 Sample image
The task is to demonstrate the creation of a series of vertical pinstripes across the entire width of the display.

 in the first quarter the pinstripes should alternate one pixel white, one pixel black = 1 pixel wide vertical pinestripes
 Quarter of the way down the display, we can switch to a wider 2 pixel wide vertical pinstripe pattern, alternating two pixels white, two pixels black. 
 Half way down the display, we switch to 3 pixels wide, 
 for the lower quarter of the display we use 4 pixels.


c.f. Colour_pinstripe/Display

 
#lang racket/gui
 
(define-values [W H] (get-display-size #t))
 
(define parts 4)
 
(define (paint-pinstripe canvas dc)
  (send dc set-pen "black" 0 'solid)
  (send dc set-brush "black" 'solid)
  (define H* (round (/ H parts)))
  (for ([row parts])
    (define Y (* row H*))
    (for ([X (in-range 0 W (* (add1 row) 2))])
      (send dc draw-rectangle X Y (add1 row) H*))))
 
(define full-frame%
  (class frame%
    (define/override (on-subwindow-char r e)
      (when (eq? 'escape (send e get-key-code))
        (send this show #f)))
    (super-new
     [label "Pinstripe"] [width W] [height H]
     [style '(no-caption no-resize-border hide-menu-bar no-system-menu)])
    (define c (new canvas% [parent this] [paint-callback paint-pinstripe]))
    (send this show #t)))
 
(void (new full-frame%))
 