stk/STklos/Examples/E2.stklos

;;;;
;;;; E x a m p l e 2.  s t k
;;;;
;;;; Copyright (C) 1993,1994,1995 Erick Gallesio - I3S-CNRS/ESSI <eg@unice.fr>
;;;; 
;;;; Permission to use, copy, and/or distribute this software and its
;;;; documentation for any purpose and without fee is hereby granted, provided
;;;; that both the above copyright notice and this permission notice appear in
;;;; all copies and derived works.  Fees for distribution or use of this
;;;; software or derived works may only be charged with express written
;;;; permission of the copyright holder.  
;;;; This software is provided ``as is'' without express or implied warranty.
;;;;
;;;;           Author: Erick Gallesio [eg@kaolin.unice.fr]
;;;;    Creation date:  4-Aug-1994 15:22 
;;;; Last file update: 22-Mar-1998 17:07


(require "Canvas")
(define c (make <Canvas>))
(pack c)

;;;; Hereafter is a definition of a new composite Canvas item. This composite
;;;; object is formed of a text contained in a box.
;;;; Note how values are propagated: For instance changing the font of 
;;;; a <Boxed-text> will propagate this change to the object contained in the slot 
;;;; text-item. changing the foregroung of a  <Boxed-text> will be propagated to 
;;;; the "outline" of its box and to the "fill" of its text.

(define-class <Boxed-Text> (<Tk-Composite-item>)
  ((box-item   :accessor 	box-item)
   (text-item  :accessor 	text-item)
   ;; Propagated slots
   (text       :getter 		text-of
	       :init-keyword 	:text
	       :allocation 	:propagated 
	       :propagate-to 	(text-item))
   (coords     :getter 		coords 
	       :init-keywords 	:coords
	       :allocation 	:propagated
	       :propagate-to 	(text-item))
   (font       :getter 		font
	       :init-keyword	:font
	       :allocation 	:propagated 
	       :propagate-to 	(text-item))
   (foreground :accessor 	foreground
	       :allocation 	:propagated 
	       :propagate-to 	((box-item outline) (text-item fill)))
   (background :accessor 	background
	       :allocation 	:propagated
	       :propagate-to 	((box-item fill)))))

;;;; Herafter is a definition of the initialize-item method which will be 
;;;; automagically called upon instance creation. This is this routine which 
;;;; will create the components of the composite object.

(define-method initialize-item ((self  <Boxed-Text>) canvas coords args)
  (let* ((parent      (slot-ref self 'parent))
	 (text        (get-keyword :text args ""))
	 (t 	      (make <Text-item> :text text
			    :anchor "nw" :parent parent :coords coords))
	 (coords-rect (bounding-box t))
	 (r 	      (make <Rectangle> :parent parent :coords coords-rect))
	 (Cid 	      (gensym "group")))

    ;; set the true slots
    (slot-set! self 'Cid       Cid)
    (slot-set! self 'box-item  r)
    (slot-set! self 'text-item t)

    ;; Add the r and t component to the "Group" whith tag "Cid"
    (add-to-group self r t)

    ;; Raise the text to be sure it will not be under the rectangle
    (raise t)

    ;; Give this association a default binding allowing it to be moved with mouse
    (bind-for-dragging parent :tag Cid :only-current #f)
    
    ;; Return Cid
    Cid))
  
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;
;;;; Some methods which guarantish that the box is always the good size
;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define-method (setter font) ((bt <Boxed-text>) value)
  (let ((t (text-item bt)))
    (set! (font t) value)
    (set! (coords (box-item bt)) (bounding-box t))))

(define-method (setter text-of) ((bt <Boxed-text>) value)
  (let ((t (text-item bt)))
    (set! (text-of t) value)
    (set! (coords (box-item bt)) (bounding-box t))))

(define-method (setter coords) ((bt <Boxed-text>) value)
  (unless (and (list? value) (= (length value) 2))
     (error "coords: must be a list of 2 elements. It was ~S" value))
  (let ((t (text-item bt)))
    (set! (coords t) value)
    (set! (coords (box-item bt)) (bounding-box t))))


;;;; And now a little demo using the preceding new widget

(define (demo)
  (let ((x  (make <Boxed-text> :parent c :coords '(50 50) :text "Hello")))
    (update)
    
    (after 1000)
    (do ((i 0 (+ i 3)))
	((> i 200))
      (set! (coords x) (list i i))
      (update))

    (after 1000)
    (set! (coords x) '(100 100))
    (set! (font x)  "10x20")
    (set! (text-of x) "That's all, folks!")
    (set! (background x) "lightblue")

    ;; Destroying the group will destroy all the components and change the class
    ;; of x to <Destroyed-object>
    (update)
    (after 1000)
    (destroy x)
    (format #t "class of x = ~S\n" (class-name (class-of x)))))


;;; Run the demo
(demo)