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 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 2, 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 (defvar tpu-cursor-free nil
 136   "If non-nil, let the cursor roam free.")
 137
 138
 139 ;;;  Hooks  --  Set cursor free in picture mode.
 140 ;;;             Clean up when writing a file from cursor free mode.
 141
 142 (add-hook 'picture-mode-hook 'tpu-set-cursor-free)
 143
 144 (defun tpu-write-file-hook nil
 145   "Eliminate whitespace at ends of lines, if the cursor is free."
 146   (if (and (buffer-modified-p) tpu-cursor-free) (tpu-trim-line-ends)))
 147
 148 (or (memq 'tpu-write-file-hook write-file-functions)
 149     (setq write-file-functions
 150           (cons 'tpu-write-file-hook write-file-functions)))
 151
 152
 153 ;;;  Utility routines for implementing scroll margins
 154
 155 (defun tpu-top-check (beg lines)
 156   "Enforce scroll margin at the top of screen."
 157   (let ((margin  (/ (* (window-height) tpu-top-scroll-margin) 100)))
 158     (cond ((< beg margin) (recenter beg))
 159           ((< (- beg lines) margin) (recenter margin)))))
 160
 161 (defun tpu-bottom-check (beg lines)
 162   "Enforce scroll margin at the bottom of screen."
 163   (let* ((height (window-height))
 164          (margin (+ 1 (/ (* height tpu-bottom-scroll-margin) 100)))
 165          ;; subtract 1 from height because it includes mode line
 166          (difference (- height margin 1)))
 167     (cond ((> beg difference) (recenter beg))
 168           ((> (+ beg lines) difference) (recenter (- margin))))))
 169
 170
 171 ;;;  Movement by character
 172
 173 (defun tpu-forward-char (num)
 174   "Move right ARG characters (left if ARG is negative)."
 175   (interactive "p")
 176   (if tpu-cursor-free (picture-forward-column num) (forward-char num)))
 177
 178 (defun tpu-backward-char (num)
 179   "Move left ARG characters (right if ARG is negative)."
 180   (interactive "p")
 181   (cond ((not tpu-cursor-free)
 182          (backward-char num))
 183         (tpu-backward-char-like-tpu
 184          (picture-backward-column num))
 185         ((bolp)
 186          (backward-char 1)
 187          (picture-end-of-line)
 188          (picture-backward-column (1- num)))
 189         (t
 190          (picture-backward-column num))))
 191
 192
 193 ;;;  Movement by line
 194
 195 (defun tpu-next-line (num)
 196   "Move to next line.
 197 Prefix argument serves as a repeat count."
 198   (interactive "p")
 199   (let ((beg (tpu-current-line)))
 200     (if tpu-cursor-free (or (eobp) (picture-move-down num))
 201       (next-line-internal num))
 202     (tpu-bottom-check beg num)
 203     (setq this-command 'next-line)))
 204
 205 (defun tpu-previous-line (num)
 206   "Move to previous line.
 207 Prefix argument serves as a repeat count."
 208   (interactive "p")
 209   (let ((beg (tpu-current-line)))
 210     (if tpu-cursor-free (picture-move-up num) (next-line-internal (- num)))
 211     (tpu-top-check beg num)
 212     (setq this-command 'previous-line)))
 213
 214 (defun tpu-next-beginning-of-line (num)
 215   "Move to beginning of line; if at beginning, move to beginning of next line.
 216 Accepts a prefix argument for the number of lines to move."
 217   (interactive "p")
 218   (let ((beg (tpu-current-line)))
 219     (backward-char 1)
 220     (forward-visible-line (- 1 num))
 221     (tpu-top-check beg num)))
 222
 223 (defun tpu-next-end-of-line (num)
 224   "Move to end of line; if at end, move to end of next line.
 225 Accepts a prefix argument for the number of lines to move."
 226   (interactive "p")
 227   (let ((beg (tpu-current-line)))
 228     (cond (tpu-cursor-free
 229            (let ((beg (point)))
 230              (if (< 1 num) (forward-line num))
 231              (picture-end-of-line)
 232              (if (<= (point) beg) (progn (forward-line) (picture-end-of-line)))))
 233           (t
 234            (forward-char)
 235            (end-of-line num)))
 236     (tpu-bottom-check beg num)))
 237
 238 (defun tpu-previous-end-of-line (num)
 239   "Move EOL upward.
 240 Accepts a prefix argument for the number of lines to move."
 241   (interactive "p")
 242   (let ((beg (tpu-current-line)))
 243     (cond (tpu-cursor-free
 244            (picture-end-of-line (- 1 num)))
 245           (t
 246            (end-of-line (- 1 num))))
 247     (tpu-top-check beg num)))
 248
 249 (defun tpu-current-end-of-line nil
 250   "Move point to end of current line."
 251   (interactive)
 252   (let ((beg (point)))
 253     (if tpu-cursor-free (picture-end-of-line) (end-of-line))
 254     (if (= beg (point)) (message "You are already at the end of a line."))))
 255
 256 (defun tpu-forward-line (num)
 257   "Move to beginning of next line.
 258 Prefix argument serves as a repeat count."
 259   (interactive "p")
 260   (let ((beg (tpu-current-line)))
 261     (next-line-internal num)
 262     (tpu-bottom-check beg num)
 263     (beginning-of-line)))
 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     (next-line-internal (- num))
 272     (tpu-top-check beg num)
 273     (beginning-of-line)))
 274
 275
 276 ;;;  Movement by paragraph
 277
 278 (defun tpu-paragraph (num)
 279   "Move to the next paragraph in the current direction.
 280 A repeat count means move that many paragraphs."
 281   (interactive "p")
 282   (let* ((left nil)
 283          (beg (tpu-current-line))
 284          (height (window-height))
 285          (top-percent
 286           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 287          (bottom-percent
 288           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 289          (top-margin (/ (* height top-percent) 100))
 290          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 291          (bottom-margin (max beg (- height bottom-up-margin 1)))
 292          (top (save-excursion (move-to-window-line top-margin) (point)))
 293          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 294          (far (save-excursion
 295                 (goto-char bottom) (forward-line (- height 2)) (point))))
 296     (cond (tpu-advance
 297            (tpu-next-paragraph num)
 298            (cond((> (point) far)
 299                  (setq left (save-excursion (forward-line height)))
 300                  (if (= 0 left) (recenter top-margin)
 301                    (recenter (- left bottom-up-margin))))
 302                 (t
 303                  (and (> (point) bottom) (recenter bottom-margin)))))
 304           (t
 305            (tpu-previous-paragraph num)
 306            (and (< (point) top) (recenter (min beg top-margin)))))))
 307
 308
 309 ;;;  Movement by page
 310
 311 (defun tpu-page (num)
 312   "Move to the next page in the current direction.
 313 A repeat count means move that many pages."
 314   (interactive "p")
 315   (let* ((left nil)
 316          (beg (tpu-current-line))
 317          (height (window-height))
 318          (top-percent
 319           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 320          (bottom-percent
 321           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 322          (top-margin (/ (* height top-percent) 100))
 323          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 324          (bottom-margin (max beg (- height bottom-up-margin 1)))
 325          (top (save-excursion (move-to-window-line top-margin) (point)))
 326          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 327          (far (save-excursion
 328                 (goto-char bottom) (forward-line (- height 2)) (point))))
 329     (cond (tpu-advance
 330            (forward-page num)
 331            (cond((> (point) far)
 332                  (setq left (save-excursion (forward-line height)))
 333                  (if (= 0 left) (recenter top-margin)
 334                    (recenter (- left bottom-up-margin))))
 335                 (t
 336                  (and (> (point) bottom) (recenter bottom-margin)))))
 337           (t
 338            (backward-page num)
 339            (and (< (point) top) (recenter (min beg top-margin)))))))
 340
 341
 342 ;;;  Scrolling
 343
 344 (defun tpu-scroll-window-down (num)
 345   "Scroll the display down to the next section.
 346 A repeat count means scroll that many sections."
 347   (interactive "p")
 348   (let* ((beg (tpu-current-line))
 349          (height (1- (window-height)))
 350          (lines (* num (/ (* height tpu-percent-scroll) 100))))
 351     (next-line-internal (- lines))
 352     (tpu-top-check beg lines)))
 353
 354 (defun tpu-scroll-window-up (num)
 355   "Scroll the display up to the next section.
 356 A repeat count means scroll that many sections."
 357   (interactive "p")
 358   (let* ((beg (tpu-current-line))
 359          (height (1- (window-height)))
 360          (lines (* num (/ (* height tpu-percent-scroll) 100))))
 361     (next-line-internal lines)
 362     (tpu-bottom-check beg lines)))
 363
 364
 365 ;;;  Replace the TPU-edt internal search function
 366
 367 (defun tpu-search-internal (pat &optional quiet)
 368   "Search for a string or regular expression."
 369   (let* ((left nil)
 370          (beg (tpu-current-line))
 371          (height (window-height))
 372          (top-percent
 373           (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
 374          (bottom-percent
 375           (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
 376          (top-margin (/ (* height top-percent) 100))
 377          (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
 378          (bottom-margin (max beg (- height bottom-up-margin 1)))
 379          (top (save-excursion (move-to-window-line top-margin) (point)))
 380          (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
 381          (far (save-excursion
 382                 (goto-char bottom) (forward-line (- height 2)) (point))))
 383     (tpu-search-internal-core pat quiet)
 384     (if tpu-searching-forward
 385         (cond((> (point) far)
 386               (setq left (save-excursion (forward-line height)))
 387               (if (= 0 left) (recenter top-margin)
 388                 (recenter (- left bottom-up-margin))))
 389              (t
 390               (and (> (point) bottom) (recenter bottom-margin))))
 391       (and (< (point) top) (recenter (min beg top-margin))))))
 392
 393
 394
 395 ;;;  Replace the newline, newline-and-indent, and do-auto-fill functions
 396
 397 (or (fboundp 'tpu-old-newline)
 398     (fset 'tpu-old-newline (symbol-function 'newline)))
 399 (or (fboundp 'tpu-old-do-auto-fill)
 400     (fset 'tpu-old-do-auto-fill (symbol-function 'do-auto-fill)))
 401 (or (fboundp 'tpu-old-newline-and-indent)
 402     (fset 'tpu-old-newline-and-indent (symbol-function 'newline-and-indent)))
 403
 404 (defun newline (&optional num)
 405   "Insert a newline.  With arg, insert that many newlines.
 406 In Auto Fill mode, can break the preceding line if no numeric arg.
 407 This is the TPU-edt version that respects the bottom scroll margin."
 408   (interactive "p")
 409   (let ((beg (tpu-current-line)))
 410     (or num (setq num 1))
 411     (tpu-old-newline num)
 412     (tpu-bottom-check beg num)))
 413
 414 (defun newline-and-indent nil
 415   "Insert a newline, then indent according to major mode.
 416 Indentation is done using the current indent-line-function.
 417 In programming language modes, this is the same as TAB.
 418 In some text modes, where TAB inserts a tab, this indents
 419 to the specified left-margin column.  This is the TPU-edt
 420 version that respects the bottom scroll margin."
 421   (interactive)
 422   (let ((beg (tpu-current-line)))
 423     (tpu-old-newline-and-indent)
 424     (tpu-bottom-check beg 1)))
 425
 426 (defun do-auto-fill nil
 427   "TPU-edt version that respects the bottom scroll margin."
 428   (let ((beg (tpu-current-line)))
 429     (tpu-old-do-auto-fill)
 430     (tpu-bottom-check beg 1)))
 431
 432
 433 ;;;  Function to set scroll margins
 434
 435 ;;;###autoload
 436 (defun tpu-set-scroll-margins (top bottom)
 437   "Set scroll margins."
 438   (interactive
 439    "sEnter top scroll margin (N lines or N%% or RETURN for current value): \
 440 \nsEnter bottom scroll margin (N lines or N%% or RETURN for current value): ")
 441   ;; set top scroll margin
 442   (or (string= top "")
 443       (if (string= "%" (substring top -1))
 444           (setq tpu-top-scroll-margin (string-to-number top))
 445         (setq tpu-top-scroll-margin
 446               (/ (1- (+ (* (string-to-number top) 100) (window-height)))
 447                  (window-height)))))
 448   ;; set bottom scroll margin
 449   (or (string= bottom "")
 450       (if (string= "%" (substring bottom -1))
 451           (setq tpu-bottom-scroll-margin (string-to-number bottom))
 452         (setq tpu-bottom-scroll-margin
 453               (/ (1- (+ (* (string-to-number bottom) 100) (window-height)))
 454                  (window-height)))))
 455   ;; report scroll margin settings if running interactively
 456   (and (interactive-p)
 457        (message "Scroll margins set.  Top = %s%%, Bottom = %s%%"
 458                 tpu-top-scroll-margin tpu-bottom-scroll-margin)))
 459
 460
 461 ;;;  Functions to set cursor bound or free
 462
 463 ;;;###autoload
 464 (defun tpu-set-cursor-free nil
 465   "Allow the cursor to move freely about the screen."
 466   (interactive)
 467   (setq tpu-cursor-free t)
 468   (substitute-key-definition 'tpu-set-cursor-free
 469                              'tpu-set-cursor-bound
 470                              GOLD-map)
 471   (message "The cursor will now move freely about the screen."))
 472
 473 ;;;###autoload
 474 (defun tpu-set-cursor-bound nil
 475   "Constrain the cursor to the flow of the text."
 476   (interactive)
 477   (tpu-trim-line-ends)
 478   (setq tpu-cursor-free nil)
 479   (substitute-key-definition 'tpu-set-cursor-bound
 480                              'tpu-set-cursor-free
 481                              GOLD-map)
 482   (message "The cursor is now bound to the flow of your text."))
 483
 484 ;;; arch-tag: 89676fa4-33ec-48cb-9135-6f3bf230ab1a
 485 ;;; tpu-extras.el ends here