;;; sml-modeline.el --- Show position in a scrollbar like way in mode-line
;;
;; Author: Lennart Borgman (lennart O borgman A gmail O com)
;; Created: 2010-03-16 Tue
;; Version:
;; Last-Updated:
;; URL:
;; Keywords:
;; Compatibility:
;;
;; Features that might be required by this library:
;;
;;   None
;;
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;;
;;; Commentary:
;;
;; Show scrollbar like position indicator in mode line.
;;
;; Idea and part of this code is adapted from Drew Adam's code in this
;; mail message:
;;
;;   http://permalink.gmane.org/gmane.emacs.devel/122038
;;
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;;
;;; Change log:
;;
;;
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;;
;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 3, or
;; (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth
;; Floor, Boston, MA 02110-1301, USA.
;;
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;;
;;; Code:

(defgroup sml-modeline nil
  "Customization group for `sml-mode'."
  :group 'frames)

(defcustom sml-len 12
  "Mode line indicator total length."
  :type 'integer
  :group 'sml-modeline)

(defcustom sml-borders nil
  "Indicator borders.
This is a pair of indicators, like [] or nil."
  :type '(choice (const :tag "None" nil)
                 (cons (string :tag "Left border")
                       (string :tag "Right border")))
  :group 'sml-modeline)

;;(sml-create)
(defun sml-create ()
 (let* ((wstart (window-start))
        (wend (window-end))
        (real-point-max (save-restriction (widen) (point-max)))
        (percentage-beg (/ (float wstart) (float real-point-max)))
        (percentage-end (/ (float wend) (float real-point-max)))
        (sml-begin (or (car sml-borders) ""))
        (sml-end   (or (cdr sml-borders) ""))
        (inner-len (- sml-len (length sml-begin) (length sml-end)))
        bpad-len
        epad-len
        (start (floor (* percentage-beg inner-len)))
        (end (ceiling (* percentage-end inner-len)))
        string)
   (if (not (or (< wend real-point-max) (> wstart 1)))
       ""
     (setq string
           (concat (format "%02d" (round (* percentage-beg 100))) ""
                   "-"
                   (format "%02d" (round (* percentage-end 100))) "%%"
                   ))
     (setq bpad-len (/ (- inner-len (length string)) 2))
     (setq epad-len (- inner-len (length string) bpad-len))
     (setq string (concat sml-begin
                          (make-string bpad-len 32)
                          string
                          (make-string epad-len 32)
                          sml-end))
     (assert (= (length string) sml-len) t)
     (setq start (+ start (length sml-begin)))
     (when (= start
              (setq end (+ end (length sml-begin))))
       (setq end  (1+ end)))
     (when (and (= (elt string start) 37)
                (= (elt string end) 37))
       (setq end  (1+ end)))
     (put-text-property
      start end
      'face `(:background ,(face-foreground 'mode-line)
              :foreground ,(face-background 'mode-line))
      string)
     (when (and (= 0 (length sml-begin))
                (= 0 (length sml-end)))
       (put-text-property
        0 start
        'face `(:background ,(face-foreground 'mode-line-inactive)
                :foreground ,(face-background 'mode-line))
        string)
       (put-text-property
        end sml-len
        'face `(:background ,(face-foreground 'mode-line-inactive)
                :foreground ,(face-background 'mode-line))
        string)
       )
     string)))

(defvar sml-old-car-mode-line-position nil)

(define-minor-mode sml-mode
  "Show buffer size and position like scrollbar in mode line."
  :global t
  :group 'sml-modeline
  (if sml-mode
      (progn
        (unless sml-old-car-mode-line-position
          (setq sml-old-car-mode-line-position (car mode-line-position)))
        (setcar mode-line-position '(:eval (list (sml-create)))))
    (setcar mode-line-position sml-old-car-mode-line-position)))


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;;; sml-modeline.el ends here