lisp/emulation/tpu-extras.el

   1 ;;; tpu-extras.el --- scroll margins and free cursor mode for TPU-edt
   2
   3 ;; Copyright (C) 1993, 1994, 1995, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008 Free Software Foundation, Inc.
   5
   6 ;; Author: Rob Riepel <riepel@networking.stanford.edu>
   7 ;; Maintainer: Rob Riepel <riepel@networking.stanford.edu>
   8 ;; Keywords: emulations
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 3, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;;  Use the functions defined here to customize TPU-edt to your tastes by
  30 ;;  setting scroll margins and/or turning on free cursor mode.  Here's an
  31 ;;  example for your .emacs file.
  32
  33 ;;     (tpu-set-cursor-free)                   ; Set cursor free.
  34 ;;     (tpu-set-scroll-margins "10%" "15%")    ; Set scroll margins.
  35
  36 ;;  Scroll margins and cursor binding can be changed from within emacs using
  37 ;;  the following commands:
  38
  39 ;;     tpu-set-scroll-margins  or   set scroll margins
  40 ;;     tpu-set-cursor-bound    or   set cursor bound
  41 ;;     tpu-set-cursor-free     or   set cursor free
  42
  43 ;;  Additionally, Gold-F toggles between bound and free cursor modes.
  44
  45 ;;  Note that switching out of free cursor mode or exiting TPU-edt while in
  46 ;;  free cursor mode strips trailing whitespace from every line in the file.
  47
  48
  49 ;;; Details:
  50
  51 ;;  The functions contained in this file implement scroll margins and free
  52 ;;  cursor mode.  The following keys and commands are affected.
  53
  54 ;;       key/command   function                        scroll   cursor
  55
  56 ;;       Up-Arrow      previous line                     x        x
  57 ;;       Down-Arrow    next line                         x        x
  58 ;;       Right-Arrow   next character                             x
  59 ;;       Left-Arrow    previous character                         x
  60 ;;       KP0           next or previous line             x
  61 ;;       KP7           next or previous page             x
  62 ;;       KP8           next or previous screen           x
  63 ;;       KP2           next or previous end-of-line      x        x
  64 ;;       Control-e     current end-of-line                        x
  65 ;;       Control-h     previous beginning-of-line        x
  66 ;;       Next Scr      next screen                       x
  67 ;;       Prev Scr      previous screen                   x
  68 ;;       Search        find a string                     x
  69 ;;       Replace       find and replace a string         x
  70 ;;       Newline       insert a newline                  x
  71 ;;       Paragraph     next or previous paragraph        x
  72 ;;       Auto-Fill     break lines on spaces             x
  73
  74 ;;  These functions are not part of the base TPU-edt for the following
  75 ;;  reasons:
  76
  77 ;;  Free cursor mode is implemented with the emacs picture-mode functions.
  78 ;;  These functions support moving the cursor all over the screen, however,
  79 ;;  when the cursor is moved past the end of a line, spaces or tabs are
  80 ;;  appended to the line - even if no text is entered in that area.  In
  81 ;;  order for a free cursor mode to work exactly like TPU/edt, this trailing
  82 ;;  whitespace needs to be dealt with in every function that might encounter
  83 ;;  it.  Such global changes are impractical, however, free cursor mode is
  84 ;;  too valuable to abandon completely, so it has been implemented in those
  85 ;;  functions where it serves best.
  86
  87 ;;  The implementation of scroll margins adds overhead to previously
  88 ;;  simple and often used commands.  These commands are now responsible
  89 ;;  for their normal operation and part of the display function.  There
  90 ;;  is a possibility that this display overhead could adversely affect the
  91 ;;  performance of TPU-edt on slower computers.  In order to support the
  92 ;;  widest range of computers, scroll margin support is optional.
  93
  94 ;;  It's actually not known whether the overhead associated with scroll
  95 ;;  margin support is significant.  If you find that it is, please send
  96 ;;  a note describing the extent of the performance degradation.  Be sure
  97 ;;  to include a description of the platform where you're running TPU-edt.
  98 ;;  Send your note to the address provided by Gold-V.
  99
 100 ;;  Even with these differences and limitations, these functions implement
 101 ;;  important aspects of the real TPU/edt.  Those who miss free cursor mode
 102 ;;  and/or scroll margins will appreciate these implementations.
 103
 104 ;;; Code:
 105
 106
 107 ;;;  Gotta have tpu-edt
 108
 109 (require 'tpu-edt)
 110
 111
 112 ;;;  Customization variables
 113
 114 (defcustom tpu-top-scroll-margin 0
 115   "Scroll margin at the top of the screen.
 116 Interpreted as a percent of the current window size."
 117   :type 'integer
 118   :group 'tpu)
 119 (defcustom tpu-bottom-scroll-margin 0
 120   "Scroll margin at the bottom of the screen.
 121 Interpreted as a percent of the current window size."
 122   :type 'integer
 123   :group 'tpu)
 124
 125 (defcustom tpu-backward-char-like-tpu t
 126   "If non-nil, in free cursor mode backward-char (left-arrow) works
 127 just like TPU/edt.  Otherwise, backward-char will move to the end of
 128 the previous line when starting from a line beginning."
 129   :type 'boolean
 130   :group 'tpu)
 131
 132
 133 ;;;  Global variables
 134
 135 ;;;###autoload
 136 (define-minor-mode tpu-cursor-free-mode
 137   "Minor mode to allow the cursor to move freely about the screen."
 138   :init-value nil
 139   (if (not tpu-cursor-free-mode)
 140       (tpu-trim-line-ends)))
 141
 142
 143 ;;;  Hooks  --  Set cursor free in picture mode.
 144 ;;;             Clean up when writing a file from cursor free mode.
 145
 146 (add-hook 'picture-mode-hook 'tpu-set-cursor-free)
 147
 148 (defun tpu-trim-line-ends-if-needed ()
 149   "Eliminate whitespace at ends of lines, if the cursor is free."
 150   (if (and (buffer-modified-p) tpu-cursor-free-mode) (tpu-trim-line-ends)))
 151 (add-hook 'before-save-hook 'tpu-trim-line-ends-if-needed)
 152
 153
 154 ;;;  Utility routines for implementing scroll margins
 155
 156 (defun tpu-top-check (beg lines)
 157   "Enforce scroll margin at the top of screen."
 158   (let ((margin  (/ (* (window-height) tpu-top-scroll-margin) 100)))
 159     (cond ((< beg margin) (recenter beg))
 160           ((< (- beg lines) margin) (recenter margin)))))
 161
 162 (defun tpu-bottom-check (beg lines)
 163   "Enforce scroll margin at the bottom of screen."
 164   (let* ((height (window-height))
 165          (margin (+ 1 (/ (* height tpu-bottom-scroll-margin) 100)))
 166          ;; subtract 1 from height because it includes mode line
 167          (difference (- height margin 1)))
 168     (cond ((> beg difference) (recenter beg))
 169           ((> (+ beg lines) difference) (recenter (- margin))))))
 170
 171
 172 ;;;  Movement by character
 173
 174 (defun tpu-forward-char (num)
 175   "Move right ARG characters (left if ARG is negative)."
 176   (interactive "p")
 177   (if tpu-cursor-free-mode (picture-forward-column num) (forward-char num)))
 178
 179 (defun tpu-backward-char (num)
 180   "Move left ARG characters (right if ARG is negative)."
 181   (interactive "p")
 182   (cond ((not tpu-cursor-free-mode)
 183          (backward-char num))
 184         (tpu-backward-char-like-tpu
 185          (picture-backward-column num))
 186         ((bolp)
 187          (backward-char 1)
 188          (picture-end-of-line)
 189          (picture-backward-column (1- num)))
 190         (t
 191          (picture-backward-column num))))
 192
 193
 194 ;;;  Movement by line
 195
 196 (defun tpu-next-line (num)
 197   "Move to next line.
 198 Prefix argument serves as a repeat count."
 199   (interactive "p")
 200   (let ((beg (tpu-current-line)))
 201     (if tpu-cursor-free-mode (or (eobp) (picture-move-down num))
 202       (line-move num))
 203     (tpu-bottom-check beg num)
 204     (setq this-command 'next-line)))
 205
 206 (defun tpu-previous-line (num)
 207   "Move to previous line.
 208 Prefix argument serves as a repeat count."
 209   (interactive "p")
 210   (let ((beg (tpu-current-line)))
 211     (if tpu-cursor-free-mode (picture-move-up num) (line-move (- num)))
 212     (tpu-top-check beg num)
 213     (setq this-command 'previous-line)))
 214
 215 (defun tpu-next-beginning-of-line (num)
 216   "Move to beginning of line; if at beginning, move to beginning of next line.
 217 Accepts a prefix argument for the number of lines to move."
 218   (interactive "p")
 219   (let ((beg (tpu-current-line)))
 220     (backward-char 1)
 221     (forward-visible-line (- 1 num))
 222     (tpu-top-check beg num)))
 223
 224 (defun tpu-next-end-of-line (num)
 225   "Move to end of line; if at end, move to end of next line.
 226 Accepts a prefix argument for the number of lines to move."
 227   (interactive "p")
 228   (let ((beg (tpu-current-line)))
 229     (cond (tpu-cursor-free-mode
 230            (let ((beg (point)))
 231              (if (< 1 num) (forward-line num))
 232              (picture-end-of-line)
 233              (if (<= (point) beg) (progn (forward-line) (picture-end-of-line)))))
 234           (t
 235            (forward-char)
 236            (end-of-line num)))
 237     (tpu-bottom-check beg num)))
 238
 239 (defun tpu-previous-end-of-line (num)
 240   "Move EOL upward.
 241 Accepts a prefix argument for the number of lines to move."
 242   (interactive "p")
 243   (let ((beg (tpu-current-line)))
 244     (cond (tpu-cursor-free-mode
 245            (picture-end-of-line (- 1 num)))
 246           (t
 247            (end-of-line (- 1 num))))
 248     (tpu-top-check beg num)))
 249
 250 (defun tpu-current-end-of-line ()
 251   "Move point to end of current line."
 252   (interactive)
 253   (let ((beg (point)))
 254     (if tpu-cursor-free-mode (picture-end-of-line) (end-of-line))
 255     (if (= beg (point)) (message "You are already at the end of a line."))))
 256
 257 (defun tpu-forward-line (num)
 258   "Move to beginning of next line.
 259 Prefix argument serves as a repeat count."
 260   (interactive "p")
 261   (let ((beg (tpu-current-line)))
 262     (forward-line num)
 263     (tpu-bottom-check beg num)))
 264
 265 (defun tpu-backward-line (num)
 266   "Move to beginning of previous line.
 267 Prefix argument serves as repeat count."
 268   (interactive "p")
 269   (let ((beg (tpu-current-line)))
 270     (or (bolp) (>= 0 num) (setq num (- num 1)))
 271     (forward-line (- num))
 272     (tpu-top-check beg num)))
 273
 274
 275 ;;;  Movement by paragraph
 276
 277 (defun tpu-paragraph (num)
 278   "Move to the next paragraph in the current direction.
 279 A repeat count means move that many paragraphs."
 280   (interactive "p")
 281   (let* ((left nil)
 282          (beg (tpu-current-line))
 283          (height (window-height))
 284          (top-percent
 285           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 286          (bottom-percent
 287           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 288          (top-margin (/ (* height top-percent) 100))
 289          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 290          (bottom-margin (max beg (- height bottom-up-margin 1)))
 291          (top (save-excursion (move-to-window-line top-margin) (point)))
 292          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 293          (far (save-excursion
 294                 (goto-char bottom) (forward-line (- height 2)) (point))))
 295     (cond (tpu-advance
 296            (tpu-next-paragraph num)
 297            (cond((> (point) far)
 298                  (setq left (save-excursion (forward-line height)))
 299                  (if (= 0 left) (recenter top-margin)
 300                    (recenter (- left bottom-up-margin))))
 301                 (t
 302                  (and (> (point) bottom) (recenter bottom-margin)))))
 303           (t
 304            (tpu-previous-paragraph num)
 305            (and (< (point) top) (recenter (min beg top-margin)))))))
 306
 307
 308 ;;;  Movement by page
 309
 310 (defun tpu-page (num)
 311   "Move to the next page in the current direction.
 312 A repeat count means move that many pages."
 313   (interactive "p")
 314   (let* ((left nil)
 315          (beg (tpu-current-line))
 316          (height (window-height))
 317          (top-percent
 318           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 319          (bottom-percent
 320           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 321          (top-margin (/ (* height top-percent) 100))
 322          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 323          (bottom-margin (max beg (- height bottom-up-margin 1)))
 324          (top (save-excursion (move-to-window-line top-margin) (point)))
 325          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 326          (far (save-excursion
 327                 (goto-char bottom) (forward-line (- height 2)) (point))))
 328     (cond (tpu-advance
 329            (forward-page num)
 330            (cond((> (point) far)
 331                  (setq left (save-excursion (forward-line height)))
 332                  (if (= 0 left) (recenter top-margin)
 333                    (recenter (- left bottom-up-margin))))
 334                 (t
 335                  (and (> (point) bottom) (recenter bottom-margin)))))
 336           (t
 337            (backward-page num)
 338            (and (< (point) top) (recenter (min beg top-margin)))))))
 339
 340
 341 ;;;  Scrolling
 342
 343 (defun tpu-scroll-window-down (num)
 344   "Scroll the display down to the next section.
 345 A repeat count means scroll that many sections."
 346   (interactive "p")
 347   (let* ((beg (tpu-current-line))
 348          (height (1- (window-height)))
 349          (lines (* num (/ (* height tpu-percent-scroll) 100))))
 350     (line-move (- lines))
 351     (tpu-top-check beg lines)))
 352
 353 (defun tpu-scroll-window-up (num)
 354   "Scroll the display up to the next section.
 355 A repeat count means scroll that many sections."
 356   (interactive "p")
 357   (let* ((beg (tpu-current-line))
 358          (height (1- (window-height)))
 359          (lines (* num (/ (* height tpu-percent-scroll) 100))))
 360     (line-move lines)
 361     (tpu-bottom-check beg lines)))
 362
 363
 364 ;;;  Replace the TPU-edt internal search function
 365
 366 (defun tpu-search-internal (pat &optional quiet)
 367   "Search for a string or regular expression."
 368   (let* ((left nil)
 369          (beg (tpu-current-line))
 370          (height (window-height))
 371          (top-percent
 372           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 373          (bottom-percent
 374           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 375          (top-margin (/ (* height top-percent) 100))
 376          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 377          (bottom-margin (max beg (- height bottom-up-margin 1)))
 378          (top (save-excursion (move-to-window-line top-margin) (point)))
 379          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 380          (far (save-excursion
 381                 (goto-char bottom) (forward-line (- height 2)) (point))))
 382     (tpu-search-internal-core pat quiet)
 383     (if tpu-searching-forward
 384         (cond((> (point) far)
 385               (setq left (save-excursion (forward-line height)))
 386               (if (= 0 left) (recenter top-margin)
 387                 (recenter (- left bottom-up-margin))))
 388              (t
 389               (and (> (point) bottom) (recenter bottom-margin))))
 390       (and (< (point) top) (recenter (min beg top-margin))))))
 391
 392
 393
 394 ;; Advise the newline, newline-and-indent, and do-auto-fill functions.
 395 (defadvice newline (around tpu-respect-bottom-scroll-margin activate disable)
 396   "Respect `tpu-bottom-scroll-margin'."
 397   (let ((beg (tpu-current-line))
 398         (num (prefix-numeric-value (ad-get-arg 0))))
 399     ad-do-it
 400     (tpu-bottom-check beg num)))
 401
 402 (defadvice newline-and-indent (around tpu-respect-bottom-scroll-margin)
 403   "Respect `tpu-bottom-scroll-margin'."
 404   (let ((beg (tpu-current-line)))
 405     ad-do-it
 406     (tpu-bottom-check beg 1)))
 407
 408 (defadvice do-auto-fill (around tpu-respect-bottom-scroll-margin)
 409   "Respect `tpu-bottom-scroll-margin'."
 410   (let ((beg (tpu-current-line)))
 411     ad-do-it
 412     (tpu-bottom-check beg 1)))
 413
 414
 415 ;;;  Function to set scroll margins
 416
 417 ;;;###autoload
 418 (defun tpu-set-scroll-margins (top bottom)
 419   "Set scroll margins."
 420   (interactive
 421    "sEnter top scroll margin (N lines or N%% or RETURN for current value): \
 422 \nsEnter bottom scroll margin (N lines or N%% or RETURN for current value): ")
 423   ;; set top scroll margin
 424   (or (string= top "")
 425       (setq tpu-top-scroll-margin
 426             (if (string= "%" (substring top -1))
 427                 (string-to-number top)
 428               (/ (1- (+ (* (string-to-number top) 100) (window-height)))
 429                  (window-height)))))
 430   ;; set bottom scroll margin
 431   (or (string= bottom "")
 432       (setq tpu-bottom-scroll-margin
 433             (if (string= "%" (substring bottom -1))
 434                 (string-to-number bottom)
 435               (/ (1- (+ (* (string-to-number bottom) 100) (window-height)))
 436                  (window-height)))))
 437   (dolist (f '(newline newline-and-indent do-auto-fill))
 438     (ad-enable-advice f 'around 'tpu-respect-bottom-scroll-margin)
 439     (ad-activate f))
 440   ;; report scroll margin settings if running interactively
 441   (and (interactive-p)
 442        (message "Scroll margins set.  Top = %s%%, Bottom = %s%%"
 443                 tpu-top-scroll-margin tpu-bottom-scroll-margin)))
 444
 445
 446 ;;;  Functions to set cursor bound or free
 447
 448 ;;;###autoload
 449 (defun tpu-set-cursor-free ()
 450   "Allow the cursor to move freely about the screen."
 451   (interactive)
 452   (tpu-cursor-free-mode 1)
 453   (message "The cursor will now move freely about the screen."))
 454
 455 ;;;###autoload
 456 (defun tpu-set-cursor-bound ()
 457   "Constrain the cursor to the flow of the text."
 458   (interactive)
 459   (tpu-cursor-free-mode -1)
 460   (message "The cursor is now bound to the flow of your text."))
 461
 462 ;; Local Variables:
 463 ;; generated-autoload-file: "tpu-edt.el"
 464 ;; End:
 465
 466 ;; arch-tag: 89676fa4-33ec-48cb-9135-6f3bf230ab1a
 467 ;;; tpu-extras.el ends here