typesetting/pitfall/pitfall/page.rkt

#lang pitfall/racket
(provide PDFPage)

(define PDFPage
  (class object%
    (super-new)
    (init-field [(@document document)] [(@options options) (mhash)])
    (field [(@size size) (hash-ref @options 'size "letter")])
    (field [(@layout layout) (hash-ref @options 'layout "portrait")])

    ;; process margins
    (field [(@margins margins)
            (let ([margin-value (hash-ref @options 'margin #f)])
              (if (number? margin-value)
                  (mhash 'top margin-value
                         'left margin-value
                         'bottom margin-value
                         'right margin-value)
                  ;; default to 1 inch margins
                  (hash-ref @options 'margins DEFAULT_MARGINS)))])

    ;; calculate page dimensions
    (define dimensions (if (list? @size)
                           @size
                           (hash-ref SIZES (string-upcase @size))))
    (field [(@width width) (list-ref dimensions (if (equal? @layout "portrait") 0 1))])
    (field [(@height height) (list-ref dimensions (if (equal? @layout "portrait") 1 0))])

    (field [(@content content) (· @document ref)])

    ;; Initialize the Font, XObject, and ExtGState dictionaries
    (field [(@resources resources) (send @document ref (mhash 'ProcSet '("PDF" "Text" "ImageB" "ImageC" "ImageI")))])

    ;; Lazily create these dictionaries
    (define/public (fonts)
      (hash-ref! (· @resources data) 'Font (make-hash)))

    (define/public (xobjects)
      (hash-ref! (· @resources data) 'XObject (make-hash)))

    (define/public (ext_gstates)
      (hash-ref! (· @resources data) 'ExtGState (make-hash)))

    (define/public (patterns)
      (hash-ref! (· @resources data) 'Pattern (make-hash)))

    (define/public (annotations)
      (hash-ref! (· @resources data) 'Annots null))
          
    ;; The page dictionary
    (field [(@dictionary dictionary)
            (send @document ref
                  (mhash 'Type "Page"
                         'Parent (· @document _root data Pages)
                         'MediaBox (list 0 0 @width @height)
                         'Contents @content
                         'Resources @resources))])

    (public [@maxY maxY])
    (define (@maxY)
      (- @height (· @margins bottom)))

    (public [@write write])
    (define (@write chunk)
      (void)
      (send @content write chunk)) ; resume here

    (public [@end end])
    (define (@end)
      (send @dictionary end)
      (send @resources end)
      (send @content end))
    
    
    ))


(define DEFAULT_MARGINS 
  (hasheq 'top 72
          'left 72
          'bottom 72
          'right 72))

(define SIZES
  (hash
   "4A0" '(4767.87 6740.79)
   "2A0" '(3370.39 4767.87)
   "A0" '(2383.94 3370.39)
   "A1" '(1683.78 2383.94)
   "A2" '(1190.55 1683.78)
   "A3" '(841.89 1190.55)
   "A4" '(595.28 841.89)
   "A5" '(419.53 595.28)
   "A6" '(297.64 419.53)
   "A7" '(209.76 297.64)
   "A8" '(147.40 209.76)
   "A9" '(104.88 147.40)
   "A10" '(73.70 104.88)
   "B0" '(2834.65 4008.19)
   "B1" '(2004.09 2834.65)
   "B2" '(1417.32 2004.09)
   "B3" '(1000.63 1417.32)
   "B4" '(708.66 1000.63)
   "B5" '(498.90 708.66)
   "B6" '(354.33 498.90)
   "B7" '(249.45 354.33)
   "B8" '(175.75 249.45)
   "B9" '(124.72 175.75)
   "B10" '(87.87 124.72)
   "C0" '(2599.37 3676.54)
   "C1" '(1836.85 2599.37)
   "C2" '(1298.27 1836.85)
   "C3" '(918.43 1298.27)
   "C4" '(649.13 918.43)
   "C5" '(459.21 649.13)
   "C6" '(323.15 459.21)
   "C7" '(229.61 323.15)
   "C8" '(161.57 229.61)
   "C9" '(113.39 161.57)
   "C10" '(79.37 113.39)
   "RA0" '(2437.80 3458.27)
   "RA1" '(1729.13 2437.80)
   "RA2" '(1218.90 1729.13)
   "RA3" '(864.57 1218.90)
   "RA4" '(609.45 864.57)
   "SRA0" '(2551.18 3628.35)
   "SRA1" '(1814.17 2551.18)
   "SRA2" '(1275.59 1814.17)
   "SRA3" '(907.09 1275.59)
   "SRA4" '(637.80 907.09)
   "EXECUTIVE" '(521.86 756.00)
   "FOLIO" '(612.00 936.00)
   "LEGAL" '(612.00 1008.00)
   "LETTER" '(612.00 792.00)
   "TABLOID" '(792.00 1224.00)))