#lang scheme/gui

(define (remove-alpha filename)
  (define bm (make-object bitmap% filename 'unknown/mask))
  (define bm2 (make-object bitmap% 
                (send bm get-width)
                (send bm get-height)))
  (define bdc (make-object bitmap-dc% bm2))
  
  (send bdc clear)
  (send bdc draw-bitmap 
        bm
        0
        0
        'solid
        (send the-color-database find-color "black")
        (send bm get-loaded-mask))
  (send bdc set-bitmap #f)
  (send bm2 save-file filename 'png))

;(remove-alpha "collatz.png")
;(remove-alpha "check-syntax.png")

;; (remove-alpha "struct-hierarchy.png") this one should not have an alpha channel.