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lisp/ruler-mode.el

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+;;; ruler-mode.el --- Display a ruler in the header line
+
+;; Copyright (C) 2001 Free Software Foundation, Inc.
+
+;; Author: David Ponce <david@dponce.com>
+;; Maintainer: David Ponce <david@dponce.com>
+;; Created: 24 Mar 2001
+;; Version: 1.3.1
+;; Keywords: environment
+
+;; This file is part of GNU Emacs.
+
+;; 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 2, 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., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; This library provides a minor mode to display a ruler in the header
+;; line.  It works only on Emacs 21.
+;;
+;; You can use the mouse to change the `fill-column', `window-margins'
+;; and `tab-stop-list' settings:
+;;
+;; [header-line (shift down-mouse-1)] set left margin to the ruler
+;; graduation where the mouse pointer is on.
+;;
+;; [header-line (shift down-mouse-3)] set right margin to the ruler
+;; graduation where the mouse pointer is on.
+;;
+;; [header-line down-mouse-2] set `fill-column' to the ruler
+;; graduation where the mouse pointer is on.
+;;
+;; [header-line (control down-mouse-1)] add a tab stop to the ruler
+;; graduation where the mouse pointer is on.
+;;
+;; [header-line (control down-mouse-3)] remove the tab stop at the
+;; ruler graduation where the mouse pointer is on.
+;;
+;; [header-line (control down-mouse-2)] or M-x
+;; `ruler-mode-toggle-show-tab-stops' toggle showing and visually
+;; editing `tab-stop-list' setting.  The `ruler-mode-show-tab-stops'
+;; option controls if the ruler shows tab stops by default.
+;;
+;; In the ruler the character `ruler-mode-current-column-char' shows
+;; the `current-column' location, `ruler-mode-fill-column-char' shows
+;; the `fill-column' location and `ruler-mode-tab-stop-char' shows tab
+;; stop locations.  `window-margins' areas are shown with a different
+;; background color.
+;;
+;; It is also possible to customize the following characters:
+;;
+;; - `ruler-mode-margins-char' character used to pad margin areas
+;;   (space by default).
+;; - `ruler-mode-basic-graduation-char' character used for basic
+;;   graduations ('.' by default).
+;; - `ruler-mode-inter-graduation-char' character used for
+;;   intermediate graduations ('!' by default).
+;;
+;; The following faces are customizable:
+;;
+;; - `ruler-mode-default-face' the ruler default face.
+;; - `ruler-mode-fill-column-face' the face used to highlight the
+;;   `fill-column' character.
+;; - `ruler-mode-current-column-face' the face used to highlight the
+;;   `current-column' character.
+;; - `ruler-mode-tab-stop-face' the face used to highlight tab stop
+;;   characters.
+;; - `ruler-mode-margins-face' the face used to highlight the
+;;   `window-margins' areas.
+;; - `ruler-mode-column-number-face' the face used to highlight the
+;;   number graduations.
+;;
+;; `ruler-mode-default-face' inherits from the built-in `default' face.
+;; All `ruler-mode' faces inerit from `ruler-mode-default-face'.
+;;
+;; WARNING: To keep ruler graduations aligned on text columns it is
+;; important to use the same font family and size for ruler and text
+;; areas.
+
+;; Installation
+;;
+;; To automatically display the ruler in specific major modes use:
+;;
+;;    (add-hook '<major-mode>-hook 'ruler-mode)
+;;
+
+;;; History:
+;;
+
+;;; Code:
+(eval-when-compile
+  (require 'wid-edit))
+
+(defgroup ruler-mode nil
+  "Display a ruler in the header line."
+  :version "21.2"
+  :group 'environment)
+
+(defcustom ruler-mode-show-tab-stops nil
+  "*If non-nil the ruler shows tab stop positions.
+Also allowing to visually change `tab-stop-list' setting using
+<C-down-mouse-1> and <C-down-mouse-3> on the ruler to respectively add
+or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
+<C-down-mouse-2> on the ruler toggles showing/editing of tab stops."
+  :group 'ruler-mode
+  :type 'boolean)
+
+;; IMPORTANT: This function must be defined before the following
+;; defcustoms because it is used in their :validate clause.
+(defun ruler-mode-character-validate (widget)
+  "Ensure WIDGET value is a valid character value."
+  (save-excursion
+    (let ((value (widget-value widget)))
+      (if (char-valid-p value)
+          nil
+        (widget-put widget :error
+                    (format "Invalid character value: %S" value))
+        widget))))
+      
+(defcustom ruler-mode-fill-column-char (if window-system
+                                           ?\¶
+                                         ?\|)
+  "*Character used at the `fill-column' location."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-current-column-char (if window-system
+                                              ?\¦
+                                            ?\@)
+  "*Character used at the `current-column' location."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-tab-stop-char ?\T
+  "*Character used at `tab-stop-list' locations."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-margins-char ?\ 
+  "*Character used in margin areas."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-basic-graduation-char ?\.
+  "*Character used for basic graduations."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-inter-graduation-char ?\!
+  "*Character used for intermediate graduations."
+  :group 'ruler-mode
+  :type '(choice
+          (character :tag "Character")
+          (integer :tag "Integer char value"
+                   :validate ruler-mode-character-validate)))
+
+(defface ruler-mode-default-face
+  '((((type tty))
+     (:inherit default
+               :background "grey64"
+               :foreground "grey50"
+               ))
+    (t
+     (:inherit default
+               :background "grey76"
+               :foreground "grey64"
+               :box (:color "grey76"
+                            :line-width 1
+                            :style released-button)
+               )))
+  "Default face used by the ruler."
+  :group 'ruler-mode)
+
+(defface ruler-mode-column-number-face
+  '((t
+     (:inherit ruler-mode-default-face
+               :foreground "black"
+               )))
+  "Face used to highlight number graduations."
+  :group 'ruler-mode)
+
+(defface ruler-mode-fill-column-face
+  '((t
+     (:inherit ruler-mode-default-face
+               :foreground "red"
+               )))
+  "Face used to highlight the fill column character."
+  :group 'ruler-mode)
+
+(defface ruler-mode-tab-stop-face
+  '((t
+     (:inherit ruler-mode-default-face
+               :foreground "steelblue"
+               )))
+  "Face used to highlight tab stop characters."
+  :group 'ruler-mode)
+
+(defface ruler-mode-margins-face
+  '((((type tty))
+     (:inherit ruler-mode-default-face
+               :background "grey50"
+               ))
+    (t
+     (:inherit ruler-mode-default-face
+               :background "grey64"
+               )))
+  "Face used to highlight the `window-margins' areas."
+  :group 'ruler-mode)
+
+(defface ruler-mode-current-column-face
+  '((t
+     (:inherit ruler-mode-default-face
+               :weight bold
+               :foreground "yellow"
+               )))
+  "Face used to highlight the `current-column' character."
+  :group 'ruler-mode)
+
+(defun ruler-mode-mouse-set-left-margin (start-event)
+  "Set left margin to the graduation where the mouse pointer is on.
+START-EVENT is the mouse click event."
+  (interactive "e")
+  (let* ((start (event-start start-event))
+         (end   (event-end   start-event))
+         w col m lm0 lm rm)
+    (if (eq start end) ;; mouse click
+        (save-selected-window
+          (select-window (posn-window start))
+          (setq m   (window-margins)
+                lm0 (or (car m) 0)
+                rm  (or (cdr m) 0)
+                w   (window-width)
+                col (car (posn-col-row start))
+                lm  (min (- w rm) col))
+          (message "Left margin set to %d (was %d)" lm lm0)
+          (set-window-margins nil lm rm)))))
+
+(defun ruler-mode-mouse-set-right-margin (start-event)
+  "Set right margin to the graduation where the mouse pointer is on.
+START-EVENT is the mouse click event."
+  (interactive "e")
+  (let* ((start (event-start start-event))
+         (end   (event-end   start-event))
+         m col w lm rm0 rm)
+    (if (eq start end) ;; mouse click
+        (save-selected-window
+          (select-window (posn-window start))
+          (setq m   (window-margins)
+                rm0 (or (cdr m) 0)
+                lm  (or (car m) 0)
+                col (car (posn-col-row start))
+                w   (window-width)
+                rm  (max 0 (- w col)))
+          (message "Right margin set to %d (was %d)" rm rm0)
+          (set-window-margins nil lm rm)))))
+
+(defun ruler-mode-mouse-set-fill-column (start-event)
+  "Set `fill-column' to the graduation where the mouse pointer is on.
+START-EVENT is the mouse click event."
+  (interactive "e")
+  (let* ((start (event-start start-event))
+         (end   (event-end   start-event))
+         m col w lm rm hs fc)
+    (if (eq start end) ;; mouse click
+        (save-selected-window
+          (select-window (posn-window start))
+          (setq m   (window-margins)
+                lm  (or (car m) 0)
+                rm  (or (cdr m) 0)
+                col (- (car (posn-col-row start)) lm)
+                w   (window-width)
+                hs  (window-hscroll)
+                fc  (+ col hs))
+          (and (>= col 0) (< (+ col lm rm) w)
+               (progn
+                 (message "Fill column set to %d (was %d)" fc fill-column)
+                 (setq fill-column fc)))))))
+
+(defun ruler-mode-mouse-add-tab-stop (start-event)
+  "Add a tab stop to the graduation where the mouse pointer is on.
+START-EVENT is the mouse click event."
+  (interactive "e")
+  (if ruler-mode-show-tab-stops
+      (let* ((start (event-start start-event))
+             (end   (event-end   start-event))
+             m col w lm rm hs ts)
+        (if (eq start end) ;; mouse click
+            (save-selected-window
+              (select-window (posn-window start))
+              (setq m   (window-margins)
+                    lm  (or (car m) 0)
+                    rm  (or (cdr m) 0)
+                    col (- (car (posn-col-row start)) lm)
+                    w   (window-width)
+                    hs  (window-hscroll)
+                    ts  (+ col hs))
+              (and (>= col 0) (< (+ col lm rm) w)
+                   (not (member ts tab-stop-list))
+                   (progn
+                     (message "Tab stop set to %d" ts)
+                     (setq tab-stop-list
+                           (sort (cons ts tab-stop-list)
+                                 #'<)))))))))
+
+(defun ruler-mode-mouse-del-tab-stop (start-event)
+  "Delete tab stop at the graduation where the mouse pointer is on.
+START-EVENT is the mouse click event."
+  (interactive "e")
+  (if ruler-mode-show-tab-stops
+      (let* ((start (event-start start-event))
+             (end   (event-end   start-event))
+             m col w lm rm hs ts)
+        (if (eq start end) ;; mouse click
+            (save-selected-window
+              (select-window (posn-window start))
+              (setq m   (window-margins)
+                    lm  (or (car m) 0)
+                    rm  (or (cdr m) 0)
+                    col (- (car (posn-col-row start)) lm)
+                    w   (window-width)
+                    hs  (window-hscroll)
+                    ts  (+ col hs))     
+              (and (>= col 0) (< (+ col lm rm) w)
+                   (member ts tab-stop-list)
+                   (progn
+                     (message "Tab stop at %d deleted" ts)
+                     (setq tab-stop-list
+                           (delete ts tab-stop-list)))))))))
+
+(defun ruler-mode-toggle-show-tab-stops ()
+  "Toggle showing of tab stops on the ruler."
+  (interactive)
+  (when ruler-mode
+    (setq ruler-mode-show-tab-stops (not ruler-mode-show-tab-stops))
+    (force-mode-line-update)))
+
+(defvar ruler-mode-map
+  (let ((km (make-sparse-keymap)))
+    (define-key km [header-line down-mouse-1]
+      #'ignore)
+    (define-key km [header-line down-mouse-3]
+      #'ignore)
+    (define-key km [header-line down-mouse-2]
+      #'ruler-mode-mouse-set-fill-column)
+    (define-key km [header-line (shift down-mouse-1)]
+      #'ruler-mode-mouse-set-left-margin)
+    (define-key km [header-line (shift down-mouse-3)]
+      #'ruler-mode-mouse-set-right-margin)
+    (define-key km [header-line (control down-mouse-1)]
+      #'ruler-mode-mouse-add-tab-stop)
+    (define-key km [header-line (control down-mouse-3)]
+      #'ruler-mode-mouse-del-tab-stop)
+    (define-key km [header-line (control down-mouse-2)]
+      #'ruler-mode-toggle-show-tab-stops)
+    km)
+  "Keymap for ruler minor mode.")
+
+(defvar ruler-mode-header-line-format-old nil
+  "Hold previous value of `header-line-format'.")
+(make-variable-buffer-local 'ruler-mode-header-line-format-old)
+
+(defconst ruler-mode-header-line-format
+  '(:eval (ruler-mode-ruler))
+  "`header-line-format' used in ruler mode.")
+
+;;;###autoload
+(define-minor-mode ruler-mode
+  "Display a ruler in the header line if ARG > 0."
+  nil nil
+  ruler-mode-map
+  :group 'ruler-mode
+  (if ruler-mode
+      (progn
+        ;; When `ruler-mode' is on save previous header line format
+        ;; and install the ruler header line format.
+        (setq ruler-mode-header-line-format-old header-line-format
+              header-line-format ruler-mode-header-line-format)
+        (add-hook 'post-command-hook    ; add local hook
+                  #'force-mode-line-update nil t))
+    ;; When `ruler-mode' is off restore previous header line format if
+    ;; the current one is the ruler header line format.
+    (if (eq header-line-format ruler-mode-header-line-format)
+        (setq header-line-format ruler-mode-header-line-format-old))
+    (remove-hook 'post-command-hook     ; remove local hook
+                 #'force-mode-line-update t)))
+
+;; Add ruler-mode to the the minor mode menu in the mode line
+(define-key mode-line-mode-menu [ruler-mode]
+  `(menu-item "Ruler" ruler-mode
+	      :button (:toggle . ruler-mode)))
+
+(defconst ruler-mode-ruler-help-echo
+  "\
+S-mouse-1/3: set L/R margin, \
+mouse-2: set fill col, \
+C-mouse-2: show tabs"
+  "Help string shown when mouse pointer is over the ruler.
+`ruler-mode-show-tab-stops' is nil.")
+
+(defconst ruler-mode-ruler-help-echo-tab
+  "\
+C-mouse1/3: set/unset tab, \
+C-mouse-2: hide tabs"
+  "Help string shown when mouse pointer is over the ruler.
+`ruler-mode-show-tab-stops' is non-nil.")
+
+(defconst ruler-mode-left-margin-help-echo
+  "Left margin %S"
+  "Help string shown when mouse is over the left margin area.")
+
+(defconst ruler-mode-right-margin-help-echo
+  "Right margin %S"
+  "Help string shown when mouse is over the right margin area.")
+
+(defvar ruler-mode-left-fringe-cols nil
+  "Hold last result of function `ruler-mode-left-fringe-cols'.
+This cache is local to each frame.")
+(make-variable-frame-local 'ruler-mode-left-fringe-cols)
+
+(defun ruler-mode-left-fringe-cols (&optional check)
+  "Return the character width of fringe and left vertical scrollbar.
+That is a pair (FRINGE-COLS . VSCROLLBAR-COLS) where:
+
+- - FRINGE-COLS is the number of columns occupied by a fringe area.
+
+- - VSCROLLBAR-COLS is the number of columns occupied by the left
+    vertical scrollbar or 0 if there is no vertical scrollbar on the
+    left side.
+
+The first time this function is called its result is saved in a frame
+local cache and then returned on next calls.  If optional argument
+CHECK is non-nil or if the frame 'vertical-scroll-bars parameter has
+been changed the function re-computes the result."
+  (let* ((f   (selected-frame))
+         (vsb (frame-parameter f 'vertical-scroll-bars))
+         (lfc (frame-parameter f 'ruler-mode-left-fringe-cols)))
+    (if (or check (not (eq (cdr lfc) vsb)))
+        (let* ((w   (frame-first-window f))
+               (sbw (frame-pixel-width f))
+               (chw (frame-char-width f))
+               (chx (/ 1.0 (float chw)))
+               (pos (cons 0.0 0))
+               (lfw 0.0)
+               coord)
+          (if vsb
+              (modify-frame-parameters
+               f '((vertical-scroll-bars . nil))))
+          (setq coord (coordinates-in-window-p pos w))
+          (while (not (memq coord '(left-fringe mode-line)))
+            (setcdr pos (1+ (cdr pos)))
+            (setq coord (coordinates-in-window-p pos w)))
+          (while (eq coord 'left-fringe)
+            (setcar pos (+ (car pos) chx))
+            (setq lfw   (+ lfw chx)
+                  coord (coordinates-in-window-p pos w)))
+          (or vsb
+              (modify-frame-parameters
+               f '((vertical-scroll-bars . right))))
+          (setq sbw (/ (abs (- sbw (frame-pixel-width f))) chw)
+                lfw (floor lfw))
+          (setq lfc (cons (cons lfw (if (eq vsb 'left) sbw 0)) vsb))
+          (modify-frame-parameters
+           f (list (cons 'vertical-scroll-bars vsb)
+                   (cons 'ruler-mode-left-fringe-cols lfc)))))
+    (car lfc)))
+
+(defun ruler-mode-ruler ()
+  "Return a string ruler."
+  (if ruler-mode
+      (let* ((lfr   (ruler-mode-left-fringe-cols))
+             (w     (+ (window-width) 1 (cdr lfr)))
+             (m     (window-margins))
+             (l     (or (car m) 0))
+             (r     (or (cdr m) 0))
+             (j     (+ (car lfr) (cdr lfr)))
+             (o     (- (window-hscroll) l j))
+             (i     0)
+             (ruler (concat
+                     ;; unit graduations
+                     (make-string w ruler-mode-basic-graduation-char)
+                     ;; extra space to fill the header line
+                     (make-string j ?\ )))
+             c k)
+
+        ;; Setup default face and help echo.
+        (put-text-property 0 (length ruler)
+                           'face 'ruler-mode-default-face
+                           ruler)
+        (put-text-property 0 (length ruler)
+                           'help-echo 
+                           (if ruler-mode-show-tab-stops
+                               ruler-mode-ruler-help-echo-tab
+                             ruler-mode-ruler-help-echo)
+                           ruler)
+        ;; Setup the local map.
+        (put-text-property 0 (length ruler)
+                           'local-map ruler-mode-map
+                           ruler)
+
+        (setq j (+ l j))
+        ;; Setup the left margin area.
+        (put-text-property
+         i j 'face 'ruler-mode-margins-face
+         ruler)
+        (put-text-property
+         i j 'help-echo (format ruler-mode-left-margin-help-echo l)
+         ruler)
+        (while (< i j)
+          (aset ruler i ruler-mode-margins-char)
+          (setq i (1+ i)))
+
+        ;; Setup the ruler area.
+        (setq r (- w r))
+        (while (< i r)
+          (setq j (+ i o))
+          (cond
+           ((= (mod j 10) 0)
+            (setq c (number-to-string (/ j 10))
+                  m (length c)
+                  k i)
+            (put-text-property
+             i (1+ i) 'face 'ruler-mode-column-number-face
+             ruler)
+            (while (and (> m 0) (>= k 0))
+              (aset ruler k (aref c (setq m (1- m))))
+              (setq k (1- k)))
+            )
+           ((= (mod j 5) 0)
+            (aset ruler i ruler-mode-inter-graduation-char)
+            )
+           )
+          (setq i (1+ i)))
+
+        ;; Setup the right margin area.
+        (put-text-property
+         i (length ruler) 'face 'ruler-mode-margins-face
+         ruler)
+        (put-text-property
+         i (length ruler) 'help-echo
+         (format ruler-mode-right-margin-help-echo (- w r))
+         ruler)
+        (while (< i (length ruler))
+          (aset ruler i ruler-mode-margins-char)
+          (setq i (1+ i)))
+         
+        ;; Show the `fill-column' marker.
+        (setq i (- fill-column o))
+        (and (>= i 0) (< i r)
+             (aset ruler i ruler-mode-fill-column-char)
+             (put-text-property
+              i (1+ i) 'face 'ruler-mode-fill-column-face
+              ruler))
+
+        ;; Show the `tab-stop-list' markers.
+        (if ruler-mode-show-tab-stops
+            (let ((tsl tab-stop-list) ts)
+              (while tsl
+                (setq ts  (car tsl)
+                      tsl (cdr tsl)
+                      i   (- ts o))
+                (and (>= i 0) (< i r)
+                     (aset ruler i ruler-mode-tab-stop-char)
+                     (put-text-property
+                      i (1+ i)
+                      'face (cond
+                             ;; Don't override the fill-column face
+                             ((eq ts fill-column)
+                              'ruler-mode-fill-column-face)
+                             (t
+                              'ruler-mode-tab-stop-face))
+                      ruler)))))
+
+        ;; Show the `current-column' marker.
+        (setq i (- (current-column) o))
+        (and (>= i 0) (< i r)
+             (aset ruler i ruler-mode-current-column-char)
+             (put-text-property
+              i (1+ i) 'face 'ruler-mode-current-column-face
+              ruler))
+         
+        ruler)))
+
+(provide 'ruler-mode)
+
+;; Local Variables:
+;; coding: iso-latin-1
+;; End:
+
+;;; ruler-mode.el ends here