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802b0ea7 | 1 | @c This is part of the Emacs manual. |
b65d8176 TTN |
2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, |
3 | @c 2002, 2003, 2004, 2005 Free Software Foundation, Inc. | |
6bf7aab6 DL |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Display, Search, Registers, Top | |
6 | @chapter Controlling the Display | |
7 | ||
8 | Since only part of a large buffer fits in the window, Emacs tries to | |
9 | show a part that is likely to be interesting. Display-control commands | |
10 | allow you to specify which part of the text you want to see, and how to | |
11 | display it. | |
12 | ||
13 | @menu | |
b8f3a9e3 | 14 | * Faces:: How to change the display style using faces. |
43d08eb9 | 15 | * Standard Faces:: Emacs' predefined faces. |
b8f3a9e3 | 16 | * Font Lock:: Minor mode for syntactic highlighting using faces. |
b8f3a9e3 | 17 | * Highlight Interactively:: Tell Emacs what text to highlight. |
b26533d6 | 18 | * Highlight Changes:: Using colors to show where you changed the buffer. |
6bf7aab6 DL |
19 | * Scrolling:: Moving text up and down in a window. |
20 | * Horizontal Scrolling:: Moving text left and right in a window. | |
fad78d58 RS |
21 | * Fringes:: Enabling or disabling window fringes. |
22 | * Useless Whitespace:: Showing possibly-spurious trailing whitespace. | |
6bf7aab6 DL |
23 | * Follow Mode:: Follow mode lets two windows scroll as one. |
24 | * Selective Display:: Hiding lines with lots of indentation. | |
25 | * Optional Mode Line:: Optional mode line display features. | |
26 | * Text Display:: How text characters are normally displayed. | |
099bfef9 | 27 | * Cursor Display:: Features for displaying the cursor. |
0015d677 | 28 | * Display Custom:: Information on variables for customizing display. |
6bf7aab6 DL |
29 | @end menu |
30 | ||
b8f3a9e3 GM |
31 | @node Faces |
32 | @section Using Multiple Typefaces | |
33 | @cindex faces | |
34 | ||
0015d677 RS |
35 | You can specify various styles for displaying text using |
36 | @dfn{faces}. Each face can specify various @dfn{face attributes}, | |
37 | such as the font family, the height, weight and slant of the | |
38 | characters, the foreground and background color, and underlining or | |
39 | overlining. A face does not have to specify all of these attributes; | |
40 | often it inherits most of them from another face. | |
306da12e RS |
41 | |
42 | On a window system, all the Emacs face attributes are meaningful. | |
43 | On a character terminal, only some of them work. Some character | |
44 | terminals support inverse video, bold, and underline attributes; some | |
45 | support colors. Character terminals generally do not support changing | |
46 | the height and width or the font family. | |
c1b45553 | 47 | |
43d08eb9 RS |
48 | The easiest way to use faces is to turn on Font Lock mode. |
49 | @xref{Font Lock}, for more information about Font Lock mode and | |
50 | syntactic highlighting. You can print out the buffer with the | |
51 | highlighting that appears on your screen using the command | |
52 | @code{ps-print-buffer-with-faces}. @xref{PostScript}. | |
53 | ||
6bb2ed9b EZ |
54 | Features which rely on text in multiple faces (such as Font Lock mode) |
55 | will also work on non-windowed terminals that can display more than one | |
56 | face, whether by colors or underlining and emboldening. This includes | |
57 | the console on GNU/Linux, an @code{xterm} which supports colors, the | |
58 | MS-DOS display (@pxref{MS-DOS}), and the MS-Windows version invoked with | |
59 | the @option{-nw} option. Emacs determines automatically whether the | |
60 | terminal has this capability. | |
b8f3a9e3 | 61 | |
0073fd65 RS |
62 | You control the appearance of a part of the text in the buffer by |
63 | specifying the face or faces to use for it. The style of display used | |
64 | for any given character is determined by combining the attributes of | |
65 | all the applicable faces specified for that character. Any attribute | |
0ec1f115 | 66 | that isn't specified by these faces is taken from the @code{default} face, |
04d0b662 | 67 | whose attributes reflect the default settings of the frame itself. |
b8f3a9e3 GM |
68 | |
69 | Enriched mode, the mode for editing formatted text, includes several | |
0073fd65 RS |
70 | commands and menus for specifying faces for text in the buffer. |
71 | @xref{Format Faces}, for how to specify the font for text in the | |
72 | buffer. @xref{Format Colors}, for how to specify the foreground and | |
73 | background color. | |
b8f3a9e3 GM |
74 | |
75 | @cindex face colors, setting | |
76 | @findex set-face-foreground | |
77 | @findex set-face-background | |
0073fd65 RS |
78 | To alter the appearance of a face, use the customization buffer. |
79 | @xref{Face Customization}. You can also use X resources to specify | |
186e9bcc | 80 | attributes of particular faces (@pxref{Resources}). Alternatively, |
0073fd65 RS |
81 | you can change the foreground and background colors of a specific face |
82 | with @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}. | |
83 | These commands prompt in the minibuffer for a face name and a color | |
84 | name, with completion, and then set that face to use the specified | |
3ae02d92 EZ |
85 | color. Changing the colors of the @code{default} face also changes |
86 | the foreground and background colors on all frames, both existing and | |
87 | those to be created in the future. (You can also set foreground and | |
88 | background colors for the current frame only; see @ref{Frame | |
89 | Parameters}.) | |
0073fd65 | 90 | |
1b35090d RS |
91 | Emacs can correctly display variable-width fonts, but Emacs commands |
92 | that calculate width and indentation do not know how to calculate | |
93 | variable widths. This can sometimes lead to incorrect results when | |
94 | you use variable-width fonts. In particular, indentation commands can | |
95 | give inconsistent results, so we recommend you avoid variable-width | |
96 | fonts for editing program source code. Filling will sometimes make | |
97 | lines too long or too short. We plan to address these issues in | |
98 | future Emacs versions. | |
b8f3a9e3 | 99 | |
43d08eb9 RS |
100 | @node Standard Faces |
101 | @section Standard Faces | |
102 | ||
b8f3a9e3 | 103 | @findex list-faces-display |
43d08eb9 RS |
104 | To see what faces are currently defined, and what they look like, |
105 | type @kbd{M-x list-faces-display}. It's possible for a given face to | |
106 | look different in different frames; this command shows the appearance | |
3b91a16d JL |
107 | in the frame in which you type it. |
108 | ||
109 | Here are the standard faces for specifying text appearance. You can | |
110 | use them on specific text, when you want the effects they produce. | |
b8f3a9e3 GM |
111 | |
112 | @table @code | |
113 | @item default | |
114 | This face is used for ordinary text that doesn't specify any other face. | |
43d08eb9 RS |
115 | @item bold |
116 | This face uses a bold variant of the default font, if it has one. | |
3b91a16d JL |
117 | It's up to you to choose a default font that has a bold variant, |
118 | if you want to use one. | |
43d08eb9 RS |
119 | @item italic |
120 | This face uses an italic variant of the default font, if it has one. | |
121 | @item bold-italic | |
122 | This face uses a bold italic variant of the default font, if it has one. | |
123 | @item underline | |
124 | This face underlines text. | |
125 | @item fixed-pitch | |
3b91a16d | 126 | This face forces use of a particular fixed-width font. |
43d08eb9 | 127 | @item variable-pitch |
3b91a16d JL |
128 | This face forces use of a particular variable-width font. It's |
129 | reasonable to customize this to use a different variable-width font, | |
130 | if you like, but you should not make it a fixed-width font. | |
131 | @item shadow | |
132 | This face is used for making the text less noticeable than the surrounding | |
133 | ordinary text. Usually this can be achieved by using shades of gray in | |
134 | contrast with either black or white default foreground color. | |
43d08eb9 RS |
135 | @end table |
136 | ||
137 | Here's an incomplete list of faces used to highlight parts of the | |
138 | text temporarily for specific purposes. (Many other modes define | |
139 | their own faces for this purpose.) | |
140 | ||
141 | @table @code | |
142 | @item highlight | |
143 | This face is used for highlighting portions of text, in various modes. | |
144 | For example, mouse-sensitive text is highlighted using this face. | |
43d08eb9 RS |
145 | @item isearch |
146 | This face is used for highlighting Isearch matches. | |
147 | @item lazy-highlight | |
148 | This face is used for lazy highlighting of Isearch and Query Replace | |
149 | matches other than the current one. | |
150 | @item region | |
151 | This face is used for displaying a selected region (when Transient Mark | |
152 | mode is enabled---see below). | |
153 | @item secondary-selection | |
154 | This face is used for displaying a secondary X selection (@pxref{Secondary | |
155 | Selection}). | |
156 | @item trailing-whitespace | |
3b91a16d JL |
157 | The face for highlighting excess spaces and tabs at the end of a line |
158 | when @code{show-trailing-whitespace} is non-@code{nil}; see | |
159 | @ref{Useless Whitespace}. | |
43d08eb9 RS |
160 | @item nobreak-space |
161 | The face for displaying the character ``nobreak space''. | |
162 | @item escape-glyph | |
163 | The face for highlighting the @samp{\} or @samp{^} that indicates | |
164 | a control character. It's also used when @samp{\} indicates a | |
165 | nobreak space or nobreak (soft) hyphen. | |
43d08eb9 RS |
166 | @end table |
167 | ||
168 | @cindex @code{region} face | |
169 | When Transient Mark mode is enabled, the text of the region is | |
170 | highlighted when the mark is active. This uses the face named | |
171 | @code{region}; you can control the style of highlighting by changing the | |
172 | style of this face (@pxref{Face Customization}). @xref{Transient Mark}, | |
173 | for more information about Transient Mark mode and activation and | |
174 | deactivation of the mark. | |
175 | ||
176 | These faces control the appearance of parts of the Emacs frame. | |
177 | They exist as faces to provide a consistent way to customize the | |
178 | appearance of these parts of the frame. | |
179 | ||
180 | @table @code | |
b8f3a9e3 | 181 | @item mode-line |
3b91a16d JL |
182 | @itemx modeline |
183 | This face is used for the mode line of the currently selected window, | |
184 | and for menu bars when toolkit menus are not used. By default, it's | |
185 | drawn with shadows for a ``raised'' effect on window systems, and | |
186 | drawn as the inverse of the default face on non-windowed terminals. | |
187 | @code{modeline} is an alias for the @code{mode-line} face, for | |
188 | compatibility with old Emacs versions. | |
b9e58bf2 EZ |
189 | @item mode-line-inactive |
190 | Like @code{mode-line}, but used for mode lines of the windows other | |
191 | than the selected one (if @code{mode-line-in-non-selected-windows} is | |
ac6875fc RS |
192 | non-@code{nil}). This face inherits from @code{mode-line}, so changes |
193 | in that face affect mode lines in all windows. | |
d545c9fd JL |
194 | @item mode-line-highlight |
195 | Like @code{highlight}, but used for portions of text on mode lines. | |
196 | @item mode-line-buffer-id | |
197 | This face is used for buffer identification parts in the mode line. | |
b8f3a9e3 GM |
198 | @item header-line |
199 | Similar to @code{mode-line} for a window's header line. Most modes | |
3b91a16d | 200 | don't use the header line, but some special modes, such the Info mode, do. |
53abc3bf | 201 | @item vertical-border |
58f1b4d8 JL |
202 | This face is used for the vertical divider between windows. |
203 | By default this face inherits from the @code{mode-line-inactive} face | |
204 | on character terminals. On window systems the foreground color of | |
205 | this face is used for the vertical line between windows without | |
206 | scrollbars. | |
3094ad7a | 207 | @item minibuffer-prompt |
3b91a16d JL |
208 | @cindex @code{minibuffer-prompt} face |
209 | @vindex minibuffer-prompt-properties | |
3094ad7a | 210 | This face is used for the prompt strings displayed in the minibuffer. |
3b91a16d JL |
211 | By default, Emacs automatically adds this face to the value of |
212 | @code{minibuffer-prompt-properties}, which is a list of text | |
213 | properties used to display the prompt text. | |
b8f3a9e3 | 214 | @item fringe |
3b91a16d | 215 | @cindex @code{fringe} face |
b8f3a9e3 GM |
216 | The face for the fringes to the left and right of windows on graphic |
217 | displays. (The fringes are the narrow portions of the Emacs frame | |
940627fe | 218 | between the text area and the window's right and left borders.) |
43d08eb9 | 219 | @xref{Fringes}. |
b8f3a9e3 GM |
220 | @item scroll-bar |
221 | This face determines the visual appearance of the scroll bar. | |
43d08eb9 | 222 | @xref{Scroll Bars}. |
b8f3a9e3 GM |
223 | @item border |
224 | This face determines the color of the frame border. | |
225 | @item cursor | |
226 | This face determines the color of the cursor. | |
227 | @item mouse | |
228 | This face determines the color of the mouse pointer. | |
229 | @item tool-bar | |
230 | This is the basic tool-bar face. No text appears in the tool bar, but the | |
43d08eb9 | 231 | colors of this face affect the appearance of tool bar icons. @xref{Tool Bars}. |
b8f3a9e3 | 232 | @item tooltip |
43d08eb9 | 233 | This face is used for tooltips. @xref{Tooltips}. |
b8f3a9e3 | 234 | @item menu |
9e6bb19f EZ |
235 | @cindex menu bar appearance |
236 | @cindex @code{menu} face, no effect if customized | |
237 | @cindex customization of @code{menu} face | |
238 | This face determines the colors and font of Emacs's menus. @xref{Menu | |
239 | Bars}. Setting the font of LessTif/Motif menus is currently not | |
240 | supported; attempts to set the font are ignored in this case. | |
241 | Likewise, attempts to customize this face in Emacs built with GTK and | |
242 | in the MS-Windows port are ignored by the respective GUI toolkits; | |
243 | you need to use system-wide styles and options to change the | |
244 | appearance of the menus. | |
b8f3a9e3 GM |
245 | @end table |
246 | ||
b8f3a9e3 GM |
247 | @node Font Lock |
248 | @section Font Lock mode | |
249 | @cindex Font Lock mode | |
250 | @cindex mode, Font Lock | |
251 | @cindex syntax highlighting and coloring | |
252 | ||
8cc11660 | 253 | Font Lock mode is a minor mode, always local to a particular buffer, |
0015d677 | 254 | which highlights (or ``fontifies'') the buffer contents according to |
8cc11660 RS |
255 | the syntax of the text you are editing. It can recognize comments and |
256 | strings in most languages; in several languages, it can also recognize | |
257 | and properly highlight various other important constructs---for | |
258 | example, names of functions being defined or reserved keywords. | |
259 | Some special modes, such as Occur mode and Info mode, have completely | |
260 | specialized ways of assigning fonts for Font Lock mode. | |
b8f3a9e3 GM |
261 | |
262 | @findex font-lock-mode | |
c4e8acbc CY |
263 | Font Lock mode is turned on by default in all modes which support it. |
264 | You can toggle font-lock for each buffer with the command @kbd{M-x | |
265 | font-lock-mode}. Using a positive argument unconditionally turns Font | |
266 | Lock mode on, and a negative or zero argument turns it off. | |
b8f3a9e3 GM |
267 | |
268 | @findex global-font-lock-mode | |
269 | @vindex global-font-lock-mode | |
c4e8acbc CY |
270 | If you do not wish Font Lock mode to be turned on by default, |
271 | customize the variable @code{global-font-lock-mode} using the Customize | |
272 | interface (@pxref{Easy Customization}), or use the function | |
d239287a | 273 | @code{global-font-lock-mode} in your @file{.emacs} file, like this: |
b8f3a9e3 GM |
274 | |
275 | @example | |
c4e8acbc | 276 | (global-font-lock-mode 0) |
b8f3a9e3 GM |
277 | @end example |
278 | ||
c4e8acbc CY |
279 | @findex turn-on-font-lock |
280 | If you have disabled Global Font Lock mode, you can still enable font | |
281 | lock for specific major modes by adding the function | |
282 | @code{turn-on-font-lock} to the mode hooks (@pxref{Hooks}). For | |
283 | example, to enable Font Lock mode for editing C files, you can do this: | |
284 | ||
285 | @example | |
286 | (add-hook 'c-mode-hook 'turn-on-font-lock) | |
287 | @end example | |
0015d677 | 288 | |
b8f3a9e3 GM |
289 | Font Lock mode uses several specifically named faces to do its job, |
290 | including @code{font-lock-string-face}, @code{font-lock-comment-face}, | |
a26126e7 JL |
291 | and others. The easiest way to find them all is to use |
292 | @kbd{M-x customize-group @key{RET} font-lock-faces @key{RET}}. | |
b8f3a9e3 GM |
293 | |
294 | To change the colors or the fonts used by Font Lock mode to fontify | |
295 | different parts of text, just change these faces. There are | |
296 | two ways to do it: | |
297 | ||
298 | @itemize @bullet | |
299 | @item | |
300 | Invoke @kbd{M-x set-face-foreground} or @kbd{M-x set-face-background} | |
301 | to change the colors of a particular face used by Font Lock. | |
302 | @xref{Faces}. The command @kbd{M-x list-faces-display} displays all | |
303 | the faces currently known to Emacs, including those used by Font Lock. | |
304 | ||
305 | @item | |
306 | Customize the faces interactively with @kbd{M-x customize-face}, as | |
307 | described in @ref{Face Customization}. | |
308 | @end itemize | |
309 | ||
b8f3a9e3 GM |
310 | @vindex font-lock-maximum-decoration |
311 | The variable @code{font-lock-maximum-decoration} specifies the | |
312 | preferred level of fontification, for modes that provide multiple | |
313 | levels. Level 1 is the least amount of fontification; some modes | |
314 | support levels as high as 3. The normal default is ``as high as | |
315 | possible.'' You can specify an integer, which applies to all modes, or | |
316 | you can specify different numbers for particular major modes; for | |
317 | example, to use level 1 for C/C++ modes, and the default level | |
318 | otherwise, use this: | |
319 | ||
320 | @example | |
321 | (setq font-lock-maximum-decoration | |
322 | '((c-mode . 1) (c++-mode . 1))) | |
323 | @end example | |
324 | ||
325 | @vindex font-lock-maximum-size | |
326 | Fontification can be too slow for large buffers, so you can suppress | |
327 | it. The variable @code{font-lock-maximum-size} specifies a buffer size, | |
328 | beyond which buffer fontification is suppressed. | |
329 | ||
330 | @c @w is used below to prevent a bad page-break. | |
331 | @vindex font-lock-beginning-of-syntax-function | |
e07e854d EZ |
332 | @cindex incorrect fontification |
333 | @cindex parenthesis in column zero and fontification | |
334 | @cindex brace in column zero and fontification | |
b8f3a9e3 GM |
335 | Comment and string fontification (or ``syntactic'' fontification) |
336 | relies on analysis of the syntactic structure of the buffer text. For | |
0ec1f115 | 337 | the sake of speed, some modes, including C mode and Lisp mode, |
04d0b662 RS |
338 | rely on a special convention: an open-parenthesis or open-brace in the |
339 | leftmost column always defines the @w{beginning} of a defun, and is | |
ee6038a6 | 340 | thus always outside any string or comment. (@xref{Left Margin |
9048ad82 | 341 | Paren}.) If you don't follow this convention, Font Lock mode can |
ee6038a6 RS |
342 | misfontify the text that follows an open-parenthesis or open-brace in |
343 | the leftmost column that is inside a string or comment. | |
b8f3a9e3 | 344 | |
6bb2ed9b | 345 | @cindex slow display during scrolling |
b8f3a9e3 GM |
346 | The variable @code{font-lock-beginning-of-syntax-function} (always |
347 | buffer-local) specifies how Font Lock mode can find a position | |
348 | guaranteed to be outside any comment or string. In modes which use the | |
349 | leftmost column parenthesis convention, the default value of the variable | |
350 | is @code{beginning-of-defun}---that tells Font Lock mode to use the | |
351 | convention. If you set this variable to @code{nil}, Font Lock no longer | |
352 | relies on the convention. This avoids incorrect results, but the price | |
353 | is that, in some cases, fontification for a changed text must rescan | |
6bb2ed9b EZ |
354 | buffer text from the beginning of the buffer. This can considerably |
355 | slow down redisplay while scrolling, particularly if you are close to | |
356 | the end of a large buffer. | |
b8f3a9e3 GM |
357 | |
358 | @findex font-lock-add-keywords | |
359 | Font Lock highlighting patterns already exist for many modes, but you | |
360 | may want to fontify additional patterns. You can use the function | |
361 | @code{font-lock-add-keywords}, to add your own highlighting patterns for | |
362 | a particular mode. For example, to highlight @samp{FIXME:} words in C | |
363 | comments, use this: | |
364 | ||
365 | @example | |
366 | (font-lock-add-keywords | |
367 | 'c-mode | |
368 | '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t))) | |
369 | @end example | |
370 | ||
4063fff3 EZ |
371 | @findex font-lock-remove-keywords |
372 | To remove keywords from the font-lock highlighting patterns, use the | |
cd77ce13 | 373 | function @code{font-lock-remove-keywords}. @xref{Search-based |
09139bc5 LT |
374 | Fontification,,, elisp, The Emacs Lisp Reference Manual}, for |
375 | documentation of the format of this list. | |
4063fff3 | 376 | |
3be9b0ca EZ |
377 | @cindex just-in-time (JIT) font-lock |
378 | @cindex background syntax highlighting | |
379 | Fontifying large buffers can take a long time. To avoid large | |
380 | delays when a file is visited, Emacs fontifies only the visible | |
381 | portion of a buffer. As you scroll through the buffer, each portion | |
382 | that becomes visible is fontified as soon as it is displayed. The | |
383 | parts of the buffer that are not displayed are fontified | |
de4a4c41 | 384 | ``stealthily,'' in the background, i.e.@: when Emacs is idle. You can |
bdc3b3be RS |
385 | control this background fontification, also called @dfn{Just-In-Time} |
386 | (or @dfn{JIT}) Lock, by customizing variables in the customization | |
387 | group @samp{jit-lock}. @xref{Specific Customization}. | |
3be9b0ca | 388 | |
b8f3a9e3 GM |
389 | @node Highlight Interactively |
390 | @section Interactive Highlighting by Matching | |
391 | @cindex highlighting by matching | |
392 | @cindex interactive highlighting | |
393 | ||
cedf175b EZ |
394 | It is sometimes useful to temporarily highlight text that |
395 | matches a certain regular expression. For example, you might wish to | |
396 | see all the references to a certain variable in a program source file, | |
397 | highlight certain parts in a voluminous output of some program, or | |
398 | make certain names stand out in an article. | |
b8f3a9e3 GM |
399 | |
400 | @findex hi-lock-mode | |
401 | Use the @kbd{M-x hi-lock-mode} command to turn on a minor mode that | |
cedf175b EZ |
402 | allows you to interactively add and remove regular expressions |
403 | specifying text to be highlighted. Hi Lock mode works like Font Lock | |
404 | mode (@pxref{Font Lock}), except that it lets you easily add and | |
405 | remove regular expressions while you are editing a buffer. To enable | |
406 | Hi Lock mode for all buffers use @kbd{M-x global-hi-lock-mode} or | |
407 | place @code{(global-hi-lock-mode 1)} in your @file{.emacs} file. | |
408 | ||
409 | You control Hi Lock mode with these commands: | |
b8f3a9e3 GM |
410 | |
411 | @table @kbd | |
412 | @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET} | |
413 | @kindex C-x w h | |
414 | @findex highlight-regexp | |
cedf175b EZ |
415 | Highlight text that matches @var{regexp} using face @var{face} |
416 | (@code{highlight-regexp}). By using this command more than once, you | |
630acdcc | 417 | can highlight various parts of the text in different ways. The |
cedf175b EZ |
418 | highlighting will remain as long as the buffer is loaded. For |
419 | example, to highlight all occurrences of the word ``whim'' using the | |
420 | default face (a yellow background) @kbd{C-x w h whim @key{RET} | |
421 | @key{RET}}. Any face can be used for highlighting, Hi Lock provides | |
630acdcc JL |
422 | several of its own and these are pre-loaded into a history list. While |
423 | being prompted for a face use @kbd{M-p} and @kbd{M-n} to cycle through | |
cedf175b | 424 | them. |
b8f3a9e3 GM |
425 | |
426 | @item C-x w r @var{regexp} @key{RET} | |
427 | @kindex C-x w r | |
428 | @findex unhighlight-regexp | |
630acdcc | 429 | Unhighlight @var{regexp} (@code{unhighlight-regexp}). |
cedf175b EZ |
430 | When activated from the menu select the expression to unhighlight from |
431 | a list. When activated from the keyboard the most recently added | |
630acdcc JL |
432 | expression will be shown. Use @kbd{M-p} to show the next older |
433 | expression and @kbd{M-n} to select the next newer expression. When | |
cedf175b | 434 | the expression to unhighlight appears press @kbd{@key{RET}} to unhighlight |
630acdcc | 435 | it. The expression can also be typed and completion is available. |
b8f3a9e3 GM |
436 | |
437 | @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET} | |
438 | @kindex C-x w l | |
439 | @findex highlight-lines-matching-regexp | |
440 | @cindex lines, highlighting | |
441 | @cindex highlighting lines of text | |
04d0b662 | 442 | Highlight entire lines containing a match for @var{regexp}, using face |
b8f3a9e3 GM |
443 | @var{face} (@code{highlight-lines-matching-regexp}). |
444 | ||
445 | @item C-x w b | |
446 | @kindex C-x w b | |
447 | @findex hi-lock-write-interactive-patterns | |
448 | Insert all the current highlighting regexp/face pairs into the buffer | |
449 | at point, with comment delimiters to prevent them from changing your | |
450 | program. This key binding runs the | |
451 | @code{hi-lock-write-interactive-patterns} command. | |
452 | ||
453 | These patterns will be read the next time you visit the file while | |
cedf175b | 454 | Hi Lock mode is enabled, or whenever you use the @kbd{M-x |
b8f3a9e3 GM |
455 | hi-lock-find-patterns} command. |
456 | ||
457 | @item C-x w i | |
458 | @kindex C-x w i | |
459 | @findex hi-lock-find-patterns | |
460 | @vindex hi-lock-exclude-modes | |
461 | Re-read regexp/face pairs in the current buffer | |
630acdcc | 462 | (@code{hi-lock-write-interactive-patterns}). Users familiar with Font |
cedf175b EZ |
463 | Lock keywords might interactively enter patterns |
464 | (@code{highlight-regexp}), write them into the file | |
465 | (@code{hi-lock-write-interactive-patterns}), edit them, perhaps | |
466 | including different faces for different parenthesized parts of the | |
467 | match, and finally use this command | |
468 | (@code{hi-lock-write-interactive-patterns}) to have Hi Lock highlight | |
469 | them. | |
b8f3a9e3 GM |
470 | |
471 | This command does nothing if the major mode is a member of the list | |
472 | @code{hi-lock-exclude-modes}. | |
473 | @end table | |
474 | ||
b26533d6 JL |
475 | @node Highlight Changes |
476 | @section Highlight Changes Mode | |
477 | ||
478 | @findex highlight-changes-mode | |
479 | Use @kbd{M-x highlight-changes-mode} to enable a minor mode | |
480 | that uses faces (colors, typically) to indicate which parts of | |
481 | the buffer were changed most recently. | |
482 | ||
6bf7aab6 DL |
483 | @node Scrolling |
484 | @section Scrolling | |
485 | ||
486 | If a buffer contains text that is too large to fit entirely within a | |
487 | window that is displaying the buffer, Emacs shows a contiguous portion of | |
488 | the text. The portion shown always contains point. | |
489 | ||
490 | @cindex scrolling | |
491 | @dfn{Scrolling} means moving text up or down in the window so that | |
492 | different parts of the text are visible. Scrolling forward means that text | |
493 | moves up, and new text appears at the bottom. Scrolling backward moves | |
494 | text down and new text appears at the top. | |
495 | ||
496 | Scrolling happens automatically if you move point past the bottom or top | |
497 | of the window. You can also explicitly request scrolling with the commands | |
498 | in this section. | |
499 | ||
500 | @table @kbd | |
501 | @item C-l | |
502 | Clear screen and redisplay, scrolling the selected window to center | |
503 | point vertically within it (@code{recenter}). | |
504 | @item C-v | |
505 | Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}). | |
506 | @item @key{NEXT} | |
04d0b662 | 507 | @itemx @key{PAGEDOWN} |
6bf7aab6 DL |
508 | Likewise, scroll forward. |
509 | @item M-v | |
510 | Scroll backward (@code{scroll-down}). | |
511 | @item @key{PRIOR} | |
04d0b662 | 512 | @itemx @key{PAGEUP} |
6bf7aab6 DL |
513 | Likewise, scroll backward. |
514 | @item @var{arg} C-l | |
515 | Scroll so point is on line @var{arg} (@code{recenter}). | |
516 | @item C-M-l | |
517 | Scroll heuristically to bring useful information onto the screen | |
518 | (@code{reposition-window}). | |
519 | @end table | |
520 | ||
521 | @kindex C-l | |
522 | @findex recenter | |
523 | The most basic scrolling command is @kbd{C-l} (@code{recenter}) with | |
0015d677 RS |
524 | no argument. It scrolls the selected window so that point is halfway |
525 | down from the top of the window. On a text terminal, it also clears | |
526 | the screen and redisplays all windows. That is useful in case the | |
527 | screen is garbled (@pxref{Screen Garbled}). | |
6bf7aab6 DL |
528 | |
529 | @kindex C-v | |
530 | @kindex M-v | |
531 | @kindex NEXT | |
532 | @kindex PRIOR | |
04d0b662 RS |
533 | @kindex PAGEDOWN |
534 | @kindex PAGEUP | |
6bf7aab6 DL |
535 | @findex scroll-up |
536 | @findex scroll-down | |
6bf7aab6 | 537 | @vindex next-screen-context-lines |
04d0b662 RS |
538 | To read the buffer a windowful at a time, use @kbd{C-v} |
539 | (@code{scroll-up}) with no argument. This scrolls forward by nearly | |
540 | the whole window height. The effect is to take the two lines at the | |
541 | bottom of the window and put them at the top, followed by nearly a | |
542 | whole windowful of lines that were not previously visible. If point | |
543 | was in the text that scrolled off the top, it ends up at the new top | |
544 | of the window. | |
545 | ||
0ec1f115 RS |
546 | @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in |
547 | a similar way, also with overlap. The number of lines of overlap | |
548 | across a @kbd{C-v} or @kbd{M-v} is controlled by the variable | |
04d0b662 RS |
549 | @code{next-screen-context-lines}; by default, it is 2. The function |
550 | keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and @key{PAGEUP}, | |
551 | are equivalent to @kbd{C-v} and @kbd{M-v}. | |
552 | ||
553 | The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll | |
554 | the text in the selected window up or down a few lines. @kbd{C-v} | |
555 | with an argument moves the text and point up, together, that many | |
556 | lines; it brings the same number of new lines into view at the bottom | |
557 | of the window. @kbd{M-v} with numeric argument scrolls the text | |
558 | downward, bringing that many new lines into view at the top of the | |
559 | window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice | |
560 | versa. | |
561 | ||
562 | The names of scroll commands are based on the direction that the | |
563 | text moves in the window. Thus, the command to scroll forward is | |
564 | called @code{scroll-up} because it moves the text upward on the | |
565 | screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names | |
566 | and customary meanings from a different convention that developed | |
567 | elsewhere; hence the strange result that @key{PAGEDOWN} runs | |
568 | @code{scroll-up}. | |
6bf7aab6 DL |
569 | |
570 | @vindex scroll-preserve-screen-position | |
571 | Some users like the full-screen scroll commands to keep point at the | |
572 | same screen line. To enable this behavior, set the variable | |
a0c283e6 RS |
573 | @code{scroll-preserve-screen-position} to a non-@code{nil} value. In |
574 | this mode, when scrolling shifts point off the screen, or into the | |
575 | scrolling margins, Emacs moves point to keep the same vertical | |
576 | position within the window. This mode is convenient for browsing | |
577 | through a file by scrolling by screenfuls; if you come back to the | |
578 | screen where you started, point goes back to the line where it | |
579 | started. However, this mode is inconvenient when you move to the next | |
580 | screen in order to move point to the text there. | |
6bf7aab6 DL |
581 | |
582 | Another way to do scrolling is with @kbd{C-l} with a numeric argument. | |
583 | @kbd{C-l} does not clear the screen when given an argument; it only scrolls | |
584 | the selected window. With a positive argument @var{n}, it repositions text | |
585 | to put point @var{n} lines down from the top. An argument of zero puts | |
586 | point on the very top line. Point does not move with respect to the text; | |
587 | rather, the text and point move rigidly on the screen. @kbd{C-l} with a | |
588 | negative argument puts point that many lines from the bottom of the window. | |
589 | For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u | |
04d0b662 RS |
590 | - 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put |
591 | point at the center (vertically) of the selected window. | |
6bf7aab6 DL |
592 | |
593 | @kindex C-M-l | |
594 | @findex reposition-window | |
595 | The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current | |
596 | window heuristically in a way designed to get useful information onto | |
597 | the screen. For example, in a Lisp file, this command tries to get the | |
598 | entire current defun onto the screen if possible. | |
599 | ||
600 | @vindex scroll-conservatively | |
04d0b662 RS |
601 | Scrolling happens automatically when point moves out of the visible |
602 | portion of the text. Normally, automatic scrolling centers point | |
603 | vertically within the window. However, if you set | |
604 | @code{scroll-conservatively} to a small number @var{n}, then if you | |
605 | move point just a little off the screen---less than @var{n} | |
606 | lines---then Emacs scrolls the text just far enough to bring point | |
607 | back on screen. By default, @code{scroll-conservatively} is 0. | |
6bf7aab6 | 608 | |
6dd5e8cc EZ |
609 | @cindex aggressive scrolling |
610 | @vindex scroll-up-aggressively | |
177c0ea7 | 611 | @vindex scroll-down-aggressively |
e598186c RS |
612 | When the window does scroll by a longer distance, you can control |
613 | how aggressively it scrolls, by setting the variables | |
614 | @code{scroll-up-aggressively} and @code{scroll-down-aggressively}. | |
615 | The value of @code{scroll-up-aggressively} should be either | |
616 | @code{nil}, or a fraction @var{f} between 0 and 1. A fraction | |
617 | specifies where on the screen to put point when scrolling upward. | |
618 | More precisely, when a window scrolls up because point is above the | |
619 | window start, the new start position is chosen to put point @var{f} | |
620 | part of the window height from the top. The larger @var{f}, the more | |
621 | aggressive the scrolling. | |
622 | ||
623 | @code{nil}, which is the default, scrolls to put point at the center. | |
624 | So it is equivalent to .5. | |
625 | ||
626 | Likewise, @code{scroll-down-aggressively} is used for scrolling | |
627 | down. The value, @var{f}, specifies how far point should be placed | |
628 | from the bottom of the window; thus, as with | |
629 | @code{scroll-up-aggressively}, a larger value is more aggressive. | |
6dd5e8cc | 630 | |
6bf7aab6 DL |
631 | @vindex scroll-margin |
632 | The variable @code{scroll-margin} restricts how close point can come | |
633 | to the top or bottom of a window. Its value is a number of screen | |
634 | lines; if point comes within that many lines of the top or bottom of the | |
635 | window, Emacs recenters the window. By default, @code{scroll-margin} is | |
636 | 0. | |
637 | ||
638 | @node Horizontal Scrolling | |
639 | @section Horizontal Scrolling | |
640 | @cindex horizontal scrolling | |
641 | ||
642 | @dfn{Horizontal scrolling} means shifting all the lines sideways | |
e598186c | 643 | within a window---so that some of the text near the left margin is not |
0015d677 RS |
644 | displayed at all. When the text in a window is scrolled horizontally, |
645 | text lines are truncated rather than continued (@pxref{Display | |
646 | Custom}). Whenever a window shows truncated lines, Emacs | |
647 | automatically updates its horizontal scrolling whenever point moves | |
648 | off the left or right edge of the screen. You can also use these | |
649 | commands to do explicit horizontal scrolling. | |
6bf7aab6 DL |
650 | |
651 | @table @kbd | |
652 | @item C-x < | |
653 | Scroll text in current window to the left (@code{scroll-left}). | |
654 | @item C-x > | |
655 | Scroll to the right (@code{scroll-right}). | |
656 | @end table | |
657 | ||
6bf7aab6 DL |
658 | @kindex C-x < |
659 | @kindex C-x > | |
660 | @findex scroll-left | |
661 | @findex scroll-right | |
662 | The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected | |
663 | window to the left by @var{n} columns with argument @var{n}. This moves | |
664 | part of the beginning of each line off the left edge of the window. | |
665 | With no argument, it scrolls by almost the full width of the window (two | |
666 | columns less, to be precise). | |
667 | ||
668 | @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The | |
669 | window cannot be scrolled any farther to the right once it is displayed | |
670 | normally (with each line starting at the window's left margin); | |
671 | attempting to do so has no effect. This means that you don't have to | |
672 | calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large | |
673 | argument will restore the normal display. | |
674 | ||
0015d677 RS |
675 | If you use those commands to scroll a window horizontally, that sets |
676 | a lower bound for automatic horizontal scrolling. Automatic scrolling | |
677 | will continue to scroll the window, but never farther to the right | |
678 | than the amount you previously set by @code{scroll-left}. | |
6bf7aab6 | 679 | |
c86cd4e4 EZ |
680 | @vindex hscroll-margin |
681 | The value of the variable @code{hscroll-margin} controls how close | |
682 | to the window's edges point is allowed to get before the window will | |
683 | be automatically scrolled. It is measured in columns. If the value | |
684 | is 5, then moving point within 5 columns of the edge causes horizontal | |
685 | scrolling away from that edge. | |
686 | ||
687 | @vindex hscroll-step | |
688 | The variable @code{hscroll-step} determines how many columns to | |
689 | scroll the window when point gets too close to the edge. If it's | |
690 | zero, horizontal scrolling centers point horizontally within the | |
691 | window. If it's a positive integer, it specifies the number of | |
9b474b4e RS |
692 | columns to scroll by. If it's a floating-point number, it specifies |
693 | the fraction of the window's width to scroll by. The default is zero. | |
04bee768 | 694 | |
c86cd4e4 | 695 | @vindex auto-hscroll-mode |
e598186c | 696 | To disable automatic horizontal scrolling, set the variable |
c86cd4e4 | 697 | @code{auto-hscroll-mode} to @code{nil}. |
03ff8aab | 698 | |
fad78d58 RS |
699 | @node Fringes |
700 | @section Window Fringes | |
701 | @cindex fringes | |
702 | ||
703 | On a graphical display, each Emacs window normally has narrow | |
704 | @dfn{fringes} on the left and right edges. The fringes display | |
705 | indications about the text in the window. | |
706 | ||
707 | The most common use of the fringes is to indicate a continuation | |
708 | line, when one line of text is split into multiple lines on the | |
709 | screen. The left fringe shows a curving arrow for each screen line | |
710 | except the first, indicating that ``this is not the real beginning.'' | |
711 | The right fringe shows a curving arrow for each screen line except the | |
712 | last, indicating that ``this is not the real end.'' | |
713 | ||
566da2e7 | 714 | The fringes indicate line truncation with short horizontal arrows |
fad78d58 | 715 | meaning ``there's more text on this line which is scrolled |
566da2e7 EZ |
716 | horizontally out of view;'' clicking the mouse on one of the arrows |
717 | scrolls the display horizontally in the direction of the arrow. The | |
d239287a | 718 | fringes can also indicate other things, such as empty lines, or where a |
566da2e7 | 719 | program you are debugging is executing (@pxref{Debuggers}). |
fad78d58 RS |
720 | |
721 | @findex set-fringe-style | |
722 | @findex fringe-mode | |
723 | You can enable and disable the fringes for all frames using | |
724 | @kbd{M-x fringe-mode}. To enable and disable the fringes | |
725 | for the selected frame, use @kbd{M-x set-fringe-style}. | |
726 | ||
727 | @node Useless Whitespace | |
728 | @section Useless Whitespace | |
729 | ||
730 | @cindex trailing whitespace | |
731 | @cindex whitespace, trailing | |
732 | @vindex show-trailing-whitespace | |
733 | It is easy to leave unnecessary spaces at the end of a line, or | |
734 | empty lines at the end of a file, without realizing it. In most | |
735 | cases, this @dfn{trailing whitespace} has no effect, but there are | |
736 | special circumstances where it matters. | |
737 | ||
738 | You can make trailing whitespace at the end of a line visible on the | |
739 | screen by setting the buffer-local variable | |
740 | @code{show-trailing-whitespace} to @code{t}. Then Emacs displays | |
741 | trailing whitespace in the face @code{trailing-whitespace}. | |
742 | ||
743 | This feature does not apply when point is at the end of the line | |
744 | containing the whitespace. Strictly speaking, that is ``trailing | |
745 | whitespace'' nonetheless, but displaying it specially in that case | |
746 | looks ugly while you are typing in new text. In this special case, | |
747 | the location of point is enough to show you that the spaces are | |
748 | present. | |
749 | ||
750 | @findex delete-trailing-whitespace | |
751 | To delete all trailing whitespace within the current buffer's | |
752 | accessible portion (@pxref{Narrowing}), type @kbd{M-x | |
753 | delete-trailing-whitespace @key{RET}}. (This command does not remove | |
754 | the form-feed characters.) | |
755 | ||
23e3383d | 756 | @vindex indicate-empty-lines |
fad78d58 | 757 | @vindex default-indicate-empty-lines |
877db12e RS |
758 | @cindex unused lines |
759 | @cindex fringes, and unused line indication | |
760 | Emacs can indicate unused lines at the end of the window with a | |
761 | small image in the left fringe (@pxref{Fringes}). The image appears | |
762 | for window lines that do not correspond to any buffer text. Blank | |
763 | lines at the end of the buffer then stand out because they do not have | |
764 | this image in the fringe. | |
765 | ||
766 | To enable this feature, set the buffer-local variable | |
23e3383d | 767 | @code{indicate-empty-lines} to a non-@code{nil} value. The default |
877db12e | 768 | value of this variable is controlled by the variable |
23e3383d | 769 | @code{default-indicate-empty-lines}; by setting that variable, you |
877db12e RS |
770 | can enable or disable this feature for all new buffers. (This feature |
771 | currently doesn't work on character terminals.) | |
fad78d58 | 772 | |
6bf7aab6 DL |
773 | @node Follow Mode |
774 | @section Follow Mode | |
775 | @cindex Follow mode | |
776 | @cindex mode, Follow | |
fd3d3075 RS |
777 | @findex follow-mode |
778 | @cindex windows, synchronizing | |
779 | @cindex synchronizing windows | |
6bf7aab6 | 780 | |
0015d677 RS |
781 | @dfn{Follow mode} is a minor mode that makes two windows, both |
782 | showing the same buffer, scroll as a single tall ``virtual window.'' | |
783 | To use Follow mode, go to a frame with just one window, split it into | |
784 | two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x | |
785 | follow-mode}. From then on, you can edit the buffer in either of the | |
786 | two windows, or scroll either one; the other window follows it. | |
6bf7aab6 | 787 | |
8f399c9b RS |
788 | In Follow mode, if you move point outside the portion visible in one |
789 | window and into the portion visible in the other window, that selects | |
790 | the other window---again, treating the two as if they were parts of | |
791 | one large window. | |
792 | ||
6bf7aab6 DL |
793 | To turn off Follow mode, type @kbd{M-x follow-mode} a second time. |
794 | ||
795 | @node Selective Display | |
796 | @section Selective Display | |
4946337d | 797 | @cindex selective display |
6bf7aab6 DL |
798 | @findex set-selective-display |
799 | @kindex C-x $ | |
800 | ||
801 | Emacs has the ability to hide lines indented more than a certain number | |
802 | of columns (you specify how many columns). You can use this to get an | |
803 | overview of a part of a program. | |
804 | ||
d239287a LT |
805 | To hide lines in the current buffer, type @kbd{C-x $} |
806 | (@code{set-selective-display}) with a numeric argument @var{n}. Then | |
807 | lines with at least @var{n} columns of indentation disappear from the | |
808 | screen. The only indication of their presence is that three dots | |
809 | (@samp{@dots{}}) appear at the end of each visible line that is | |
810 | followed by one or more hidden ones. | |
6bf7aab6 DL |
811 | |
812 | The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as | |
813 | if they were not there. | |
814 | ||
815 | The hidden lines are still present in the buffer, and most editing | |
816 | commands see them as usual, so you may find point in the middle of the | |
817 | hidden text. When this happens, the cursor appears at the end of the | |
818 | previous line, after the three dots. If point is at the end of the | |
819 | visible line, before the newline that ends it, the cursor appears before | |
820 | the three dots. | |
821 | ||
822 | To make all lines visible again, type @kbd{C-x $} with no argument. | |
823 | ||
824 | @vindex selective-display-ellipses | |
825 | If you set the variable @code{selective-display-ellipses} to | |
826 | @code{nil}, the three dots do not appear at the end of a line that | |
827 | precedes hidden lines. Then there is no visible indication of the | |
828 | hidden lines. This variable becomes local automatically when set. | |
829 | ||
0015d677 RS |
830 | See also @ref{Outline Mode} for another way to hide part of |
831 | the text in a buffer. | |
832 | ||
6bf7aab6 DL |
833 | @node Optional Mode Line |
834 | @section Optional Mode Line Features | |
835 | ||
b213b767 LK |
836 | @cindex buffer size display |
837 | @cindex display of buffer size | |
838 | @findex size-indication-mode | |
839 | The buffer percentage @var{pos} indicates the percentage of the | |
840 | buffer above the top of the window. You can additionally display the | |
841 | size of the buffer by typing @kbd{M-x size-indication-mode} to turn on | |
842 | Size Indication mode. The size will be displayed immediately | |
843 | following the buffer percentage like this: | |
844 | ||
845 | @example | |
846 | @var{POS} of @var{SIZE} | |
847 | @end example | |
848 | ||
849 | @noindent | |
850 | Here @var{SIZE} is the human readable representation of the number of | |
851 | characters in the buffer, which means that @samp{k} for 10^3, @samp{M} | |
852 | for 10^6, @samp{G} for 10^9, etc., are used to abbreviate. | |
853 | ||
854 | @cindex narrowing, and buffer size display | |
855 | If you have narrowed the buffer (@pxref{Narrowing}), the size of the | |
856 | accessible part of the buffer is shown. | |
857 | ||
e598186c RS |
858 | @cindex line number display |
859 | @cindex display of line number | |
6bf7aab6 DL |
860 | @findex line-number-mode |
861 | The current line number of point appears in the mode line when Line | |
862 | Number mode is enabled. Use the command @kbd{M-x line-number-mode} to | |
863 | turn this mode on and off; normally it is on. The line number appears | |
b213b767 | 864 | after the buffer percentage @var{pos}, with the letter @samp{L} to |
6bf7aab6 DL |
865 | indicate what it is. @xref{Minor Modes}, for more information about |
866 | minor modes and about how to use this command. | |
867 | ||
43f971ab EZ |
868 | @cindex narrowing, and line number display |
869 | If you have narrowed the buffer (@pxref{Narrowing}), the displayed | |
870 | line number is relative to the accessible portion of the buffer. | |
871 | ||
6bf7aab6 DL |
872 | @vindex line-number-display-limit |
873 | If the buffer is very large (larger than the value of | |
874 | @code{line-number-display-limit}), then the line number doesn't appear. | |
875 | Emacs doesn't compute the line number when the buffer is large, because | |
43f971ab EZ |
876 | that would be too slow. Set it to @code{nil} to remove the limit. |
877 | ||
878 | @vindex line-number-display-limit-width | |
879 | Line-number computation can also be slow if the lines in the buffer | |
880 | are too long. For this reason, Emacs normally doesn't display line | |
881 | numbers if the average width, in characters, of lines near point is | |
882 | larger than the value of the variable | |
883 | @code{line-number-display-limit-width}. The default value is 200 | |
884 | characters. | |
6bf7aab6 DL |
885 | |
886 | @cindex Column Number mode | |
887 | @cindex mode, Column Number | |
888 | @findex column-number-mode | |
889 | You can also display the current column number by turning on Column | |
890 | Number mode. It displays the current column number preceded by the | |
891 | letter @samp{C}. Type @kbd{M-x column-number-mode} to toggle this mode. | |
892 | ||
893 | @findex display-time | |
894 | @cindex time (on mode line) | |
895 | Emacs can optionally display the time and system load in all mode | |
4f00b8c1 DL |
896 | lines. To enable this feature, type @kbd{M-x display-time} or customize |
897 | the option @code{display-time-mode}. The information added to the mode | |
898 | line usually appears after the buffer name, before the mode names and | |
899 | their parentheses. It looks like this: | |
6bf7aab6 DL |
900 | |
901 | @example | |
902 | @var{hh}:@var{mm}pm @var{l.ll} | |
903 | @end example | |
904 | ||
905 | @noindent | |
906 | @vindex display-time-24hr-format | |
907 | Here @var{hh} and @var{mm} are the hour and minute, followed always by | |
908 | @samp{am} or @samp{pm}. @var{l.ll} is the average number of running | |
909 | processes in the whole system recently. (Some fields may be missing if | |
910 | your operating system cannot support them.) If you prefer time display | |
911 | in 24-hour format, set the variable @code{display-time-24hr-format} | |
912 | to @code{t}. | |
913 | ||
914 | @cindex mail (on mode line) | |
72bd7b7b DL |
915 | @vindex display-time-use-mail-icon |
916 | @vindex display-time-mail-face | |
fad78d58 RS |
917 | @vindex display-time-mail-file |
918 | @vindex display-time-mail-directory | |
6bf7aab6 | 919 | The word @samp{Mail} appears after the load level if there is mail |
72bd7b7b DL |
920 | for you that you have not read yet. On a graphical display you can use |
921 | an icon instead of @samp{Mail} by customizing | |
922 | @code{display-time-use-mail-icon}; this may save some space on the mode | |
923 | line. You can customize @code{display-time-mail-face} to make the mail | |
fad78d58 RS |
924 | indicator prominent. Use @code{display-time-mail-file} to specify |
925 | the mail file to check, or set @code{display-time-mail-directory} | |
926 | to specify the directory to check for incoming mail (any nonempty regular | |
927 | file in the directory is considered as ``newly arrived mail''). | |
6bf7aab6 | 928 | |
47d7776c | 929 | @cindex mode line, 3D appearance |
bd3ead08 EZ |
930 | @cindex attributes of mode line, changing |
931 | @cindex non-integral number of lines in a window | |
04d0b662 RS |
932 | By default, the mode line is drawn on graphics displays with |
933 | 3D-style highlighting, like that of a button when it is not being | |
934 | pressed. If you don't like this effect, you can disable the 3D | |
935 | highlighting of the mode line, by customizing the attributes of the | |
936 | @code{mode-line} face in your @file{.emacs} init file, like this: | |
bd3ead08 EZ |
937 | |
938 | @example | |
04d0b662 | 939 | (set-face-attribute 'mode-line nil :box nil) |
bd3ead08 EZ |
940 | @end example |
941 | ||
942 | @noindent | |
04d0b662 | 943 | Alternatively, you can turn off the box attribute in your |
bd3ead08 EZ |
944 | @file{.Xdefaults} file: |
945 | ||
946 | @example | |
04d0b662 | 947 | Emacs.mode-line.AttributeBox: off |
bd3ead08 EZ |
948 | @end example |
949 | ||
b9e58bf2 | 950 | @cindex non-selected windows, mode line appearance |
ac6875fc | 951 | By default, the mode line of nonselected windows is displayed in a |
1c9f5f23 | 952 | different face, called @code{mode-line-inactive}. Only the selected |
ac6875fc RS |
953 | window is displayed in the @code{mode-line} face. This helps show |
954 | which window is selected. When the minibuffer is selected, since | |
955 | it has no mode line, the window from which you activated the minibuffer | |
956 | has its mode line displayed using @code{mode-line}; as a result, | |
957 | ordinary entry to the minibuffer does not change any mode lines. | |
958 | ||
959 | @vindex mode-line-in-non-selected-windows | |
960 | You can disable use of @code{mode-line-inactive} by setting variable | |
1c9f5f23 KS |
961 | @code{mode-line-in-non-selected-windows} to @code{nil}; then all mode |
962 | lines are displayed in the @code{mode-line} face. | |
b9e58bf2 | 963 | |
589a3f9f RS |
964 | @vindex eol-mnemonic-unix |
965 | @vindex eol-mnemonic-dos | |
966 | @vindex eol-mnemonic-mac | |
967 | @vindex eol-mnemonic-undecided | |
968 | You can customize the mode line display for each of the end-of-line | |
969 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
970 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
971 | @code{eol-mnemonic-undecided} to any string you find appropriate. | |
972 | @xref{Variables}, for an explanation of how to set variables. | |
973 | ||
6bf7aab6 DL |
974 | @node Text Display |
975 | @section How Text Is Displayed | |
976 | @cindex characters (in text) | |
977 | ||
76dd3692 | 978 | @acronym{ASCII} printing characters (octal codes 040 through 0176) in Emacs |
13b9ee95 | 979 | buffers are displayed with their graphics, as are non-ASCII multibyte |
6bf7aab6 DL |
980 | printing characters (octal codes above 0400). |
981 | ||
76dd3692 | 982 | Some @acronym{ASCII} control characters are displayed in special ways. The |
6bf7aab6 DL |
983 | newline character (octal code 012) is displayed by starting a new line. |
984 | The tab character (octal code 011) is displayed by moving to the next | |
985 | tab stop column (normally every 8 columns). | |
986 | ||
76dd3692 | 987 | Other @acronym{ASCII} control characters are normally displayed as a caret |
6bf7aab6 DL |
988 | (@samp{^}) followed by the non-control version of the character; thus, |
989 | control-A is displayed as @samp{^A}. | |
990 | ||
76dd3692 | 991 | Non-@acronym{ASCII} characters 0200 through 0237 (octal) are displayed with |
7c9960d7 DL |
992 | octal escape sequences; thus, character code 0230 (octal) is displayed |
993 | as @samp{\230}. The display of character codes 0240 through 0377 | |
994 | (octal) may be either as escape sequences or as graphics. They do not | |
04d0b662 | 995 | normally occur in multibyte buffers, but if they do, they are displayed |
7c9960d7 DL |
996 | as Latin-1 graphics. In unibyte mode, if you enable European display |
997 | they are displayed using their graphics (assuming your terminal supports | |
998 | them), otherwise as escape sequences. @xref{Single-Byte Character | |
999 | Support}. | |
6bf7aab6 | 1000 | |
470a11a3 | 1001 | @vindex nobreak-char-display |
367aa52c RS |
1002 | @cindex no-break space, display |
1003 | @cindex no-break hyphen, display | |
1004 | @cindex soft hyphen, display | |
470a11a3 RS |
1005 | Some character sets define ``no-break'' versions of the space and |
1006 | hyphen characters, which are used where a line should not be broken. | |
1007 | Emacs normally displays these characters with special faces | |
1008 | (respectively, @code{nobreak-space} and @code{escape-glyph}) to | |
1009 | distinguish them from ordinary spaces and hyphens. You can turn off | |
1010 | this feature by setting the variable @code{nobreak-char-display} to | |
1011 | @code{nil}. If you set the variable to any other value, that means to | |
1012 | prefix these characters with an escape character. | |
b5cced4b | 1013 | |
0015d677 RS |
1014 | @node Cursor Display |
1015 | @section Displaying the Cursor | |
1016 | ||
1017 | @findex blink-cursor-mode | |
1018 | @vindex blink-cursor-alist | |
1019 | @cindex cursor, locating visually | |
1020 | @cindex cursor, blinking | |
1021 | You can customize the cursor's color, and whether it blinks, using | |
1022 | the @code{cursor} Custom group (@pxref{Easy Customization}). On | |
1023 | graphical terminals, the command @kbd{M-x blink-cursor-mode} enables | |
1024 | or disables the blinking of the cursor. (On text terminals, the | |
1025 | terminal itself blinks the cursor, and Emacs has no control over it.) | |
1026 | You can control how the cursor appears when it blinks off by setting | |
1027 | the variable @code{blink-cursor-alist}. | |
1028 | ||
468160b7 SM |
1029 | @vindex visible-cursor |
1030 | Some text terminals offer two different cursors: the normal cursor | |
1031 | and the very visible cursor, where the latter may be e.g. bigger or | |
1032 | blinking. By default Emacs uses the very visible cursor. Setting the | |
1033 | variable @code{visible-cursor} to @code{nil} makes it use the | |
1034 | normal cursor. | |
1035 | ||
0015d677 RS |
1036 | @cindex cursor in non-selected windows |
1037 | @vindex cursor-in-non-selected-windows | |
1038 | Normally, the cursor appears in non-selected windows in the ``off'' | |
1039 | state, with the same appearance as when the blinking cursor blinks | |
1040 | ``off''. For a box cursor, this is a hollow box; for a bar cursor, | |
1041 | this is a thinner bar. To turn off cursors in non-selected windows, | |
1042 | customize the variable @code{cursor-in-non-selected-windows} and assign | |
1043 | it a @code{nil} value. | |
1044 | ||
1045 | @vindex x-stretch-cursor | |
1046 | @cindex wide block cursor | |
1047 | On graphical terminals, Emacs can optionally draw the block cursor | |
1048 | as wide as the character under the cursor---for example, if the cursor | |
1049 | is on a tab character, it would cover the full width occupied by that | |
1050 | tab character. To enable this feature, set the variable | |
1051 | @code{x-stretch-cursor} to a non-@code{nil} value. | |
1052 | ||
1053 | @findex hl-line-mode | |
1054 | @findex global-hl-line-mode | |
1055 | @cindex highlight current line | |
1056 | If you find it hard to see the cursor, you might like HL Line mode, | |
1057 | a minor mode that highlights the line containing point. Use @kbd{M-x | |
1058 | hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x | |
1059 | global-hl-line-mode} enables or disables the same mode globally. | |
1060 | ||
e598186c RS |
1061 | @node Display Custom |
1062 | @section Customization of Display | |
6bf7aab6 | 1063 | |
589a3f9f RS |
1064 | This section describes variables (@pxref{Variables}) that you can |
1065 | change to customize how Emacs displays text. Beginning users can skip | |
1066 | it. | |
1067 | @c the reason for that pxref is because an xref early in the | |
1068 | @c ``echo area'' section leads here. | |
6bf7aab6 | 1069 | |
6bf7aab6 DL |
1070 | @vindex inverse-video |
1071 | If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts | |
1072 | to invert all the lines of the display from what they normally are. | |
1073 | ||
1074 | @vindex visible-bell | |
1075 | If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts | |
1076 | to make the whole screen blink when it would normally make an audible bell | |
1077 | sound. This variable has no effect if your terminal does not have a way | |
0015d677 | 1078 | to make the screen blink. |
6bf7aab6 DL |
1079 | |
1080 | @vindex no-redraw-on-reenter | |
0015d677 RS |
1081 | On a text terminal, when you reenter Emacs after suspending, Emacs |
1082 | normally clears the screen and redraws the entire display. On some | |
1083 | terminals with more than one page of memory, it is possible to arrange | |
1084 | the termcap entry so that the @samp{ti} and @samp{te} strings (output | |
1085 | to the terminal when Emacs is entered and exited, respectively) switch | |
1086 | between pages of memory so as to use one page for Emacs and another | |
1087 | page for other output. Then you might want to set the variable | |
1088 | @code{no-redraw-on-reenter} non-@code{nil}; this tells Emacs to | |
1089 | assume, when resumed, that the screen page it is using still contains | |
1090 | what Emacs last wrote there. | |
6bf7aab6 DL |
1091 | |
1092 | @vindex echo-keystrokes | |
1093 | The variable @code{echo-keystrokes} controls the echoing of multi-character | |
1094 | keys; its value is the number of seconds of pause required to cause echoing | |
1095 | to start, or zero meaning don't echo at all. @xref{Echo Area}. | |
1096 | ||
1097 | @vindex ctl-arrow | |
13b9ee95 | 1098 | If the variable @code{ctl-arrow} is @code{nil}, all control characters in |
6bf7aab6 DL |
1099 | the buffer are displayed with octal escape sequences, except for newline |
1100 | and tab. Altering the value of @code{ctl-arrow} makes it local to the | |
1101 | current buffer; until that time, the default value is in effect. The | |
1102 | default is initially @code{t}. @xref{Display Tables,, Display Tables, | |
1103 | elisp, The Emacs Lisp Reference Manual}. | |
1104 | ||
1105 | @vindex tab-width | |
0015d677 | 1106 | @vindex default-tab-width |
6bf7aab6 DL |
1107 | Normally, a tab character in the buffer is displayed as whitespace which |
1108 | extends to the next display tab stop position, and display tab stops come | |
1109 | at intervals equal to eight spaces. The number of spaces per tab is | |
1110 | controlled by the variable @code{tab-width}, which is made local by | |
1111 | changing it, just like @code{ctl-arrow}. Note that how the tab character | |
1112 | in the buffer is displayed has nothing to do with the definition of | |
1113 | @key{TAB} as a command. The variable @code{tab-width} must have an | |
0015d677 RS |
1114 | integer value between 1 and 1000, inclusive. The variable |
1115 | @code{default-tab-width} controls the default value of this variable | |
1116 | for buffers where you have not set it locally. | |
1117 | ||
1118 | @cindex truncation | |
1119 | @cindex line truncation, and fringes | |
1120 | As an alternative to continuation, Emacs can display long lines by | |
1121 | @dfn{truncation}. This means that all the characters that do not fit | |
1122 | in the width of the screen or window do not appear at all. On | |
1123 | graphical terminals, a small straight arrow in the fringe indicates | |
1124 | truncation at either end of the line. On text terminals, @samp{$} | |
1125 | appears in the first column when there is text truncated to the left, | |
1126 | and in the last column when there is text truncated to the right. | |
1127 | ||
1128 | @vindex truncate-lines | |
1129 | @findex toggle-truncate-lines | |
1130 | Horizontal scrolling automatically causes line truncation | |
1131 | (@pxref{Horizontal Scrolling}). You can explicitly enable line | |
1132 | truncation for a particular buffer with the command @kbd{M-x | |
1133 | toggle-truncate-lines}. This works by locally changing the variable | |
1134 | @code{truncate-lines}. If that variable is non-@code{nil}, long lines | |
1135 | are truncated; if it is @code{nil}, they are continued onto multiple | |
1136 | screen lines. Setting the variable @code{truncate-lines} in any way | |
1137 | makes it local to the current buffer; until that time, the default | |
1138 | value is in effect. The default value is normally @code{nil}. | |
6bf7aab6 DL |
1139 | |
1140 | @c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows. | |
1141 | If the variable @code{truncate-partial-width-windows} is | |
1142 | non-@code{nil}, it forces truncation rather than continuation in any | |
1143 | window less than the full width of the screen or frame, regardless of | |
1144 | the value of @code{truncate-lines}. For information about side-by-side | |
1145 | windows, see @ref{Split Window}. See also @ref{Display,, Display, | |
1146 | elisp, The Emacs Lisp Reference Manual}. | |
1147 | ||
80174a97 KS |
1148 | @vindex overflow-newline-into-fringe |
1149 | If the variable @code{overflow-newline-into-fringe} is | |
1150 | non-@code{nil} on a window system, it specifies that lines which are | |
1151 | exactly as wide as the window (not counting the final newline | |
1152 | character) shall not be broken into two lines on the display (with | |
1153 | just the newline on the second line). Instead, the newline | |
1154 | overflows into the right fringe, and the cursor will be displayed in | |
1155 | the fringe when positioned on that newline. | |
80174a97 KS |
1156 | |
1157 | @vindex indicate-buffer-boundaries | |
1158 | On a window system, Emacs may indicate the buffer boundaries in the | |
1159 | fringes. The buffer boundaries, i.e. first and last line in the | |
1160 | buffer, can be marked with angle bitmaps in the left or right fringe. | |
1161 | This can be combined with up and down arrow bitmaps shown at the top | |
1162 | and bottom of the left or right fringe if the window can be scrolled | |
1163 | in either direction. | |
1164 | ||
62ea61af | 1165 | The buffer-local variable @code{indicate-buffer-boundaries} controls |
80174a97 KS |
1166 | how the buffer boundaries and window scrolling is indicated in the |
1167 | fringes. | |
1168 | ||
62ea61af | 1169 | If the value is @code{left} or @code{right}, both angle and arrow |
80174a97 | 1170 | bitmaps are displayed in the left or right fringe, respectively. |
62ea61af KS |
1171 | |
1172 | If value is an alist, each element @code{(@var{indicator} . | |
1173 | @var{position})} specifies the position of one of the indicators. | |
1174 | The @var{indicator} must be one of @code{top}, @code{bottom}, | |
1175 | @code{up}, @code{down}, or @code{t} which specifies the default | |
1176 | position for the indicators not present in the alist. | |
c49edde4 | 1177 | The @var{position} is one of @code{left}, @code{right}, or @code{nil} |
62ea61af KS |
1178 | which specifies not to show this indicator. |
1179 | ||
1180 | For example, @code{((top . left) (t . right))} places the top angle | |
1181 | bitmap in left fringe, the bottom angle bitmap in right fringe, and | |
1182 | both arrow bitmaps in right fringe. To show just the angle bitmaps in | |
1183 | the left fringe, but no arrow bitmaps, use @code{((top . left) | |
1184 | (bottom . left))}. | |
80174a97 KS |
1185 | |
1186 | @vindex default-indicate-buffer-boundaries | |
1187 | The value of the variable @code{default-indicate-buffer-boundaries} | |
1188 | is the default value for @code{indicate-buffer-boundaries} in buffers | |
1189 | that do not override it. | |
1190 | ||
6bf7aab6 | 1191 | @vindex baud-rate |
01460f97 | 1192 | The variable @anchor{baud-rate}@code{baud-rate} holds the output speed of the |
87c8b5fd RS |
1193 | terminal, as far as Emacs knows. Setting this variable does not |
1194 | change the speed of actual data transmission, but the value is used | |
1195 | for calculations. On terminals, it affects padding, and decisions | |
1196 | about whether to scroll part of the screen or redraw it instead. | |
c39937ea | 1197 | It also affects the behavior of incremental search. |
860dab78 | 1198 | |
e598186c RS |
1199 | On window-systems, @code{baud-rate} is only used to determine how |
1200 | frequently to look for pending input during display updating. A | |
1201 | higher value of @code{baud-rate} means that check for pending input | |
1202 | will be done less frequently. | |
6bf7aab6 DL |
1203 | |
1204 | You can customize the way any particular character code is displayed | |
1205 | by means of a display table. @xref{Display Tables,, Display Tables, | |
1206 | elisp, The Emacs Lisp Reference Manual}. | |
e598186c | 1207 | |
62095f01 GM |
1208 | @cindex hourglass pointer display |
1209 | @vindex hourglass-delay | |
099bfef9 RS |
1210 | On a window system, Emacs can optionally display the mouse pointer |
1211 | in a special shape to say that Emacs is busy. To turn this feature on | |
1212 | or off, customize the group @code{cursor}. You can also control the | |
1213 | amount of time Emacs must remain busy before the busy indicator is | |
62095f01 | 1214 | displayed, by setting the variable @code{hourglass-delay}. |
099bfef9 | 1215 | |
a66b12be RS |
1216 | @findex tty-suppress-bold-inverse-default-colors |
1217 | On some text-only terminals, bold face and inverse video together | |
1218 | result in text that is hard to read. Call the function | |
1219 | @code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil} | |
1220 | argument to suppress the effect of bold-face in this case. | |
1221 | ||
ab5796a9 MB |
1222 | @ignore |
1223 | arch-tag: 2219f910-2ff0-4521-b059-1bd231a536c4 | |
1224 | @end ignore |