typesetting/quad/quadwriter/render.rkt

#lang debug racket/base
(require (for-syntax racket/base racket/syntax)
         racket/match
         txexpr/base
         racket/contract
         racket/file
         racket/string
         racket/sequence
         racket/list
         pitfall
         quad
         hyphenate
         pollen/decode
         sugar/coerce
         sugar/list
         "attrs.rkt"
         "param.rkt"
         "font.rkt"
         "layout.rkt"
         "log.rkt")
(provide (all-defined-out))



(define (setup-pdf-path pdf-path-arg)
  (define fallback-path (build-path (find-system-path 'temp-dir) "quadwriter-temp.pdf"))
  (path->complete-path (simplify-path (expand-user-path (->path (or pdf-path-arg fallback-path))))))


(define-syntax (define-break-types stx)
  (syntax-case stx ()
    [(_ ALL-BREAKS-ID . TYPES)
     (with-syntax ([((TYPE-BREAK TYPE-STR Q:TYPE-BREAK) ...)
                    (for/list ([type (in-list (syntax->list #'TYPES))])
                              (list
                               (format-id #'TYPES "~a-break" type)
                               (symbol->string (syntax->datum type))
                               (format-id #'TYPES "q:~a-break" type)))])
       #'(begin
           (define TYPE-BREAK '(q ((break TYPE-STR)))) ...
           (define ALL-BREAKS-ID (list (cons TYPE-BREAK Q:TYPE-BREAK) ...))))]))

(define-break-types all-breaks para line page column hr section)

(define (replace-breaks x)
  (map-elements (λ (el)
                  (cond
                    [(assoc el all-breaks) => cdr]
                    [else el])) x))


(define (handle-hyphenate qs)
  ;; find quads that want hyphenation and split them into smaller pieces
  ;; do this before ->string-quad so that it can handle the sizing promises
  (apply append
         (for/list ([q (in-list qs)])
                   (cond 
                     [(and (quad-ref q :hyphenate) (pair? (quad-elems q)) (andmap string? (quad-elems q)))
                      (for*/list ([str (in-list (quad-elems q))]
                                  [hyphen-char (in-value #\u00AD)]
                                  [hstr (in-value (hyphenate str hyphen-char
                                                             #:min-left-length 3
                                                             #:min-right-length 3))]
                                  [substr (in-list (regexp-match* (regexp (string hyphen-char)) hstr #:gap-select? #t))])
                                 (quad-copy q [elems (list substr)]))]
                     [else (list q)]))))


(define (string->feature-list str)
  (for/list ([kv (in-slice 2 (string-split str))])
            (cons (string->bytes/utf-8 (first kv)) (string->number (second kv)))))

(define (parse-font-features! attrs)
  (match (hash-ref attrs :font-features-adjust #f)
    [(? string? str)
     ;; override any existing features
     (define parsed-features (string->feature-list str))
     (hash-update! attrs :font-features (λ (fs) (remove-duplicates (append parsed-features fs) equal? #:key car)))
     ;; adjustment is incorporated, so delete it
     (hash-set! attrs :font-features-adjust #false)]
    [_ (match (hash-ref attrs :font-features #f)
         [(? string? str)
          (define parsed-features (string->feature-list str))
          (hash-set! attrs :font-features parsed-features)]
         [_ (void)])]))


(define (parse-dimension-strings! attrs)
  (for ([k (in-hash-keys attrs)]
        #:when (takes-dimension-string? k))
       (hash-update! attrs k parse-dimension))
  attrs)

(define (downcase-values! attrs)
  (for ([k (in-hash-keys attrs)]
        #:unless (has-case-sensitive-value? k))
       (hash-update! attrs k (λ (val) (match val
                                        [(? string? str) (string-downcase str)]
                                        [_ val]))))
  attrs)

(define (complete-every-path! attrs)
  ;; relies on `current-directory` being parameterized to source file's dir
  (for ([k (in-hash-keys attrs)]
        #:when (takes-path? k))
       (hash-update! attrs k (compose1 path->string path->complete-path)))
  attrs)

(define (handle-cascading-attrs attrs)
  (for ([proc (in-list (list downcase-values!
                             parse-dimension-strings!
                             complete-every-path!
                             resolve-font-path!
                             resolve-font-size!
                             resolve-line-height!
                             parse-font-features!))])
       (proc attrs)))

(define default-line-height-multiplier 1.42)
(define (setup-qs qx-arg base-dir)
  (define qexpr (decode qx-arg
                        #:string-proc (λ (str) (smart-ellipses (smart-dashes str)))
                        #:txexpr-proc smart-quotes))
  (define super-qexpr (replace-breaks qexpr))
  (define the-quad
    (qexpr->quad (list 'q (list->attrs
                           :font-family default-font-family
                           :font-size (number->string default-font-size)
                           :line-height (number->string (floor (* default-line-height-multiplier default-font-size)))) super-qexpr)))
  (setup-font-path-table! base-dir)
  (define atomized-qs (atomize the-quad
                               #:attrs-proc handle-cascading-attrs
                               #:missing-glyph-action 'fallback
                               #:fallback "fallback"
                               #:emoji "fallback-emoji"
                               #:math "fallback-math"
                               #:font-path-resolver resolve-font-path!))
  (define hyphenated-qs (time-log hyphenate (handle-hyphenate atomized-qs)))
  (define typed-quads (map generic->typed-quad hyphenated-qs))
  (define indented-qs (insert-first-line-indents typed-quads))
  indented-qs)

(define (setup-margins qs page-width page-height)
  ;; if only left or right margin is provided, copy other value in preference to default margin
  (define q (car qs))
  (define default-side-margin (min (* 72 1.5) (floor (* .20 page-width))))
  (define default-top-margin (min 72 (floor (* .10 page-height))))
  
  (define left (cond
                 [(debug-x-margin)]
                 [(quad-ref q :page-margin-left)]
                 [(quad-ref q :page-margin-right)]
                 [else default-side-margin]))
  
  (define right (cond
                  [(debug-x-margin)]
                  [(quad-ref q :page-margin-right)]
                  [(quad-ref q :page-margin-left)]
                  [else default-side-margin]))
  
  (define top (cond
                [(debug-y-margin)]
                [(quad-ref q :page-margin-top)]
                [(quad-ref q :page-margin-bottom)]
                [else default-top-margin]))
  
  (define bottom (cond
                   [(debug-y-margin)]
                   [(quad-ref q :page-margin-bottom)]
                   [else
                    (define vert-optical-adjustment 10)
                    (+ vert-optical-adjustment
                       (cond
                         [(quad-ref q :page-margin-top)]
                         [else (* default-top-margin 1.4)]))]))
  
  (list left top right bottom))

(define default-column-count 1)
(define (setup-column-count qs)
  (define cc (or (debug-column-count) (quad-ref (car qs) :column-count default-column-count)))
  (unless (exact-nonnegative-integer? cc)
    (raise-argument-error 'render-pdf "positive integer" cc))
  cc)

(define default-column-gap 36)
(define (setup-column-gap qs)
  (or (debug-column-gap)  (quad-ref (car qs) :column-gap default-column-gap)))

(define (setup-pdf-metadata! qs pdf)
  (for ([k (in-list (list :pdf-title
                          :pdf-author
                          :pdf-subject
                          :pdf-keywords))]
        [pdf-k (in-list (list 'Title
                              'Author
                              'Subject
                              'Keywords))])
       (hash-set! (pdf-info pdf) pdf-k (quad-ref (car qs) k "")))
  (hash-set! (pdf-info pdf) 'Creator (format "Racket ~a [Quad library]" (version))))

(define (footnote-flow? q) (equal? (quad-ref q 'flow) "footnote"))

(define/contract (render-pdf qx-arg
                             [pdf-path-arg #false]
                             [base-dir-arg #false]
                             #:replace [replace-existing-file? #t]
                             #:compress [compress? #t])
  ((qexpr?)
   ((or/c #false path? path-string?)
    (or/c #false path? path-string?)
    #:replace any/c
    #:compress any/c) . ->* . (or/c void? bytes?))

  (define base-dir (match base-dir-arg
                     [#false (current-directory)]
                     [path (define-values (dir name _) (split-path path))
                           dir]))

  (define pdf-path (setup-pdf-path pdf-path-arg))
  (unless replace-existing-file?
    (when (file-exists? pdf-path)
      (raise-argument-error 'render-pdf "path that doesn't exist" pdf-path)))

  (define the-pdf (make-pdf #:compress compress?
                            #:auto-first-page #false
                            #:output-path pdf-path))
  (parameterize ([current-pdf the-pdf]
                 ;; set `current-directory` so that ops like `path->complete-path`
                 ;; will be handled relative to the original directory
                 [current-directory base-dir]
                 [section-pages-used 0]
                 [verbose-quad-printing? #false])
    (define qs (time-log setup-qs (setup-qs qx-arg base-dir)))
    (when (pair? qs)
      (setup-pdf-metadata! qs the-pdf))
    (define sections
      (for/fold ([sections-acc null]
                 #:result (reverse sections-acc))
                ([qs (in-list (filter-split qs section-break-quad?))])
        (match-define (list page-width page-height) (parse-page-size (and (pair? qs) (car qs))))
        (match-define (list left-margin top-margin right-margin bottom-margin)
          (setup-margins qs page-width page-height))
        (define gutter-margin (and (pair? qs) (quad-ref (car qs) :page-margin-gutter 0)))
        (define printable-width (- page-width left-margin right-margin gutter-margin))
        (define printable-height (- page-height top-margin bottom-margin))
        (define column-count (setup-column-count qs))
        (define column-gap (setup-column-gap qs))

        (define-values (fn-qs main-qs) (partition footnote-flow? qs))
    
        (define line-wrap-size (/ (- printable-width (* (sub1 column-count) column-gap)) column-count))
        (define line-qs (time-log line-wrap (apply-keeps (line-wrap main-qs line-wrap-size))))
        (define fn-line-qs (time-log fn-line-wrap (apply-keeps (line-wrap fn-qs line-wrap-size))))
    
        (define col-quad-prototype (quad-copy q:column
                                              [size (pt line-wrap-size printable-height)]))
        (define column-qs (time-log column-wrap (column-wrap line-qs fn-line-qs printable-height column-gap col-quad-prototype)))

        (define page-quad-prototype
          (λ (page-count)
            (define left-shift (+ left-margin (if (odd? page-count) gutter-margin 0)))
            (quad-copy q:page
                       [shift (pt left-shift top-margin)]
                       [size (pt line-wrap-size printable-height)])))

        (define section-starting-side (string->symbol (quad-ref (car qs) :page-side-start "right")))
        (define insert-blank-page?
          (and (pair? qs)
               ;; if we need a 'left page and will get 'right (or vice versa) then insert page
               (let ([next-page-side (if (even? (add1 (section-pages-used))) 'left 'right)])
                 (not (eq? section-starting-side next-page-side)))))
        ;; update page count before starting page wrap
        (when insert-blank-page?
          (section-pages-used (add1 (section-pages-used))))
        
        (define section-pages (time-log page-wrap (page-wrap column-qs printable-width page-quad-prototype)))

        (define (section-empty? section-pages) (zero? (length section-pages)))
        
        (begin0
          (cond
            ;; ignore empty section
            [(section-empty? section-pages) sections-acc]
            [insert-blank-page?
             (match section-starting-side
               ['left
                ;; blank page goes at beginning of current section
                (define page-from-current-section (car section-pages))
                (define blank-page (quad-copy page-from-current-section [elems null]))
                (define new-section (quad-copy q:section [elems (cons blank-page section-pages)]))
                (cons new-section sections-acc)]
               [_ ;; must be 'right
                ;; blank page goes at end of previous section (if it exists)
                (define new-section (quad-copy q:section [elems section-pages]))
                (match sections-acc
                  [(cons previous-section other-sections)
                   (define previous-section-pages (quad-elems previous-section))
                   ;; we know previous section has pages because we ignore empty sections
                   (define page-from-previous-section (car previous-section-pages))
                   (define blank-page (quad-copy page-from-previous-section [elems null]))
                   (define updated-previous-section
                     (quad-update! previous-section
                                   [elems (append previous-section-pages (list blank-page))]))
                   (list* new-section updated-previous-section other-sections)]
                  [_ (list new-section)])])]
            [else (define new-section (quad-copy q:section [elems section-pages]) )
                  (cons new-section sections-acc)])
          (section-pages-used (+ (section-pages-used) (length section-pages))))))
    
    (define doc (quad-copy q:doc [elems sections]))

    ;; correct lines with inner / outer alignment
    (for* ([(page page-idx) (in-indexed (for*/list ([section (in-list (quad-elems doc))]
                                                    [page (in-list (quad-elems section))])
                                                   page))]
           [col (in-list (quad-elems page))]
           [block (in-list (quad-elems col))]
           [line (in-list (quad-elems block))])
          ;; all inner / outer lines are initially filled as if they were right-aligned
          (define zero-filler-side (if (odd? (add1 page-idx)) "inner" "outer"))
          (when (equal? zero-filler-side (quad-ref line :line-align))
            (match (quad-elems line)
              [(cons (? filler-quad? fq) _) (set-quad-size! fq (pt 0 0))]
              [_ (void)])))
    
    (define positioned-doc (time-log position (position doc)))
    (time-log draw (draw positioned-doc (current-pdf))))

  (if pdf-path-arg
      (log-quadwriter-info (format "wrote PDF to ~a" pdf-path))
      (begin0
        (file->bytes pdf-path)
        (delete-file pdf-path))))