;;;;
;;;; B a l l o o n . s t k l o s  	  --  Help-Balloon class definition
;;;;
;;;; Copyright © 1996-1998 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.
;;;;
;;;; $Id: Balloon.stklos 1.3 Thu, 10 Sep 1998 23:44:28 +0200 eg $
;;;;
;;;;           Author: Erick Gallesio [eg@unice.fr]
;;;;    Creation date: 23-Oct-1996 17:02
;;;; Last file update: 31-Aug-1998 16:18
;;;;

(require "Basics")

(select-module STklos+Tk)

(export add-balloon)

;=============================================================================
;
;				 <Help-Balloon>
;
;=============================================================================

;;;;
;;;; Resources
;;;;
(option 'add "*HelpBalloon*Background"  	"#ffffb0" "widgetDefault")
(option 'add "*HelpBalloon*Font"        	"fixed"   "widgetDefault")
(option 'add "*HelpBalloon*Relief"		"flat"    "widgetDefault")
(option 'add "*HelpBalloon*HighlightThickness"	0 	  "widgetDefault")

;;;;
;;;; Class definition
;;;;
(define-class <Help-Balloon> (<Tk-composite-toplevel> <Label>)
  ((label :accessor 	label-of)
   (class :init-keyword :class
	  :init-form    "HelpBalloon")
   (delay :initform 	1000 ; ms
	  :init-keyword :delay 
	  :accessor	 delay)))

;;
;; Initialize-composite-widget
;;
(define-method initialize-composite-widget ((self <Help-balloon>) initargs parent)
  (let ((l (make <Label> :parent parent)))
    (next-method)
    (make-transient parent)
    
    ;; Pack the label in the parent window    
    (pack (Id l) :expand #t :fill "both")
    
    ; Set true slots
    (slot-set! self 'Id     (slot-ref l 'Id))
    (slot-set! self 'label  l)))

;;
;; Add-balloon
;;
(define-method add-balloon ((self <Help-Balloon>) who txt)
  (define handler #f)
  
  (define (display W txt)
    (after 'cancel handler)
    (let ((delay (delay self)))
      (when (>= delay 0)
	(set! handler
	      (after delay
		     (lambda ()
		       (let ((height (winfo 'height W))
			     (pos-y  (winfo 'rooty  W))
			     (top    (frame-of self)))
			 ;; Change the help text
			 (set! (text-of self) txt)
			 ;; place the balloon just outside the widget
			 (set! (geometry top) (format #f "+~A+~A"
						      (winfo 'pointerx W) 
						      (+ pos-y height 2)))
			 ;; Deiconify
			 (deiconify top)
			 (raise top))))))))
  (define (delete)
    (withdraw (frame-of self))
    (after 'cancel  handler))
    
  ;; Associate new bindings to a "ballooned" widget
  (bind who "<Enter>" (lambda () (display who txt)))
  (bind who "<Leave>" (lambda () (delete))))

(provide "Balloon")

#|
  Example:
	(define b  (make <Help-Balloon> :background "PaleGreen"))
	(define b1 (make <Button> :text "B1"))
	(define b2 (make <Button> :text "B2"))
	(pack b1 b2 :side "left")
	 
	(add-balloon b b1 "This is button b1")
	(add-balloon b b2 "This one is\n called b2")
|#