X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/a5f7cb26edfbe40b892d0ef248f40dd4332939f9..21f8fcfd24dc96790589ad578c7ee54593fcfd10:/lisp/ruler-mode.el

diff --git a/lisp/ruler-mode.el b/lisp/ruler-mode.el
index 9d86074a0f..a441c3a112 100644
--- a/lisp/ruler-mode.el
+++ b/lisp/ruler-mode.el
@@ -1,12 +1,13 @@
-;;; ruler-mode.el --- Display a ruler in the header line
+;;; ruler-mode.el --- display a ruler in the header line
 
-;; Copyright (C) 2001 Free Software Foundation, Inc.
+;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
+;;   2006 Free Software Foundation, Inc.
 
 ;; Author: David Ponce <david@dponce.com>
 ;; Maintainer: David Ponce <david@dponce.com>
 ;; Created: 24 Mar 2001
-;; Version: 1.4
-;; Keywords: environment
+;; Version: 1.6
+;; Keywords: convenience
 
 ;; This file is part of GNU Emacs.
 
@@ -22,25 +23,25 @@
 
 ;; 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.
+;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, 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:
+;; You can use the mouse to change the `fill-column' `comment-column',
+;; `goal-column', `window-margins' and `tab-stop-list' settings:
 ;;
-;; [header-line (shift down-mouse-1)] set left margin to the ruler
+;; [header-line (shift down-mouse-1)] set left margin end 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 (shift down-mouse-3)] set right margin beginning 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 down-mouse-2] Drag the `fill-column', `comment-column'
+;; or `goal-column' to a ruler graduation.
 ;;
 ;; [header-line (control down-mouse-1)] add a tab stop to the ruler
 ;; graduation where the mouse pointer is on.
@@ -55,14 +56,14 @@
 ;;
 ;; 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.
+;; the `fill-column' location, `ruler-mode-comment-column-char' shows
+;; the `comment-column' location, `ruler-mode-goal-column-char' shows
+;; the `goal-column' and `ruler-mode-tab-stop-char' shows tab stop
+;; locations.  Graduations in `window-margins' and `window-fringes'
+;; areas are shown with a different foreground 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
@@ -70,24 +71,33 @@
 ;;
 ;; The following faces are customizable:
 ;;
-;; - `ruler-mode-default-face' the ruler default face.
-;; - `ruler-mode-fill-column-face' the face used to highlight the
+;; - `ruler-mode-default' the ruler default face.
+;; - `ruler-mode-fill-column' the face used to highlight the
 ;;   `fill-column' character.
-;; - `ruler-mode-current-column-face' the face used to highlight the
+;; - `ruler-mode-comment-column' the face used to highlight the
+;;   `comment-column' character.
+;; - `ruler-mode-goal-column' the face used to highlight the
+;;   `goal-column' character.
+;; - `ruler-mode-current-column' the face used to highlight the
 ;;   `current-column' character.
-;; - `ruler-mode-tab-stop-face' the face used to highlight tab stop
+;; - `ruler-mode-tab-stop' 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-margins' the face used to highlight graduations
+;;   in the `window-margins' areas.
+;; - `ruler-mode-fringes' the face used to highlight graduations
+;;   in the `window-fringes' areas.
+;; - `ruler-mode-column-number' the face used to highlight the
+;;   numbered graduations.
 ;;
-;; `ruler-mode-default-face' inherits from the built-in `default' face.
-;; All `ruler-mode' faces inerit from `ruler-mode-default-face'.
+;; `ruler-mode-default' inherits from the built-in `default' face.
+;; All `ruler-mode' faces inherit from `ruler-mode-default'.
 ;;
 ;; 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.
+;;
+;; You can override the ruler format by defining an appropriate
+;; function as the buffer-local value of `ruler-mode-ruler-function'.
 
 ;; Installation
 ;;
@@ -102,11 +112,13 @@
 ;;; Code:
 (eval-when-compile
   (require 'wid-edit))
+(require 'scroll-bar)
+(require 'fringe)
 
 (defgroup ruler-mode nil
   "Display a ruler in the header line."
-  :version "21.2"
-  :group 'environment)
+  :version "22.1"
+  :group 'convenience)
 
 (defcustom ruler-mode-show-tab-stops nil
   "*If non-nil the ruler shows tab stop positions.
@@ -128,8 +140,8 @@ or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
         (widget-put widget :error
                     (format "Invalid character value: %S" value))
         widget))))
-      
-(defcustom ruler-mode-fill-column-char (if window-system
+
+(defcustom ruler-mode-fill-column-char (if (char-displayable-p ?¶)
                                            ?\¶
                                          ?\|)
   "*Character used at the `fill-column' location."
@@ -139,26 +151,34 @@ or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
           (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."
+(defcustom ruler-mode-comment-column-char ?\#
+  "*Character used at the `comment-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."
+(defcustom ruler-mode-goal-column-char ?G
+  "*Character used at the `goal-column' location."
   :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."
+(defcustom ruler-mode-current-column-char (if (char-displayable-p ?¦)
+                                              ?\¦
+                                            ?\@)
+  "*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")
@@ -180,8 +200,13 @@ or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
           (character :tag "Character")
           (integer :tag "Integer char value"
                    :validate ruler-mode-character-validate)))
+
+(defcustom ruler-mode-set-goal-column-ding-flag t
+  "*Non-nil means do `ding' when `goal-column' is set."
+  :group 'ruler-mode
+  :type 'boolean)
 
-(defface ruler-mode-default-face
+(defface ruler-mode-default
   '((((type tty))
      (:inherit default
                :background "grey64"
@@ -198,161 +223,285 @@ or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
   "Default face used by the ruler."
   :group 'ruler-mode)
 
-(defface ruler-mode-column-number-face
+(defface ruler-mode-pad
+  '((((type tty))
+     (:inherit ruler-mode-default
+               :background "grey50"
+               ))
+    (t
+     (:inherit ruler-mode-default
+               :background "grey64"
+               )))
+  "Face used to pad inactive ruler areas."
+  :group 'ruler-mode)
+
+(defface ruler-mode-margins
+  '((t
+     (:inherit ruler-mode-default
+               :foreground "white"
+               )))
+  "Face used to highlight margin areas."
+  :group 'ruler-mode)
+
+(defface ruler-mode-fringes
+  '((t
+     (:inherit ruler-mode-default
+               :foreground "green"
+               )))
+  "Face used to highlight fringes areas."
+  :group 'ruler-mode)
+
+(defface ruler-mode-column-number
   '((t
-     (:inherit ruler-mode-default-face
+     (:inherit ruler-mode-default
                :foreground "black"
                )))
   "Face used to highlight number graduations."
   :group 'ruler-mode)
 
-(defface ruler-mode-fill-column-face
+(defface ruler-mode-fill-column
   '((t
-     (:inherit ruler-mode-default-face
+     (:inherit ruler-mode-default
                :foreground "red"
                )))
   "Face used to highlight the fill column character."
   :group 'ruler-mode)
 
-(defface ruler-mode-tab-stop-face
+(defface ruler-mode-comment-column
   '((t
-     (:inherit ruler-mode-default-face
-               :foreground "steelblue"
+     (:inherit ruler-mode-default
+               :foreground "red"
                )))
-  "Face used to highlight tab stop characters."
+  "Face used to highlight the comment column character."
   :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"
+(defface ruler-mode-goal-column
+  '((t
+     (:inherit ruler-mode-default
+               :foreground "red"
                )))
-  "Face used to highlight the `window-margins' areas."
+  "Face used to highlight the goal column character."
   :group 'ruler-mode)
 
-(defface ruler-mode-current-column-face
+(defface ruler-mode-tab-stop
   '((t
-     (:inherit ruler-mode-default-face
+     (:inherit ruler-mode-default
+               :foreground "steelblue"
+               )))
+  "Face used to highlight tab stop characters."
+  :group 'ruler-mode)
+
+(defface ruler-mode-current-column
+  '((t
+     (:inherit ruler-mode-default
                :weight bold
                :foreground "yellow"
                )))
   "Face used to highlight the `current-column' character."
   :group 'ruler-mode)
 
+
+(defsubst ruler-mode-full-window-width ()
+  "Return the full width of the selected window."
+  (let ((edges (window-edges)))
+    (- (nth 2 edges) (nth 0 edges))))
+
+(defsubst ruler-mode-window-col (n)
+  "Return a column number relative to the selected window.
+N is a column number relative to selected frame."
+  (- n
+     (car (window-edges))
+     (or (car (window-margins)) 0)
+     (fringe-columns 'left)
+     (scroll-bar-columns 'left)))
+
 (defun ruler-mode-mouse-set-left-margin (start-event)
-  "Set left margin to the graduation where the mouse pointer is on.
+  "Set left margin end 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)))))
+         col w lm rm)
+    (when (eq start end) ;; mouse click
+      (save-selected-window
+        (select-window (posn-window start))
+        (setq col (- (car (posn-col-row start)) (car (window-edges))
+                     (scroll-bar-columns 'left))
+              w   (- (ruler-mode-full-window-width)
+                     (scroll-bar-columns 'left)
+                     (scroll-bar-columns 'right)))
+        (when (and (>= col 0) (< col w))
+          (setq lm (window-margins)
+                rm (or (cdr lm) 0)
+                lm (or (car lm) 0))
+          (message "Left margin set to %d (was %d)" col lm)
+          (set-window-margins nil col rm))))))
 
 (defun ruler-mode-mouse-set-right-margin (start-event)
-  "Set right margin to the graduation where the mouse pointer is on.
+  "Set right margin beginning 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."
+         col w lm rm)
+    (when (eq start end) ;; mouse click
+      (save-selected-window
+        (select-window (posn-window start))
+        (setq col (- (car (posn-col-row start)) (car (window-edges))
+                     (scroll-bar-columns 'left))
+              w   (- (ruler-mode-full-window-width)
+                     (scroll-bar-columns 'left)
+                     (scroll-bar-columns 'right)))
+        (when (and (>= col 0) (< col w))
+          (setq lm  (window-margins)
+                rm  (or (cdr lm) 0)
+                lm  (or (car lm) 0)
+                col (- w col 1))
+          (message "Right margin set to %d (was %d)" col rm)
+          (set-window-margins nil lm col))))))
+
+(defvar ruler-mode-dragged-symbol nil
+  "Column symbol dragged in the ruler.
+That is `fill-column', `comment-column', `goal-column', or nil when
+nothing is dragged.")
+
+(defun ruler-mode-mouse-grab-any-column (start-event)
+  "Drag a column symbol on the ruler.
+Start dragging on mouse down event START-EVENT, and update the column
+symbol value with the current value of the ruler graduation while
+dragging.  See also the variable `ruler-mode-dragged-symbol'."
   (interactive "e")
+  (setq ruler-mode-dragged-symbol nil)
+  (let* ((start (event-start start-event))
+         col newc oldc)
+    (save-selected-window
+      (select-window (posn-window start))
+      (setq col  (ruler-mode-window-col (car (posn-col-row start)))
+            newc (+ col (window-hscroll)))
+      (and
+       (>= col 0) (< col (window-width))
+       (cond
+
+        ;; Handle the fill column.
+        ((eq newc fill-column)
+         (setq oldc fill-column
+               ruler-mode-dragged-symbol 'fill-column)
+         t) ;; Start dragging
+
+        ;; Handle the comment column.
+        ((eq newc comment-column)
+         (setq oldc comment-column
+               ruler-mode-dragged-symbol 'comment-column)
+         t) ;; Start dragging
+
+        ;; Handle the goal column.
+        ;; A. On mouse down on the goal column character on the ruler,
+        ;;    update the `goal-column' value while dragging.
+        ;; B. If `goal-column' is nil, set the goal column where the
+        ;;    mouse is clicked.
+        ;; C. On mouse click on the goal column character on the
+        ;;    ruler, unset the goal column.
+        ((eq newc goal-column)          ; A. Drag the goal column.
+         (setq oldc goal-column
+               ruler-mode-dragged-symbol 'goal-column)
+         t) ;; Start dragging
+
+        ((null goal-column)             ; B. Set the goal column.
+         (setq oldc goal-column
+               goal-column newc)
+         ;; mouse-2 coming AFTER drag-mouse-2 invokes `ding'.  This
+         ;; `ding' flushes the next messages about setting goal
+         ;; column.  So here I force fetch the event(mouse-2) and
+         ;; throw away.
+         (read-event)
+         ;; Ding BEFORE `message' is OK.
+         (when ruler-mode-set-goal-column-ding-flag
+           (ding))
+         (message "Goal column set to %d (click on %s again to unset it)"
+                  newc
+                  (propertize (char-to-string ruler-mode-goal-column-char)
+                              'face 'ruler-mode-goal-column))
+         nil) ;; Don't start dragging.
+        )
+       (if (eq 'click (ruler-mode-mouse-drag-any-column-iteration
+                       (posn-window start)))
+           (when (eq 'goal-column ruler-mode-dragged-symbol)
+             ;; C. Unset the goal column.
+             (set-goal-column t))
+         ;; At end of dragging, report the updated column symbol.
+         (message "%s is set to %d (was %d)"
+                  ruler-mode-dragged-symbol
+                  (symbol-value ruler-mode-dragged-symbol)
+                  oldc))))))
+
+(defun ruler-mode-mouse-drag-any-column-iteration (window)
+  "Update the ruler while dragging the mouse.
+WINDOW is the window where occurred the last down-mouse event.
+Return the symbol `drag' if the mouse has been dragged, or `click' if
+the mouse has been clicked."
+  (let ((drags 0)
+        event)
+    (track-mouse
+      (while (mouse-movement-p (setq event (read-event)))
+        (setq drags (1+ drags))
+        (when (eq window (posn-window (event-end event)))
+          (ruler-mode-mouse-drag-any-column event)
+          (force-mode-line-update))))
+    (if (and (zerop drags) (eq 'click (car (event-modifiers event))))
+        'click
+      'drag)))
+
+(defun ruler-mode-mouse-drag-any-column (start-event)
+  "Update the value of the symbol dragged on the ruler.
+Called on each mouse motion event START-EVENT."
   (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)))))))
+         col newc)
+    (save-selected-window
+      (select-window (posn-window start))
+      (setq col  (ruler-mode-window-col (car (posn-col-row end)))
+            newc (+ col (window-hscroll)))
+      (when (and (>= col 0) (< col (window-width)))
+        (set ruler-mode-dragged-symbol newc)))))
 
 (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)
-                                 #'<)))))))))
+  (when ruler-mode-show-tab-stops
+    (let* ((start (event-start start-event))
+           (end   (event-end   start-event))
+           col ts)
+      (when (eq start end) ;; mouse click
+        (save-selected-window
+          (select-window (posn-window start))
+          (setq col (ruler-mode-window-col (car (posn-col-row start)))
+                ts  (+ col (window-hscroll)))
+          (and (>= col 0) (< col (window-width))
+               (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)))))))))
+  (when ruler-mode-show-tab-stops
+    (let* ((start (event-start start-event))
+           (end   (event-end   start-event))
+           col ts)
+      (when (eq start end) ;; mouse click
+        (save-selected-window
+          (select-window (posn-window start))
+          (setq col (ruler-mode-window-col (car (posn-col-row start)))
+                ts  (+ col (window-hscroll)))
+          (and (>= col 0) (< col (window-width))
+               (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."
@@ -367,7 +516,7 @@ START-EVENT is the mouse click event."
     (define-key km [header-line down-mouse-3]
       #'ignore)
     (define-key km [header-line down-mouse-2]
-      #'ruler-mode-mouse-set-fill-column)
+      #'ruler-mode-mouse-grab-any-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)]
@@ -383,11 +532,15 @@ START-EVENT is the mouse click event."
 
 (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)
+
+(defvar ruler-mode-ruler-function 'ruler-mode-ruler
+  "Function to call to return ruler header line format.
+This variable is expected to be made buffer-local by modes.")
 
 (defconst ruler-mode-header-line-format
-  '(:eval (ruler-mode-ruler))
-  "`header-line-format' used in ruler mode.")
+  '(:eval (funcall ruler-mode-ruler-function))
+  "`header-line-format' used in ruler mode.
+Call `ruler-mode-ruler-function' to compute the ruler value.")
 
 ;;;###autoload
 (define-minor-mode ruler-mode
@@ -399,173 +552,199 @@ START-EVENT is the mouse click event."
       (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 (local-variable-p 'header-line-format)
+          (set (make-local-variable 'ruler-mode-header-line-format-old)
+               header-line-format))
+        (setq header-line-format ruler-mode-header-line-format)
+        (add-hook 'post-command-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)))
+    (when (eq header-line-format ruler-mode-header-line-format)
+      (kill-local-variable 'header-line-format)
+      (when (local-variable-p 'ruler-mode-header-line-format-old)
+        (setq header-line-format ruler-mode-header-line-format-old)
+        (kill-local-variable 'ruler-mode-header-line-format-old)))
+    (remove-hook 'post-command-hook 'force-mode-line-update t)))
 
-;; Add ruler-mode to the the minor mode menu in the mode line
+;; Add ruler-mode to 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)))
+              :button (:toggle . ruler-mode)))
 
 (defconst ruler-mode-ruler-help-echo
   "\
 S-mouse-1/3: set L/R margin, \
-mouse-2: set fill col, \
+mouse-2: set goal column, \
 C-mouse-2: show tabs"
-  "Help string shown when mouse pointer is over the ruler.
+  "Help string shown when mouse is over the ruler.
 `ruler-mode-show-tab-stops' is nil.")
 
-(defconst ruler-mode-ruler-help-echo-tab
+(defconst ruler-mode-ruler-help-echo-when-goal-column
+  "\
+S-mouse-1/3: set L/R margin, \
+C-mouse-2: show tabs"
+  "Help string shown when mouse is over the ruler.
+`goal-column' is set and `ruler-mode-show-tab-stops' is nil.")
+
+(defconst ruler-mode-ruler-help-echo-when-tab-stops
   "\
 C-mouse1/3: set/unset tab, \
 C-mouse-2: hide tabs"
-  "Help string shown when mouse pointer is over the ruler.
+  "Help string shown when mouse 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.")
-
-(defun ruler-mode-extra-left-cols ()
-  "Return number of extra columns on the left side of selected frame.
-That is the number of columns occupied by the left fringe area and
-vertical scrollbar on the left side of the selected frame."
-  (let ((w  (frame-first-window))
-        (xy (cons 0 0)))
-    (with-current-buffer (window-buffer w)
-      (let (header-line-format)
-        (while (not (listp (coordinates-in-window-p xy w)))
-          (setcar xy (1+ (car xy))))
-        (car xy)))))
+(defconst ruler-mode-fill-column-help-echo
+  "drag-mouse-2: set fill column"
+  "Help string shown when mouse is on the fill column character.")
+
+(defconst ruler-mode-comment-column-help-echo
+  "drag-mouse-2: set comment column"
+  "Help string shown when mouse is on the comment column character.")
+
+(defconst ruler-mode-goal-column-help-echo
+  "\
+drag-mouse-2: set goal column, \
+mouse-2: unset goal column"
+  "Help string shown when mouse is on the goal column character.")
+
+(defconst ruler-mode-margin-help-echo
+  "%s margin %S"
+  "Help string shown when mouse is over a margin area.")
+
+(defconst ruler-mode-fringe-help-echo
+  "%s fringe %S"
+  "Help string shown when mouse is over a fringe area.")
+
+(defsubst ruler-mode-space (width &rest props)
+  "Return a single space string of WIDTH times the normal character width.
+Optional argument PROPS specifies other text properties to apply."
+  (apply 'propertize " " 'display (list 'space :width width) props))
 
 (defun ruler-mode-ruler ()
-  "Return a string ruler."
-  (if ruler-mode
-      (let* ((j     (ruler-mode-extra-left-cols))
-             (k     (/ (or (frame-parameter nil 'right-fringe) 0)
-                       (frame-char-width)))
-             (w     (+ (window-width) j))
-             (m     (window-margins))
-             (l     (or (car m) 0))
-             (r     (or (cdr m) 0))
-             (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 k ?\ )))
-             c)
-
-        ;; 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.
+  "Compute and return an header line ruler."
+  (let* ((w (window-width))
+         (m (window-margins))
+         (f (window-fringes))
+         (i 0)
+         (j (window-hscroll))
+         ;; Setup the scrollbar, fringes, and margins areas.
+         (lf (ruler-mode-space
+              'left-fringe
+              'face 'ruler-mode-fringes
+              'help-echo (format ruler-mode-fringe-help-echo
+                                 "Left" (or (car f) 0))))
+         (rf (ruler-mode-space
+              'right-fringe
+              'face 'ruler-mode-fringes
+              'help-echo (format ruler-mode-fringe-help-echo
+                                 "Right" (or (cadr f) 0))))
+         (lm (ruler-mode-space
+              'left-margin
+              'face 'ruler-mode-margins
+              'help-echo (format ruler-mode-margin-help-echo
+                                 "Left" (or (car m) 0))))
+         (rm (ruler-mode-space
+              'right-margin
+              'face 'ruler-mode-margins
+              'help-echo (format ruler-mode-margin-help-echo
+                                 "Right" (or (cdr m) 0))))
+         (sb (ruler-mode-space
+              'scroll-bar
+              'face 'ruler-mode-pad))
+         ;; Remember the scrollbar vertical type.
+         (sbvt (car (window-current-scroll-bars)))
+         ;; Create an "clean" ruler.
+         (ruler
+          (propertize
+           (make-string w ruler-mode-basic-graduation-char)
+           'face 'ruler-mode-default
+           'local-map ruler-mode-map
+           'help-echo (cond
+                       (ruler-mode-show-tab-stops
+                        ruler-mode-ruler-help-echo-when-tab-stops)
+                       (goal-column
+                        ruler-mode-ruler-help-echo-when-goal-column)
+                       (ruler-mode-ruler-help-echo))))
+         k c)
+    ;; Setup the active area.
+    (while (< i w)
+      ;; Graduations.
+      (cond
+       ;; Show a number graduation.
+       ((= (mod j 10) 0)
+        (setq c (number-to-string (/ j 10))
+              m (length c)
+              k i)
         (put-text-property
-         i j 'face 'ruler-mode-margins-face
+         i (1+ i) 'face 'ruler-mode-column-number
          ruler)
+        (while (and (> m 0) (>= k 0))
+          (aset ruler k (aref c (setq m (1- m))))
+          (setq k (1- k))))
+       ;; Show an intermediate graduation.
+       ((= (mod j 5) 0)
+        (aset ruler i ruler-mode-inter-graduation-char)))
+      ;; Special columns.
+      (cond
+       ;; Show the `current-column' marker.
+       ((= j (current-column))
+        (aset ruler i ruler-mode-current-column-char)
         (put-text-property
-         i j 'help-echo (format ruler-mode-left-margin-help-echo l)
+         i (1+ i) 'face 'ruler-mode-current-column
+         ruler))
+       ;; Show the `goal-column' marker.
+       ((and goal-column (= j goal-column))
+        (aset ruler i ruler-mode-goal-column-char)
+        (put-text-property
+         i (1+ i) 'face 'ruler-mode-goal-column
+         ruler)
+	(put-text-property
+         i (1+ i) 'mouse-face 'mode-line-highlight
          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
+         i (1+ i) 'help-echo ruler-mode-goal-column-help-echo
+         ruler))
+       ;; Show the `comment-column' marker.
+       ((= j comment-column)
+        (aset ruler i ruler-mode-comment-column-char)
+        (put-text-property
+         i (1+ i) 'face 'ruler-mode-comment-column
          ruler)
+	(put-text-property
+         i (1+ i) 'mouse-face 'mode-line-highlight
+         ruler)
+        (put-text-property
+         i (1+ i) 'help-echo ruler-mode-comment-column-help-echo
+         ruler))
+       ;; Show the `fill-column' marker.
+       ((= j fill-column)
+        (aset ruler i ruler-mode-fill-column-char)
         (put-text-property
-         i (length ruler) 'help-echo
-         (format ruler-mode-right-margin-help-echo (- w r))
+         i (1+ i) 'face 'ruler-mode-fill-column
+         ruler)
+	(put-text-property
+         i (1+ i) 'mouse-face 'mode-line-highlight
          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)))
+        (put-text-property
+         i (1+ i) 'help-echo ruler-mode-fill-column-help-echo
+         ruler))
+       ;; Show the `tab-stop-list' markers.
+       ((and ruler-mode-show-tab-stops (member j tab-stop-list))
+        (aset ruler i ruler-mode-tab-stop-char)
+        (put-text-property
+         i (1+ i) 'face 'ruler-mode-tab-stop
+         ruler)))
+      (setq i (1+ i)
+            j (1+ j)))
+    ;; Return the ruler propertized string.  Using list here,
+    ;; instead of concat visually separate the different areas.
+    (if (nth 2 (window-fringes))
+        ;; fringes outside margins.
+        (list "" (and (eq 'left sbvt) sb) lf lm
+              ruler rm rf (and (eq 'right sbvt) sb))
+      ;; fringes inside margins.
+      (list "" (and (eq 'left sbvt) sb) lm lf
+            ruler rf rm (and (eq 'right sbvt) sb)))))
 
 (provide 'ruler-mode)
 
@@ -573,4 +752,5 @@ vertical scrollbar on the left side of the selected frame."
 ;; coding: iso-latin-1
 ;; End:
 
+;;; arch-tag: b2f24546-5605-44c4-b67b-c9a4eeba3ee8
 ;;; ruler-mode.el ends here