rkt

@@ -7,4 +7,5 @@
      "glyph-position.rkt"
      "subset.rkt"
      "bbox.rkt"
-     "tables.rkt")
+     "tables.rkt"
+     "glyphrun.rkt")