129 lines
5.1 KiB
Racket
129 lines
5.1 KiB
Racket
#lang racket
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(require racket/gui/base)
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;;Step 1. Create a window to draw into
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(define frame(new frame% [label "Example"]))
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;;I don't know what frame% means, but new must be a procedure
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;;(send frame show #t) Running this command displays the frame
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;;send appears to be a command to be a procedure that takes a frame
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;; followed by a command and a boolean.
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;;the boolean is fed into the command in this case
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;;if you said #f it would close the window
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;;that is usefull
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;;Below is a slight expantion on example code
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;;letting the button be a toggle
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(define frame2 (new frame%[label "Example2"]))
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(define msg (new message% [parent frame2] [label " Nothing "]))
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(define thingy #t)
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(define button-to-click (new button%
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[parent frame2]
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[label "Click"]
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[callback (lambda (button event)
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(if thingy
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(begin (set! thingy #f)
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(send msg set-label "Something"))
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(begin (set! thingy #t)
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(send msg set-label " Nothing "))))]))
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;;Frames are okay ish for error messages but the real stuff is
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;;in canvas stuff
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(define my-canvas%
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(class canvas%
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(define/override (on-event event)
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(send msg set-label "Canvas mouse"))
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(define/override (on-char event)
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(send msg set-label "Canvas keyboard"))
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(super-new)));;Don't know what that one means
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(define canvas-thing (new my-canvas% [parent frame2]));;unfortunately
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;;we still need to re-size it manually
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;;Now I wonder if we could create a procedure to make any text
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;;appear
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(define frame3 (new frame%[label "Example3"]))
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(define blank (new message% [parent frame3] [label " "]))
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(define (make-text string) (begin (send blank set-label string)))
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;(send frame3 show #t)
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;(make-text "Hello World") works exactly fine.
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;;Now lets do something more complicated
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;;We want to create a procedure that creates a new line
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;;each time it is called so...
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(define frame4 (new frame%[label "Example4"]))
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;;now blank4 should be a procedure to create multiple lines in the frame
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(define (make-text-line string) (begin (new message%
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[parent frame4]
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[label string])))
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;;display with
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;;(send frame4 show #t)
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;;add text with
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;;(make-text-line "Hello World!")
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;;This works for not but there are a few problems
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;;first of all the window starts really small and doesn't restrict
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;;resizing. Second it is always in the middle of the frame
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;;Third, once text is on screen there is no way to get it off
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;;But we can do better
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(define frame5 (new frame%
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[label "Example5"]
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[width 300]
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[height 300]))
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(define canvas5 (new canvas% [parent frame5]
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[paint-callback
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(lambda (canvas dc)
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(send dc set-scale 3 3)
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(send dc set-text-foreground "blue")
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(send dc draw-text "Don't Panic!" 0 0))]))
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;;above is the example code to write some simple text, however
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;;we can apply this to what we learned above to make something abit
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;;more
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(define frame6 (new frame%
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[label "Example6"]
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[width 600]
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[height 700]))
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(define (make-color-text string color)
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(begin (new canvas%
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[parent frame6]
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[paint-callback
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(lambda (canvas dc)
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(send dc set-text-foreground color)
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(send dc draw-text string 0 0 #f))])))
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;;display with
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;;(send frame6 show #t)
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;;write text with
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;;(make-color-text "Hello World!" "purple")
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;;Okay that doesn't exactly work as planned...
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;;the problem with this is that each message is it's own canvas now
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;;not only that but it means we can only print each line in it's
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;;own color. So new plan is to make it so it adds on new strings
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;;to one canvas, adding \n as nessessary. Except nevermind since
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;;\n doesn't exist in this apparently
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;;Lets switch back to text and we can change it later
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(define frame7 (new frame%
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[label "Example7"]
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[width 600]
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[height 200]))
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(define (make-blank-line i)
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(new message%
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[parent frame7]
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[label " "]))
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;;80 space characters
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;;the i is only there to make the build-list command happy
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(define Message-list (build-list 10 make-blank-line))
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;;10 make-blank-lines
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;;that build-list command is super usefull for something like this
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(define (move-down-list list)
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(if (eq? '() (cdr list))
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'()
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(begin
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(move-down-list (cdr list))
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(send (car (cdr list)) set-label (send (car list) get-label)))))
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(define (send-word string)
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(begin
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(move-down-list Message-list)
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(send (car Message-list) set-label string)))
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;;display with
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;;(send frame7 show #t)
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;;add text with
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;;(send-word "Hello World")
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;;Now using the send-word command I can make each word appear on the
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;;screen in the place where it used to be. Starting at the top of the
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;;screen and working it's way down the more text is added.
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;;on the bottom line, after adding 10 lines of text, it will remove the bottom
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;;most line |