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 Free Software Foundation, Inc.
   4
   5 ;; Author: Rob Riepel <riepel@networking.stanford.edu>
   6 ;; Maintainer: Rob Riepel <riepel@networking.stanford.edu>
   7 ;; Keywords: emulations
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;;  Use the functions defined here to customize TPU-edt to your tastes by
  29 ;;  setting scroll margins and/or turning on free cursor mode.  Here's an
  30 ;;  example for your .emacs file.
  31
  32 ;;     (tpu-set-cursor-free)                   ; Set cursor free.
  33 ;;     (tpu-set-scroll-margins "10%" "15%")    ; Set scroll margins.
  34
  35 ;;  Scroll margins and cursor binding can be changed from within emacs using
  36 ;;  the following commands:
  37
  38 ;;     tpu-set-scroll-margins  or   set scroll margins
  39 ;;     tpu-set-cursor-bound    or   set cursor bound
  40 ;;     tpu-set-cursor-free     or   set cursor free
  41
  42 ;;  Additionally, Gold-F toggles between bound and free cursor modes.
  43
  44 ;;  Note that switching out of free cursor mode or exiting TPU-edt while in
  45 ;;  free cursor mode strips trailing whitespace from every line in the file.
  46
  47
  48 ;;; Details:
  49
  50 ;;  The functions contained in this file implement scroll margins and free
  51 ;;  cursor mode.  The following keys and commands are affected.
  52
  53 ;;       key/command   function                        scroll   cursor
  54
  55 ;;       Up-Arrow      previous line                     x        x
  56 ;;       Down-Arrow    next line                         x        x
  57 ;;       Right-Arrow   next character                             x
  58 ;;       Left-Arrow    previous character                         x
  59 ;;       KP0           next or previous line             x
  60 ;;       KP7           next or previous page             x
  61 ;;       KP8           next or previous screen           x
  62 ;;       KP2           next or previous end-of-line      x        x
  63 ;;       Control-e     current end-of-line                        x
  64 ;;       Control-h     previous beginning-of-line        x
  65 ;;       Next Scr      next screen                       x
  66 ;;       Prev Scr      previous screen                   x
  67 ;;       Search        find a string                     x
  68 ;;       Replace       find and replace a string         x
  69 ;;       Newline       insert a newline                  x
  70 ;;       Paragraph     next or previous paragraph        x
  71 ;;       Auto-Fill     break lines on spaces             x
  72
  73 ;;  These functions are not part of the base TPU-edt for the following
  74 ;;  reasons:
  75
  76 ;;  Free cursor mode is implemented with the emacs picture-mode functions.
  77 ;;  These functions support moving the cursor all over the screen, however,
  78 ;;  when the cursor is moved past the end of a line, spaces or tabs are
  79 ;;  appended to the line - even if no text is entered in that area.  In
  80 ;;  order for a free cursor mode to work exactly like TPU/edt, this trailing
  81 ;;  whitespace needs to be dealt with in every function that might encounter
  82 ;;  it.  Such global changes are impractical, however, free cursor mode is
  83 ;;  too valuable to abandon completely, so it has been implemented in those
  84 ;;  functions where it serves best.
  85
  86 ;;  The implementation of scroll margins adds overhead to previously
  87 ;;  simple and often used commands.  These commands are now responsible
  88 ;;  for their normal operation and part of the display function.  There
  89 ;;  is a possibility that this display overhead could adversely affect the
  90 ;;  performance of TPU-edt on slower computers.  In order to support the
  91 ;;  widest range of computers, scroll margin support is optional.
  92
  93 ;;  It's actually not known whether the overhead associated with scroll
  94 ;;  margin support is significant.  If you find that it is, please send
  95 ;;  a note describing the extent of the performance degradation.  Be sure
  96 ;;  to include a description of the platform where you're running TPU-edt.
  97 ;;  Send your note to the address provided by Gold-V.
  98
  99 ;;  Even with these differences and limitations, these functions implement
 100 ;;  important aspects of the real TPU/edt.  Those who miss free cursor mode
 101 ;;  and/or scroll margins will appreciate these implementations.
 102
 103 ;;; Code:
 104
 105
 106 ;;;  Gotta have tpu-edt
 107
 108 (require 'tpu-edt)
 109
 110
 111 ;;;  Customization variables
 112
 113 (defcustom tpu-top-scroll-margin 0
 114   "*Scroll margin at the top of the screen.
 115 Interpreted as a percent of the current window size."
 116   :type 'integer
 117   :group 'tpu)
 118 (defcustom tpu-bottom-scroll-margin 0
 119   "*Scroll margin at the bottom of the screen.
 120 Interpreted as a percent of the current window size."
 121   :type 'integer
 122   :group 'tpu)
 123
 124 (defcustom tpu-backward-char-like-tpu t
 125   "*If non-nil, in free cursor mode backward-char (left-arrow) works
 126 just like TPU/edt.  Otherwise, backward-char will move to the end of
 127 the previous line when starting from a line beginning."
 128   :type 'boolean
 129   :group 'tpu)
 130
 131
 132 ;;;  Global variables
 133
 134 (defvar tpu-cursor-free nil
 135   "If non-nil, let the cursor roam free.")
 136
 137
 138 ;;;  Hooks  --  Set cursor free in picture mode.
 139 ;;;             Clean up when writing a file from cursor free mode.
 140
 141 (add-hook 'picture-mode-hook 'tpu-set-cursor-free)
 142
 143 (defun tpu-write-file-hook nil
 144   "Eliminate whitespace at ends of lines, if the cursor is free."
 145   (if (and (buffer-modified-p) tpu-cursor-free) (tpu-trim-line-ends)))
 146
 147 (or (memq 'tpu-write-file-hook write-file-hooks)
 148     (setq write-file-hooks
 149           (cons 'tpu-write-file-hook write-file-hooks)))
 150
 151
 152 ;;;  Utility routines for implementing scroll margins
 153
 154 (defun tpu-top-check (beg lines)
 155   "Enforce scroll margin at the top of screen."
 156   (let ((margin  (/ (* (window-height) tpu-top-scroll-margin) 100)))
 157     (cond ((< beg margin) (recenter beg))
 158           ((< (- beg lines) margin) (recenter margin)))))
 159
 160 (defun tpu-bottom-check (beg lines)
 161   "Enforce scroll margin at the bottom of screen."
 162   (let* ((height (window-height))
 163          (margin (+ 1 (/ (* height tpu-bottom-scroll-margin) 100)))
 164          ;; subtract 1 from height because it includes mode line
 165          (difference (- height margin 1)))
 166     (cond ((> beg difference) (recenter beg))
 167           ((> (+ beg lines) difference) (recenter (- margin))))))
 168
 169
 170 ;;;  Movement by character
 171
 172 (defun tpu-forward-char (num)
 173   "Move right ARG characters (left if ARG is negative)."
 174   (interactive "p")
 175   (if tpu-cursor-free (picture-forward-column num) (forward-char num)))
 176
 177 (defun tpu-backward-char (num)
 178   "Move left ARG characters (right if ARG is negative)."
 179   (interactive "p")
 180   (cond ((not tpu-cursor-free)
 181          (backward-char num))
 182         (tpu-backward-char-like-tpu
 183          (picture-backward-column num))
 184         ((bolp)
 185          (backward-char 1)
 186          (picture-end-of-line)
 187          (picture-backward-column (1- num)))
 188         (t
 189          (picture-backward-column num))))
 190
 191
 192 ;;;  Movement by line
 193
 194 (defun tpu-next-line (num)
 195   "Move to next line.
 196 Prefix argument serves as a repeat count."
 197   (interactive "p")
 198   (let ((beg (tpu-current-line)))
 199     (if tpu-cursor-free (or (eobp) (picture-move-down num))
 200       (next-line-internal num))
 201     (tpu-bottom-check beg num)
 202     (setq this-command 'next-line)))
 203
 204 (defun tpu-previous-line (num)
 205   "Move to previous line.
 206 Prefix argument serves as a repeat count."
 207   (interactive "p")
 208   (let ((beg (tpu-current-line)))
 209     (if tpu-cursor-free (picture-move-up num) (next-line-internal (- num)))
 210     (tpu-top-check beg num)
 211     (setq this-command 'previous-line)))
 212
 213 (defun tpu-next-beginning-of-line (num)
 214   "Move to beginning of line; if at beginning, move to beginning of next line.
 215 Accepts a prefix argument for the number of lines to move."
 216   (interactive "p")
 217   (let ((beg (tpu-current-line)))
 218     (backward-char 1)
 219     (forward-visible-line (- 1 num))
 220     (tpu-top-check beg num)))
 221
 222 (defun tpu-next-end-of-line (num)
 223   "Move to end of line; if at end, move to end of next line.
 224 Accepts a prefix argument for the number of lines to move."
 225   (interactive "p")
 226   (let ((beg (tpu-current-line)))
 227     (cond (tpu-cursor-free
 228            (let ((beg (point)))
 229              (if (< 1 num) (forward-line num))
 230              (picture-end-of-line)
 231              (if (<= (point) beg) (progn (forward-line) (picture-end-of-line)))))
 232           (t
 233            (forward-char)
 234            (end-of-line num)))
 235     (tpu-bottom-check beg num)))
 236
 237 (defun tpu-previous-end-of-line (num)
 238   "Move EOL upward.
 239 Accepts a prefix argument for the number of lines to move."
 240   (interactive "p")
 241   (let ((beg (tpu-current-line)))
 242     (cond (tpu-cursor-free
 243            (picture-end-of-line (- 1 num)))
 244           (t
 245            (end-of-line (- 1 num))))
 246     (tpu-top-check beg num)))
 247
 248 (defun tpu-current-end-of-line nil
 249   "Move point to end of current line."
 250   (interactive)
 251   (let ((beg (point)))
 252     (if tpu-cursor-free (picture-end-of-line) (end-of-line))
 253     (if (= beg (point)) (message "You are already at the end of a line."))))
 254
 255 (defun tpu-forward-line (num)
 256   "Move to beginning of next line.
 257 Prefix argument serves as a repeat count."
 258   (interactive "p")
 259   (let ((beg (tpu-current-line)))
 260     (next-line-internal num)
 261     (tpu-bottom-check beg num)
 262     (beginning-of-line)))
 263
 264 (defun tpu-backward-line (num)
 265   "Move to beginning of previous line.
 266 Prefix argument serves as repeat count."
 267   (interactive "p")
 268   (let ((beg (tpu-current-line)))
 269     (or (bolp) (>= 0 num) (setq num (- num 1)))
 270     (next-line-internal (- num))
 271     (tpu-top-check beg num)
 272     (beginning-of-line)))
 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     (next-line-internal (- 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     (next-line-internal 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 ;;;  Replace the newline, newline-and-indent, and do-auto-fill functions
 395
 396 (or (fboundp 'tpu-old-newline)
 397     (fset 'tpu-old-newline (symbol-function 'newline)))
 398 (or (fboundp 'tpu-old-do-auto-fill)
 399     (fset 'tpu-old-do-auto-fill (symbol-function 'do-auto-fill)))
 400 (or (fboundp 'tpu-old-newline-and-indent)
 401     (fset 'tpu-old-newline-and-indent (symbol-function 'newline-and-indent)))
 402
 403 (defun newline (&optional num)
 404   "Insert a newline.  With arg, insert that many newlines.
 405 In Auto Fill mode, can break the preceding line if no numeric arg.
 406 This is the TPU-edt version that respects the bottom scroll margin."
 407   (interactive "p")
 408   (let ((beg (tpu-current-line)))
 409     (or num (setq num 1))
 410     (tpu-old-newline num)
 411     (tpu-bottom-check beg num)))
 412
 413 (defun newline-and-indent nil
 414   "Insert a newline, then indent according to major mode.
 415 Indentation is done using the current indent-line-function.
 416 In programming language modes, this is the same as TAB.
 417 In some text modes, where TAB inserts a tab, this indents
 418 to the specified left-margin column.  This is the TPU-edt
 419 version that respects the bottom scroll margin."
 420   (interactive)
 421   (let ((beg (tpu-current-line)))
 422     (tpu-old-newline-and-indent)
 423     (tpu-bottom-check beg 1)))
 424
 425 (defun do-auto-fill nil
 426   "TPU-edt version that respects the bottom scroll margin."
 427   (let ((beg (tpu-current-line)))
 428     (tpu-old-do-auto-fill)
 429     (tpu-bottom-check beg 1)))
 430
 431
 432 ;;;  Function to set scroll margins
 433
 434 ;;;###autoload
 435 (defun tpu-set-scroll-margins (top bottom)
 436   "Set scroll margins."
 437   (interactive
 438    "sEnter top scroll margin (N lines or N%% or RETURN for current value): \
 439 \nsEnter bottom scroll margin (N lines or N%% or RETURN for current value): ")
 440   ;; set top scroll margin
 441   (or (string= top "")
 442       (if (string= "%" (substring top -1))
 443           (setq tpu-top-scroll-margin (string-to-int top))
 444         (setq tpu-top-scroll-margin
 445               (/ (1- (+ (* (string-to-int top) 100) (window-height)))
 446                  (window-height)))))
 447   ;; set bottom scroll margin
 448   (or (string= bottom "")
 449       (if (string= "%" (substring bottom -1))
 450           (setq tpu-bottom-scroll-margin (string-to-int bottom))
 451         (setq tpu-bottom-scroll-margin
 452               (/ (1- (+ (* (string-to-int bottom) 100) (window-height)))
 453                  (window-height)))))
 454   ;; report scroll margin settings if running interactively
 455   (and (interactive-p)
 456        (message "Scroll margins set.  Top = %s%%, Bottom = %s%%"
 457                 tpu-top-scroll-margin tpu-bottom-scroll-margin)))
 458
 459
 460 ;;;  Functions to set cursor bound or free
 461
 462 ;;;###autoload
 463 (defun tpu-set-cursor-free nil
 464   "Allow the cursor to move freely about the screen."
 465   (interactive)
 466   (setq tpu-cursor-free t)
 467   (substitute-key-definition 'tpu-set-cursor-free
 468                              'tpu-set-cursor-bound
 469                              GOLD-map)
 470   (message "The cursor will now move freely about the screen."))
 471
 472 ;;;###autoload
 473 (defun tpu-set-cursor-bound nil
 474   "Constrain the cursor to the flow of the text."
 475   (interactive)
 476   (tpu-trim-line-ends)
 477   (setq tpu-cursor-free nil)
 478   (substitute-key-definition 'tpu-set-cursor-bound
 479                              'tpu-set-cursor-free
 480                              GOLD-map)
 481   (message "The cursor is now bound to the flow of your text."))
 482
 483 ;;; tpu-extras.el ends here