[racket] Problem scrolling contents of text% in editor-snip%

There's currently no support in `editor-snip%' for scrolling within the
snip. All scrolling actions are propagated to the enclosing view, which
in this case would mean scrolling the canvas so that the editor snip is
itself visible.

At Mon, 14 May 2012 16:32:46 -0600, Kieron Hardy wrote:
> Hi all,
> 
> I'm having problems getting the contents in a text% to scroll within an
> editor-snip%.
> 
> The attached code displays part of a long string within a text% object in a
> smaller editor-snip% object. The print statements successfully show a few
> of the edit locations at some selected (x, y) points in the editor.
> 
> I think I've tried all of the scrolling functions in each of the various
> components (editor-canvas%, editor-admin%, editor-snip%, text%) and am
> unable to change the portion of the string that displays. I'm probably
> doing something stupid, can anyone give me any hints?
> 
> Cheers,
> 
> Kieron.
> 
> ****
> 
> #lang racket/gui
> 
> (define f (instantiate frame% ("Pasteboard Test" #f 600 400)))
> (define c (instantiate editor-canvas% (f)))
> 
> (define p (instantiate pasteboard% ()))
> (send c set-editor p)
> 
> (send f show #t)
> 
> (define t (new text% [auto-wrap #f]))
> (send t insert "hello world .... pasteboard one two three ... goodbye world
> ... alpha bravo charlie delta echo foxtrot golf hotel india juliet kilo
> lima mike november oscar papa quebec romeo sierra tango uniform victor
> whiskey xray yacht zulu" 0)
> 
> (define s (new editor-snip% [editor t]))
> 
> (send s set-min-width 250)
> (send s set-max-width 250)
> 
> (send p insert s)
> 
> (printf "  text dimensions:(~a ~a) (~a ~a)~n"
>         (send t get-min-width) (send t get-min-height)
>         (send t get-max-width) (send t get-max-height))
> (printf "  snip dimensions:(~a ~a) (~a ~a)~n"
>         (send s get-min-width) (send s get-min-height)
>         (send s get-max-width) (send s get-max-height))
> 
> ;; print information about certain locations in the text
> ;(send t find-position x y at-eol? on-it? edge-close?)
> (define at-eol? (box 0))
> (define on-it? (box 0))
> (define edge-close? (box 0))
> (printf "  (5,5): ~a ~a ~a ~a~n"
>         (send t find-position   5 5 at-eol? on-it? edge-close?) (unbox
> at-eol?) (unbox on-it?) (unbox edge-close?))
> (printf " (25,5): ~a ~a ~a ~a~n"
>         (send t find-position  25 5 at-eol? on-it? edge-close?) (unbox
> at-eol?) (unbox on-it?) (unbox edge-close?))
> (printf "(100,5): ~a ~a ~a ~a~n"
>         (send t find-position 100 5 at-eol? on-it? edge-close?) (unbox
> at-eol?) (unbox on-it?) (unbox edge-close?))
> (printf "(200,5): ~a ~a ~a ~a~n"
>         (send t find-position 200 5 at-eol? on-it? edge-close?) (unbox
> at-eol?) (unbox on-it?) (unbox edge-close?))
> (printf "(400,5): ~a ~a ~a ~a~n"
>         (send t find-position 400 5 at-eol? on-it? edge-close?) (unbox
> at-eol?) (unbox on-it?) (unbox edge-close?))
> 
> ;; scroll to certain locations in the text
> (define (do-scroll-text)
>   (printf "scroll:~a~n" (send (send t get-admin) scroll-to -400 0 50 50 #t
> 'none))
>   (sleep 1.0)
>   (printf "scroll:~a~n" (send t scroll-to s 200 0 50 50 #t 'start))
>   (sleep 1.0)
>   (printf "scroll:~a~n" (send p scroll-to s 400 5 50 50 #t 'start))
>   (sleep 1.0)
>   (printf "scroll:~a~n" (send t scroll-to s 800 5 50 50 #t 'start))
>   (sleep 1.0)
>   )
> 
> (thread do-scroll-text)
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users