respect underline position & thickness

pitfall/pitfall/core.rkt

@@ -38,6 +38,8 @@
                   id
                   ascender
                   descender
+                  underline-position
+                  underline-thickness
                   line-gap
                   bbox
                   ref

pitfall/pitfall/font-embedded.rkt

@@ -48,13 +48,13 @@ https://github.com/mbutterick/pdfkit/blob/master/lib/font/embedded.coffee
   (define widths (mhasheq 0 (glyph-advance-width (get-glyph font 0))))
   (define name (font-postscript-name font))
   (define scale (/ 1000.0 (font-units-per-em font)))
-  (define ascender (exactify (* (font-ascent font) scale)))
-  (define descender (exactify (* (font-descent font) scale)))
+  (match-define (list ascender descender underline-position underline-thickness line-gap)
+    (for/list ([proc (in-list (list font-ascent font-descent font-underline-position font-underline-thickness font-linegap))])
+      (exactify (* (proc font) scale))))
   (define bbox (font-bbox font))
-  (define line-gap (exactify (* (font-linegap font) scale)))
   (define encoding-cache (make-hash)) ; needs to be per font, not in top level of module
   (efont
-   name id ascender descender line-gap bbox #f #f efont-embedded efont-encode efont-measure-string
+   name id ascender descender underline-position underline-thickness line-gap bbox #f #f efont-embedded efont-encode efont-measure-string
    font subset unicode widths scale encoding-cache))
 
 (define (efont-encode ef str [features-in null])

pitfall/pitfall/font-standard.rkt

@@ -24,11 +24,13 @@
   (define kern-pairs (make-hash kps))
   (define ascender (string->number (hash-ref attributes 'Ascender "0")))
   (define descender (string->number (hash-ref attributes 'Descender "0")))
+  (define underline-position (string->number (hash-ref attributes 'UnderlinePosition "-100")))
+  (define underline-thickness (string->number (hash-ref attributes 'UnderlineThickness "50")))
   (define bbox (for/list ([attr (in-list (string-split (hash-ref attributes 'FontBBox)))])
                  (or (string->number attr) 0)))
   (define line-gap (- (third bbox) (first bbox) ascender descender))
   (sfont
-   name id ascender descender line-gap bbox #f #f sfont-embed sfont-encode sfont-measure-string
+   name id ascender descender underline-position underline-thickness line-gap bbox #f #f sfont-embed sfont-encode sfont-measure-string
    attributes glyph-widths kern-pairs))
 
 (define (sfont-embed sf)

pitfall/pitfall/text.rkt

@@ -21,17 +21,28 @@ https://github.com/mbutterick/pdfkit/blob/master/lib/mixins/text.coffee
 |#
 
 (define (do-horiz-line doc x y width [underline? #f])
+  (define (scale-to-em x) (* (pdf-current-font-size doc) (/ x 1000.0)))
   (save doc)
   (when underline?
     (apply stroke-color doc (pdf-current-fill-color doc)))
-  (define new-line-width (max 0.5 (floor (/ (pdf-current-font-size doc) 10))))
-  (line-width doc new-line-width)
+  (define stroke-width
+    (cond
+      [(or (not underline?) (test-mode)) (max 0.5 (floor (/ (pdf-current-font-size doc) 10)))]
+      [else
+       (scale-to-em (pdf-font-underline-thickness (pdf-current-font doc)))]))
+  (line-width doc stroke-width)
   (define vert-em-adjustment (if underline? 1 0.6))
-  (define vert-line-pos (+ y
+  (define vert-line-adj
+    (+ y
        (* (current-line-height doc) vert-em-adjustment)
-                           (- (if underline? new-line-width 0))))
-  (move-to doc x vert-line-pos)
-  (line-to doc (+ x width) vert-line-pos)
+       (- (cond
+            [(test-mode) stroke-width]
+            [underline?
+             ;; underline-position field is negative, by convention, so we change the sign
+             (scale-to-em (- (pdf-font-underline-position (pdf-current-font doc))))]
+            [else 0]))))
+  (move-to doc x vert-line-adj)
+  (line-to doc (+ x width) vert-line-adj)
   (stroke doc)
   (restore doc))
 
@@ -108,8 +119,6 @@ https://github.com/mbutterick/pdfkit/blob/master/lib/mixins/text.coffee
   (define x (pdf-x doc))
   (define y (pdf-y doc))
 
-  ;; 180109: character spacing works in pdf, but quad doesn't account for it yet
-
   (define character-tracking (or character-tracking-arg 0))
   ;; calculate the actual rendered width of the string after word and character spacing
   (define rendered-width