From 1da4c0e511640e7913a13ef5cf9d53c2207f9e8d Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Wed, 9 Jan 2019 13:33:40 -0800
Subject: [PATCH] line spacer

---
 quad/qtest/hyphenate.rkt |  2 +-
 quad/qtest/markdown.rkt  | 31 +++++++++++++++----------------
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/quad/qtest/hyphenate.rkt b/quad/qtest/hyphenate.rkt
index a0c5184f..a76603a0 100644
--- a/quad/qtest/hyphenate.rkt
+++ b/quad/qtest/hyphenate.rkt
@@ -1,6 +1,6 @@
 #lang qtest/markdown
 
-A simple _hyphenation engine_ that uses the Knuth–Liang hyphenation algorithm originally developed for TeX.
+ A simple _hyphenation engine_ that uses the Knuth–Liang hyphenation algorithm originally developed for TeX.
 
 I **have added little** to their work. Accordingly, I take no credit, except a spoonful of *snako-bits.*
 
diff --git a/quad/qtest/markdown.rkt b/quad/qtest/markdown.rkt
index 8353c9fd..9d7972d6 100644
--- a/quad/qtest/markdown.rkt
+++ b/quad/qtest/markdown.rkt
@@ -58,9 +58,12 @@
 (define q:line (q #:size (pt +inf.0 line-height)
                   #:out 'sw
                   #:printable #true))
-(define q:line-spacer (q #:size (pt +inf.0 (/ line-height 2))
-                  #:out 'sw
-                  #:printable #true))
+(struct line-spacer quad () #:transparent)
+(define q:line-spacer (q #:type line-spacer
+                         #:size (pt +inf.0 (* line-height 0.7))
+                         #:out 'sw
+                         #:printable (λ (q sig)
+                                       (not (memq sig '(start end))))))
 
 (define softies (map string '(#\space #\- #\u00AD)))
 (define (soft-break-for-line? q)
@@ -76,19 +79,13 @@
     (define new-run (struct-copy quad q:string
                                  [attrs (quad-attrs (car pcs))]
                                  [elems (merge-adjacent-strings (apply append (for/list ([pc (in-list run-pcs)])
-                                                                                (quad-elems pc))))]
+                                                                                        (quad-elems pc))))]
                                  [size (delay (pt (for/sum ([pc (in-list run-pcs)])
-                                                    (pt-x (size pc)))
+                                                           (pt-x (size pc)))
                                                   (pt-y (size (car pcs)))))]))
     (values (cons new-run runs) rest)))
 
-;; 190108 feels like this needs separate finish-wraps for soft and hard.
-;; and maybe pass in the quad that triggered the wrap.
-;; otherwise within line-wrap, the finish-wrap-proc can't tell the difference between
-;; 1) ordinary word space (permits wrap to next line)
-;; 2) hard line break (forces wrap to next line)
-;; 3) paragraph break (forces wrap to next line and also triggers first-line behavior,
-;; e.g., more space above or first-line indent.)
+
 (define (line-wrap xs size)
   (break xs size
          #:hard-break-proc (λ (q) (equal? "¶" (car (quad-elems q))))
@@ -97,17 +94,19 @@
                               (append
                                (if (= idx 1) (list q:line-spacer) null)
                                (list (struct-copy quad q:line
-                                                        [elems (consolidate-runs pcs)]))))))
+                                                  [elems (consolidate-runs pcs)]))))))
 
 (define q:page (q #:offset '(36 36)
                   #:pre-draw (λ (q doc) (add-page doc))))
 
 (define q:doc (q #:pre-draw (λ (q doc) (start-doc doc))
-                #:post-draw (λ (q doc) (end-doc doc))))
+                 #:post-draw (λ (q doc) (end-doc doc))))
 
 
 (define (page-wrap xs vertical-height)
-  (break xs vertical-height #:finish-wrap-proc (λ (pcs q idx) (list (struct-copy quad q:page [elems pcs])))))
+  (break xs vertical-height
+         #:soft-break-proc line-spacer?
+         #:finish-wrap-proc (λ (pcs q idx) (list (struct-copy quad q:page [elems pcs])))))
 
 (define (run xs path)
   (define pdf (time-name make-pdf (make-pdf #:compress #t
@@ -120,7 +119,7 @@
          [x (time-name line-wrap (line-wrap x line-width))]
          [x (time-name page-wrap (page-wrap x vertical-height))]
          [x (time-name position (position (struct-copy quad q:doc [elems x])))])
-      (time-name draw (draw x pdf))))
+    (time-name draw (draw x pdf))))
 
 (define-syntax (mb stx)
   (syntax-case stx ()