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pitfall/pitfall/embedded.rkt

@@ -30,15 +30,17 @@ https://github.com/mbutterick/pdfkit/blob/master/lib/font/embedded.coffee
    embed
    toUnicodeCmap))
 
-(define/contract (widthOfString this string size [features #f])
-  ((string? number?) ((option/c list?)) . ->*m . number?)
-  (cond
-    [features ; #f disables features ; null enables default features ; list adds features
-     (define run (send (· this font) layout string features))
+(define width-cache (make-hash))
+(define (widthOfString this string size [features #f])
+  ((string? number?) ((option/c (listof symbol?))) . ->*m . number?)
+  ; #f disables features ; null enables default features ; list adds features
+  (hash-ref! width-cache
+             (list string size (and features (sort features symbol<?)))
+             (λ ()
+               (define run (send (· this font) layout string features))
                (define width (· run advanceWidth))
                (define scale (/ size (+ (· this font unitsPerEm) 0.0)))
-     (* width scale)]
-    [else (send (· this font) measure-string string size)]))
+               (* width scale))))
 
 
 ;; called from text.rkt

pitfall/pitfall/text.rkt

@@ -197,6 +197,7 @@ https://github.com/mbutterick/pdfkit/blob/master/lib/mixins/text.coffee
   ;; since the normal Tw operator only works on character code 32, which isn't
   ;; used for embedded fonts.
   ;; 180321: the first call to this operation is very slow from Quad
+  ;; 181126: because `encode` calls `layout`
   (match-define (list encoded-char-strs positions)
     (if (not (zero? wordSpacing))
         (error 'unimplemented-brach) ; todo

pitfall/ptest/test0.pdf

@@ -27,7 +27,7 @@ endobj
 <<
 /Producer (PDFKit)
 /Creator (PDFKit)
-/CreationDate (D:20181120220342Z)
+/CreationDate (D:20181126220022Z)
 >>
 endobj
 2 0 obj