lisp/ruler-mode.el

   1 ;;; ruler-mode.el --- display a ruler in the header line
   2
   3 ;; Copyright (C) 2001-2016 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 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; This library provides a minor mode to display a ruler in the header
  29 ;; line.  It works from Emacs 21 onwards.
  30 ;;
  31 ;; You can use the mouse to change the `fill-column' `comment-column',
  32 ;; `goal-column', `window-margins' and `tab-stop-list' settings:
  33 ;;
  34 ;; [header-line (shift down-mouse-1)] set left margin end to the ruler
  35 ;; graduation where the mouse pointer is on.
  36 ;;
  37 ;; [header-line (shift down-mouse-3)] set right margin beginning to
  38 ;; the ruler graduation where the mouse pointer is on.
  39 ;;
  40 ;; [header-line down-mouse-2] Drag the `fill-column', `comment-column'
  41 ;; or `goal-column' to a ruler graduation.
  42 ;;
  43 ;; [header-line (control down-mouse-1)] add a tab stop to the ruler
  44 ;; graduation where the mouse pointer is on.
  45 ;;
  46 ;; [header-line (control down-mouse-3)] remove the tab stop at the
  47 ;; ruler graduation where the mouse pointer is on.
  48 ;;
  49 ;; [header-line (control down-mouse-2)] or M-x
  50 ;; `ruler-mode-toggle-show-tab-stops' toggle showing and visually
  51 ;; editing `tab-stop-list' setting.  The `ruler-mode-show-tab-stops'
  52 ;; option controls if the ruler shows tab stops by default.
  53 ;;
  54 ;; In the ruler the character `ruler-mode-current-column-char' shows
  55 ;; the `current-column' location, `ruler-mode-fill-column-char' shows
  56 ;; the `fill-column' location, `ruler-mode-comment-column-char' shows
  57 ;; the `comment-column' location, `ruler-mode-goal-column-char' shows
  58 ;; the `goal-column' and `ruler-mode-tab-stop-char' shows tab stop
  59 ;; locations.  Graduations in `window-margins' and `window-fringes'
  60 ;; areas are shown with a different foreground color.
  61 ;;
  62 ;; It is also possible to customize the following characters:
  63 ;;
  64 ;; - `ruler-mode-basic-graduation-char' character used for basic
  65 ;;   graduations ('.' by default).
  66 ;; - `ruler-mode-inter-graduation-char' character used for
  67 ;;   intermediate graduations ('!' by default).
  68 ;;
  69 ;; The following faces are customizable:
  70 ;;
  71 ;; - `ruler-mode-default' the ruler default face.
  72 ;; - `ruler-mode-fill-column' the face used to highlight the
  73 ;;   `fill-column' character.
  74 ;; - `ruler-mode-comment-column' the face used to highlight the
  75 ;;   `comment-column' character.
  76 ;; - `ruler-mode-goal-column' the face used to highlight the
  77 ;;   `goal-column' character.
  78 ;; - `ruler-mode-current-column' the face used to highlight the
  79 ;;   `current-column' character.
  80 ;; - `ruler-mode-tab-stop' the face used to highlight tab stop
  81 ;;   characters.
  82 ;; - `ruler-mode-margins' the face used to highlight graduations
  83 ;;   in the `window-margins' areas.
  84 ;; - `ruler-mode-fringes' the face used to highlight graduations
  85 ;;   in the `window-fringes' areas.
  86 ;; - `ruler-mode-column-number' the face used to highlight the
  87 ;;   numbered graduations.
  88 ;;
  89 ;; `ruler-mode-default' inherits from the built-in `default' face.
  90 ;; All `ruler-mode' faces inherit from `ruler-mode-default'.
  91 ;;
  92 ;; WARNING: To keep ruler graduations aligned on text columns it is
  93 ;; important to use the same font family and size for ruler and text
  94 ;; areas.
  95 ;;
  96 ;; You can override the ruler format by defining an appropriate
  97 ;; function as the buffer-local value of `ruler-mode-ruler-function'.
  98
  99 ;; Installation
 100 ;;
 101 ;; To automatically display the ruler in specific major modes use:
 102 ;;
 103 ;;    (add-hook '<major-mode>-hook 'ruler-mode)
 104 ;;
 105
 106 ;;; History:
 107 ;;
 108 \f
 109 ;;; Code:
 110 (eval-when-compile
 111   (require 'wid-edit))
 112 (require 'scroll-bar)
 113 (require 'fringe)
 114
 115 (defgroup ruler-mode nil
 116   "Display a ruler in the header line."
 117   :version "22.1"
 118   :group 'convenience)
 119
 120 (defcustom ruler-mode-show-tab-stops nil
 121   "If non-nil the ruler shows tab stop positions.
 122 Also allowing to visually change `tab-stop-list' setting using
 123 <C-down-mouse-1> and <C-down-mouse-3> on the ruler to respectively add
 124 or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
 125 <C-down-mouse-2> on the ruler toggles showing/editing of tab stops."
 126   :group 'ruler-mode
 127   :type 'boolean)
 128
 129 ;; IMPORTANT: This function must be defined before the following
 130 ;; defcustoms because it is used in their :validate clause.
 131 (defun ruler-mode-character-validate (widget)
 132   "Ensure WIDGET value is a valid character value."
 133   (save-excursion
 134     (let ((value (widget-value widget)))
 135       (unless (characterp value)
 136         (widget-put widget :error
 137                     (format "Invalid character value: %S" value))
 138         widget))))
 139
 140 (defcustom ruler-mode-fill-column-char (if (char-displayable-p ?¶)
 141                                            ?\¶
 142                                          ?\|)
 143   "Character used at the `fill-column' location."
 144   :group 'ruler-mode
 145   :type '(choice
 146           (character :tag "Character")
 147           (integer :tag "Integer char value"
 148                    :validate ruler-mode-character-validate)))
 149
 150 (defcustom ruler-mode-comment-column-char ?\#
 151   "Character used at the `comment-column' location."
 152   :group 'ruler-mode
 153   :type '(choice
 154           (character :tag "Character")
 155           (integer :tag "Integer char value"
 156                    :validate ruler-mode-character-validate)))
 157
 158 (defcustom ruler-mode-goal-column-char ?G
 159   "Character used at the `goal-column' location."
 160   :group 'ruler-mode
 161   :type '(choice
 162           (character :tag "Character")
 163           (integer :tag "Integer char value"
 164                    :validate ruler-mode-character-validate)))
 165
 166 (defcustom ruler-mode-current-column-char (if (char-displayable-p ?¦)
 167                                               ?\¦
 168                                             ?\@)
 169   "Character used at the `current-column' location."
 170   :group 'ruler-mode
 171   :type '(choice
 172           (character :tag "Character")
 173           (integer :tag "Integer char value"
 174                    :validate ruler-mode-character-validate)))
 175
 176 (defcustom ruler-mode-tab-stop-char ?\T
 177   "Character used at `tab-stop-list' locations."
 178   :group 'ruler-mode
 179   :type '(choice
 180           (character :tag "Character")
 181           (integer :tag "Integer char value"
 182                    :validate ruler-mode-character-validate)))
 183
 184 (defcustom ruler-mode-basic-graduation-char ?\.
 185   "Character used for basic graduations."
 186   :group 'ruler-mode
 187   :type '(choice
 188           (character :tag "Character")
 189           (integer :tag "Integer char value"
 190                    :validate ruler-mode-character-validate)))
 191
 192 (defcustom ruler-mode-inter-graduation-char ?\!
 193   "Character used for intermediate graduations."
 194   :group 'ruler-mode
 195   :type '(choice
 196           (character :tag "Character")
 197           (integer :tag "Integer char value"
 198                    :validate ruler-mode-character-validate)))
 199
 200 (defcustom ruler-mode-set-goal-column-ding-flag t
 201   "Non-nil means do `ding' when `goal-column' is set."
 202   :group 'ruler-mode
 203   :type 'boolean)
 204 \f
 205 (defface ruler-mode-default
 206   '((((type tty))
 207      (:inherit default
 208                :background "grey64"
 209                :foreground "grey50"
 210                ))
 211     (t
 212      (:inherit default
 213                :background "grey76"
 214                :foreground "grey64"
 215                :box (:color "grey76"
 216                             :line-width 1
 217                             :style released-button)
 218                )))
 219   "Default face used by the ruler."
 220   :group 'ruler-mode)
 221
 222 (defface ruler-mode-pad
 223   '((((type tty))
 224      (:inherit ruler-mode-default
 225                :background "grey50"
 226                ))
 227     (t
 228      (:inherit ruler-mode-default
 229                :background "grey64"
 230                )))
 231   "Face used to pad inactive ruler areas."
 232   :group 'ruler-mode)
 233
 234 (defface ruler-mode-margins
 235   '((t
 236      (:inherit ruler-mode-default
 237                :foreground "white"
 238                )))
 239   "Face used to highlight margin areas."
 240   :group 'ruler-mode)
 241
 242 (defface ruler-mode-fringes
 243   '((t
 244      (:inherit ruler-mode-default
 245                :foreground "green"
 246                )))
 247   "Face used to highlight fringes areas."
 248   :group 'ruler-mode)
 249
 250 (defface ruler-mode-column-number
 251   '((t
 252      (:inherit ruler-mode-default
 253                :foreground "black"
 254                )))
 255   "Face used to highlight number graduations."
 256   :group 'ruler-mode)
 257
 258 (defface ruler-mode-fill-column
 259   '((t
 260      (:inherit ruler-mode-default
 261                :foreground "red"
 262                )))
 263   "Face used to highlight the fill column character."
 264   :group 'ruler-mode)
 265
 266 (defface ruler-mode-comment-column
 267   '((t
 268      (:inherit ruler-mode-default
 269                :foreground "red"
 270                )))
 271   "Face used to highlight the comment column character."
 272   :group 'ruler-mode)
 273
 274 (defface ruler-mode-goal-column
 275   '((t
 276      (:inherit ruler-mode-default
 277                :foreground "red"
 278                )))
 279   "Face used to highlight the goal column character."
 280   :group 'ruler-mode)
 281
 282 (defface ruler-mode-tab-stop
 283   '((t
 284      (:inherit ruler-mode-default
 285                :foreground "steelblue"
 286                )))
 287   "Face used to highlight tab stop characters."
 288   :group 'ruler-mode)
 289
 290 (defface ruler-mode-current-column
 291   '((t
 292      (:inherit ruler-mode-default
 293                :weight bold
 294                :foreground "yellow"
 295                )))
 296   "Face used to highlight the `current-column' character."
 297   :group 'ruler-mode)
 298 \f
 299
 300 (defsubst ruler-mode-full-window-width ()
 301   "Return the full width of the selected window."
 302   (let ((edges (window-edges)))
 303     (- (nth 2 edges) (nth 0 edges))))
 304
 305 (defsubst ruler-mode-window-col (n)
 306   "Return a column number relative to the selected window.
 307 N is a column number relative to selected frame."
 308   (- n
 309      (or (car (window-margins)) 0)
 310      (fringe-columns 'left)
 311      (scroll-bar-columns 'left)))
 312 \f
 313 (defun ruler-mode-mouse-set-left-margin (start-event)
 314   "Set left margin end to the graduation where the mouse pointer is on.
 315 START-EVENT is the mouse click event."
 316   (interactive "e")
 317   (let* ((start (event-start start-event))
 318          (end   (event-end   start-event))
 319          col w lm rm)
 320     (when (eq start end) ;; mouse click
 321       (save-selected-window
 322         (select-window (posn-window start))
 323         (setq col (- (car (posn-col-row start))
 324                      (scroll-bar-columns 'left))
 325               w   (- (ruler-mode-full-window-width)
 326                      (scroll-bar-columns 'left)
 327                      (scroll-bar-columns 'right)))
 328         (when (and (>= col 0) (< col w))
 329           (setq lm (window-margins)
 330                 rm (or (cdr lm) 0)
 331                 lm (or (car lm) 0))
 332           (message "Left margin set to %d (was %d)" col lm)
 333           (set-window-margins nil col rm))))))
 334
 335 (defun ruler-mode-mouse-set-right-margin (start-event)
 336   "Set right margin beginning to the graduation where the mouse pointer is on.
 337 START-EVENT is the mouse click event."
 338   (interactive "e")
 339   (let* ((start (event-start start-event))
 340          (end   (event-end   start-event))
 341          col w lm rm)
 342     (when (eq start end) ;; mouse click
 343       (save-selected-window
 344         (select-window (posn-window start))
 345         (setq col (- (car (posn-col-row start))
 346                      (scroll-bar-columns 'left))
 347               w   (- (ruler-mode-full-window-width)
 348                      (scroll-bar-columns 'left)
 349                      (scroll-bar-columns 'right)))
 350         (when (and (>= col 0) (< col w))
 351           (setq lm  (window-margins)
 352                 rm  (or (cdr lm) 0)
 353                 lm  (or (car lm) 0)
 354                 col (- w col 1))
 355           (message "Right margin set to %d (was %d)" col rm)
 356           (set-window-margins nil lm col))))))
 357
 358 (defvar ruler-mode-dragged-symbol nil
 359   "Column symbol dragged in the ruler.
 360 That is `fill-column', `comment-column', `goal-column', or nil when
 361 nothing is dragged.")
 362
 363 (defun ruler-mode-mouse-grab-any-column (start-event)
 364   "Drag a column symbol on the ruler.
 365 Start dragging on mouse down event START-EVENT, and update the column
 366 symbol value with the current value of the ruler graduation while
 367 dragging.  See also the variable `ruler-mode-dragged-symbol'."
 368   (interactive "e")
 369   (setq ruler-mode-dragged-symbol nil)
 370   (let* ((start (event-start start-event))
 371          col newc oldc)
 372     (save-selected-window
 373       (select-window (posn-window start))
 374       (setq col  (ruler-mode-window-col (car (posn-col-row start)))
 375             newc (+ col (window-hscroll)))
 376       (and
 377        (>= col 0) (< col (window-width))
 378        (cond
 379
 380         ;; Handle the fill column.
 381         ((eq newc fill-column)
 382          (setq oldc fill-column
 383                ruler-mode-dragged-symbol 'fill-column)
 384          t) ;; Start dragging
 385
 386         ;; Handle the comment column.
 387         ((eq newc comment-column)
 388          (setq oldc comment-column
 389                ruler-mode-dragged-symbol 'comment-column)
 390          t) ;; Start dragging
 391
 392         ;; Handle the goal column.
 393         ;; A. On mouse down on the goal column character on the ruler,
 394         ;;    update the `goal-column' value while dragging.
 395         ;; B. If `goal-column' is nil, set the goal column where the
 396         ;;    mouse is clicked.
 397         ;; C. On mouse click on the goal column character on the
 398         ;;    ruler, unset the goal column.
 399         ((eq newc goal-column)          ; A. Drag the goal column.
 400          (setq oldc goal-column
 401                ruler-mode-dragged-symbol 'goal-column)
 402          t) ;; Start dragging
 403
 404         ((null goal-column)             ; B. Set the goal column.
 405          (setq oldc goal-column
 406                goal-column newc)
 407          ;; mouse-2 coming AFTER drag-mouse-2 invokes `ding'.  This
 408          ;; `ding' flushes the next messages about setting goal
 409          ;; column.  So here I force fetch the event(mouse-2) and
 410          ;; throw away.
 411          (read-event)
 412          ;; Ding BEFORE `message' is OK.
 413          (when ruler-mode-set-goal-column-ding-flag
 414            (ding))
 415          (message "Goal column set to %d (click on %s again to unset it)"
 416                   newc
 417                   (propertize (char-to-string ruler-mode-goal-column-char)
 418                               'face 'ruler-mode-goal-column))
 419          nil) ;; Don't start dragging.
 420         )
 421        (if (eq 'click (ruler-mode-mouse-drag-any-column-iteration
 422                        (posn-window start)))
 423            (when (eq 'goal-column ruler-mode-dragged-symbol)
 424              ;; C. Unset the goal column.
 425              (set-goal-column t))
 426          ;; At end of dragging, report the updated column symbol.
 427          (message "%s is set to %d (was %d)"
 428                   ruler-mode-dragged-symbol
 429                   (symbol-value ruler-mode-dragged-symbol)
 430                   oldc))))))
 431
 432 (defun ruler-mode-mouse-drag-any-column-iteration (window)
 433   "Update the ruler while dragging the mouse.
 434 WINDOW is the window where occurred the last down-mouse event.
 435 Return the symbol `drag' if the mouse has been dragged, or `click' if
 436 the mouse has been clicked."
 437   (let ((drags 0)
 438         event)
 439     (track-mouse
 440       ;; Signal the display engine to freeze the mouse pointer shape.
 441       (setq track-mouse 'dragging)
 442       (while (mouse-movement-p (setq event (read-event)))
 443         (setq drags (1+ drags))
 444         (when (eq window (posn-window (event-end event)))
 445           (ruler-mode-mouse-drag-any-column event)
 446           (force-mode-line-update))))
 447     (if (and (zerop drags) (eq 'click (car (event-modifiers event))))
 448         'click
 449       'drag)))
 450
 451 (defun ruler-mode-mouse-drag-any-column (start-event)
 452   "Update the value of the symbol dragged on the ruler.
 453 Called on each mouse motion event START-EVENT."
 454   (let* ((start (event-start start-event))
 455          (end   (event-end   start-event))
 456          col newc)
 457     (save-selected-window
 458       (select-window (posn-window start))
 459       (setq col  (ruler-mode-window-col (car (posn-col-row end)))
 460             newc (+ col (window-hscroll)))
 461       (when (and (>= col 0) (< col (window-width)))
 462         (set ruler-mode-dragged-symbol newc)))))
 463 \f
 464 (defun ruler-mode-mouse-add-tab-stop (start-event)
 465   "Add a tab stop to the graduation where the mouse pointer is on.
 466 START-EVENT is the mouse click event."
 467   (interactive "e")
 468   (when ruler-mode-show-tab-stops
 469     (let* ((start (event-start start-event))
 470            (end   (event-end   start-event))
 471            col ts)
 472       (when (eq start end) ;; mouse click
 473         (save-selected-window
 474           (select-window (posn-window start))
 475           (setq col (ruler-mode-window-col (car (posn-col-row start)))
 476                 ts  (+ col (window-hscroll)))
 477           (and (>= col 0) (< col (window-width))
 478                (not (member ts tab-stop-list))
 479                (progn
 480                  (message "Tab stop set to %d" ts)
 481                  (when (null tab-stop-list)
 482                    (setq tab-stop-list (indent-accumulate-tab-stops (1- ts))))
 483                  (setq tab-stop-list (sort (cons ts tab-stop-list) #'<)))))))))
 484
 485 (defun ruler-mode-mouse-del-tab-stop (start-event)
 486   "Delete tab stop at the graduation where the mouse pointer is on.
 487 START-EVENT is the mouse click event."
 488   (interactive "e")
 489   (when ruler-mode-show-tab-stops
 490     (let* ((start (event-start start-event))
 491            (end   (event-end   start-event))
 492            col ts)
 493       (when (eq start end) ;; mouse click
 494         (save-selected-window
 495           (select-window (posn-window start))
 496           (setq col (ruler-mode-window-col (car (posn-col-row start)))
 497                 ts  (+ col (window-hscroll)))
 498           (and (>= col 0) (< col (window-width))
 499                (member ts tab-stop-list)
 500                (progn
 501                  (message "Tab stop at %d deleted" ts)
 502                  (setq tab-stop-list (delete ts tab-stop-list)))))))))
 503
 504 (defun ruler-mode-toggle-show-tab-stops ()
 505   "Toggle showing of tab stops on the ruler."
 506   (interactive)
 507   (setq ruler-mode-show-tab-stops (not ruler-mode-show-tab-stops))
 508   (force-mode-line-update))
 509 \f
 510 (defvar ruler-mode-map
 511   (let ((km (make-sparse-keymap)))
 512     (define-key km [header-line down-mouse-1]
 513       #'ignore)
 514     (define-key km [header-line down-mouse-3]
 515       #'ignore)
 516     (define-key km [header-line down-mouse-2]
 517       #'ruler-mode-mouse-grab-any-column)
 518     (define-key km [header-line (shift down-mouse-1)]
 519       #'ruler-mode-mouse-set-left-margin)
 520     (define-key km [header-line (shift down-mouse-3)]
 521       #'ruler-mode-mouse-set-right-margin)
 522     (define-key km [header-line (control down-mouse-1)]
 523       #'ruler-mode-mouse-add-tab-stop)
 524     (define-key km [header-line (control down-mouse-3)]
 525       #'ruler-mode-mouse-del-tab-stop)
 526     (define-key km [header-line (control down-mouse-2)]
 527       #'ruler-mode-toggle-show-tab-stops)
 528     (define-key km [header-line (shift mouse-1)]
 529       'ignore)
 530     (define-key km [header-line (shift mouse-3)]
 531       'ignore)
 532     (define-key km [header-line (control mouse-1)]
 533       'ignore)
 534     (define-key km [header-line (control mouse-3)]
 535       'ignore)
 536     (define-key km [header-line (control mouse-2)]
 537       'ignore)
 538     km)
 539   "Keymap for ruler minor mode.")
 540
 541 (defvar ruler-mode-header-line-format-old nil
 542   "Hold previous value of `header-line-format'.")
 543
 544 (defvar ruler-mode-ruler-function 'ruler-mode-ruler
 545   "Function to call to return ruler header line format.
 546 This variable is expected to be made buffer-local by modes.")
 547
 548 (defconst ruler-mode-header-line-format
 549   '(:eval (funcall ruler-mode-ruler-function))
 550   "`header-line-format' used in ruler mode.
 551 Call `ruler-mode-ruler-function' to compute the ruler value.")
 552
 553 ;;;###autoload
 554 (defvar ruler-mode nil
 555   "Non-nil if Ruler mode is enabled.
 556 Use the command `ruler-mode' to change this variable.")
 557 (make-variable-buffer-local 'ruler-mode)
 558
 559 (defun ruler--save-header-line-format ()
 560   "Install the header line format for Ruler mode.
 561 Unless Ruler mode is already enabled, save the old header line
 562 format first."
 563   (when (and (not ruler-mode)
 564              (local-variable-p 'header-line-format)
 565              (not (local-variable-p 'ruler-mode-header-line-format-old)))
 566     (set (make-local-variable 'ruler-mode-header-line-format-old)
 567          header-line-format))
 568   (setq header-line-format ruler-mode-header-line-format))
 569
 570 ;;;###autoload
 571 (define-minor-mode ruler-mode
 572   "Toggle display of ruler in header line (Ruler mode).
 573 With a prefix argument ARG, enable Ruler mode if ARG is positive,
 574 and disable it otherwise.  If called from Lisp, enable the mode
 575 if ARG is omitted or nil."
 576   nil nil
 577   ruler-mode-map
 578   :group 'ruler-mode
 579   :variable (ruler-mode
 580              . (lambda (enable)
 581                  (when enable
 582                    (ruler--save-header-line-format))
 583                  (setq ruler-mode enable)))
 584   (if ruler-mode
 585       (add-hook 'post-command-hook 'force-mode-line-update nil t)
 586     ;; When `ruler-mode' is off restore previous header line format if
 587     ;; the current one is the ruler header line format.
 588     (when (eq header-line-format ruler-mode-header-line-format)
 589       (kill-local-variable 'header-line-format)
 590       (when (local-variable-p 'ruler-mode-header-line-format-old)
 591         (setq header-line-format ruler-mode-header-line-format-old)
 592         (kill-local-variable 'ruler-mode-header-line-format-old)))
 593     (remove-hook 'post-command-hook 'force-mode-line-update t)))
 594 \f
 595 ;; Add ruler-mode to the minor mode menu in the mode line
 596 (define-key mode-line-mode-menu [ruler-mode]
 597   `(menu-item "Ruler" ruler-mode
 598               :button (:toggle . ruler-mode)))
 599
 600 (defconst ruler-mode-ruler-help-echo
 601   "\
 602 S-mouse-1/3: set L/R margin, \
 603 mouse-2: set goal column, \
 604 C-mouse-2: show tabs"
 605   "Help string shown when mouse is over the ruler.
 606 `ruler-mode-show-tab-stops' is nil.")
 607
 608 (defconst ruler-mode-ruler-help-echo-when-goal-column
 609   "\
 610 S-mouse-1/3: set L/R margin, \
 611 C-mouse-2: show tabs"
 612   "Help string shown when mouse is over the ruler.
 613 `goal-column' is set and `ruler-mode-show-tab-stops' is nil.")
 614
 615 (defconst ruler-mode-ruler-help-echo-when-tab-stops
 616   "\
 617 C-mouse1/3: set/unset tab, \
 618 C-mouse-2: hide tabs"
 619   "Help string shown when mouse is over the ruler.
 620 `ruler-mode-show-tab-stops' is non-nil.")
 621
 622 (defconst ruler-mode-fill-column-help-echo
 623   "drag-mouse-2: set fill column"
 624   "Help string shown when mouse is on the fill column character.")
 625
 626 (defconst ruler-mode-comment-column-help-echo
 627   "drag-mouse-2: set comment column"
 628   "Help string shown when mouse is on the comment column character.")
 629
 630 (defconst ruler-mode-goal-column-help-echo
 631   "\
 632 drag-mouse-2: set goal column, \
 633 mouse-2: unset goal column"
 634   "Help string shown when mouse is on the goal column character.")
 635
 636 (defconst ruler-mode-margin-help-echo
 637   "%s margin %S"
 638   "Help string shown when mouse is over a margin area.")
 639
 640 (defconst ruler-mode-fringe-help-echo
 641   "%s fringe %S"
 642   "Help string shown when mouse is over a fringe area.")
 643
 644 (defsubst ruler-mode-space (width &rest props)
 645   "Return a single space string of WIDTH times the normal character width.
 646 Optional argument PROPS specifies other text properties to apply."
 647   (apply 'propertize " " 'display (list 'space :width width) props))
 648 \f
 649 (defun ruler-mode-ruler ()
 650   "Compute and return a header line ruler."
 651   (let* ((w (window-width))
 652          (m (window-margins))
 653          (f (window-fringes))
 654          (i 0)
 655          (j (window-hscroll))
 656          ;; Setup the scrollbar, fringes, and margins areas.
 657          (lf (ruler-mode-space
 658               'left-fringe
 659               'face 'ruler-mode-fringes
 660               'help-echo (format ruler-mode-fringe-help-echo
 661                                  "Left" (or (car f) 0))))
 662          (rf (ruler-mode-space
 663               'right-fringe
 664               'face 'ruler-mode-fringes
 665               'help-echo (format ruler-mode-fringe-help-echo
 666                                  "Right" (or (cadr f) 0))))
 667          (lm (ruler-mode-space
 668               'left-margin
 669               'face 'ruler-mode-margins
 670               'help-echo (format ruler-mode-margin-help-echo
 671                                  "Left" (or (car m) 0))))
 672          (rm (ruler-mode-space
 673               'right-margin
 674               'face 'ruler-mode-margins
 675               'help-echo (format ruler-mode-margin-help-echo
 676                                  "Right" (or (cdr m) 0))))
 677          (sb (ruler-mode-space
 678               'scroll-bar
 679               'face 'ruler-mode-pad))
 680          ;; Remember the scrollbar vertical type.
 681          (sbvt (car (window-current-scroll-bars)))
 682          ;; Create an "clean" ruler.
 683          (ruler
 684           (propertize
 685            (string-to-multibyte
 686             (make-string w ruler-mode-basic-graduation-char))
 687            'face 'ruler-mode-default
 688            'local-map ruler-mode-map
 689            'help-echo (cond
 690                        (ruler-mode-show-tab-stops
 691                         ruler-mode-ruler-help-echo-when-tab-stops)
 692                        (goal-column
 693                         ruler-mode-ruler-help-echo-when-goal-column)
 694                        (ruler-mode-ruler-help-echo))))
 695          k c)
 696     ;; Setup the active area.
 697     (while (< i w)
 698       ;; Graduations.
 699       (cond
 700        ;; Show a number graduation.
 701        ((= (mod j 10) 0)
 702         (setq c (number-to-string (/ j 10))
 703               m (length c)
 704               k i)
 705         (put-text-property
 706          i (1+ i) 'face 'ruler-mode-column-number
 707          ruler)
 708         (while (and (> m 0) (>= k 0))
 709           (aset ruler k (aref c (setq m (1- m))))
 710           (setq k (1- k))))
 711        ;; Show an intermediate graduation.
 712        ((= (mod j 5) 0)
 713         (aset ruler i ruler-mode-inter-graduation-char)))
 714       ;; Special columns.
 715       (cond
 716        ;; Show the `current-column' marker.
 717        ((= j (current-column))
 718         (aset ruler i ruler-mode-current-column-char)
 719         (put-text-property
 720          i (1+ i) 'face 'ruler-mode-current-column
 721          ruler))
 722        ;; Show the `goal-column' marker.
 723        ((and goal-column (= j goal-column))
 724         (aset ruler i ruler-mode-goal-column-char)
 725         (put-text-property
 726          i (1+ i) 'face 'ruler-mode-goal-column
 727          ruler)
 728         (put-text-property
 729          i (1+ i) 'mouse-face 'mode-line-highlight
 730          ruler)
 731         (put-text-property
 732          i (1+ i) 'help-echo ruler-mode-goal-column-help-echo
 733          ruler))
 734        ;; Show the `comment-column' marker.
 735        ((= j comment-column)
 736         (aset ruler i ruler-mode-comment-column-char)
 737         (put-text-property
 738          i (1+ i) 'face 'ruler-mode-comment-column
 739          ruler)
 740         (put-text-property
 741          i (1+ i) 'mouse-face 'mode-line-highlight
 742          ruler)
 743         (put-text-property
 744          i (1+ i) 'help-echo ruler-mode-comment-column-help-echo
 745          ruler))
 746        ;; Show the `fill-column' marker.
 747        ((= j fill-column)
 748         (aset ruler i ruler-mode-fill-column-char)
 749         (put-text-property
 750          i (1+ i) 'face 'ruler-mode-fill-column
 751          ruler)
 752         (put-text-property
 753          i (1+ i) 'mouse-face 'mode-line-highlight
 754          ruler)
 755         (put-text-property
 756          i (1+ i) 'help-echo ruler-mode-fill-column-help-echo
 757          ruler))
 758        ;; Show the `tab-stop-list' markers.
 759        ((and ruler-mode-show-tab-stops (= j (indent-next-tab-stop (1- j))))
 760         (aset ruler i ruler-mode-tab-stop-char)
 761         (put-text-property
 762          i (1+ i) 'face 'ruler-mode-tab-stop
 763          ruler)))
 764       (setq i (1+ i)
 765             j (1+ j)))
 766     ;; Return the ruler propertized string.  Using list here,
 767     ;; instead of concat visually separate the different areas.
 768     (if (nth 2 (window-fringes))
 769         ;; fringes outside margins.
 770         (list "" (and (eq 'left sbvt) sb) lf lm
 771               ruler rm rf (and (eq 'right sbvt) sb))
 772       ;; fringes inside margins.
 773       (list "" (and (eq 'left sbvt) sb) lm lf
 774             ruler rf rm (and (eq 'right sbvt) sb)))))
 775
 776 (provide 'ruler-mode)
 777
 778 ;;; ruler-mode.el ends here