allow em sizes for all dimension strings

quad/quad/scribblings/quad.scrbl

@@ -455,7 +455,7 @@ A section is a contiguous series of pages. Each section has its own @secref{Sect
 
 These are the attributes that can be used inside a @tech{Q-expression} passed to @racketmodname[quadwriter]. Inside a Q-expression, every attribute is a @tech[#:doc '(lib "scribblings/guide/guide.scrbl")]{symbol}, and every attribute value is a @tech[#:doc '(lib "scribblings/guide/guide.scrbl")]{string}.
 
-A @deftech{dimension string} represents a distance in the plane. If unitless, it is treated as points (where 1 point = 1/72 of an inch). If the number has @racket[in], @racket[cm], or @racket[mm] as a suffix, it is treated as inches, centimeters, or millimeters respectively.
+A @deftech{dimension string} represents a distance in the plane. If unitless, it is treated as points (where 1 point = 1/72 of an inch). If the number has @racket[in], @racket[cm], or @racket[mm] as a suffix, it is treated as inches, centimeters, or millimeters respectively. If the number has @racket[em] as a suffix, it is treated as an em measurement, which is a multiple of the current font size.
 
 @subsubsection{Document-level attributes}
 
@@ -627,7 +627,7 @@ Sets the display type. Value is a string. Supply @racket["block"] as a value of
 }
 
 @defthing[#:kind "attribute" font-size symbol?]{
-Sets the point size for text. Value is a @tech{dimension string} or an em size (like @racket["1.2em"]). If an em size is provided, the font size is the size of the parent multiplied by the em.
+Sets the point size for text. Value is a @tech{dimension string}.
 }
 
 @defthing[#:kind "attribute" font-family symbol?]{
@@ -654,7 +654,7 @@ Sets OpenType layout features. @racket[font-features] takes a @deftech{feature s
  
 
 @defthing[#:kind "attribute" font-tracking symbol?]{
-Space between characters. Value is a @tech{dimension string} or an em size (like @racket["0.15em"]). If an em size is provided, the font tracking is the current font size multiplied by the em.
+Space between characters. Value is a @tech{dimension string}.
 }
 
 @defthing[#:kind "attribute" font-baseline-shift symbol?]{
@@ -667,7 +667,7 @@ Case transformation of string. Possibilities are @racket["uppercase"], @racket["
 
 
 @defthing[#:kind "attribute" line-height symbol?]{
-Sets the distance between baselines. Value is a @tech{dimension string} or an em size (like @racket["1.2em"]). If an em size is provided, the line height is the current font size multiplied by em.
+Sets the distance between baselines. Value is a @tech{dimension string}.
 }
 
 TK: OT feature attributes, bullet attributes

quad/quadwriter/attrs.rkt

@@ -13,7 +13,7 @@
 (define (in->pts x) (* 72 x))
 (define (mm->cm x) (/ x 10.0))
 
-(define (parse-dimension x)
+(define (parse-dimension x [em-resolution-attrs #false])
   (match x
     [#false #false]
     [(? number? num) num]
@@ -26,7 +26,10 @@
            [(regexp #rx"in(ch(es)?)?$") in->pts] ; inches
            [(regexp #rx"cms?$") (compose1 in->pts cm->in)] ; cm
            [(regexp #rx"mms?$") (compose1 in->pts cm->in mm->cm)] ; mm
-           [(regexp #rx"ems?$") (λ (num) (format "~aem" num))] ; em
+           [(regexp #rx"ems?$") (if em-resolution-attrs
+                                    (λ (num) (* (hash-ref em-resolution-attrs :font-size) num))
+                                    ;; if we don't have attrs for resolving the em string, we leave it alone
+                                    (λ (num) (format "~aem" num)))] ; em
            [_ (raise-argument-error 'parse-dimension "dimension string" str)]) (string->number num-string))])]))
 
 (define (copy-block-attrs source-hash dest-hash)

quad/quadwriter/font.rkt

@@ -80,29 +80,19 @@
     (define this-italic (hash-ref! attrs :font-italic #false))
     (hash-set! attrs :font-path (font-attrs->path this-font-family this-bold this-italic))))
 
-(define (parse-adjustment pstr suffix)
+(define (parse-em pstr)
+  (define em-suffix "em")
   (and
    pstr
    (string? pstr)
-   (string-suffix? pstr suffix)
-   (string->number (string-trim pstr suffix))))
-
-(define (parse-em str)
-  (parse-adjustment str "em"))
-
-(define (parse-percentage pstr)
-  (match (parse-adjustment pstr "%")
-    [#false #false]
-    [res (/ res 100.0)]))
-
-(define (parse-percentage-or-em str)
-  (or (parse-percentage str) (parse-em str)))
+   (string-suffix? pstr em-suffix)
+   (string->number (string-trim pstr em-suffix))))
 
 (define (resolve-font-size! attrs)
   ;; convert font-size attributes into a simple font size
   ;; we stashed the previous size in private key 'font-size-previous
   (define prev-font-size-key 'font-size-previous)
-  (define val (hash-ref attrs :font-size default-font-size))
+  (define val (parse-dimension (hash-ref attrs :font-size default-font-size)))
   (define adjustment (parse-em val))
   ;; if our value represents an adjustment, we apply the adjustment to the previous value
   ;; otherwise we use our value directly
@@ -113,22 +103,3 @@
   ;; of font-size (but font-size-previous will persist)
   (hash-set! attrs :font-size base-size-adjusted)
   (hash-set! attrs prev-font-size-key base-size-adjusted))
-
-(define ((make-updater-based-on-font-size attrs) val)
-  (define em-adjustment (parse-em val))
-  (define base-height (if em-adjustment (hash-ref attrs :font-size) val))
-  (and base-height (* base-height (or em-adjustment 1))))
-
-(define (resolve-em attrs key)
-  (match (hash-ref attrs key #f)
-    [#false (void)]
-    [val
-     (define updater (make-updater-based-on-font-size attrs))
-     (hash-set! attrs key (updater val))]))
-
-(define (resolve-line-height! attrs)
-  ;; convert line-height attributes into a simple line height
-  (resolve-em attrs :line-height))
-
-(define (resolve-font-tracking! attrs)
-  (resolve-em attrs :font-tracking))

quad/quadwriter/render.rkt

@@ -94,7 +94,7 @@
   ;; we parse them into the equivalent measurement in points.
   (for ([k (in-hash-keys attrs)]
         #:when (takes-dimension-string? k))
-       (hash-update! attrs k parse-dimension))
+       (hash-update! attrs k (λ (val) (parse-dimension val attrs))))
   attrs)
 
 (define (downcase-values! attrs)
@@ -119,14 +119,12 @@
 (define (handle-cascading-attrs attrs)
   ;; various housekeeping on attributes as they are propagated downward during atomization.
   (for ([proc (in-list (list downcase-values!
-                             parse-dimension-strings!
                              complete-every-path!
                              resolve-font-path!
                              resolve-font-size!
-                             ;; we resolve font tracking & line height after font size
-                             ;; because they can be denoted relative to font size
-                             resolve-font-tracking!
-                             resolve-line-height! 
+                             ;; we resolve dimension strings after font size
+                             ;; because they can be denoted relative to em size
+                             parse-dimension-strings!
                              parse-font-features!))])
        (proc attrs)))
 
@@ -329,7 +327,7 @@
   (for* ([(page page-idx) (in-indexed (for*/list ([section (in-list (quad-elems doc))]
                                                   [page (in-list (quad-elems section))])
                                                  page))]
-        ;; all inner / outer lines are initially filled as if they were right-aligned
+         ;; all inner / outer lines are initially filled as if they were right-aligned
          [zero-filler-side (in-value (if (odd? (add1 page-idx)) "inner" "outer"))]
          [col (in-list (quad-elems page))]
          [block (in-list (quad-elems col))]