;;; ezd - easy drawing for X11 displays.
;;;
;;; The procedures in this module implement popup menus.

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;;; The procedure DEFINE-POPUP defines a procedure that implements a popup
;;; menu.  The user supplies a procedure name, a list of menu entries and
;;; actions and optionally a font.  Each menu entry/action is a list of either
;;; a string, a procedure, or an expression that evaluates to a string and an
;;; action procedure or expression to be evaluated.
;;;
;;; The menu is attached to some object by using a WHEN command to associate
;;; the evaluation of the popup procedure with a button press.  When the button
;;; is pressed, the menu will come up under the button.  When the button comes
;;; up, the action associated with the menu entry is executed.  Moving the
;;; mouse outside the menu without releasing the button will cause the menu to
;;; disappear.
;;;
;;; The popup menu object has the following attributes.  Address them in the
;;; drawing "popup-name", object POPUP.
;;;
;;;	ENTRIES
;;;	REPLACE-NAME
;;;	REPLACE-ACTION
;;;	FOREGROUND
;;;	BACKGROUND
;;;	FONT
;;;
;;;	DELETE-OBJECT
;;;	ATTRIBUTES

(define (define-popup popup-name name-action-list colors font)
    
    (define foreground (if colors (car colors) 'black))
    (define background (if colors (cadr colors) 'white))
    
    (define window #f)
    (define visible #f)
    
    (define menu-x #f)
    (define menu-y #f)
    (define menu-width 0)
    (define menu-height 0)
    (define menu-length (length name-action-list))
    (define popped-window #f)
    (define popped-drawing #f)
    (define popped-object #f)
    (define popped-object-x #f)
    (define popped-object-y #f)
    
    (define (any-button?) (or *mouse-button1* *mouse-button2* *mouse-button3*
			      *mouse-button4* *mouse-button5*))
    
    ;;; Compute the size of a menu entry text string.
    
    (define (compute-menu-width-and-height text)
	    (let ((height-width (text->height-width (string-append "  " text
							"  ") font)))
		 (set! menu-height
		       (max menu-height (* 2 (car height-width))))
		 (set! menu-width
		       (max menu-width (cadr height-width)))))
    
    ;;; Service procedure to make the window invisible.
    
    (define (make-invisible)
	    (when visible
		  (set! visible #f)
		  (ezd `(delete-view ,popup-name ,popup-name))))
    
    ;;; When the window is initially poped up, the following procedure is
    ;;; called to verify that the mouse is still in the window.
    
    (define (drop-when-not-there)
	    (if (and visible
		     (or (< *mouse-x* menu-x)
			 (> *mouse-x* (+ menu-x menu-width))
			 (< *mouse-y* menu-y)
			 (> *mouse-y* (* menu-length (+ menu-y menu-height)))
			 (not (any-button?))))
		(make-invisible)))
    
    ;;; When the button event occurs, the following procedure is called to
    ;;; display the popup menu in its own window.
    
    (define (popitup)
	    (set! menu-x (max 0 (- *mouse-x* (quotient menu-width 2))))
	    (set! menu-y (max 0 (- *mouse-y* (quotient menu-height 2))))
	    (set! popped-window *user-event-window*)
	    (set! popped-drawing *user-event-drawing*)
	    (set! popped-object *user-event-object*)
	    (set! popped-object-x *user-event-x*)
	    (set! popped-object-y *user-event-y*)
	    (if window
		(xmovewindow *dpy* (window-xwindow window) menu-x menu-y)
		(begin (ezd `(window ,popup-name ,menu-x ,menu-y ,menu-width
				     ,(* menu-length menu-height)))
		       (set! window (name->window popup-name))
                       (let-temporary ((x (make-xsetwindowattributes) free-xsetwindowattributes))
			 (set-xsetwindowattributes-save_under! x 1)
			 (set-xsetwindowattributes-override_redirect! x 1)
		         (xchangewindowattributes *dpy* (window-xwindow window)
			   (bit-or CWSAVEUNDER CWOVERRIDEREDIRECT)
                           x))))
	    (set! visible #t)
	    (ezd `(overlay ,popup-name ,popup-name)))
    
    ;;; Procedures to draw a menu entry as either high or low lighted.
    
    (define (highlight object y text)
	    (draw-text object y text background foreground #f))
    
    (define (lowlight object y text)
	    (draw-text object y text foreground background #f))
    
    (define (draw-text object y text forecolor backcolor stipple)
	    (ezd `(set-drawing ,popup-name)
		 `(object ,object (fill-rectangle 0 ,y ,menu-width
				      ,menu-height ,backcolor)
			  (text 0 ,y ,menu-width ,menu-height center center
				,(menu-text text) ,forecolor
				,@(if stipple (list stipple) '())
				,@(if font (list font) '())))))
    
    ;;; Compute the actual text string.
    
    (define (menu-text menu-name)
	    (cond ((string? menu-name) menu-name)
		  ((procedure? menu-name) (menu-name))
		  (else (eval menu-name))))
    
    ;;; The following procedure "configures" the drawing representing the
    ;;; popup menu.  It is called 
    
    (define  (configure-popup)
	(if window (ezd `(delete-window ,popup-name)))
	(set! window #f)
	(set! visible #f)
	(set! menu-width 0)
	(set! menu-height 0)
	(set! menu-length (length name-action-list))
	;;; 1. Compute size of the menu.
	(for-each
	    (lambda (name-action) (compute-menu-width-and-height
				      (menu-text (car name-action))))
	    name-action-list)
	;;; 2. Draw the entries in the menu and arm their event handlers.
	(ezd '(save-drawing)
	     `(set-drawing ,popup-name)
	     '(object popup)
	     `(when popup get-attributes ,get-attributes)
	     `(when popup set-attributes ,set-attributes))
	(let loop ((y 0) (args name-action-list))
	     (if (pair? args)
		 (let* ((name-action (car args))
			(object (string->symbol (format "~s-~s" popup-name y)))
			(text (car name-action))
			(action (cadr name-action)))
		       
		       (define (enter-obj)
			       (if (any-button?)
				   (if action (highlight object y text))
				   (make-invisible)))
		       
		       (define (exit-obj)
			       (if action (lowlight object y text))
			       (unless (and *mouse-window*
					    (eq? (window-name *mouse-window*)
						 popup-name)
					    *mouse-object*)
				       (make-invisible)))
		       
		       (define (execute-obj)
			       (lowlight object y text)
			       (make-invisible)
			       (set! *user-event-type* 'popup)
			       (set! *user-event-window* popped-window)
			       (set! *user-event-drawing* popped-drawing)
			       (set! *user-event-object* popped-object)
			       (set! *user-event-x* popped-object-x)
			       (set! *user-event-y* popped-object-y)
			       (set! *user-event-misc*
				     (list popup-name (menu-text text)))
			       (ezd `(set-drawing *user-event-drawing*)
				    '(draw-now))
			       (if (procedure? action) (action) (eval action)))
		       
		       (draw-text object y text foreground background
			   (if action #f 's8))
		       (if action
			   (ezd `(when ,object button1up ,execute-obj)
				`(when ,object button2up ,execute-obj)
				`(when ,object button3up ,execute-obj)
				`(when ,object button4up ,execute-obj)
				`(when ,object button5up ,execute-obj))
			   (ezd `(when ,object * #f)))
		       (ezd `(when ,object enter ,enter-obj)
			    `(when ,object exit ,exit-obj))
		       (loop (+ y menu-height) (cdr args)))))
	(ezd `(when * expose ,drop-when-not-there)
	     '(restore-drawing)))
    
    ;;; Attributes are accessed via the following procedure.
    
    (define (get-attributes)
	    (map (lambda (a)
			 (case a
			       ((entries) (flatten name-action-list))
			       ((foreground) foreground)
			       ((background) background)
			       ((font) font)
			       ((attributes) '(entries replace-name
						  replace-action foreground
						  background font delete-object
						  attributes))
			       (else (ezd-error 'check-button
					 "Illegal attribute: ~s" a))))
		 *user-event-misc*))
    
    ;;; List conversion functions ((a b) (c d)) <--> (a b c d)
    
    (define (flatten x)
	    (if (pair? x) (cons* (caar x) (cadar x) (flatten (cdr x))) '()))
    
    (define (pair-up x)
	    (if (pair? x)
		(cons (list (car x) (cadr x)) (pair-up (cddr x)))
		'()))
    
    ;;; Attribute argument parsers.
    
    (define (name-action-list? x)
	    (or (null? x)
		(and (pair? x) (popup-entry-name? (car x))
		     (pair? (cdr x)) (popup-entry-action? (cadr x))
		     (name-action-list? (cddr x)))))
    
    (define (entry-index? x)
	    (and (exact? x) (<= 0 x) (< x (length name-action-list))))
    
    ;;; Attributes are changed via the following procedure.
    
    (define (set-attributes)
	    (let ((delete #f))
		 (for-each
		     (lambda (a)
			     (cond ((and (pair? a) (eq? (car a) 'entries)
					 (name-action-list? (cdr a)))
				    (set! name-action-list (pair-up (cdr a))))
				   ((match? (replace-name entry-index?
						popup-entry-name?) a)
				    (set-car!
					(list-ref name-action-list (cadr a))
					(caddr a)))
				   ((match? (replace-action entry-index?
						popup-entry-action?) a)
				    (set-car!
					(cdr (list-ref name-action-list
						 (cadr a)))
					(caddr a)))
				   ((match? (foreground color?) a)
				    (set! foreground (cadr a)))
				   ((match? (background color?) a)
				    (set! background (cadr a)))
				   ((match? (font string?) a)
				    (set! font (cadr a)))
				   ((equal? '(delete-object) a)
				    (set! delete #t))
				   (else (ezd-error 'slider
					     "Illegal attribute: ~s" a))))
		     *user-event-misc*)
		 (if delete
		     (ezd `(delete-window ,popup-name)
			  '(save-drawing)
			  `(set-drawing ,popup-name)
			  '(clear)
			  '(restore-drawing))
		     (begin (if visible (make-invisible))
			    (configure-popup)))))
    
    ;;; Install POPITUP as the top-level value of the value of POPUP-NAME.
    (configure-popup)
    ;; TODO less ugly hack
    (block-set! popup-name 0 popitup))

;;; Booleans for command and attribute parsing.

(define (popup-entry-name? x) (or (string? x) (procedure? x) (pair? x)))

(define (popup-entry-action? x) (or (pair? x) (procedure? x) (eq? x #f)))

(define-ezd-command
    `(define-popup ,symbol? (repeat ,popup-entry-name? ,popup-entry-action?)
	 (optional ,color? ,color?) (optional ,string?))
    "(define-popup popup-name item-action-list [foreground background] [\"font\"])"
    define-popup)