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4.15.9 Form Windows

The form windows concept is pretty much similar to menu windows. Every form is associated with a main window and a subwindow. The form main window displays any title or border associated or whatever the user wishes. The subwindow contains all the fields and displays them according to their position. This gives the flexibility of manipulating fancy form displays easily.

Since this pretty similar to menu windows, I am providing a very similar example.


(use-modules (srfi srfi-1)
             (ncurses curses)
             (ncurses form))

;; Helper procedure to center a text
(define (print-in-middle win starty startx width str color)
  (let ((length (string-length str)))

    (attr-on! win color)
    (addstr win str
            #:y starty
            #:x (+ startx (/ (- width length) 2)))

    (attr-off! win color)
    (refresh stdscr)))

;; Initialize curses
(define stdscr (initscr))
(keypad! stdscr #t)

;;Initialize a few color pairs
(init-pair! 1 COLOR_RED COLOR_BLACK)

(define field (list
               (new-field 1 10 6 1 0 0)
               (new-field 1 10 8 1 0 0)))

;; Set field options
(set-field-back! (first field) A_UNDERLINE)
(field-opts-off! (first field) O_AUTOSKIP)

(set-field-back! (second field) A_UNDERLINE)
(field-opts-off! (second field) O_AUTOSKIP)

;; Create a new form
(define my-form (new-form field))

;; Calculate the area associated with the form
(define xy (scale-form my-form))
(define rows (car xy))
(define cols (cadr xy))

;; Create the window to be associated with the form
(define my-form-win (newwin (+ 4 rows)
                            (+ 4 cols)
(keypad! my-form-win #t)

;; Set main window and subwindow
(set-form-win! my-form my-form-win)
(set-form-sub! my-form (derwin my-form-win rows cols 2 2))

;; Print a border around the main window and print a title
(box my-form-win 0 0)
(print-in-middle my-form-win 1 0 (+ cols 4) "My Form" (color-pair 1))

(post-form my-form)
(refresh my-form-win)

(addstr stdscr "Use UP, DOWN arrow keys to switch between fields"
        #:y (- (lines) 2) #:x 0)
(refresh stdscr)

;; Loop through to get user requests
(let loop ((ch (getch my-form-win)))
  (if (not (eqv? ch (key-f 1)))
       ((eqv? ch KEY_DOWN)
          ;; Go to the end of the next field
          (form-driver my-form REQ_NEXT_FIELD)
          (form-driver my-form REQ_END_LINE)
          (loop (getch my-form-win))))
       ((eqv? ch KEY_UP)
          ;; Go to the end of the previous field
          (form-driver my-form REQ_PREV_FIELD)
          (form-driver my-form REQ_END_LINE)
          (loop (getch my-form-win))))
          ;; Print any normal character
          (form-driver my-form ch)
          (loop (getch my-form-win)))))))

;; Unpost the form
(unpost-form my-form)


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