 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

link graphics
 
procedure main()  # pinstripe
 
   WOpen("canvas=hidden")                   # hide for query
   height := WAttrib("displayheight") - 45  # adjust for ...
   width  := WAttrib("displaywidth") - 20   # ... window 7 borders
   WClose(&window)
 
   W := WOpen("size="||width||","||height,"bg=black","fg=white") | 
        stop("Unable to open window")   
 
   maxbands := 4                             # bands to draw
   bandheight := height / maxbands           # height of each band
   every bands := 1 to maxbands do {         # for each band
         top   := 1 + bandheight * (bands-1) # .. top of band
         step  := 2^bands                    # .. number of steps (width)
         lines := step / 2                   # .. number (width) of stripes
         every c := 1 to width by step & l := 0 to lines-1 do 
            DrawLine(c+l,top,c+l,top+bandheight-1)
         }
   WDone(W)                                  # q to exit
end