lisp/ruler-mode.el

   1 ;;; ruler-mode.el --- display a ruler in the header line
   2
   3 ;; Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4
   5 ;; Author: David Ponce <david@dponce.com>
   6 ;; Maintainer: David Ponce <david@dponce.com>
   7 ;; Created: 24 Mar 2001
   8 ;; Version: 1.6
   9 ;; Keywords: convenience
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; This program is free software; you can redistribute it and/or
  14 ;; modify it under the terms of the GNU General Public License as
  15 ;; published by the Free Software Foundation; either version 2, or (at
  16 ;; your option) any later version.
  17
  18 ;; This program is distributed in the hope that it will be useful, but
  19 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21 ;; General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with this program; see the file COPYING.  If not, write to
  25 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  26 ;; Boston, MA 02111-1307, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; This library provides a minor mode to display a ruler in the header
  31 ;; line.  It works only on Emacs 21.
  32 ;;
  33 ;; You can use the mouse to change the `fill-column' `comment-column',
  34 ;; `goal-column', `window-margins' and `tab-stop-list' settings:
  35 ;;
  36 ;; [header-line (shift down-mouse-1)] set left margin end to the ruler
  37 ;; graduation where the mouse pointer is on.
  38 ;;
  39 ;; [header-line (shift down-mouse-3)] set right margin beginning to
  40 ;; the ruler graduation where the mouse pointer is on.
  41 ;;
  42 ;; [header-line down-mouse-2] Drag the `fill-column', `comment-column'
  43 ;; or `goal-column' to a ruler graduation.
  44 ;;
  45 ;; [header-line (control down-mouse-1)] add a tab stop to the ruler
  46 ;; graduation where the mouse pointer is on.
  47 ;;
  48 ;; [header-line (control down-mouse-3)] remove the tab stop at the
  49 ;; ruler graduation where the mouse pointer is on.
  50 ;;
  51 ;; [header-line (control down-mouse-2)] or M-x
  52 ;; `ruler-mode-toggle-show-tab-stops' toggle showing and visually
  53 ;; editing `tab-stop-list' setting.  The `ruler-mode-show-tab-stops'
  54 ;; option controls if the ruler shows tab stops by default.
  55 ;;
  56 ;; In the ruler the character `ruler-mode-current-column-char' shows
  57 ;; the `current-column' location, `ruler-mode-fill-column-char' shows
  58 ;; the `fill-column' location, `ruler-mode-comment-column-char' shows
  59 ;; the `comment-column' location, `ruler-mode-goal-column-char' shows
  60 ;; the `goal-column' and `ruler-mode-tab-stop-char' shows tab stop
  61 ;; locations.  Graduations in `window-margins' and `window-fringes'
  62 ;; areas are shown with a different foreground color.
  63 ;;
  64 ;; It is also possible to customize the following characters:
  65 ;;
  66 ;; - `ruler-mode-basic-graduation-char' character used for basic
  67 ;;   graduations ('.' by default).
  68 ;; - `ruler-mode-inter-graduation-char' character used for
  69 ;;   intermediate graduations ('!' by default).
  70 ;;
  71 ;; The following faces are customizable:
  72 ;;
  73 ;; - `ruler-mode-default-face' the ruler default face.
  74 ;; - `ruler-mode-fill-column-face' the face used to highlight the
  75 ;;   `fill-column' character.
  76 ;; - `ruler-mode-comment-column-face' the face used to highlight the
  77 ;;   `comment-column' character.
  78 ;; - `ruler-mode-goal-column-face' the face used to highlight the
  79 ;;   `goal-column' character.
  80 ;; - `ruler-mode-current-column-face' the face used to highlight the
  81 ;;   `current-column' character.
  82 ;; - `ruler-mode-tab-stop-face' the face used to highlight tab stop
  83 ;;   characters.
  84 ;; - `ruler-mode-margins-face' the face used to highlight graduations
  85 ;;   in the `window-margins' areas.
  86 ;; - `ruler-mode-fringes-face' the face used to highlight graduations
  87 ;;   in the `window-fringes' areas.
  88 ;; - `ruler-mode-column-number-face' the face used to highlight the
  89 ;;   numbered graduations.
  90 ;;
  91 ;; `ruler-mode-default-face' inherits from the built-in `default' face.
  92 ;; All `ruler-mode' faces inherit from `ruler-mode-default-face'.
  93 ;;
  94 ;; WARNING: To keep ruler graduations aligned on text columns it is
  95 ;; important to use the same font family and size for ruler and text
  96 ;; areas.
  97 ;;
  98 ;; You can override the ruler format by defining an appropriate
  99 ;; function as the buffer-local value of `ruler-mode-ruler-function'.
 100
 101 ;; Installation
 102 ;;
 103 ;; To automatically display the ruler in specific major modes use:
 104 ;;
 105 ;;    (add-hook '<major-mode>-hook 'ruler-mode)
 106 ;;
 107
 108 ;;; History:
 109 ;;
 110 \f
 111 ;;; Code:
 112 (eval-when-compile
 113   (require 'wid-edit))
 114 (require 'scroll-bar)
 115 (require 'fringe)
 116
 117 (defgroup ruler-mode nil
 118   "Display a ruler in the header line."
 119   :version "22.1"
 120   :group 'convenience)
 121
 122 (defcustom ruler-mode-show-tab-stops nil
 123   "*If non-nil the ruler shows tab stop positions.
 124 Also allowing to visually change `tab-stop-list' setting using
 125 <C-down-mouse-1> and <C-down-mouse-3> on the ruler to respectively add
 126 or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
 127 <C-down-mouse-2> on the ruler toggles showing/editing of tab stops."
 128   :group 'ruler-mode
 129   :type 'boolean)
 130
 131 ;; IMPORTANT: This function must be defined before the following
 132 ;; defcustoms because it is used in their :validate clause.
 133 (defun ruler-mode-character-validate (widget)
 134   "Ensure WIDGET value is a valid character value."
 135   (save-excursion
 136     (let ((value (widget-value widget)))
 137       (if (char-valid-p value)
 138           nil
 139         (widget-put widget :error
 140                     (format "Invalid character value: %S" value))
 141         widget))))
 142
 143 (defcustom ruler-mode-fill-column-char (if (char-displayable-p ?¶)
 144                                            ?\¶
 145                                          ?\|)
 146   "*Character used at the `fill-column' location."
 147   :group 'ruler-mode
 148   :type '(choice
 149           (character :tag "Character")
 150           (integer :tag "Integer char value"
 151                    :validate ruler-mode-character-validate)))
 152
 153 (defcustom ruler-mode-comment-column-char ?\#
 154   "*Character used at the `comment-column' location."
 155   :group 'ruler-mode
 156   :type '(choice
 157           (character :tag "Character")
 158           (integer :tag "Integer char value"
 159                    :validate ruler-mode-character-validate)))
 160
 161 (defcustom ruler-mode-goal-column-char ?G
 162   "*Character used at the `goal-column' location."
 163   :group 'ruler-mode
 164   :type '(choice
 165           (character :tag "Character")
 166           (integer :tag "Integer char value"
 167                    :validate ruler-mode-character-validate)))
 168
 169 (defcustom ruler-mode-current-column-char (if (char-displayable-p ?¦)
 170                                               ?\¦
 171                                             ?\@)
 172   "*Character used at the `current-column' location."
 173   :group 'ruler-mode
 174   :type '(choice
 175           (character :tag "Character")
 176           (integer :tag "Integer char value"
 177                    :validate ruler-mode-character-validate)))
 178
 179 (defcustom ruler-mode-tab-stop-char ?\T
 180   "*Character used at `tab-stop-list' locations."
 181   :group 'ruler-mode
 182   :type '(choice
 183           (character :tag "Character")
 184           (integer :tag "Integer char value"
 185                    :validate ruler-mode-character-validate)))
 186
 187 (defcustom ruler-mode-basic-graduation-char ?\.
 188   "*Character used for basic graduations."
 189   :group 'ruler-mode
 190   :type '(choice
 191           (character :tag "Character")
 192           (integer :tag "Integer char value"
 193                    :validate ruler-mode-character-validate)))
 194
 195 (defcustom ruler-mode-inter-graduation-char ?\!
 196   "*Character used for intermediate graduations."
 197   :group 'ruler-mode
 198   :type '(choice
 199           (character :tag "Character")
 200           (integer :tag "Integer char value"
 201                    :validate ruler-mode-character-validate)))
 202
 203 (defcustom ruler-mode-set-goal-column-ding-flag t
 204   "*Non-nil means do `ding' when `goal-column' is set."
 205   :group 'ruler-mode
 206   :type 'boolean)
 207 \f
 208 (defface ruler-mode-default-face
 209   '((((type tty))
 210      (:inherit default
 211                :background "grey64"
 212                :foreground "grey50"
 213                ))
 214     (t
 215      (:inherit default
 216                :background "grey76"
 217                :foreground "grey64"
 218                :box (:color "grey76"
 219                             :line-width 1
 220                             :style released-button)
 221                )))
 222   "Default face used by the ruler."
 223   :group 'ruler-mode)
 224
 225 (defface ruler-mode-pad-face
 226   '((((type tty))
 227      (:inherit ruler-mode-default-face
 228                :background "grey50"
 229                ))
 230     (t
 231      (:inherit ruler-mode-default-face
 232                :background "grey64"
 233                )))
 234   "Face used to pad inactive ruler areas."
 235   :group 'ruler-mode)
 236
 237 (defface ruler-mode-margins-face
 238   '((t
 239      (:inherit ruler-mode-default-face
 240                :foreground "white"
 241                )))
 242   "Face used to highlight margin areas."
 243   :group 'ruler-mode)
 244
 245 (defface ruler-mode-fringes-face
 246   '((t
 247      (:inherit ruler-mode-default-face
 248                :foreground "green"
 249                )))
 250   "Face used to highlight fringes areas."
 251   :group 'ruler-mode)
 252
 253 (defface ruler-mode-column-number-face
 254   '((t
 255      (:inherit ruler-mode-default-face
 256                :foreground "black"
 257                )))
 258   "Face used to highlight number graduations."
 259   :group 'ruler-mode)
 260
 261 (defface ruler-mode-fill-column-face
 262   '((t
 263      (:inherit ruler-mode-default-face
 264                :foreground "red"
 265                )))
 266   "Face used to highlight the fill column character."
 267   :group 'ruler-mode)
 268
 269 (defface ruler-mode-comment-column-face
 270   '((t
 271      (:inherit ruler-mode-default-face
 272                :foreground "red"
 273                )))
 274   "Face used to highlight the comment column character."
 275   :group 'ruler-mode)
 276
 277 (defface ruler-mode-goal-column-face
 278   '((t
 279      (:inherit ruler-mode-default-face
 280                :foreground "red"
 281                )))
 282   "Face used to highlight the goal column character."
 283   :group 'ruler-mode)
 284
 285 (defface ruler-mode-tab-stop-face
 286   '((t
 287      (:inherit ruler-mode-default-face
 288                :foreground "steelblue"
 289                )))
 290   "Face used to highlight tab stop characters."
 291   :group 'ruler-mode)
 292
 293 (defface ruler-mode-current-column-face
 294   '((t
 295      (:inherit ruler-mode-default-face
 296                :weight bold
 297                :foreground "yellow"
 298                )))
 299   "Face used to highlight the `current-column' character."
 300   :group 'ruler-mode)
 301 \f
 302
 303 (defsubst ruler-mode-full-window-width ()
 304   "Return the full width of the selected window."
 305   (let ((edges (window-edges)))
 306     (- (nth 2 edges) (nth 0 edges))))
 307
 308 (defsubst ruler-mode-window-col (n)
 309   "Return a column number relative to the selected window.
 310 N is a column number relative to selected frame."
 311   (- n
 312      (car (window-edges))
 313      (or (car (window-margins)) 0)
 314      (fringe-columns 'left)
 315      (scroll-bar-columns 'left)))
 316 \f
 317 (defun ruler-mode-mouse-set-left-margin (start-event)
 318   "Set left margin end to the graduation where the mouse pointer is on.
 319 START-EVENT is the mouse click event."
 320   (interactive "e")
 321   (let* ((start (event-start start-event))
 322          (end   (event-end   start-event))
 323          col w lm rm)
 324     (when (eq start end) ;; mouse click
 325       (save-selected-window
 326         (select-window (posn-window start))
 327         (setq col (- (car (posn-col-row start)) (car (window-edges))
 328                      (scroll-bar-columns 'left))
 329               w   (- (ruler-mode-full-window-width)
 330                      (scroll-bar-columns 'left)
 331                      (scroll-bar-columns 'right)))
 332         (when (and (>= col 0) (< col w))
 333           (setq lm (window-margins)
 334                 rm (or (cdr lm) 0)
 335                 lm (or (car lm) 0))
 336           (message "Left margin set to %d (was %d)" col lm)
 337           (set-window-margins nil col rm))))))
 338
 339 (defun ruler-mode-mouse-set-right-margin (start-event)
 340   "Set right margin beginning to the graduation where the mouse pointer is on.
 341 START-EVENT is the mouse click event."
 342   (interactive "e")
 343   (let* ((start (event-start start-event))
 344          (end   (event-end   start-event))
 345          col w lm rm)
 346     (when (eq start end) ;; mouse click
 347       (save-selected-window
 348         (select-window (posn-window start))
 349         (setq col (- (car (posn-col-row start)) (car (window-edges))
 350                      (scroll-bar-columns 'left))
 351               w   (- (ruler-mode-full-window-width)
 352                      (scroll-bar-columns 'left)
 353                      (scroll-bar-columns 'right)))
 354         (when (and (>= col 0) (< col w))
 355           (setq lm  (window-margins)
 356                 rm  (or (cdr lm) 0)
 357                 lm  (or (car lm) 0)
 358                 col (- w col 1))
 359           (message "Right margin set to %d (was %d)" col rm)
 360           (set-window-margins nil lm col))))))
 361
 362 (defvar ruler-mode-dragged-symbol nil
 363   "Column symbol dragged in the ruler.
 364 That is `fill-column', `comment-column', `goal-column', or nil when
 365 nothing is dragged.")
 366
 367 (defun ruler-mode-mouse-grab-any-column (start-event)
 368   "Drag a column symbol on the ruler.
 369 Start dragging on mouse down event START-EVENT, and update the column
 370 symbol value with the current value of the ruler graduation while
 371 dragging.  See also the variable `ruler-mode-dragged-symbol'."
 372   (interactive "e")
 373   (setq ruler-mode-dragged-symbol nil)
 374   (let* ((start (event-start start-event))
 375          col newc oldc)
 376     (save-selected-window
 377       (select-window (posn-window start))
 378       (setq col  (ruler-mode-window-col (car (posn-col-row start)))
 379             newc (+ col (window-hscroll)))
 380       (and
 381        (>= col 0) (< col (window-width))
 382        (cond
 383
 384         ;; Handle the fill column.
 385         ((eq newc fill-column)
 386          (setq oldc fill-column
 387                ruler-mode-dragged-symbol 'fill-column)
 388          t) ;; Start dragging
 389
 390         ;; Handle the comment column.
 391         ((eq newc comment-column)
 392          (setq oldc comment-column
 393                ruler-mode-dragged-symbol 'comment-column)
 394          t) ;; Start dragging
 395
 396         ;; Handle the goal column.
 397         ;; A. On mouse down on the goal column character on the ruler,
 398         ;;    update the `goal-column' value while dragging.
 399         ;; B. If `goal-column' is nil, set the goal column where the
 400         ;;    mouse is clicked.
 401         ;; C. On mouse click on the goal column character on the
 402         ;;    ruler, unset the goal column.
 403         ((eq newc goal-column)          ; A. Drag the goal column.
 404          (setq oldc goal-column
 405                ruler-mode-dragged-symbol 'goal-column)
 406          t) ;; Start dragging
 407
 408         ((null goal-column)             ; B. Set the goal column.
 409          (setq oldc goal-column
 410                goal-column newc)
 411          ;; mouse-2 coming AFTER drag-mouse-2 invokes `ding'.  This
 412          ;; `ding' flushes the next messages about setting goal
 413          ;; column.  So here I force fetch the event(mouse-2) and
 414          ;; throw away.
 415          (read-event)
 416          ;; Ding BEFORE `message' is OK.
 417          (when ruler-mode-set-goal-column-ding-flag
 418            (ding))
 419          (message "Goal column set to %d (click on %s again to unset it)"
 420                   newc
 421                   (propertize (char-to-string ruler-mode-goal-column-char)
 422                               'face 'ruler-mode-goal-column-face))
 423          nil) ;; Don't start dragging.
 424         )
 425        (if (eq 'click (ruler-mode-mouse-drag-any-column-iteration
 426                        (posn-window start)))
 427            (when (eq 'goal-column ruler-mode-dragged-symbol)
 428              ;; C. Unset the goal column.
 429              (set-goal-column t))
 430          ;; At end of dragging, report the updated column symbol.
 431          (message "%s is set to %d (was %d)"
 432                   ruler-mode-dragged-symbol
 433                   (symbol-value ruler-mode-dragged-symbol)
 434                   oldc))))))
 435
 436 (defun ruler-mode-mouse-drag-any-column-iteration (window)
 437   "Update the ruler while dragging the mouse.
 438 WINDOW is the window where occurred the last down-mouse event.
 439 Return the symbol `drag' if the mouse has been dragged, or `click' if
 440 the mouse has been clicked."
 441   (let ((drags 0)
 442         event)
 443     (track-mouse
 444       (while (mouse-movement-p (setq event (read-event)))
 445         (setq drags (1+ drags))
 446         (when (eq window (posn-window (event-end event)))
 447           (ruler-mode-mouse-drag-any-column event)
 448           (force-mode-line-update))))
 449     (if (and (zerop drags) (eq 'click (car (event-modifiers event))))
 450         'click
 451       'drag)))
 452
 453 (defun ruler-mode-mouse-drag-any-column (start-event)
 454   "Update the value of the symbol dragged on the ruler.
 455 Called on each mouse motion event START-EVENT."
 456   (let* ((start (event-start start-event))
 457          (end   (event-end   start-event))
 458          col newc)
 459     (save-selected-window
 460       (select-window (posn-window start))
 461       (setq col  (ruler-mode-window-col (car (posn-col-row end)))
 462             newc (+ col (window-hscroll)))
 463       (when (and (>= col 0) (< col (window-width)))
 464         (set ruler-mode-dragged-symbol newc)))))
 465 \f
 466 (defun ruler-mode-mouse-add-tab-stop (start-event)
 467   "Add a tab stop to the graduation where the mouse pointer is on.
 468 START-EVENT is the mouse click event."
 469   (interactive "e")
 470   (when ruler-mode-show-tab-stops
 471     (let* ((start (event-start start-event))
 472            (end   (event-end   start-event))
 473            col ts)
 474       (when (eq start end) ;; mouse click
 475         (save-selected-window
 476           (select-window (posn-window start))
 477           (setq col (ruler-mode-window-col (car (posn-col-row start)))
 478                 ts  (+ col (window-hscroll)))
 479           (and (>= col 0) (< col (window-width))
 480                (not (member ts tab-stop-list))
 481                (progn
 482                  (message "Tab stop set to %d" ts)
 483                  (setq tab-stop-list (sort (cons ts tab-stop-list)
 484                                            #'<)))))))))
 485
 486 (defun ruler-mode-mouse-del-tab-stop (start-event)
 487   "Delete tab stop at the graduation where the mouse pointer is on.
 488 START-EVENT is the mouse click event."
 489   (interactive "e")
 490   (when ruler-mode-show-tab-stops
 491     (let* ((start (event-start start-event))
 492            (end   (event-end   start-event))
 493            col ts)
 494       (when (eq start end) ;; mouse click
 495         (save-selected-window
 496           (select-window (posn-window start))
 497           (setq col (ruler-mode-window-col (car (posn-col-row start)))
 498                 ts  (+ col (window-hscroll)))
 499           (and (>= col 0) (< col (window-width))
 500                (member ts tab-stop-list)
 501                (progn
 502                  (message "Tab stop at %d deleted" ts)
 503                  (setq tab-stop-list (delete ts tab-stop-list)))))))))
 504
 505 (defun ruler-mode-toggle-show-tab-stops ()
 506   "Toggle showing of tab stops on the ruler."
 507   (interactive)
 508   (setq ruler-mode-show-tab-stops (not ruler-mode-show-tab-stops))
 509   (force-mode-line-update))
 510 \f
 511 (defvar ruler-mode-map
 512   (let ((km (make-sparse-keymap)))
 513     (define-key km [header-line down-mouse-1]
 514       #'ignore)
 515     (define-key km [header-line down-mouse-3]
 516       #'ignore)
 517     (define-key km [header-line down-mouse-2]
 518       #'ruler-mode-mouse-grab-any-column)
 519     (define-key km [header-line (shift down-mouse-1)]
 520       #'ruler-mode-mouse-set-left-margin)
 521     (define-key km [header-line (shift down-mouse-3)]
 522       #'ruler-mode-mouse-set-right-margin)
 523     (define-key km [header-line (control down-mouse-1)]
 524       #'ruler-mode-mouse-add-tab-stop)
 525     (define-key km [header-line (control down-mouse-3)]
 526       #'ruler-mode-mouse-del-tab-stop)
 527     (define-key km [header-line (control down-mouse-2)]
 528       #'ruler-mode-toggle-show-tab-stops)
 529     km)
 530   "Keymap for ruler minor mode.")
 531
 532 (defvar ruler-mode-header-line-format-old nil
 533   "Hold previous value of `header-line-format'.")
 534
 535 (defvar ruler-mode-ruler-function 'ruler-mode-ruler
 536   "Function to call to return ruler header line format.
 537 This variable is expected to be made buffer-local by modes.")
 538
 539 (defconst ruler-mode-header-line-format
 540   '(:eval (funcall ruler-mode-ruler-function))
 541   "`header-line-format' used in ruler mode.
 542 Call `ruler-mode-ruler-function' to compute the ruler value.")
 543
 544 ;;;###autoload
 545 (define-minor-mode ruler-mode
 546   "Display a ruler in the header line if ARG > 0."
 547   nil nil
 548   ruler-mode-map
 549   :group 'ruler-mode
 550   (if ruler-mode
 551       (progn
 552         ;; When `ruler-mode' is on save previous header line format
 553         ;; and install the ruler header line format.
 554         (when (local-variable-p 'header-line-format)
 555           (set (make-local-variable 'ruler-mode-header-line-format-old)
 556                header-line-format))
 557         (setq header-line-format ruler-mode-header-line-format)
 558         (add-hook 'post-command-hook 'force-mode-line-update nil t))
 559     ;; When `ruler-mode' is off restore previous header line format if
 560     ;; the current one is the ruler header line format.
 561     (when (eq header-line-format ruler-mode-header-line-format)
 562       (kill-local-variable 'header-line-format)
 563       (when (local-variable-p 'ruler-mode-header-line-format-old)
 564         (setq header-line-format ruler-mode-header-line-format-old)
 565         (kill-local-variable 'ruler-mode-header-line-format-old)))
 566     (remove-hook 'post-command-hook 'force-mode-line-update t)))
 567 \f
 568 ;; Add ruler-mode to the minor mode menu in the mode line
 569 (define-key mode-line-mode-menu [ruler-mode]
 570   `(menu-item "Ruler" ruler-mode
 571               :button (:toggle . ruler-mode)))
 572
 573 (defconst ruler-mode-ruler-help-echo
 574   "\
 575 S-mouse-1/3: set L/R margin, \
 576 mouse-2: set goal column, \
 577 C-mouse-2: show tabs"
 578   "Help string shown when mouse is over the ruler.
 579 `ruler-mode-show-tab-stops' is nil.")
 580
 581 (defconst ruler-mode-ruler-help-echo-when-goal-column
 582   "\
 583 S-mouse-1/3: set L/R margin, \
 584 C-mouse-2: show tabs"
 585   "Help string shown when mouse is over the ruler.
 586 `goal-column' is set and `ruler-mode-show-tab-stops' is nil.")
 587
 588 (defconst ruler-mode-ruler-help-echo-when-tab-stops
 589   "\
 590 C-mouse1/3: set/unset tab, \
 591 C-mouse-2: hide tabs"
 592   "Help string shown when mouse is over the ruler.
 593 `ruler-mode-show-tab-stops' is non-nil.")
 594
 595 (defconst ruler-mode-fill-column-help-echo
 596   "drag-mouse-2: set fill column"
 597   "Help string shown when mouse is on the fill column character.")
 598
 599 (defconst ruler-mode-comment-column-help-echo
 600   "drag-mouse-2: set comment column"
 601   "Help string shown when mouse is on the comment column character.")
 602
 603 (defconst ruler-mode-goal-column-help-echo
 604   "\
 605 drag-mouse-2: set goal column, \
 606 mouse-2: unset goal column"
 607   "Help string shown when mouse is on the goal column character.")
 608
 609 (defconst ruler-mode-margin-help-echo
 610   "%s margin %S"
 611   "Help string shown when mouse is over a margin area.")
 612
 613 (defconst ruler-mode-fringe-help-echo
 614   "%s fringe %S"
 615   "Help string shown when mouse is over a fringe area.")
 616
 617 (defsubst ruler-mode-space (width &rest props)
 618   "Return a single space string of WIDTH times the normal character width.
 619 Optional argument PROPS specifies other text properties to apply."
 620   (apply 'propertize " " 'display (list 'space :width width) props))
 621 \f
 622 (defun ruler-mode-ruler ()
 623   "Compute and return an header line ruler."
 624   (let* ((w (window-width))
 625          (m (window-margins))
 626          (f (window-fringes))
 627          (i 0)
 628          (j (window-hscroll))
 629          ;; Setup the scrollbar, fringes, and margins areas.
 630          (lf (ruler-mode-space
 631               'left-fringe
 632               'face 'ruler-mode-fringes-face
 633               'help-echo (format ruler-mode-fringe-help-echo
 634                                  "Left" (or (car f) 0))))
 635          (rf (ruler-mode-space
 636               'right-fringe
 637               'face 'ruler-mode-fringes-face
 638               'help-echo (format ruler-mode-fringe-help-echo
 639                                  "Right" (or (cadr f) 0))))
 640          (lm (ruler-mode-space
 641               'left-margin
 642               'face 'ruler-mode-margins-face
 643               'help-echo (format ruler-mode-margin-help-echo
 644                                  "Left" (or (car m) 0))))
 645          (rm (ruler-mode-space
 646               'right-margin
 647               'face 'ruler-mode-margins-face
 648               'help-echo (format ruler-mode-margin-help-echo
 649                                  "Right" (or (cdr m) 0))))
 650          (sb (ruler-mode-space
 651               'scroll-bar
 652               'face 'ruler-mode-pad-face))
 653          ;; Remember the scrollbar vertical type.
 654          (sbvt (car (window-current-scroll-bars)))
 655          ;; Create an "clean" ruler.
 656          (ruler
 657           (propertize
 658            (make-string w ruler-mode-basic-graduation-char)
 659            'face 'ruler-mode-default-face
 660            'local-map ruler-mode-map
 661            'help-echo (cond
 662                        (ruler-mode-show-tab-stops
 663                         ruler-mode-ruler-help-echo-when-tab-stops)
 664                        (goal-column
 665                         ruler-mode-ruler-help-echo-when-goal-column)
 666                        (ruler-mode-ruler-help-echo))))
 667          k c)
 668     ;; Setup the active area.
 669     (while (< i w)
 670       ;; Graduations.
 671       (cond
 672        ;; Show a number graduation.
 673        ((= (mod j 10) 0)
 674         (setq c (number-to-string (/ j 10))
 675               m (length c)
 676               k i)
 677         (put-text-property
 678          i (1+ i) 'face 'ruler-mode-column-number-face
 679          ruler)
 680         (while (and (> m 0) (>= k 0))
 681           (aset ruler k (aref c (setq m (1- m))))
 682           (setq k (1- k))))
 683        ;; Show an intermediate graduation.
 684        ((= (mod j 5) 0)
 685         (aset ruler i ruler-mode-inter-graduation-char)))
 686       ;; Special columns.
 687       (cond
 688        ;; Show the `current-column' marker.
 689        ((= j (current-column))
 690         (aset ruler i ruler-mode-current-column-char)
 691         (put-text-property
 692          i (1+ i) 'face 'ruler-mode-current-column-face
 693          ruler))
 694        ;; Show the `goal-column' marker.
 695        ((and goal-column (= j goal-column))
 696         (aset ruler i ruler-mode-goal-column-char)
 697         (put-text-property
 698          i (1+ i) 'face 'ruler-mode-goal-column-face
 699          ruler)
 700         (put-text-property
 701          i (1+ i) 'help-echo ruler-mode-goal-column-help-echo
 702          ruler))
 703        ;; Show the `comment-column' marker.
 704        ((= j comment-column)
 705         (aset ruler i ruler-mode-comment-column-char)
 706         (put-text-property
 707          i (1+ i) 'face 'ruler-mode-comment-column-face
 708          ruler)
 709         (put-text-property
 710          i (1+ i) 'help-echo ruler-mode-comment-column-help-echo
 711          ruler))
 712        ;; Show the `fill-column' marker.
 713        ((= j fill-column)
 714         (aset ruler i ruler-mode-fill-column-char)
 715         (put-text-property
 716          i (1+ i) 'face 'ruler-mode-fill-column-face
 717          ruler)
 718         (put-text-property
 719          i (1+ i) 'help-echo ruler-mode-fill-column-help-echo
 720          ruler))
 721        ;; Show the `tab-stop-list' markers.
 722        ((and ruler-mode-show-tab-stops (member j tab-stop-list))
 723         (aset ruler i ruler-mode-tab-stop-char)
 724         (put-text-property
 725          i (1+ i) 'face 'ruler-mode-tab-stop-face
 726          ruler)))
 727       (setq i (1+ i)
 728             j (1+ j)))
 729     ;; Return the ruler propertized string.  Using list here,
 730     ;; instead of concat visually separate the different areas.
 731     (if (nth 2 (window-fringes))
 732         ;; fringes outside margins.
 733         (list "" (and (eq 'left sbvt) sb) lf lm
 734               ruler rm rf (and (eq 'right sbvt) sb))
 735       ;; fringes inside margins.
 736       (list "" (and (eq 'left sbvt) sb) lm lf
 737             ruler rf rm (and (eq 'right sbvt) sb)))))
 738
 739 (provide 'ruler-mode)
 740
 741 ;; Local Variables:
 742 ;; coding: iso-latin-1
 743 ;; End:
 744
 745 ;;; arch-tag: b2f24546-5605-44c4-b67b-c9a4eeba3ee8
 746 ;;; ruler-mode.el ends here