球拍博士中的位图[关闭]

如何在 drracket 中的框架（gui）上加载位图？？？ 请给出必要的代码和参考文献......

我承认，我很难在文档中找到正确的位置来指向您。这是一些执行此操作的代码，但我偷偷怀疑有一种更简单的方法可以完成此操作：

#lang racket

(require racket/draw
         mred)

;; define a canvas that displays a bitmap when its on-paint
;; method is called
(define bitmap-canvas%
  (class canvas%
    (init-field [bitmap #f])
    (inherit get-dc)
    (define/override (on-paint)
      (send (get-dc) draw-bitmap bitmap 0 0))
    (super-new)))

;; load the bitmap
(define bitmap (read-bitmap "/tmp/red-arrow.bmp"))

;; create a new frame (top-level window)
(define f (new frame% [label "foo"] [width 100] [height 100]))

;; create a canvas
(define the-canvas (new bitmap-canvas% [parent f] [bitmap bitmap]))

;; show the canvas
(send f show #t)

更新：Matthew Flatt 建议：您可以使用“message%”并将位图作为其标签。这肯定少了很多代码。这取决于你要做什么。

#lang racket/gui

(define bitmap (read-bitmap "/tmp/red-arrow.bmp"))

(define f (new frame% [label "Bitmap"]))
(new message% [parent f] [label bitmap])
(send f show #t)