chickadee » pstk

PS/Tk

PS/Tk provides an interface to the Tk toolkit, and is an effective tool for creating graphical interfaces.

Examples

Several examples can be found in the git repository for this egg, as well as a detailed guide to using Tk from Scheme.

Hello World

(import pstk)

(tk-start)

(tk/pack 
  (tk 'create-widget 'button 'text: "Hello" 
      'command: (lambda () (display "Hello world") (newline)))
  'padx: 20 'pady: 20)
(tk-event-loop)

Simple Dialog

(import pstk)

(define (celsius->fahrenheit item)
  (let ((number (string->number item)))
    (if (number? number)
      (+ (* number 9/5) 32)
      0.0)))

(tk-start)
(tk/wm 'title tk "Celsius to Fahrenheit")

(let* ((celsius (tk 'create-widget 'entry))
       (label (tk 'create-widget 'label))
       (button (tk 'create-widget 'button
		   'text: 'Calculate
		   'command: (lambda () 
			       (label 'configure 
				      'text: (number->string (celsius->fahrenheit (celsius 'get))))))))
  ; layout widgets in a grid
  (tk/grid celsius 'column: 2 'row: 1 'sticky: 'we 'padx: 5 'pady: 5)
  (tk/grid label 'column: 2 'row: 2 'sticky: 'we 'padx: 5 'pady: 5)
  (tk/grid button 'column: 2 'row: 3 'sticky: 'we 'padx: 5 'pady: 5)
  (tk/grid (tk 'create-widget 'label 'text: "celsius") 
	   'column: 3 'row: 1 'sticky: 'w 'padx: 5 'pady: 5)
  (tk/grid (tk 'create-widget 'label 'text: "is") 
	   'column: 1 'row: 2 'sticky: 'e 'padx: 5 'pady: 5)
  (tk/grid (tk 'create-widget 'label 'text: "fahrenheit") 
	   'column: 3 'row: 2 'sticky: 'w 'padx: 5 'pady: 5)

  (tk-event-loop))

Tips on Using PS/Tk

• By default, the program tclsh8.6 is called, but an alternative program may be provided as an optional argument to (tk-start). For a distributable application, you can bundle tclkit with your application, and call the tclkit application in tk-start.
• Under windows, there is a problem with keyboard input. Currently, the fix is to show a dialog box which is dismissed by pressing 'Enter' (not clicking!) directly after starting tk.

(tk-start "wish85")
(tk/message-box 'title: "starting program" 'message: "Press ENTER" 'type: 'ok)
(tk-wm title tk "PROGRAM") 
etc

• It is helpful to put an exception handler around your tk code to prevent orphaned shells, especially when developing your program. e.g.

(handle-exceptions
  exn
  (tk-end)  ; make sure tk is closed in event of any error
  ; begin program
  (tk-start)
 ; rest of  gui setup
 )

• By default, PS/Tk just prints Tcl/Tk errors to stdout. To make PS/Tk throw an exception on Tk errors, run

(tk-throw-exceptions #t)

• PS/Tk currently does not work on Windows 7 due some problem with Posix/process. It will simply hang after (tk-start "tclsh85") See http://bugs.call-cc.org/ticket/765 for a workaround (You need to add

(set! process (lambda (#!rest rest)
    (receive (a b c d) (apply process* rest)
    (values a b c))))

to your .scm file like this:

(require-extension pstk)

;; http://bugs.call-cc.org/ticket/765
;; broken posix/process function under Windows 7 (MingW)
(set! process (lambda (#!rest rest)
    (receive (a b c d) (apply process* rest)
    (values a b c))))
(tk-start "tclsh85")
(tk/pack 
  (tk 'create-widget 'button 'text: "Hello" 
      'command: (lambda () (display "Hello world") (newline)))
  'padx: 20 'pady: 20)
(tk-event-loop)

• If you want to display unicode characters then you need to add the following to pstk.scm:

     (tk-init-string
       (string-intersperse
                          '("package require Tk"
                            "fconfigure stdin -encoding utf-8"
                            "fconfigure stdout -encoding utf-8"
                            "if {[package version tile] != \"\"} {"
                            "    package require tile"
                            "}"

Alternatively, add the following in your script:

(tk-start)
(tk-eval "fconfigure stdin -encoding ascii")
(tk-eval "fconfigure stdout -encoding ascii")

Authors

Kenneth A Dickey, Nils M Holm and Wolf-Dieter Busch created the initial versions of pstk. This port to Chicken, plus some additions, is by Peter Lane.

Repository

https://github.com/utz82/pstk

License

BSD 2-clause

Requirements

Requires an installation of tcltk or tclkit.

Version History

• version 1.4.1: add tk/font (T. Kurt Bond)
• version 1.4.0: exit Tk application when parent Scheme process crashes, provide an option to throw exceptions on Tcl/Tk errors
• version 1.3.1: remove legacy keyword support detection, map panedwindow to ttk/panedwindow
• version 1.3.0: set default tcl/tk runtime to tclsh8.6, Chicken 5 compatibility
• version 1.2.2: get rid of implicit dependency on letrec*-semantics in letrec call (Peter Bex)
• version 1.2.1: avoid hitting apply argument limit (Jim Ursetto)
• version 1.2: removed posix dependency from meta file (felix)
• version 1.1: working on windows as well as linux
• version 1.0: first package.