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1 ;;; tpu-extras.el --- Scroll margins and free cursor mode for TPU-edt
2
3 ;; Copyright (C) 1993 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 XEmacs.
10
11 ;; XEmacs is free software; you can redistribute it and/or modify it
12 ;; 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 ;; XEmacs is distributed in the hope that it will be useful, but
17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 ;; General Public License for more details.
20
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with XEmacs; see the file COPYING. If not, write to the Free
23 ;; Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
24
25 ;;; Commentary:
26
27 ;; The functions contained in this file implement scroll margins and free
28 ;; cursor mode. The following keys and commands are affected.
29
30 ;; key/command function scroll cursor
31
32 ;; Up-Arrow previous line x x
33 ;; Down-Arrow next line x x
34 ;; Right-Arrow next character x
35 ;; Left-Arrow previous character x
36 ;; KP0 next or previous line x
37 ;; KP7 next or previous page x
38 ;; KP8 next or previous screen x
39 ;; KP2 next or previous end-of-line x x
40 ;; Control-e current end-of-line x
41 ;; Control-h previous beginning-of-line x
42 ;; Next Scr next screen x
43 ;; Prev Scr previous screen x
44 ;; Search find a string x
45 ;; Replace find and replace a string x
46 ;; Newline insert a newline x
47 ;; Paragraph next or previous paragraph x
48 ;; Auto-Fill break lines on spaces x
49
50 ;; These functions are not part of the base TPU-edt for the following
51 ;; reasons:
52
53 ;; Free cursor mode is implemented with the emacs picture-mode functions.
54 ;; These functions support moving the cursor all over the screen, however,
55 ;; when the cursor is moved past the end of a line, spaces or tabs are
56 ;; appended to the line - even if no text is entered in that area. In
57 ;; order for a free cursor mode to work exactly like TPU/edt, this trailing
58 ;; whitespace needs to be dealt with in every function that might encounter
59 ;; it. Such global changes are impractical, however, free cursor mode is
60 ;; too valuable to abandon completely, so it has been implemented in those
61 ;; functions where it serves best.
62
63 ;; The implementation of scroll margins adds overhead to previously
64 ;; simple and often used commands. These commands are now responsible
65 ;; for their normal operation and part of the display function. There
66 ;; is a possibility that this display overhead could adversely affect the
67 ;; performance of TPU-edt on slower computers. In order to support the
68 ;; widest range of computers, scroll margin support is optional.
69
70 ;; I don't know for a fact that the overhead associated with scroll
71 ;; margin support is significant. If you find that it is, please send me
72 ;; a note describing the extent of the performance degradation. Be sure
73 ;; to include a description of the platform where you're running TPU-edt.
74 ;; Send your note to the address provided by Gold-V.
75
76 ;; Even with these differences and limitations, these functions implement
77 ;; important aspects of the real TPU/edt. Those who miss free cursor mode
78 ;; and/or scroll margins will appreciate these implementations.
79
80 ;;; Usage:
81
82 ;; To use this file, simply load it after loading TPU-edt. After that,
83 ;; customize TPU-edt to your tastes by setting scroll margins and/or
84 ;; turning on free cursor mode. Here's an example for your .emacs file.
85
86 ;; (load "tpu-edt") ; Load the base TPU-edt
87 ;; (load "tpu-extras") ; and the extras.
88 ;; (tpu-set-scroll-margins "10%" "15%") ; Set scroll margins.
89
90 ;; Once the extras are loaded, scroll margins and cursor binding can be
91 ;; changed with the following commands:
92
93 ;; tpu-set-scroll-margins or set scroll margins
94 ;; tpu-set-cursor-bound or set cursor bound
95 ;; tpu-set-cursor-free or set cursor free
96
97 ;; Additionally, Gold-F toggles between bound and free cursor modes.
98
99 ;; Note that switching out of free cursor mode or exiting TPU-edt while in
100 ;; free cursor mode strips trailing whitespace from every line in the file.
101
102 ;;; Code:
103
104
105 ;;; Revision Information
106
107 (defconst tpu-extras-revision "!Revision: 1.6 !"
108 "Revision number of the TPU-edt extras.")
109
110
111 ;;; Customization variables
112
113 (defconst 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 (defconst tpu-bottom-scroll-margin 0
117 "*Scroll margin at the bottom of the screen.
118 Interpreted as a percent of the current window size.")
119
120 (defvar tpu-backward-char-like-tpu t
121 "*If non-nil, in free cursor mode backward-char (left-arrow) works
122 just like TPU/edt. Otherwise, backward-char will move to the end of
123 the previous line when starting from a line beginning.")
124
125
126 ;;; Global variables
127
128 (defvar tpu-cursor-free nil
129 "If non-nil, let the cursor roam free.")
130
131
132 ;;; Hooks -- Set cursor free in picture mode.
133 ;;; Clean up when writing a file from cursor free mode.
134
135 (if tpu-gnu-emacs18-p
136 (or (memq 'tpu-set-cursor-free edit-picture-hook)
137 (setq edit-picture-hook
138 (cons 'tpu-set-cursor-free edit-picture-hook)))
139 (add-hook 'picture-mode-hook 'tpu-set-cursor-free))
140
141 (defun tpu-write-file-hook nil
142 "Eliminate whitespace at ends of lines, if the cursor is free."
143 (if (and (buffer-modified-p) tpu-cursor-free) (picture-clean)))
144
145 (or (memq 'tpu-write-file-hook write-file-hooks)
146 (setq write-file-hooks
147 (cons 'tpu-write-file-hook write-file-hooks)))
148
149
150 ;;; Utility routines for implementing scroll margins
151
152 (defun tpu-top-check (beg lines)
153 "Enforce scroll margin at the top of screen."
154 (let ((margin (/ (* (window-height) tpu-top-scroll-margin) 100)))
155 (cond ((< beg margin) (recenter beg))
156 ((< (- beg lines) margin) (recenter margin)))))
157
158 (defun tpu-bottom-check (beg lines)
159 "Enforce scroll margin at the bottom of screen."
160 (let* ((height (window-height))
161 (margin (+ 1 (/ (* height tpu-bottom-scroll-margin) 100)))
162 ;; subtract 1 from height because it includes mode line
163 (difference (- height margin 1)))
164 (cond ((> beg difference) (recenter beg))
165 ((> (+ beg lines) difference) (recenter (- margin))))))
166
167
168 ;;; Movement by character
169
170 (defun tpu-forward-char (num)
171 "Move right ARG characters (left if ARG is negative)."
172 (interactive "p")
173 (if tpu-cursor-free (picture-forward-column num) (forward-char num)))
174
175 (defun tpu-backward-char (num)
176 "Move left ARG characters (right if ARG is negative)."
177 (interactive "p")
178 (cond ((not tpu-cursor-free)
179 (backward-char num))
180 (tpu-backward-char-like-tpu
181 (picture-backward-column num))
182 ((bolp)
183 (backward-char 1)
184 (picture-end-of-line)
185 (picture-backward-column (1- num)))
186 (t
187 (picture-backward-column num))))
188
189
190 ;;; Movement by line
191
192 (defun tpu-next-line (num)
193 "Move to next line.
194 Prefix argument serves as a repeat count."
195 (interactive "p")
196 (let ((beg (tpu-current-line)))
197 (if tpu-cursor-free (or (eobp) (picture-move-down num))
198 (next-line-internal num))
199 (tpu-bottom-check beg num)
200 (setq this-command 'next-line)))
201
202 (defun tpu-previous-line (num)
203 "Move to previous line.
204 Prefix argument serves as a repeat count."
205 (interactive "p")
206 (let ((beg (tpu-current-line)))
207 (if tpu-cursor-free (picture-move-up num) (next-line-internal (- num)))
208 (tpu-top-check beg num)
209 (setq this-command 'previous-line)))
210
211 (defun tpu-next-beginning-of-line (num)
212 "Move to beginning of line; if at beginning, move to beginning of next line.
213 Accepts a prefix argument for the number of lines to move."
214 (interactive "p")
215 (let ((beg (tpu-current-line)))
216 (backward-char 1)
217 (forward-line (- 1 num))
218 (tpu-top-check beg num)))
219
220 (defun tpu-next-end-of-line (num)
221 "Move to end of line; if at end, move to end of next line.
222 Accepts a prefix argument for the number of lines to move."
223 (interactive "p")
224 (let ((beg (tpu-current-line)))
225 (cond (tpu-cursor-free
226 (let ((beg (point)))
227 (if (< 1 num) (forward-line num))
228 (picture-end-of-line)
229 (if (<= (point) beg) (progn (forward-line) (picture-end-of-line)))))
230 (t
231 (forward-char)
232 (end-of-line num)))
233 (tpu-bottom-check beg num)))
234
235 (defun tpu-previous-end-of-line (num)
236 "Move EOL upward.
237 Accepts a prefix argument for the number of lines to move."
238 (interactive "p")
239 (let ((beg (tpu-current-line)))
240 (cond (tpu-cursor-free
241 (picture-end-of-line (- 1 num)))
242 (t
243 (end-of-line (- 1 num))))
244 (tpu-top-check beg num)))
245
246 (defun tpu-current-end-of-line nil
247 "Move point to end of current line."
248 (interactive)
249 (let ((beg (point)))
250 (if tpu-cursor-free (picture-end-of-line) (end-of-line))
251 (if (= beg (point)) (message "You are already at the end of a line."))))
252
253 (defun tpu-forward-line (num)
254 "Move to beginning of next line.
255 Prefix argument serves as a repeat count."
256 (interactive "p")
257 (let ((beg (tpu-current-line)))
258 (next-line-internal num)
259 (tpu-bottom-check beg num)
260 (beginning-of-line)))
261
262 (defun tpu-backward-line (num)
263 "Move to beginning of previous line.
264 Prefix argument serves as repeat count."
265 (interactive "p")
266 (let ((beg (tpu-current-line)))
267 (next-line-internal (- num))
268 (tpu-top-check beg num)
269 (beginning-of-line)))
270
271
272 ;;; Movement by paragraph
273
274 (defun tpu-paragraph (num)
275 "Move to the next paragraph in the current direction.
276 A repeat count means move that many paragraphs."
277 (interactive "p")
278 (let* ((left nil)
279 (beg (tpu-current-line))
280 (height (window-height))
281 (top-percent
282 (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
283 (bottom-percent
284 (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
285 (top-margin (/ (* height top-percent) 100))
286 (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
287 (bottom-margin (max beg (- height bottom-up-margin 1)))
288 (top (save-excursion (move-to-window-line top-margin) (point)))
289 (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
290 (far (save-excursion
291 (goto-char bottom) (forward-line (- height 2)) (point))))
292 (cond (tpu-advance
293 (tpu-next-paragraph num)
294 (cond((> (point) far)
295 (setq left (save-excursion (forward-line height)))
296 (if (= 0 left) (recenter top-margin)
297 (recenter (- left bottom-up-margin))))
298 (t
299 (and (> (point) bottom) (recenter bottom-margin)))))
300 (t
301 (tpu-previous-paragraph num)
302 (and (< (point) top) (recenter (min beg top-margin)))))))
303
304
305 ;;; Movement by page
306
307 (defun tpu-page (num)
308 "Move to the next page in the current direction.
309 A repeat count means move that many pages."
310 (interactive "p")
311 (let* ((left nil)
312 (beg (tpu-current-line))
313 (height (window-height))
314 (top-percent
315 (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
316 (bottom-percent
317 (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
318 (top-margin (/ (* height top-percent) 100))
319 (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
320 (bottom-margin (max beg (- height bottom-up-margin 1)))
321 (top (save-excursion (move-to-window-line top-margin) (point)))
322 (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
323 (far (save-excursion
324 (goto-char bottom) (forward-line (- height 2)) (point))))
325 (cond (tpu-advance
326 (forward-page num)
327 (cond((> (point) far)
328 (setq left (save-excursion (forward-line height)))
329 (if (= 0 left) (recenter top-margin)
330 (recenter (- left bottom-up-margin))))
331 (t
332 (and (> (point) bottom) (recenter bottom-margin)))))
333 (t
334 (backward-page num)
335 (and (< (point) top) (recenter (min beg top-margin)))))))
336
337
338 ;;; Scrolling
339
340 (defun tpu-scroll-window-down (num)
341 "Scroll the display down to the next section.
342 A repeat count means scroll that many sections."
343 (interactive "p")
344 (let* ((beg (tpu-current-line))
345 (height (1- (window-height)))
346 (lines (* num (/ (* height tpu-percent-scroll) 100))))
347 (next-line-internal (- lines))
348 (tpu-top-check beg lines)))
349
350 (defun tpu-scroll-window-up (num)
351 "Scroll the display up to the next section.
352 A repeat count means scroll that many sections."
353 (interactive "p")
354 (let* ((beg (tpu-current-line))
355 (height (1- (window-height)))
356 (lines (* num (/ (* height tpu-percent-scroll) 100))))
357 (next-line-internal lines)
358 (tpu-bottom-check beg lines)))
359
360
361 ;;; Replace the TPU-edt internal search function
362
363 (defun tpu-search-internal (pat &optional quiet)
364 "Search for a string or regular expression."
365 (let* ((left nil)
366 (beg (tpu-current-line))
367 (height (window-height))
368 (top-percent
369 (if (= 0 tpu-top-scroll-margin) 10 tpu-top-scroll-margin))
370 (bottom-percent
371 (if (= 0 tpu-bottom-scroll-margin) 15 tpu-bottom-scroll-margin))
372 (top-margin (/ (* height top-percent) 100))
373 (bottom-up-margin (+ 1 (/ (* height bottom-percent) 100)))
374 (bottom-margin (max beg (- height bottom-up-margin 1)))
375 (top (save-excursion (move-to-window-line top-margin) (point)))
376 (bottom (save-excursion (move-to-window-line bottom-margin) (point)))
377 (far (save-excursion
378 (goto-char bottom) (forward-line (- height 2)) (point))))
379 (tpu-search-internal-core pat quiet)
380 (if tpu-searching-forward
381 (cond((> (point) far)
382 (setq left (save-excursion (forward-line height)))
383 (if (= 0 left) (recenter top-margin)
384 (recenter (- left bottom-up-margin))))
385 (t
386 (and (> (point) bottom) (recenter bottom-margin))))
387 (and (< (point) top) (recenter (min beg top-margin))))))
388
389
390
391 ;;; Replace the newline, newline-and-indent, and do-auto-fill functions
392
393 (or (fboundp 'tpu-old-newline)
394 (fset 'tpu-old-newline (symbol-function 'newline)))
395 (or (fboundp 'tpu-old-do-auto-fill)
396 (fset 'tpu-old-do-auto-fill (symbol-function 'do-auto-fill)))
397 (or (fboundp 'tpu-old-newline-and-indent)
398 (fset 'tpu-old-newline-and-indent (symbol-function 'newline-and-indent)))
399
400 (defun newline (&optional num)
401 "Insert a newline. With arg, insert that many newlines.
402 In Auto Fill mode, can break the preceding line if no numeric arg.
403 This is the TPU-edt version that respects the bottom scroll margin."
404 (interactive "p")
405 (let ((beg (tpu-current-line)))
406 (or num (setq num 1))
407 (tpu-old-newline num)
408 (tpu-bottom-check beg num)))
409
410 (defun newline-and-indent nil
411 "Insert a newline, then indent according to major mode.
412 Indentation is done using the current indent-line-function.
413 In programming language modes, this is the same as TAB.
414 In some text modes, where TAB inserts a tab, this indents
415 to the specified left-margin column. This is the TPU-edt
416 version that respects the bottom scroll margin."
417 (interactive)
418 (let ((beg (tpu-current-line)))
419 (tpu-old-newline-and-indent)
420 (tpu-bottom-check beg 1)))
421
422 (defun do-auto-fill nil
423 "TPU-edt version that respects the bottom scroll margin."
424 (let ((beg (tpu-current-line)))
425 (tpu-old-do-auto-fill)
426 (tpu-bottom-check beg 1)))
427
428
429 ;;; Function to set scroll margins
430
431 ;;;jwz: don't autoload this by default ###autoload
432 (defun tpu-set-scroll-margins (top bottom)
433 "Set scroll margins."
434 (interactive
435 "sEnter top scroll margin (N lines or N%% or RETURN for current value): \
436 \nsEnter bottom scroll margin (N lines or N%% or RETURN for current value): ")
437 ;; set top scroll margin
438 (or (string= top "")
439 (if (string= "%" (substring top -1))
440 (setq tpu-top-scroll-margin (string-to-int top))
441 (setq tpu-top-scroll-margin
442 (/ (1- (+ (* (string-to-int top) 100) (window-height)))
443 (window-height)))))
444 ;; set bottom scroll margin
445 (or (string= bottom "")
446 (if (string= "%" (substring bottom -1))
447 (setq tpu-bottom-scroll-margin (string-to-int bottom))
448 (setq tpu-bottom-scroll-margin
449 (/ (1- (+ (* (string-to-int bottom) 100) (window-height)))
450 (window-height)))))
451 ;; report scroll margin settings if running interactively
452 (and (interactive-p)
453 (message "Scroll margins set. Top = %s%%, Bottom = %s%%"
454 tpu-top-scroll-margin tpu-bottom-scroll-margin)))
455
456
457 ;;; Functions to set cursor bound or free
458
459 ;;;jwz: don't autoload this by default ###autoload
460 (defun tpu-set-cursor-free nil
461 "Allow the cursor to move freely about the screen."
462 (interactive)
463 (setq tpu-cursor-free t)
464 (substitute-key-definition 'tpu-set-cursor-free
465 'tpu-set-cursor-bound
466 GOLD-map)
467 (message "The cursor will now move freely about the screen."))
468
469 ;;;jwz: don't autoload this by default ###autoload
470 (defun tpu-set-cursor-bound nil
471 "Constrain the cursor to the flow of the text."
472 (interactive)
473 (picture-clean)
474 (setq tpu-cursor-free nil)
475 (substitute-key-definition 'tpu-set-cursor-bound
476 'tpu-set-cursor-free
477 GOLD-map)
478 (message "The cursor is now bound to the flow of your text."))
479
480 ;;; tpu-extras.el ends here