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802b0ea7 | 1 | @c This is part of the Emacs manual. |
acaf905b | 2 | @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2012 |
0419b8d6 GM |
3 | @c Free Software Foundation, Inc. |
4 | ||
6bf7aab6 DL |
5 | @c See file emacs.texi for copying conditions. |
6 | @node Display, Search, Registers, Top | |
7 | @chapter Controlling the Display | |
8 | ||
41859241 CY |
9 | Since only part of a large buffer fits in the window, Emacs has to |
10 | show only a part of it. This chapter describes commands and variables | |
11 | that let you specify which part of the text you want to see, and how | |
12 | the text is displayed. | |
6bf7aab6 DL |
13 | |
14 | @menu | |
8838673e | 15 | * Scrolling:: Commands to move text up and down in a window. |
e7a3ff06 | 16 | * Recentering:: A scroll command that centers the current line. |
43d67313 | 17 | * Auto Scrolling:: Redisplay scrolls text automatically when needed. |
54952612 | 18 | * Horizontal Scrolling:: Moving text left and right in a window. |
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19 | * Narrowing:: Restricting display and editing to a portion |
20 | of the buffer. | |
a6326082 | 21 | * View Mode:: Viewing read-only buffers. |
54952612 | 22 | * Follow Mode:: Follow mode lets two windows scroll as one. |
8838673e | 23 | * Faces:: How to change the display style using faces. |
8863a584 | 24 | * Colors:: Specifying colors for faces. |
43d08eb9 | 25 | * Standard Faces:: Emacs' predefined faces. |
d366bd53 | 26 | * Text Scale:: Increasing or decreasing text size in a buffer. |
b8f3a9e3 | 27 | * Font Lock:: Minor mode for syntactic highlighting using faces. |
b8f3a9e3 | 28 | * Highlight Interactively:: Tell Emacs what text to highlight. |
fad78d58 | 29 | * Fringes:: Enabling or disabling window fringes. |
9d2908a6 | 30 | * Displaying Boundaries:: Displaying top and bottom of the buffer. |
fad78d58 | 31 | * Useless Whitespace:: Showing possibly-spurious trailing whitespace. |
6bf7aab6 DL |
32 | * Selective Display:: Hiding lines with lots of indentation. |
33 | * Optional Mode Line:: Optional mode line display features. | |
34 | * Text Display:: How text characters are normally displayed. | |
099bfef9 | 35 | * Cursor Display:: Features for displaying the cursor. |
9d2908a6 RS |
36 | * Line Truncation:: Truncating lines to fit the screen width instead |
37 | of continuing them to multiple screen lines. | |
458db4b6 | 38 | * Visual Line Mode:: Word wrap and screen line-based editing. |
0015d677 | 39 | * Display Custom:: Information on variables for customizing display. |
6bf7aab6 DL |
40 | @end menu |
41 | ||
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42 | @node Scrolling |
43 | @section Scrolling | |
550f41cd | 44 | @cindex scrolling |
dc917bd9 | 45 | |
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46 | If a window is too small to display all the text in its buffer, it |
47 | displays only a portion of it. @dfn{Scrolling} commands change which | |
48 | portion of the buffer is displayed. | |
dc917bd9 | 49 | |
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50 | Scrolling ``forward'' or ``up'' advances the portion of the buffer |
51 | displayed in the window; equivalently, it moves the buffer text | |
52 | upwards relative to the window. Scrolling ``backward'' or ``down'' | |
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53 | displays an earlier portion of the buffer, and moves the text |
54 | downwards relative to the window. | |
55 | ||
56 | In Emacs, scrolling ``up'' or ``down'' refers to the direction that | |
57 | the text moves in the window, @emph{not} the direction that the window | |
58 | moves relative to the text. This terminology was adopted by Emacs | |
59 | before the modern meaning of ``scrolling up'' and ``scrolling down'' | |
60 | became widespread. Hence, the strange result that @key{PageDown} | |
61 | scrolls ``up'' in the Emacs sense. | |
dc917bd9 | 62 | |
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63 | The portion of a buffer displayed in a window always contains point. |
64 | If you move point past the bottom or top of the window, scrolling | |
65 | occurs automatically to bring it back onscreen (@pxref{Auto | |
66 | Scrolling}). You can also scroll explicitly with these commands: | |
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67 | |
68 | @table @kbd | |
dc917bd9 | 69 | @item C-v |
b5700de6 CY |
70 | @itemx @key{next} |
71 | @itemx @key{PageDown} | |
61436e9f | 72 | Scroll forward by nearly a full window (@code{scroll-up-command}). |
dc917bd9 | 73 | @item M-v |
b5700de6 CY |
74 | @itemx @key{prior} |
75 | @itemx @key{PageUp} | |
61436e9f | 76 | Scroll backward (@code{scroll-down-command}). |
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77 | @end table |
78 | ||
79 | @kindex C-v | |
80 | @kindex M-v | |
81 | @kindex next | |
82 | @kindex prior | |
83 | @kindex PageDown | |
84 | @kindex PageUp | |
85 | @findex scroll-up-command | |
86 | @findex scroll-down-command | |
87 | @kbd{C-v} (@code{scroll-up-command}) scrolls forward by nearly the | |
88 | whole window height. The effect is to take the two lines at the | |
89 | bottom of the window and put them at the top, followed by lines that | |
90 | were not previously visible. If point was in the text that scrolled | |
91 | off the top, it ends up on the window's new topmost line. The | |
92 | @key{next} (or @key{PageDown}) key is equivalent to @kbd{C-v}. | |
93 | ||
94 | @kbd{M-v} (@code{scroll-down-command}) scrolls backward in a similar | |
95 | way. The @key{prior} (or @key{PageUp}) key is equivalent to | |
96 | @kbd{M-v}. | |
97 | ||
98 | @vindex next-screen-context-lines | |
99 | The number of lines of overlap left by these scroll commands is | |
100 | controlled by the variable @code{next-screen-context-lines}, whose | |
101 | default value is 2. You can supply the commands with a numeric prefix | |
102 | argument, @var{n}, to scroll by @var{n} lines; Emacs attempts to leave | |
103 | point unchanged, so that the text and point move up or down together. | |
104 | @kbd{C-v} with a negative argument is like @kbd{M-v} and vice versa. | |
105 | ||
106 | @vindex scroll-error-top-bottom | |
107 | By default, these commands signal an error (by beeping or flashing | |
108 | the screen) if no more scrolling is possible, because the window has | |
109 | reached the beginning or end of the buffer. If you change the | |
110 | variable @code{scroll-error-top-bottom} to @code{t}, the command moves | |
111 | point to the farthest possible position. If point is already there, | |
112 | the command signals an error. | |
113 | ||
114 | @vindex scroll-preserve-screen-position | |
115 | @cindex @code{scroll-command} property | |
116 | Some users like scroll commands to keep point at the same screen | |
117 | position, so that scrolling back to the same screen conveniently | |
118 | returns point to its original position. You can enable this behavior | |
119 | via the variable @code{scroll-preserve-screen-position}. If the value | |
120 | is @code{t}, Emacs adjusts point to keep the cursor at the same screen | |
121 | position whenever a scroll command moves it off-window, rather than | |
122 | moving it to the topmost or bottommost line. With any other | |
123 | non-@code{nil} value, Emacs adjusts point this way even if the scroll | |
124 | command leaves point in the window. This variable affects all the | |
125 | scroll commands documented in this section, as well as scrolling with | |
b63a8e8e | 126 | the mouse wheel (@pxref{Mouse Commands}); in general, it affects any |
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127 | command that has a non-@code{nil} @code{scroll-command} property. |
128 | @xref{Property Lists,,, elisp, The Emacs Lisp Reference Manual}. | |
129 | ||
130 | @vindex scroll-up | |
131 | @vindex scroll-down | |
132 | @findex scroll-up-line | |
133 | @findex scroll-down-line | |
134 | The commands @kbd{M-x scroll-up} and @kbd{M-x scroll-down} behave | |
135 | similarly to @code{scroll-up-command} and @code{scroll-down-command}, | |
136 | except they do not obey @code{scroll-error-top-bottom}. Prior to | |
137 | Emacs 24, these were the default commands for scrolling up and down. | |
138 | The commands @kbd{M-x scroll-up-line} and @kbd{M-x scroll-down-line} | |
139 | scroll the current window by one line at a time. If you intend to use | |
140 | any of these commands, you might want to give them key bindings | |
141 | (@pxref{Init Rebinding}). | |
142 | ||
143 | @node Recentering | |
144 | @section Recentering | |
145 | ||
146 | @table @kbd | |
147 | @item C-l | |
148 | Scroll the selected window so the current line is the center-most text | |
149 | line; on subsequent consecutive invocations, make the current line the | |
150 | top line, the bottom line, and so on in cyclic order. Possibly | |
151 | redisplay the screen too (@code{recenter-top-bottom}). | |
152 | ||
153 | @item M-x recenter | |
154 | Scroll the selected window so the current line is the center-most text | |
155 | line. Possibly redisplay the screen too. | |
156 | ||
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157 | @item C-M-l |
158 | Scroll heuristically to bring useful information onto the screen | |
159 | (@code{reposition-window}). | |
160 | @end table | |
161 | ||
162 | @kindex C-l | |
956c76ef | 163 | @findex recenter-top-bottom |
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164 | The @kbd{C-l} (@code{recenter-top-bottom}) command @dfn{recenters} |
165 | the selected window, scrolling it so that the current screen line is | |
166 | exactly in the center of the window, or as close to the center as | |
167 | possible. | |
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168 | |
169 | Typing @kbd{C-l} twice in a row (@kbd{C-l C-l}) scrolls the window | |
170 | so that point is on the topmost screen line. Typing a third @kbd{C-l} | |
171 | scrolls the window so that point is on the bottom-most screen line. | |
41859241 | 172 | Each successive @kbd{C-l} cycles through these three positions. |
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173 | |
174 | @vindex recenter-positions | |
175 | You can change the cycling order by customizing the list variable | |
176 | @code{recenter-positions}. Each list element should be the symbol | |
177 | @code{top}, @code{middle}, or @code{bottom}, or a number; an integer | |
41859241 | 178 | means to move the line to the specified screen line, while a |
91ed7ea8 | 179 | floating-point number between 0.0 and 1.0 specifies a percentage of |
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180 | the screen space from the top of the window. The default, |
181 | @code{(middle top bottom)}, is the cycling order described above. | |
182 | Furthermore, if you change the variable @code{scroll-margin} to a | |
183 | non-zero value @var{n}, @kbd{C-l} always leaves at least @var{n} | |
184 | screen lines between point and the top or bottom of the window | |
185 | (@pxref{Auto Scrolling}). | |
956c76ef | 186 | |
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187 | You can also give @kbd{C-l} a prefix argument. A plain prefix |
188 | argument, @kbd{C-u C-l}, simply recenters point. A positive argument | |
189 | @var{n} puts point @var{n} lines down from the top of the window. An | |
190 | argument of zero puts point on the topmost line. A negative argument | |
191 | @var{-n} puts point @var{n} lines from the bottom of the window. When | |
192 | given an argument, @kbd{C-l} does not clear the screen or cycle | |
193 | through different screen positions. | |
dc917bd9 | 194 | |
666e158e | 195 | @vindex recenter-redisplay |
91ed7ea8 | 196 | If the variable @code{recenter-redisplay} has a non-@code{nil} |
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197 | value, each invocation of @kbd{C-l} also clears and redisplays the |
198 | screen; the special value @code{tty} (the default) says to do this on | |
199 | text-terminal frames only. Redisplaying is useful in case the screen | |
200 | becomes garbled for any reason (@pxref{Screen Garbled}). | |
201 | ||
202 | @findex recenter | |
41859241 | 203 | The more primitive command @kbd{M-x recenter} behaves like |
550f41cd | 204 | @code{recenter-top-bottom}, but does not cycle among screen positions. |
666e158e | 205 | |
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206 | @kindex C-M-l |
207 | @findex reposition-window | |
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208 | @kbd{C-M-l} (@code{reposition-window}) scrolls the current window |
209 | heuristically in a way designed to get useful information onto the | |
210 | screen. For example, in a Lisp file, this command tries to get the | |
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211 | entire current defun onto the screen if possible. |
212 | ||
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213 | @node Auto Scrolling |
214 | @section Automatic Scrolling | |
215 | ||
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216 | Emacs performs @dfn{automatic scrolling} when point moves out of the |
217 | visible portion of the text. | |
218 | ||
dc917bd9 | 219 | @vindex scroll-conservatively |
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220 | Normally, this centers point vertically within the window. However, |
221 | if you set @code{scroll-conservatively} to a small number @var{n}, | |
222 | then if you move point just a little off the screen (less than @var{n} | |
223 | lines), Emacs scrolls the text just far enough to bring point back on | |
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224 | screen. By default, @code{scroll-conservatively} is@tie{}0. If you |
225 | set @code{scroll-conservatively} to a large number (larger than 100), | |
226 | Emacs will never center point as result of scrolling, even if point | |
227 | moves far away from the text previously displayed in the window. With | |
228 | such a large value, Emacs will always scroll text just enough for | |
229 | bringing point into view, so point will end up at the top or bottom of | |
230 | the window, depending on the scroll direction. | |
231 | ||
232 | @vindex scroll-step | |
233 | The variable @code{scroll-step} determines how many lines to scroll | |
234 | the window when point moves off the screen. If moving by that number | |
235 | of lines fails to bring point back into view, point is centered | |
236 | instead. The default value is zero, which causes point to always be | |
237 | centered after scrolling. | |
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238 | |
239 | @cindex aggressive scrolling | |
240 | @vindex scroll-up-aggressively | |
241 | @vindex scroll-down-aggressively | |
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242 | When the window does scroll by a distance longer than |
243 | @code{scroll-step}, you can control how aggressively it scrolls by | |
244 | setting the variables @code{scroll-up-aggressively} and | |
245 | @code{scroll-down-aggressively}. The value of | |
246 | @code{scroll-up-aggressively} should be either @code{nil}, or a | |
247 | fraction @var{f} between 0 and 1. A fraction specifies where on the | |
248 | screen to put point when scrolling upward, i.e.@: forward. When point | |
249 | goes off the window end, the new start position is chosen to put point | |
250 | @var{f} parts of the window height from the bottom margin. Thus, | |
251 | larger @var{f} means more aggressive scrolling: more new text is | |
252 | brought into view. The default value, @code{nil}, is equivalent to | |
253 | 0.5. | |
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254 | |
255 | Likewise, @code{scroll-down-aggressively} is used for scrolling | |
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256 | down, i.e.@: backward. The value specifies how far point should be |
257 | placed from the top margin of the window; thus, as with | |
3b361baf | 258 | @code{scroll-up-aggressively}, a larger value is more aggressive. |
dc917bd9 | 259 | |
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260 | These two variables are ignored if either @code{scroll-step} or |
261 | @code{scroll-conservatively} are set to a non-zero value. | |
262 | ||
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263 | Note that @code{scroll-margin}, described below, limits the amount |
264 | of scrolling so as to put point outside of the top or bottom margin, | |
265 | even if aggressive scrolling specifies a fraction @var{f} that is | |
266 | larger than the window portion between the top and the bottom margins. | |
267 | ||
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268 | @vindex scroll-margin |
269 | The variable @code{scroll-margin} restricts how close point can come | |
270 | to the top or bottom of a window. Its value is a number of screen | |
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271 | lines; if point comes within that many lines of the top or bottom of |
272 | the window, Emacs performs automatic scrolling. By default, | |
273 | @code{scroll-margin} is 0. | |
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274 | |
275 | @node Horizontal Scrolling | |
276 | @section Horizontal Scrolling | |
277 | @cindex horizontal scrolling | |
278 | ||
956c76ef | 279 | @vindex auto-hscroll-mode |
dc917bd9 | 280 | @dfn{Horizontal scrolling} means shifting all the lines sideways |
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281 | within a window, so that some of the text near the left margin is not |
282 | displayed. When the text in a window is scrolled horizontally, text | |
283 | lines are truncated rather than continued (@pxref{Line Truncation}). | |
284 | If a window shows truncated lines, Emacs performs automatic horizontal | |
285 | scrolling whenever point moves off the left or right edge of the | |
286 | screen. To disable automatic horizontal scrolling, set the variable | |
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287 | @code{auto-hscroll-mode} to @code{nil}. Note that when the automatic |
288 | horizontal scrolling is turned off, if point moves off the edge of the | |
41859241 | 289 | screen, the cursor disappears to indicate that. (On text-only |
6308321a | 290 | terminals, the cursor is left at the edge instead.) |
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291 | |
292 | @vindex hscroll-margin | |
293 | The variable @code{hscroll-margin} controls how close point can get | |
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294 | to the window's edges before automatic scrolling occurs. It is |
295 | measured in columns. For example, if the value is 5, then moving | |
296 | point within 5 columns of an edge causes horizontal scrolling away | |
297 | from that edge. | |
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298 | |
299 | @vindex hscroll-step | |
300 | The variable @code{hscroll-step} determines how many columns to | |
301 | scroll the window when point gets too close to the edge. Zero, the | |
302 | default value, means to center point horizontally within the window. | |
303 | A positive integer value specifies the number of columns to scroll by. | |
304 | A floating-point number specifies the fraction of the window's width | |
305 | to scroll by. | |
306 | ||
307 | You can also perform explicit horizontal scrolling with the | |
308 | following commands: | |
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309 | |
310 | @table @kbd | |
311 | @item C-x < | |
312 | Scroll text in current window to the left (@code{scroll-left}). | |
313 | @item C-x > | |
314 | Scroll to the right (@code{scroll-right}). | |
315 | @end table | |
316 | ||
317 | @kindex C-x < | |
318 | @kindex C-x > | |
319 | @findex scroll-left | |
320 | @findex scroll-right | |
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321 | @kbd{C-x <} (@code{scroll-left}) scrolls text in the selected window |
322 | to the left by the full width of the window, less two columns. (In | |
323 | other words, the text in the window moves left relative to the | |
324 | window.) With a numeric argument @var{n}, it scrolls by @var{n} | |
325 | columns. | |
326 | ||
327 | If the text is scrolled to the left, and point moves off the left | |
328 | edge of the window, the cursor will freeze at the left edge of the | |
329 | window, until point moves back to the displayed portion of the text. | |
330 | This is independent of the current setting of | |
331 | @code{auto-hscroll-mode}, which, for text scrolled to the left, only | |
332 | affects the behavior at the right edge of the window. | |
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333 | |
334 | @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. | |
335 | The window cannot be scrolled any farther to the right once it is | |
336 | displayed normally, with each line starting at the window's left | |
337 | margin; attempting to do so has no effect. This means that you don't | |
338 | have to calculate the argument precisely for @w{@kbd{C-x >}}; any | |
339 | sufficiently large argument will restore the normal display. | |
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340 | |
341 | If you use those commands to scroll a window horizontally, that sets | |
342 | a lower bound for automatic horizontal scrolling. Automatic scrolling | |
343 | will continue to scroll the window, but never farther to the right | |
344 | than the amount you previously set by @code{scroll-left}. | |
345 | ||
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346 | @node Narrowing |
347 | @section Narrowing | |
348 | @cindex widening | |
349 | @cindex restriction | |
350 | @cindex narrowing | |
351 | @cindex accessible portion | |
352 | ||
353 | @dfn{Narrowing} means focusing in on some portion of the buffer, | |
354 | making the rest temporarily inaccessible. The portion which you can | |
355 | still get to is called the @dfn{accessible portion}. Canceling the | |
356 | narrowing, which makes the entire buffer once again accessible, is | |
357 | called @dfn{widening}. The bounds of narrowing in effect in a buffer | |
358 | are called the buffer's @dfn{restriction}. | |
359 | ||
360 | Narrowing can make it easier to concentrate on a single subroutine or | |
361 | paragraph by eliminating clutter. It can also be used to limit the | |
362 | range of operation of a replace command or repeating keyboard macro. | |
363 | ||
364 | @table @kbd | |
365 | @item C-x n n | |
366 | Narrow down to between point and mark (@code{narrow-to-region}). | |
367 | @item C-x n w | |
368 | Widen to make the entire buffer accessible again (@code{widen}). | |
369 | @item C-x n p | |
370 | Narrow down to the current page (@code{narrow-to-page}). | |
371 | @item C-x n d | |
372 | Narrow down to the current defun (@code{narrow-to-defun}). | |
373 | @end table | |
374 | ||
375 | When you have narrowed down to a part of the buffer, that part appears | |
376 | to be all there is. You can't see the rest, you can't move into it | |
377 | (motion commands won't go outside the accessible part), you can't change | |
378 | it in any way. However, it is not gone, and if you save the file all | |
379 | the inaccessible text will be saved. The word @samp{Narrow} appears in | |
380 | the mode line whenever narrowing is in effect. | |
381 | ||
382 | @kindex C-x n n | |
383 | @findex narrow-to-region | |
384 | The primary narrowing command is @kbd{C-x n n} (@code{narrow-to-region}). | |
385 | It sets the current buffer's restrictions so that the text in the current | |
386 | region remains accessible, but all text before the region or after the | |
387 | region is inaccessible. Point and mark do not change. | |
388 | ||
389 | @kindex C-x n p | |
390 | @findex narrow-to-page | |
391 | @kindex C-x n d | |
392 | @findex narrow-to-defun | |
393 | Alternatively, use @kbd{C-x n p} (@code{narrow-to-page}) to narrow | |
394 | down to the current page. @xref{Pages}, for the definition of a page. | |
395 | @kbd{C-x n d} (@code{narrow-to-defun}) narrows down to the defun | |
396 | containing point (@pxref{Defuns}). | |
397 | ||
398 | @kindex C-x n w | |
399 | @findex widen | |
400 | The way to cancel narrowing is to widen with @kbd{C-x n w} | |
401 | (@code{widen}). This makes all text in the buffer accessible again. | |
402 | ||
403 | You can get information on what part of the buffer you are narrowed down | |
404 | to using the @kbd{C-x =} command. @xref{Position Info}. | |
405 | ||
406 | Because narrowing can easily confuse users who do not understand it, | |
407 | @code{narrow-to-region} is normally a disabled command. Attempting to use | |
408 | this command asks for confirmation and gives you the option of enabling it; | |
409 | if you enable the command, confirmation will no longer be required for | |
410 | it. @xref{Disabling}. | |
411 | ||
a6326082 CY |
412 | @node View Mode |
413 | @section View Mode | |
414 | @cindex View mode | |
415 | @cindex mode, View | |
416 | ||
41859241 CY |
417 | @kindex s @r{(View mode)} |
418 | @kindex SPC @r{(View mode)} | |
419 | @kindex DEL @r{(View mode)} | |
a6326082 CY |
420 | View mode is a minor mode that lets you scan a buffer by sequential |
421 | screenfuls. It provides commands for scrolling through the buffer | |
422 | conveniently but not for changing it. Apart from the usual Emacs | |
423 | cursor motion commands, you can type @key{SPC} to scroll forward one | |
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424 | windowful, @key{DEL} to scroll backward, and @kbd{s} to start an |
425 | incremental search. | |
a6326082 | 426 | |
41859241 CY |
427 | @kindex q @r{(View mode)} |
428 | @kindex e @r{(View mode)} | |
429 | @findex View-quit | |
430 | @findex View-exit | |
431 | Typing @kbd{q} (@code{View-quit}) disables View mode, and switches | |
432 | back to the buffer and position before View mode was enabled. Typing | |
433 | @kbd{e} (@code{View-exit}) disables View mode, keeping the current | |
434 | buffer and position. | |
a6326082 CY |
435 | |
436 | @findex view-buffer | |
437 | @findex view-file | |
438 | @kbd{M-x view-buffer} prompts for an existing Emacs buffer, switches | |
439 | to it, and enables View mode. @kbd{M-x view-file} prompts for a file | |
440 | and visits it with View mode enabled. | |
441 | ||
dc917bd9 RS |
442 | @node Follow Mode |
443 | @section Follow Mode | |
444 | @cindex Follow mode | |
445 | @cindex mode, Follow | |
446 | @findex follow-mode | |
447 | @cindex windows, synchronizing | |
448 | @cindex synchronizing windows | |
449 | ||
450 | @dfn{Follow mode} is a minor mode that makes two windows, both | |
451 | showing the same buffer, scroll as a single tall ``virtual window.'' | |
452 | To use Follow mode, go to a frame with just one window, split it into | |
453 | two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x | |
454 | follow-mode}. From then on, you can edit the buffer in either of the | |
455 | two windows, or scroll either one; the other window follows it. | |
456 | ||
457 | In Follow mode, if you move point outside the portion visible in one | |
458 | window and into the portion visible in the other window, that selects | |
459 | the other window---again, treating the two as if they were parts of | |
460 | one large window. | |
461 | ||
462 | To turn off Follow mode, type @kbd{M-x follow-mode} a second time. | |
463 | ||
b8f3a9e3 | 464 | @node Faces |
8863a584 | 465 | @section Text Faces |
b8f3a9e3 GM |
466 | @cindex faces |
467 | ||
d366bd53 | 468 | Emacs can display text in several different styles, called |
0015d677 | 469 | @dfn{faces}. Each face can specify various @dfn{face attributes}, |
d366bd53 CY |
470 | such as the font, height, weight, slant, foreground and background |
471 | color, and underlining or overlining. Most major modes assign faces | |
472 | to the text automatically, via Font Lock mode. @xref{Font Lock}, for | |
473 | more information about how these faces are assigned. | |
474 | ||
475 | @findex list-faces-display | |
476 | To see what faces are currently defined, and what they look like, | |
477 | type @kbd{M-x list-faces-display}. With a prefix argument, this | |
478 | prompts for a regular expression, and displays only faces with names | |
479 | matching that regular expression (@pxref{Regexps}). | |
480 | ||
481 | It's possible for a given face to look different in different | |
482 | frames. For instance, some text-only terminals do not support all | |
483 | face attributes, particularly font, height, and width, and some | |
8863a584 | 484 | support a limited range of colors. |
b8f3a9e3 | 485 | |
d366bd53 CY |
486 | @cindex background color |
487 | @cindex default face | |
488 | You can customize a face to alter its appearance, and save those | |
489 | changes for future Emacs sessions. @xref{Face Customization}. A face | |
490 | does not have to specify every single attribute; often it inherits | |
491 | most attributes from another face. Any ultimately unspecified | |
492 | attribute is taken from a face named @code{default}, whose attributes | |
493 | are all specified. The @code{default} face is the default for | |
494 | displaying text, and its background color is also used as the frame's | |
495 | background color. | |
496 | ||
497 | You can also use X resources to specify attributes of any particular | |
498 | face. @xref{Resources}. | |
956c76ef | 499 | |
8863a584 CY |
500 | Emacs can display variable-width fonts, but some Emacs commands, |
501 | particularly indentation commands, do not account for variable | |
502 | character display widths. Therefore, we recommend not using | |
503 | variable-width fonts for most faces, particularly those assigned by | |
504 | Font Lock mode. | |
505 | ||
506 | @node Colors | |
507 | @section Colors for Faces | |
508 | @cindex color name | |
509 | @cindex RGB triplet | |
510 | ||
511 | Faces can have various foreground and background colors. When you | |
512 | specify a color for a face---for instance, when customizing the face | |
513 | (@pxref{Face Customization})---you can use either a @dfn{color name} | |
514 | or an @dfn{RGB triplet}. | |
515 | ||
516 | @findex list-colors-display | |
517 | A color name is a pre-defined name, such as @samp{dark orange} or | |
518 | @samp{medium sea green}. To view a list of color names, type @kbd{M-x | |
519 | list-colors-display}. If you run this command on a graphical display, | |
520 | it shows the full range of color names known to Emacs (these are the | |
521 | standard X11 color names, defined in X's @file{rgb.txt} file). If you | |
522 | run the command on a text-only terminal, it shows only a small subset | |
523 | of colors that can be safely displayed on such terminals. However, | |
524 | Emacs understands X11 color names even on text-only terminals; if a | |
525 | face is given a color specified by an X11 color name, it is displayed | |
526 | using the closest-matching terminal color. | |
527 | ||
528 | An RGB triplet is a string of the form @samp{#RRGGBB}. Each of the | |
529 | R, G, and B components is a hexadecimal number specifying the | |
530 | component's relative intensity, one to four digits long (usually two | |
531 | digits are used). The components must have the same number of digits. | |
532 | For hexadecimal values A to F, either upper or lower case are | |
533 | acceptable. | |
534 | ||
535 | The @kbd{M-x list-colors-display} command also shows the equivalent | |
536 | RGB triplet for each named color. For instance, @samp{medium sea | |
537 | green} is equivalent to @samp{#3CB371}. | |
538 | ||
539 | @cindex face colors, setting | |
956c76ef CY |
540 | @findex set-face-foreground |
541 | @findex set-face-background | |
8863a584 CY |
542 | You can change the foreground and background colors of a face with |
543 | @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}. | |
544 | These commands prompt in the minibuffer for a face name and a color, | |
545 | with completion, and then set that face to use the specified color. | |
d366bd53 CY |
546 | They affect the face colors on all frames, but their effects do not |
547 | persist for future Emacs sessions, unlike using the customization | |
548 | buffer or X resources. You can also use frame parameters to set | |
8863a584 | 549 | foreground and background colors for a specific frame; @xref{Frame |
d366bd53 CY |
550 | Parameters}. |
551 | ||
43d08eb9 RS |
552 | @node Standard Faces |
553 | @section Standard Faces | |
554 | ||
54952612 RS |
555 | Here are the standard faces for specifying text appearance. You can |
556 | apply them to specific text when you want the effects they produce. | |
b8f3a9e3 GM |
557 | |
558 | @table @code | |
559 | @item default | |
54952612 | 560 | This face is used for ordinary text that doesn't specify any face. |
d366bd53 | 561 | Its background color is used as the frame's background color. |
43d08eb9 | 562 | @item bold |
956c76ef | 563 | This face uses a bold variant of the default font. |
43d08eb9 | 564 | @item italic |
956c76ef | 565 | This face uses an italic variant of the default font. |
43d08eb9 | 566 | @item bold-italic |
956c76ef | 567 | This face uses a bold italic variant of the default font. |
43d08eb9 RS |
568 | @item underline |
569 | This face underlines text. | |
570 | @item fixed-pitch | |
956c76ef CY |
571 | This face forces use of a fixed-width font. It's reasonable to |
572 | customize this face to use a different fixed-width font, if you like, | |
573 | but you should not make it a variable-width font. | |
43d08eb9 | 574 | @item variable-pitch |
956c76ef | 575 | This face forces use of a variable-width font. |
3b91a16d JL |
576 | @item shadow |
577 | This face is used for making the text less noticeable than the surrounding | |
578 | ordinary text. Usually this can be achieved by using shades of gray in | |
579 | contrast with either black or white default foreground color. | |
43d08eb9 RS |
580 | @end table |
581 | ||
582 | Here's an incomplete list of faces used to highlight parts of the | |
583 | text temporarily for specific purposes. (Many other modes define | |
584 | their own faces for this purpose.) | |
585 | ||
586 | @table @code | |
587 | @item highlight | |
d366bd53 CY |
588 | This face is used for text highlighting in various contexts, such as |
589 | when the mouse cursor is moved over a hyperlink. | |
43d08eb9 | 590 | @item isearch |
d366bd53 | 591 | This face is used to highlight the current Isearch match |
956c76ef | 592 | (@pxref{Incremental Search}). |
54952612 | 593 | @item query-replace |
d366bd53 | 594 | This face is used to highlight the current Query Replace match |
956c76ef | 595 | (@pxref{Replace}). |
43d08eb9 | 596 | @item lazy-highlight |
d366bd53 CY |
597 | This face is used to highlight ``lazy matches'' for Isearch and Query |
598 | Replace (matches other than the current one). | |
43d08eb9 | 599 | @item region |
d366bd53 CY |
600 | This face is used for displaying an active region (@pxref{Mark}). |
601 | When Emacs is built with GTK support, its colors are taken from the | |
602 | current GTK theme. | |
43d08eb9 RS |
603 | @item secondary-selection |
604 | This face is used for displaying a secondary X selection (@pxref{Secondary | |
605 | Selection}). | |
606 | @item trailing-whitespace | |
3b91a16d | 607 | The face for highlighting excess spaces and tabs at the end of a line |
d366bd53 CY |
608 | when @code{show-trailing-whitespace} is non-@code{nil} (@pxref{Useless |
609 | Whitespace}). | |
43d08eb9 | 610 | @item escape-glyph |
d366bd53 CY |
611 | The face for displaying control characters and escape sequences |
612 | (@pxref{Text Display}). | |
613 | @item nobreak-space | |
939db9ac | 614 | The face for displaying ``no-break'' space characters (@pxref{Text |
d366bd53 | 615 | Display}). |
43d08eb9 RS |
616 | @end table |
617 | ||
d366bd53 CY |
618 | The following faces control the appearance of parts of the Emacs |
619 | frame: | |
43d08eb9 RS |
620 | |
621 | @table @code | |
b8f3a9e3 | 622 | @item mode-line |
3b91a16d JL |
623 | This face is used for the mode line of the currently selected window, |
624 | and for menu bars when toolkit menus are not used. By default, it's | |
54952612 | 625 | drawn with shadows for a ``raised'' effect on graphical displays, and |
3b91a16d | 626 | drawn as the inverse of the default face on non-windowed terminals. |
b9e58bf2 EZ |
627 | @item mode-line-inactive |
628 | Like @code{mode-line}, but used for mode lines of the windows other | |
629 | than the selected one (if @code{mode-line-in-non-selected-windows} is | |
ac6875fc RS |
630 | non-@code{nil}). This face inherits from @code{mode-line}, so changes |
631 | in that face affect mode lines in all windows. | |
d545c9fd JL |
632 | @item mode-line-highlight |
633 | Like @code{highlight}, but used for portions of text on mode lines. | |
634 | @item mode-line-buffer-id | |
635 | This face is used for buffer identification parts in the mode line. | |
b8f3a9e3 | 636 | @item header-line |
54952612 RS |
637 | Similar to @code{mode-line} for a window's header line, which appears |
638 | at the top of a window just as the mode line appears at the bottom. | |
639 | Most windows do not have a header line---only some special modes, such | |
640 | Info mode, create one. | |
53abc3bf | 641 | @item vertical-border |
d366bd53 CY |
642 | This face is used for the vertical divider between windows on |
643 | text-only terminals. | |
3094ad7a | 644 | @item minibuffer-prompt |
3b91a16d JL |
645 | @cindex @code{minibuffer-prompt} face |
646 | @vindex minibuffer-prompt-properties | |
3094ad7a | 647 | This face is used for the prompt strings displayed in the minibuffer. |
3b91a16d JL |
648 | By default, Emacs automatically adds this face to the value of |
649 | @code{minibuffer-prompt-properties}, which is a list of text | |
43d67313 RS |
650 | properties used to display the prompt text. (This variable takes |
651 | effect when you enter the minibuffer.) | |
b8f3a9e3 | 652 | @item fringe |
3b91a16d | 653 | @cindex @code{fringe} face |
b8f3a9e3 GM |
654 | The face for the fringes to the left and right of windows on graphic |
655 | displays. (The fringes are the narrow portions of the Emacs frame | |
940627fe | 656 | between the text area and the window's right and left borders.) |
43d08eb9 | 657 | @xref{Fringes}. |
b8f3a9e3 | 658 | @item cursor |
939db9ac CY |
659 | The @code{:background} attribute of this face specifies the color of |
660 | the text cursor. @xref{Cursor Display}. | |
d366bd53 CY |
661 | @item tooltip |
662 | This face is used for tooltip text. By default, if Emacs is built | |
663 | with GTK support, tooltips are drawn via GTK and this face has no | |
664 | effect. @xref{Tooltips}. | |
b8f3a9e3 GM |
665 | @item mouse |
666 | This face determines the color of the mouse pointer. | |
d366bd53 CY |
667 | @end table |
668 | ||
669 | The following faces likewise control the appearance of parts of the | |
670 | Emacs frame, but only on text-only terminals, or when Emacs is built | |
671 | on X with no toolkit support. (For all other cases, the appearance of | |
672 | the respective frame elements is determined by system-wide settings.) | |
673 | ||
674 | @table @code | |
675 | @item scroll-bar | |
676 | This face determines the visual appearance of the scroll bar. | |
677 | @xref{Scroll Bars}. | |
b8f3a9e3 | 678 | @item tool-bar |
54952612 | 679 | This face determines the color of tool bar icons. @xref{Tool Bars}. |
b8f3a9e3 | 680 | @item menu |
9e6bb19f EZ |
681 | @cindex menu bar appearance |
682 | @cindex @code{menu} face, no effect if customized | |
683 | @cindex customization of @code{menu} face | |
684 | This face determines the colors and font of Emacs's menus. @xref{Menu | |
d366bd53 | 685 | Bars}. |
b8f3a9e3 GM |
686 | @end table |
687 | ||
d366bd53 CY |
688 | @node Text Scale |
689 | @section Text Scale | |
956c76ef CY |
690 | |
691 | @cindex adjust buffer face height | |
692 | @findex text-scale-adjust | |
693 | @kindex C-x C-+ | |
694 | @kindex C-x C-- | |
695 | @kindex C-x C-= | |
696 | @kindex C-x C-0 | |
697 | To increase the height of the default face in the current buffer, | |
698 | type @kbd{C-x C-+} or @kbd{C-x C-=}. To decrease it, type @kbd{C-x | |
699 | C--}. To restore the default (global) face height, type @kbd{C-x | |
700 | C-0}. These keys are all bound to the same command, | |
701 | @code{text-scale-adjust}, which looks at the last key typed to | |
702 | determine which action to take. | |
703 | ||
704 | The final key of these commands may be repeated without the leading | |
705 | @kbd{C-x}. For instance, @kbd{C-x C-= C-= C-=} increases the face | |
d366bd53 CY |
706 | height by three steps. Each step scales the text height by a factor |
707 | of 1.2; to change this factor, customize the variable | |
708 | @code{text-scale-mode-step}. As an exception, a numeric argument of 0 | |
709 | to the @code{text-scale-adjust} command restores the default height, | |
710 | similar to typing @kbd{C-x C-0}. | |
956c76ef CY |
711 | |
712 | @cindex increase buffer face height | |
713 | @findex text-scale-increase | |
714 | @cindex decrease buffer face height | |
715 | @findex text-scale-decrease | |
716 | The commands @code{text-scale-increase} and | |
717 | @code{text-scale-decrease} increase or decrease the height of the | |
718 | default face, just like @kbd{C-x C-+} and @kbd{C-x C--} respectively. | |
719 | You may find it convenient to bind to these commands, rather than | |
720 | @code{text-scale-adjust}. | |
721 | ||
05fbc4a9 MB |
722 | @cindex set buffer face height |
723 | @findex text-scale-set | |
d366bd53 CY |
724 | The command @code{text-scale-set} scales the height of the default |
725 | face in the current buffer to an absolute level specified by its | |
726 | prefix argument. | |
05fbc4a9 | 727 | |
956c76ef | 728 | @findex text-scale-mode |
d366bd53 CY |
729 | The above commands automatically enable the minor mode |
730 | @code{text-scale-mode} if the current font scaling is other than 1, | |
731 | and disable it otherwise. | |
956c76ef | 732 | |
b8f3a9e3 GM |
733 | @node Font Lock |
734 | @section Font Lock mode | |
735 | @cindex Font Lock mode | |
736 | @cindex mode, Font Lock | |
737 | @cindex syntax highlighting and coloring | |
738 | ||
8cc11660 | 739 | Font Lock mode is a minor mode, always local to a particular buffer, |
d366bd53 CY |
740 | which assigns faces to (or @dfn{fontifies}) the text in the buffer. |
741 | Each buffer's major mode tells Font Lock mode which text to fontify; | |
742 | for instance, programming language modes fontify syntactically | |
743 | relevant constructs like comments, strings, and function names. | |
b8f3a9e3 GM |
744 | |
745 | @findex font-lock-mode | |
d366bd53 CY |
746 | Font Lock mode is enabled by default. To toggle it in the current |
747 | buffer, type @kbd{M-x font-lock-mode}. A positive numeric argument | |
748 | unconditionally enables Font Lock mode, and a negative or zero | |
749 | argument disables it. | |
b8f3a9e3 GM |
750 | |
751 | @findex global-font-lock-mode | |
752 | @vindex global-font-lock-mode | |
d366bd53 CY |
753 | To toggle Font Lock mode in all buffers, type @kbd{M-x |
754 | global-font-lock-mode}. To impose this setting for future Emacs | |
755 | sessions, customize the variable @code{global-font-lock-mode} | |
756 | (@pxref{Easy Customization}), or add the following line to your init | |
757 | file: | |
b8f3a9e3 GM |
758 | |
759 | @example | |
c4e8acbc | 760 | (global-font-lock-mode 0) |
b8f3a9e3 GM |
761 | @end example |
762 | ||
d366bd53 CY |
763 | @noindent |
764 | If you have disabled Global Font Lock mode, you can still enable Font | |
54952612 | 765 | Lock for specific major modes by adding the function |
6e317956 CY |
766 | @code{font-lock-mode} to the mode hooks (@pxref{Hooks}). For example, |
767 | to enable Font Lock mode for editing C files, you can do this: | |
c4e8acbc CY |
768 | |
769 | @example | |
6e317956 | 770 | (add-hook 'c-mode-hook 'font-lock-mode) |
c4e8acbc | 771 | @end example |
0015d677 | 772 | |
b8f3a9e3 GM |
773 | Font Lock mode uses several specifically named faces to do its job, |
774 | including @code{font-lock-string-face}, @code{font-lock-comment-face}, | |
54952612 RS |
775 | and others. The easiest way to find them all is to use @kbd{M-x |
776 | customize-group @key{RET} font-lock-faces @key{RET}}. You can then | |
777 | use that customization buffer to customize the appearance of these | |
778 | faces. @xref{Face Customization}. | |
b8f3a9e3 | 779 | |
b8f3a9e3 | 780 | @vindex font-lock-maximum-decoration |
d366bd53 CY |
781 | You can customize the variable @code{font-lock-maximum-decoration} |
782 | to alter the amount of fontification applied by Font Lock mode, for | |
783 | major modes that support this feature. The value should be a number | |
784 | (with 1 representing a minimal amount of fontification; some modes | |
785 | support levels as high as 3); or @code{t}, meaning ``as high as | |
786 | possible'' (the default). You can also specify different numbers for | |
787 | particular major modes; for example, to use level 1 for C/C++ modes, | |
788 | and the default level otherwise, use the value | |
b8f3a9e3 GM |
789 | |
790 | @example | |
d366bd53 | 791 | '((c-mode . 1) (c++-mode . 1))) |
b8f3a9e3 GM |
792 | @end example |
793 | ||
b8f3a9e3 | 794 | @vindex font-lock-beginning-of-syntax-function |
e07e854d EZ |
795 | @cindex incorrect fontification |
796 | @cindex parenthesis in column zero and fontification | |
797 | @cindex brace in column zero and fontification | |
b8f3a9e3 GM |
798 | Comment and string fontification (or ``syntactic'' fontification) |
799 | relies on analysis of the syntactic structure of the buffer text. For | |
174862cf RS |
800 | the sake of speed, some modes, including Lisp mode, rely on a special |
801 | convention: an open-parenthesis or open-brace in the leftmost column | |
d366bd53 | 802 | always defines the beginning of a defun, and is thus always outside |
20db1522 | 803 | any string or comment. Therefore, you should avoid placing an |
d366bd53 CY |
804 | open-parenthesis or open-brace in the leftmost column, if it is inside |
805 | a string or comment. @xref{Left Margin Paren}, for details. | |
b8f3a9e3 | 806 | |
6bb2ed9b | 807 | @cindex slow display during scrolling |
ae742cb5 CY |
808 | The variable @code{font-lock-beginning-of-syntax-function}, which is |
809 | always buffer-local, specifies how Font Lock mode can find a position | |
810 | guaranteed to be outside any comment or string. In modes which use | |
811 | the leftmost column parenthesis convention, the default value of the | |
812 | variable is @code{beginning-of-defun}---that tells Font Lock mode to | |
813 | use the convention. If you set this variable to @code{nil}, Font Lock | |
814 | no longer relies on the convention. This avoids incorrect results, | |
815 | but the price is that, in some cases, fontification for a changed text | |
816 | must rescan buffer text from the beginning of the buffer. This can | |
817 | considerably slow down redisplay while scrolling, particularly if you | |
818 | are close to the end of a large buffer. | |
b8f3a9e3 GM |
819 | |
820 | @findex font-lock-add-keywords | |
d366bd53 CY |
821 | Font Lock highlighting patterns already exist for most modes, but |
822 | you may want to fontify additional patterns. You can use the function | |
823 | @code{font-lock-add-keywords}, to add your own highlighting patterns | |
824 | for a particular mode. For example, to highlight @samp{FIXME:} words | |
825 | in C comments, use this: | |
b8f3a9e3 GM |
826 | |
827 | @example | |
a152877d SM |
828 | (add-hook 'c-mode-hook |
829 | (lambda () | |
830 | (font-lock-add-keywords nil | |
ae742cb5 CY |
831 | '(("\\<\\(FIXME\\):" 1 |
832 | font-lock-warning-face t))))) | |
b8f3a9e3 GM |
833 | @end example |
834 | ||
4063fff3 | 835 | @findex font-lock-remove-keywords |
d366bd53 CY |
836 | @noindent |
837 | To remove keywords from the font-lock highlighting patterns, use the | |
cd77ce13 | 838 | function @code{font-lock-remove-keywords}. @xref{Search-based |
956c76ef | 839 | Fontification,,, elisp, The Emacs Lisp Reference Manual}. |
4063fff3 | 840 | |
3be9b0ca EZ |
841 | @cindex just-in-time (JIT) font-lock |
842 | @cindex background syntax highlighting | |
843 | Fontifying large buffers can take a long time. To avoid large | |
d366bd53 CY |
844 | delays when a file is visited, Emacs initially fontifies only the |
845 | visible portion of a buffer. As you scroll through the buffer, each | |
846 | portion that becomes visible is fontified as soon as it is displayed; | |
847 | this type of Font Lock is called @dfn{Just-In-Time} (or @dfn{JIT}) | |
848 | Lock. You can control how JIT Lock behaves, including telling it to | |
849 | perform fontification while idle, by customizing variables in the | |
956c76ef | 850 | customization group @samp{jit-lock}. @xref{Specific Customization}. |
3be9b0ca | 851 | |
b8f3a9e3 | 852 | @node Highlight Interactively |
54952612 | 853 | @section Interactive Highlighting |
b8f3a9e3 GM |
854 | @cindex highlighting by matching |
855 | @cindex interactive highlighting | |
54952612 | 856 | @cindex Highlight Changes mode |
b8f3a9e3 | 857 | |
54952612 | 858 | @findex highlight-changes-mode |
956c76ef | 859 | Highlight Changes mode is a minor mode that @dfn{highlights} the parts |
d366bd53 | 860 | of the buffer that were changed most recently, by giving that text a |
956c76ef CY |
861 | different face. To enable or disable Highlight Changes mode, use |
862 | @kbd{M-x highlight-changes-mode}. | |
b8f3a9e3 | 863 | |
54952612 | 864 | @cindex Hi Lock mode |
b8f3a9e3 | 865 | @findex hi-lock-mode |
956c76ef CY |
866 | Hi Lock mode is a minor mode that highlights text that matches |
867 | regular expressions you specify. For example, you can use it to | |
868 | highlight all the references to a certain variable in a program source | |
869 | file, highlight certain parts in a voluminous output of some program, | |
870 | or highlight certain names in an article. To enable or disable Hi | |
871 | Lock mode, use the command @kbd{M-x hi-lock-mode}. To enable Hi Lock | |
872 | mode for all buffers, use @kbd{M-x global-hi-lock-mode} or place | |
873 | @code{(global-hi-lock-mode 1)} in your @file{.emacs} file. | |
54952612 RS |
874 | |
875 | Hi Lock mode works like Font Lock mode (@pxref{Font Lock}), except | |
876 | that you specify explicitly the regular expressions to highlight. You | |
877 | control them with these commands: | |
b8f3a9e3 GM |
878 | |
879 | @table @kbd | |
880 | @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET} | |
881 | @kindex C-x w h | |
882 | @findex highlight-regexp | |
cedf175b | 883 | Highlight text that matches @var{regexp} using face @var{face} |
54952612 RS |
884 | (@code{highlight-regexp}). The highlighting will remain as long as |
885 | the buffer is loaded. For example, to highlight all occurrences of | |
886 | the word ``whim'' using the default face (a yellow background) | |
887 | @kbd{C-x w h whim @key{RET} @key{RET}}. Any face can be used for | |
888 | highlighting, Hi Lock provides several of its own and these are | |
29a483ac JL |
889 | pre-loaded into a list of default values. While being prompted |
890 | for a face use @kbd{M-n} and @kbd{M-p} to cycle through them. | |
54952612 RS |
891 | |
892 | You can use this command multiple times, specifying various regular | |
893 | expressions to highlight in different ways. | |
b8f3a9e3 GM |
894 | |
895 | @item C-x w r @var{regexp} @key{RET} | |
896 | @kindex C-x w r | |
897 | @findex unhighlight-regexp | |
630acdcc | 898 | Unhighlight @var{regexp} (@code{unhighlight-regexp}). |
54952612 RS |
899 | |
900 | If you invoke this from the menu, you select the expression to | |
901 | unhighlight from a list. If you invoke this from the keyboard, you | |
902 | use the minibuffer. It will show the most recently added regular | |
903 | expression; use @kbd{M-p} to show the next older expression and | |
904 | @kbd{M-n} to select the next newer expression. (You can also type the | |
905 | expression by hand, with completion.) When the expression you want to | |
906 | unhighlight appears in the minibuffer, press @kbd{@key{RET}} to exit | |
907 | the minibuffer and unhighlight it. | |
b8f3a9e3 GM |
908 | |
909 | @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET} | |
910 | @kindex C-x w l | |
911 | @findex highlight-lines-matching-regexp | |
912 | @cindex lines, highlighting | |
913 | @cindex highlighting lines of text | |
04d0b662 | 914 | Highlight entire lines containing a match for @var{regexp}, using face |
b8f3a9e3 GM |
915 | @var{face} (@code{highlight-lines-matching-regexp}). |
916 | ||
917 | @item C-x w b | |
918 | @kindex C-x w b | |
919 | @findex hi-lock-write-interactive-patterns | |
920 | Insert all the current highlighting regexp/face pairs into the buffer | |
921 | at point, with comment delimiters to prevent them from changing your | |
54952612 RS |
922 | program. (This key binding runs the |
923 | @code{hi-lock-write-interactive-patterns} command.) | |
b8f3a9e3 | 924 | |
3173ce7e RS |
925 | These patterns are extracted from the comments, if appropriate, if you |
926 | invoke @kbd{M-x hi-lock-find-patterns}, or if you visit the file while | |
927 | Hi Lock mode is enabled (since that runs @code{hi-lock-find-patterns}). | |
b8f3a9e3 GM |
928 | |
929 | @item C-x w i | |
930 | @kindex C-x w i | |
931 | @findex hi-lock-find-patterns | |
3173ce7e RS |
932 | Extract regexp/face pairs from comments in the current buffer |
933 | (@code{hi-lock-find-patterns}). Thus, you can enter patterns | |
934 | interactively with @code{highlight-regexp}, store them into the file | |
935 | with @code{hi-lock-write-interactive-patterns}, edit them (perhaps | |
cedf175b | 936 | including different faces for different parenthesized parts of the |
3173ce7e RS |
937 | match), and finally use this command (@code{hi-lock-find-patterns}) to |
938 | have Hi Lock highlight the edited patterns. | |
b8f3a9e3 | 939 | |
3173ce7e | 940 | @vindex hi-lock-file-patterns-policy |
d439bcd8 | 941 | The variable @code{hi-lock-file-patterns-policy} controls whether Hi |
0419b8d6 GM |
942 | Lock mode should automatically extract and highlight patterns found in a |
943 | file when it is visited. Its value can be @code{nil} (never highlight), | |
944 | @code{ask} (query the user), or a function. If it is a function, | |
945 | @code{hi-lock-find-patterns} calls it with the patterns as argument; if | |
946 | the function returns non-@code{nil}, the patterns are used. The default | |
947 | is @code{ask}. Note that patterns are always highlighted if you call | |
948 | @code{hi-lock-find-patterns} directly, regardless of the value of this | |
949 | variable. | |
3173ce7e RS |
950 | |
951 | @vindex hi-lock-exclude-modes | |
952 | Also, @code{hi-lock-find-patterns} does nothing if the current major | |
953 | mode's symbol is a member of the list @code{hi-lock-exclude-modes}. | |
b8f3a9e3 GM |
954 | @end table |
955 | ||
fad78d58 RS |
956 | @node Fringes |
957 | @section Window Fringes | |
958 | @cindex fringes | |
959 | ||
939db9ac CY |
960 | @findex set-fringe-style |
961 | @findex fringe-mode | |
962 | On graphical displays, each Emacs window normally has narrow | |
956c76ef CY |
963 | @dfn{fringes} on the left and right edges. The fringes are used to |
964 | display symbols that provide information about the text in the window. | |
939db9ac CY |
965 | You can type @kbd{M-x fringe-mode} to disable the fringes, or modify |
966 | their width. This command affects fringes in all frames; to modify | |
967 | fringes on the selected frame only, use @kbd{M-x set-fringe-style}. | |
fad78d58 RS |
968 | |
969 | The most common use of the fringes is to indicate a continuation | |
d366bd53 CY |
970 | line (@pxref{Continuation Lines}). When one line of text is split |
971 | into multiple screen lines, the left fringe shows a curving arrow for | |
972 | each screen line except the first, indicating that ``this is not the | |
973 | real beginning.'' The right fringe shows a curving arrow for each | |
974 | screen line except the last, indicating that ``this is not the real | |
975 | end.'' If the line's direction is right-to-left (@pxref{Bidirectional | |
976 | Editing}), the meanings of the curving arrows in the fringes are | |
34313041 | 977 | swapped. |
fad78d58 | 978 | |
566da2e7 | 979 | The fringes indicate line truncation with short horizontal arrows |
fad78d58 | 980 | meaning ``there's more text on this line which is scrolled |
d366bd53 CY |
981 | horizontally out of view.'' Clicking the mouse on one of the arrows |
982 | scrolls the display horizontally in the direction of the arrow. | |
983 | ||
984 | The fringes can also indicate other things, such as buffer | |
985 | boundaries (@pxref{Displaying Boundaries}), and where a program you | |
986 | are debugging is executing (@pxref{Debuggers}). | |
fad78d58 | 987 | |
939db9ac CY |
988 | @vindex overflow-newline-into-fringe |
989 | The fringe is also used for drawing the cursor, if the current line | |
990 | is exactly as wide as the window and point is at the end of the line. | |
991 | To disable this, change the variable | |
992 | @code{overflow-newline-into-fringe} to @code{nil}; this causes Emacs | |
993 | to continue or truncate lines that are exactly as wide as the window. | |
fad78d58 | 994 | |
9d2908a6 RS |
995 | @node Displaying Boundaries |
996 | @section Displaying Boundaries | |
997 | ||
998 | @vindex indicate-buffer-boundaries | |
939db9ac | 999 | On graphical displays, Emacs can indicate the buffer boundaries in |
d366bd53 CY |
1000 | the fringes. If you enable this feature, the first line and the last |
1001 | line are marked with angle images in the fringes. This can be | |
1002 | combined with up and down arrow images which say whether it is | |
1003 | possible to scroll the window. | |
9d2908a6 RS |
1004 | |
1005 | The buffer-local variable @code{indicate-buffer-boundaries} controls | |
1006 | how the buffer boundaries and window scrolling is indicated in the | |
1007 | fringes. If the value is @code{left} or @code{right}, both angle and | |
1008 | arrow bitmaps are displayed in the left or right fringe, respectively. | |
1009 | ||
1010 | If value is an alist, each element @code{(@var{indicator} . | |
1011 | @var{position})} specifies the position of one of the indicators. | |
1012 | The @var{indicator} must be one of @code{top}, @code{bottom}, | |
1013 | @code{up}, @code{down}, or @code{t} which specifies the default | |
1014 | position for the indicators not present in the alist. | |
1015 | The @var{position} is one of @code{left}, @code{right}, or @code{nil} | |
1016 | which specifies not to show this indicator. | |
1017 | ||
1018 | For example, @code{((top . left) (t . right))} places the top angle | |
1019 | bitmap in left fringe, the bottom angle bitmap in right fringe, and | |
1020 | both arrow bitmaps in right fringe. To show just the angle bitmaps in | |
1021 | the left fringe, but no arrow bitmaps, use @code{((top . left) | |
1022 | (bottom . left))}. | |
1023 | ||
fad78d58 RS |
1024 | @node Useless Whitespace |
1025 | @section Useless Whitespace | |
1026 | ||
1027 | @cindex trailing whitespace | |
1028 | @cindex whitespace, trailing | |
1029 | @vindex show-trailing-whitespace | |
1030 | It is easy to leave unnecessary spaces at the end of a line, or | |
1031 | empty lines at the end of a file, without realizing it. In most | |
1032 | cases, this @dfn{trailing whitespace} has no effect, but there are | |
956c76ef | 1033 | special circumstances where it matters, and it can be a nuisance. |
fad78d58 | 1034 | |
956c76ef CY |
1035 | You can make trailing whitespace at the end of a line visible by |
1036 | setting the buffer-local variable @code{show-trailing-whitespace} to | |
1037 | @code{t}. Then Emacs displays trailing whitespace, using the face | |
1038 | @code{trailing-whitespace}. | |
fad78d58 RS |
1039 | |
1040 | This feature does not apply when point is at the end of the line | |
1041 | containing the whitespace. Strictly speaking, that is ``trailing | |
1042 | whitespace'' nonetheless, but displaying it specially in that case | |
1043 | looks ugly while you are typing in new text. In this special case, | |
1044 | the location of point is enough to show you that the spaces are | |
1045 | present. | |
1046 | ||
1047 | @findex delete-trailing-whitespace | |
d366bd53 CY |
1048 | Type @kbd{M-x delete-trailing-whitespace} to delete all trailing |
1049 | whitespace within the buffer. If the region is active, it deletes all | |
1050 | trailing whitespace in the region instead. | |
fad78d58 | 1051 | |
23e3383d | 1052 | @vindex indicate-empty-lines |
877db12e RS |
1053 | @cindex unused lines |
1054 | @cindex fringes, and unused line indication | |
d366bd53 CY |
1055 | On graphical displays, Emacs can indicate unused lines at the end of |
1056 | the window with a small image in the left fringe (@pxref{Fringes}). | |
8863a584 CY |
1057 | The image appears for screen lines that do not correspond to any |
1058 | buffer text, so blank lines at the end of the buffer stand out because | |
1059 | they lack this image. To enable this feature, set the buffer-local | |
1060 | variable @code{indicate-empty-lines} to a non-@code{nil} value. You | |
1061 | can enable or disable this feature for all new buffers by setting the | |
1062 | default value of this variable, e.g.@: @code{(setq-default | |
1063 | indicate-empty-lines t)}. | |
fad78d58 | 1064 | |
6bf7aab6 DL |
1065 | @node Selective Display |
1066 | @section Selective Display | |
4946337d | 1067 | @cindex selective display |
6bf7aab6 DL |
1068 | @findex set-selective-display |
1069 | @kindex C-x $ | |
1070 | ||
956c76ef CY |
1071 | Emacs has the ability to hide lines indented more than a given |
1072 | number of columns. You can use this to get an overview of a part of a | |
1073 | program. | |
6bf7aab6 | 1074 | |
d239287a LT |
1075 | To hide lines in the current buffer, type @kbd{C-x $} |
1076 | (@code{set-selective-display}) with a numeric argument @var{n}. Then | |
1077 | lines with at least @var{n} columns of indentation disappear from the | |
1078 | screen. The only indication of their presence is that three dots | |
1079 | (@samp{@dots{}}) appear at the end of each visible line that is | |
1080 | followed by one or more hidden ones. | |
6bf7aab6 DL |
1081 | |
1082 | The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as | |
1083 | if they were not there. | |
1084 | ||
1085 | The hidden lines are still present in the buffer, and most editing | |
1086 | commands see them as usual, so you may find point in the middle of the | |
1087 | hidden text. When this happens, the cursor appears at the end of the | |
1088 | previous line, after the three dots. If point is at the end of the | |
1089 | visible line, before the newline that ends it, the cursor appears before | |
1090 | the three dots. | |
1091 | ||
1092 | To make all lines visible again, type @kbd{C-x $} with no argument. | |
1093 | ||
1094 | @vindex selective-display-ellipses | |
1095 | If you set the variable @code{selective-display-ellipses} to | |
1096 | @code{nil}, the three dots do not appear at the end of a line that | |
1097 | precedes hidden lines. Then there is no visible indication of the | |
1098 | hidden lines. This variable becomes local automatically when set. | |
1099 | ||
0015d677 RS |
1100 | See also @ref{Outline Mode} for another way to hide part of |
1101 | the text in a buffer. | |
1102 | ||
6bf7aab6 DL |
1103 | @node Optional Mode Line |
1104 | @section Optional Mode Line Features | |
1105 | ||
b213b767 LK |
1106 | @cindex buffer size display |
1107 | @cindex display of buffer size | |
1108 | @findex size-indication-mode | |
1109 | The buffer percentage @var{pos} indicates the percentage of the | |
1110 | buffer above the top of the window. You can additionally display the | |
1111 | size of the buffer by typing @kbd{M-x size-indication-mode} to turn on | |
1112 | Size Indication mode. The size will be displayed immediately | |
1113 | following the buffer percentage like this: | |
1114 | ||
1115 | @example | |
1116 | @var{POS} of @var{SIZE} | |
1117 | @end example | |
1118 | ||
1119 | @noindent | |
1120 | Here @var{SIZE} is the human readable representation of the number of | |
1121 | characters in the buffer, which means that @samp{k} for 10^3, @samp{M} | |
1122 | for 10^6, @samp{G} for 10^9, etc., are used to abbreviate. | |
1123 | ||
e598186c RS |
1124 | @cindex line number display |
1125 | @cindex display of line number | |
6bf7aab6 DL |
1126 | @findex line-number-mode |
1127 | The current line number of point appears in the mode line when Line | |
1128 | Number mode is enabled. Use the command @kbd{M-x line-number-mode} to | |
1129 | turn this mode on and off; normally it is on. The line number appears | |
b213b767 | 1130 | after the buffer percentage @var{pos}, with the letter @samp{L} to |
79199dd2 AM |
1131 | indicate what it is. |
1132 | ||
1133 | @cindex Column Number mode | |
1134 | @cindex mode, Column Number | |
1135 | @findex column-number-mode | |
1136 | Similarly, you can display the current column number by turning on | |
1137 | Column number mode with @kbd{M-x column-number-mode}. The column | |
1138 | number is indicated by the letter @samp{C}. However, when both of | |
1139 | these modes are enabled, the line and column numbers are displayed in | |
1140 | parentheses, the line number first, rather than with @samp{L} and | |
1141 | @samp{C}. For example: @samp{(561,2)}. @xref{Minor Modes}, for more | |
1142 | information about minor modes and about how to use these commands. | |
6bf7aab6 | 1143 | |
43f971ab EZ |
1144 | @cindex narrowing, and line number display |
1145 | If you have narrowed the buffer (@pxref{Narrowing}), the displayed | |
1146 | line number is relative to the accessible portion of the buffer. | |
54952612 RS |
1147 | Thus, it isn't suitable as an argument to @code{goto-line}. (Use |
1148 | @code{what-line} command to see the line number relative to the whole | |
1149 | file.) | |
43f971ab | 1150 | |
6bf7aab6 DL |
1151 | @vindex line-number-display-limit |
1152 | If the buffer is very large (larger than the value of | |
956c76ef CY |
1153 | @code{line-number-display-limit}), Emacs won't compute the line |
1154 | number, because that would be too slow; therefore, the line number | |
1155 | won't appear on the mode-line. To remove this limit, set | |
1156 | @code{line-number-display-limit} to @code{nil}. | |
43f971ab EZ |
1157 | |
1158 | @vindex line-number-display-limit-width | |
1159 | Line-number computation can also be slow if the lines in the buffer | |
956c76ef CY |
1160 | are too long. For this reason, Emacs doesn't display line numbers if |
1161 | the average width, in characters, of lines near point is larger than | |
1162 | the value of @code{line-number-display-limit-width}. The default | |
1163 | value is 200 characters. | |
6bf7aab6 | 1164 | |
6bf7aab6 DL |
1165 | @findex display-time |
1166 | @cindex time (on mode line) | |
1167 | Emacs can optionally display the time and system load in all mode | |
4f00b8c1 DL |
1168 | lines. To enable this feature, type @kbd{M-x display-time} or customize |
1169 | the option @code{display-time-mode}. The information added to the mode | |
bb3865e8 | 1170 | line looks like this: |
6bf7aab6 DL |
1171 | |
1172 | @example | |
1173 | @var{hh}:@var{mm}pm @var{l.ll} | |
1174 | @end example | |
1175 | ||
1176 | @noindent | |
1177 | @vindex display-time-24hr-format | |
1178 | Here @var{hh} and @var{mm} are the hour and minute, followed always by | |
4f1948eb EZ |
1179 | @samp{am} or @samp{pm}. @var{l.ll} is the average number, collected |
1180 | for the last few minutes, of processes in the whole system that were | |
1181 | either running or ready to run (i.e.@: were waiting for an available | |
1182 | processor). (Some fields may be missing if your operating system | |
1183 | cannot support them.) If you prefer time display in 24-hour format, | |
1184 | set the variable @code{display-time-24hr-format} to @code{t}. | |
6bf7aab6 DL |
1185 | |
1186 | @cindex mail (on mode line) | |
72bd7b7b DL |
1187 | @vindex display-time-use-mail-icon |
1188 | @vindex display-time-mail-face | |
fad78d58 RS |
1189 | @vindex display-time-mail-file |
1190 | @vindex display-time-mail-directory | |
6bf7aab6 | 1191 | The word @samp{Mail} appears after the load level if there is mail |
939db9ac CY |
1192 | for you that you have not read yet. On graphical displays, you can |
1193 | use an icon instead of @samp{Mail} by customizing | |
1194 | @code{display-time-use-mail-icon}; this may save some space on the | |
1195 | mode line. You can customize @code{display-time-mail-face} to make | |
1196 | the mail indicator prominent. Use @code{display-time-mail-file} to | |
1197 | specify the mail file to check, or set | |
1198 | @code{display-time-mail-directory} to specify the directory to check | |
1199 | for incoming mail (any nonempty regular file in the directory is | |
1200 | considered as ``newly arrived mail''). | |
6bf7aab6 | 1201 | |
956c76ef CY |
1202 | @cindex mail (on mode line) |
1203 | @findex display-battery-mode | |
1204 | @vindex display-battery-mode | |
1205 | @vindex battery-mode-line-format | |
1206 | When running Emacs on a laptop computer, you can display the battery | |
1207 | charge on the mode-line, by using the command | |
1208 | @code{display-battery-mode} or customizing the variable | |
1209 | @code{display-battery-mode}. The variable | |
1210 | @code{battery-mode-line-format} determines the way the battery charge | |
1211 | is displayed; the exact mode-line message depends on the operating | |
1212 | system, and it usually shows the current battery charge as a | |
1213 | percentage of the total charge. | |
1214 | ||
47d7776c | 1215 | @cindex mode line, 3D appearance |
bd3ead08 EZ |
1216 | @cindex attributes of mode line, changing |
1217 | @cindex non-integral number of lines in a window | |
939db9ac | 1218 | On graphical displays, the mode line is drawn as a 3D box. If you |
d366bd53 CY |
1219 | don't like this effect, you can disable it by customizing the |
1220 | @code{mode-line} face and setting its @code{box} attribute to | |
1221 | @code{nil}. @xref{Face Customization}. | |
bd3ead08 | 1222 | |
b9e58bf2 | 1223 | @cindex non-selected windows, mode line appearance |
ac6875fc | 1224 | By default, the mode line of nonselected windows is displayed in a |
1c9f5f23 | 1225 | different face, called @code{mode-line-inactive}. Only the selected |
ac6875fc RS |
1226 | window is displayed in the @code{mode-line} face. This helps show |
1227 | which window is selected. When the minibuffer is selected, since | |
1228 | it has no mode line, the window from which you activated the minibuffer | |
1229 | has its mode line displayed using @code{mode-line}; as a result, | |
1230 | ordinary entry to the minibuffer does not change any mode lines. | |
1231 | ||
1232 | @vindex mode-line-in-non-selected-windows | |
1233 | You can disable use of @code{mode-line-inactive} by setting variable | |
1c9f5f23 KS |
1234 | @code{mode-line-in-non-selected-windows} to @code{nil}; then all mode |
1235 | lines are displayed in the @code{mode-line} face. | |
b9e58bf2 | 1236 | |
589a3f9f RS |
1237 | @vindex eol-mnemonic-unix |
1238 | @vindex eol-mnemonic-dos | |
1239 | @vindex eol-mnemonic-mac | |
1240 | @vindex eol-mnemonic-undecided | |
1241 | You can customize the mode line display for each of the end-of-line | |
1242 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
1243 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
54952612 | 1244 | @code{eol-mnemonic-undecided} to the strings you prefer. |
589a3f9f | 1245 | |
6bf7aab6 DL |
1246 | @node Text Display |
1247 | @section How Text Is Displayed | |
1248 | @cindex characters (in text) | |
d366bd53 | 1249 | @cindex printing character |
6bf7aab6 | 1250 | |
d366bd53 CY |
1251 | Most characters are @dfn{printing characters}: when they appear in a |
1252 | buffer, they are displayed literally on the screen. Printing | |
1253 | characters include @acronym{ASCII} numbers, letters, and punctuation | |
1254 | characters, as well as many non-@acronym{ASCII} characters. | |
6bf7aab6 | 1255 | |
956c76ef | 1256 | @vindex tab-width |
a3dcc84e | 1257 | @cindex control characters on display |
d366bd53 CY |
1258 | The @acronym{ASCII} character set contains non-printing @dfn{control |
1259 | characters}. Two of these are displayed specially: the newline | |
1260 | character (Unicode code point @code{U+000A}) is displayed by starting | |
1261 | a new line, while the tab character (@code{U+0009}) is displayed as a | |
1262 | space that extends to the next tab stop column (normally every 8 | |
1263 | columns). The number of spaces per tab is controlled by the | |
1264 | buffer-local variable @code{tab-width}, which must have an integer | |
1265 | value between 1 and 1000, inclusive. Note that how the tab character | |
1266 | in the buffer is displayed has nothing to do with the definition of | |
1267 | @key{TAB} as a command. | |
1268 | ||
a3dcc84e EZ |
1269 | Other @acronym{ASCII} control characters, whose codes are below |
1270 | @code{U+0020} (octal 40, decimal 32), are displayed as a caret | |
d366bd53 CY |
1271 | (@samp{^}) followed by the non-control version of the character, with |
1272 | the @code{escape-glyph} face. For instance, the @samp{control-A} | |
1273 | character, @code{U+0001}, is displayed as @samp{^A}. | |
54952612 | 1274 | |
a3dcc84e | 1275 | @cindex octal escapes |
54952612 | 1276 | @vindex ctl-arrow |
a3dcc84e EZ |
1277 | The raw bytes with codes @code{U+0080} (octal 200) through |
1278 | @code{U+009F} (octal 237) are displayed as @dfn{octal escape | |
1279 | sequences}, with the @code{escape-glyph} face. For instance, | |
d366bd53 CY |
1280 | character code @code{U+0098} (octal 230) is displayed as @samp{\230}. |
1281 | If you change the buffer-local variable @code{ctl-arrow} to | |
a3dcc84e EZ |
1282 | @code{nil}, the @acronym{ASCII} control characters are also displayed |
1283 | as octal escape sequences instead of caret escape sequences. | |
6bf7aab6 | 1284 | |
470a11a3 | 1285 | @vindex nobreak-char-display |
939db9ac CY |
1286 | @cindex non-breaking space |
1287 | @cindex non-breaking hyphen | |
1288 | @cindex soft hyphen | |
1289 | Some non-@acronym{ASCII} characters have the same appearance as an | |
1290 | @acronym{ASCII} space or hyphen (minus) character. Such characters | |
1291 | can cause problems if they are entered into a buffer without your | |
8863a584 | 1292 | realization, e.g.@: by yanking; for instance, source code compilers |
939db9ac CY |
1293 | typically do not treat non-@acronym{ASCII} spaces as whitespace |
1294 | characters. To deal with this problem, Emacs displays such characters | |
1295 | specially: it displays @code{U+00A0} (no-break space) with the | |
1296 | @code{nobreak-space} face, and it displays @code{U+00AD} (soft | |
1297 | hyphen), @code{U+2010} (hyphen), and @code{U+2011} (non-breaking | |
1298 | hyphen) with the @code{escape-glyph} face. To disable this, change | |
1299 | the variable @code{nobreak-char-display} to @code{nil}. If you give | |
1300 | this variable a non-@code{nil} and non-@code{t} value, Emacs instead | |
1301 | displays such characters as a highlighted backslash followed by a | |
1302 | space or hyphen. | |
b5cced4b | 1303 | |
54952612 RS |
1304 | You can customize the way any particular character code is displayed |
1305 | by means of a display table. @xref{Display Tables,, Display Tables, | |
1306 | elisp, The Emacs Lisp Reference Manual}. | |
1307 | ||
0eb025fb EZ |
1308 | @cindex glyphless characters |
1309 | @cindex characters with no font glyphs | |
d366bd53 CY |
1310 | On graphical displays, some characters may have no glyphs in any of |
1311 | the fonts available to Emacs. These @dfn{glyphless characters} are | |
1312 | normally displayed as boxes containing the hexadecimal character code. | |
a3dcc84e EZ |
1313 | Similarly, on text terminals, characters that cannot be displayed |
1314 | using the terminal encoding (@pxref{Terminal Coding}) are normally | |
1315 | displayed as question signs. You can control the display method by | |
1316 | customizing the variable @code{glyphless-char-display-control}. | |
1317 | @xref{Glyphless Chars,, Glyphless Character Display, elisp, The Emacs | |
1318 | Lisp Reference Manual}, for details. | |
0eb025fb | 1319 | |
0015d677 RS |
1320 | @node Cursor Display |
1321 | @section Displaying the Cursor | |
939db9ac | 1322 | @cindex text cursor |
4cb4f3ba | 1323 | |
468160b7 | 1324 | @vindex visible-cursor |
939db9ac CY |
1325 | On a text terminal, the cursor's appearance is controlled by the |
1326 | terminal, largely out of the control of Emacs. Some terminals offer | |
1327 | two different cursors: a ``visible'' static cursor, and a ``very | |
1328 | visible'' blinking cursor. By default, Emacs uses the very visible | |
1329 | cursor, and switches to it when you start or resume Emacs. If the | |
1330 | variable @code{visible-cursor} is @code{nil} when Emacs starts or | |
1331 | resumes, it uses the normal cursor. | |
1332 | ||
1333 | @cindex cursor face | |
1334 | @vindex cursor-type | |
1335 | On a graphical display, many more properties of the text cursor can | |
1336 | be altered. To customize its color, change the @code{:background} | |
1337 | attribute of the face named @code{cursor} (@pxref{Face | |
1338 | Customization}). (The other attributes of this face have no effect; | |
1339 | the text shown under the cursor is drawn using the frame's background | |
1340 | color.) To change its shape, customize the buffer-local variable | |
1341 | @code{cursor-type}; possible values are @code{box} (the default), | |
1342 | @code{hollow} (a hollow box), @code{bar} (a vertical bar), @code{(bar | |
1343 | . @var{n})} (a vertical bar @var{n} pixels wide), @code{hbar} (a | |
1344 | horizontal bar), @code{(hbar . @var{n})} (a horizontal bar @var{n} | |
1345 | pixels tall), or @code{nil} (no cursor at all). | |
468160b7 | 1346 | |
939db9ac CY |
1347 | @findex blink-cursor-mode |
1348 | @cindex cursor, blinking | |
1349 | @cindex blinking cursor | |
1350 | @vindex blink-cursor-alist | |
1351 | To disable cursor blinking, change the variable | |
1352 | @code{blink-cursor-mode} to @code{nil} (@pxref{Easy Customization}), | |
1353 | or add the line @code{(blink-cursor-mode 0)} to your init file. | |
1354 | Alternatively, you can change how the cursor looks when it ``blinks | |
1355 | off'' by customizing the list variable @code{blink-cursor-alist}. | |
1356 | Each element in the list should have the form @code{(@var{on-type} | |
1357 | . @var{off-type})}; this means that if the cursor is displayed as | |
1358 | @var{on-type} when it blinks on (where @var{on-type} is one of the | |
1359 | cursor types described above), then it is displayed as @var{off-type} | |
1360 | when it blinks off. | |
0015d677 RS |
1361 | |
1362 | @vindex x-stretch-cursor | |
1363 | @cindex wide block cursor | |
939db9ac CY |
1364 | Some characters, such as tab characters, are ``extra wide''. When |
1365 | the cursor is positioned over such a character, it is normally drawn | |
1366 | with the default character width. You can make the cursor stretch to | |
1367 | cover wide characters, by changing the variable | |
0015d677 RS |
1368 | @code{x-stretch-cursor} to a non-@code{nil} value. |
1369 | ||
939db9ac CY |
1370 | @cindex cursor in non-selected windows |
1371 | @vindex cursor-in-non-selected-windows | |
1372 | The cursor normally appears in non-selected windows as a | |
1373 | non-blinking hollow box. (For a bar cursor, it instead appears as a | |
1374 | thinner bar.) To turn off cursors in non-selected windows, change the | |
1375 | variable @code{cursor-in-non-selected-windows} to @code{nil}. | |
1376 | ||
0015d677 RS |
1377 | @findex hl-line-mode |
1378 | @findex global-hl-line-mode | |
1379 | @cindex highlight current line | |
54952612 RS |
1380 | To make the cursor even more visible, you can use HL Line mode, a |
1381 | minor mode that highlights the line containing point. Use @kbd{M-x | |
0015d677 RS |
1382 | hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x |
1383 | global-hl-line-mode} enables or disables the same mode globally. | |
1384 | ||
9d2908a6 | 1385 | @node Line Truncation |
939db9ac | 1386 | @section Line Truncation |
0015d677 RS |
1387 | |
1388 | @cindex truncation | |
1389 | @cindex line truncation, and fringes | |
939db9ac CY |
1390 | As an alternative to continuation (@pxref{Continuation Lines}), |
1391 | Emacs can display long lines by @dfn{truncation}. This means that all | |
1392 | the characters that do not fit in the width of the screen or window do | |
1393 | not appear at all. On graphical displays, a small straight arrow in | |
1394 | the fringe indicates truncation at either end of the line. On | |
1395 | text-only terminals, this is indicated with @samp{$} signs in the | |
1396 | leftmost and/or rightmost columns. | |
0015d677 RS |
1397 | |
1398 | @vindex truncate-lines | |
1399 | @findex toggle-truncate-lines | |
1400 | Horizontal scrolling automatically causes line truncation | |
1401 | (@pxref{Horizontal Scrolling}). You can explicitly enable line | |
1402 | truncation for a particular buffer with the command @kbd{M-x | |
1403 | toggle-truncate-lines}. This works by locally changing the variable | |
1404 | @code{truncate-lines}. If that variable is non-@code{nil}, long lines | |
1405 | are truncated; if it is @code{nil}, they are continued onto multiple | |
1406 | screen lines. Setting the variable @code{truncate-lines} in any way | |
1407 | makes it local to the current buffer; until that time, the default | |
939db9ac | 1408 | value, which is normally @code{nil}, is in effect. |
6bf7aab6 | 1409 | |
939db9ac CY |
1410 | @vindex truncate-partial-width-windows |
1411 | If a split window becomes too narrow, Emacs may automatically enable | |
1412 | line truncation. @xref{Split Window}, for the variable | |
1413 | @code{truncate-partial-width-windows} which controls this. | |
80174a97 | 1414 | |
458db4b6 CY |
1415 | @node Visual Line Mode |
1416 | @section Visual Line Mode | |
1417 | ||
1418 | @cindex word wrap | |
1419 | Another alternative to ordinary line continuation is to use | |
1420 | @dfn{word wrap}. Here, each long logical line is divided into two or | |
1421 | more screen lines, like in ordinary line continuation. However, Emacs | |
1422 | attempts to wrap the line at word boundaries near the right window | |
1423 | edge. This makes the text easier to read, as wrapping does not occur | |
1424 | in the middle of words. | |
1425 | ||
1426 | @cindex Visual Line mode | |
1427 | @findex visual-line-mode | |
1428 | @findex global-visual-line-mode | |
1429 | Word wrap is enabled by Visual Line mode, an optional minor mode. | |
1430 | To turn on Visual Line mode in the current buffer, type @kbd{M-x | |
1431 | visual-line-mode}; repeating this command turns it off. You can also | |
1432 | turn on Visual Line mode using the menu bar: in the Options menu, | |
1433 | select the @samp{Line Wrapping in this Buffer} submenu, followed by | |
1434 | the @samp{Word Wrap (Visual Line Mode)} menu item. While Visual Line | |
1435 | mode is enabled, the mode-line shows the string @samp{wrap} in the | |
1436 | mode display. The command @kbd{M-x global-visual-line-mode} toggles | |
1437 | Visual Line mode in all buffers. | |
1438 | ||
1439 | @findex beginning-of-visual-line | |
1440 | @findex end-of-visual-line | |
1441 | @findex next-logical-line | |
1442 | @findex previous-logical-line | |
1443 | In Visual Line mode, some editing commands work on screen lines | |
1444 | instead of logical lines: @kbd{C-a} (@code{beginning-of-visual-line}) | |
1445 | moves to the beginning of the screen line, @kbd{C-e} | |
1446 | (@code{end-of-visual-line}) moves to the end of the screen line, and | |
1447 | @kbd{C-k} (@code{kill-visual-line}) kills text to the end of the | |
21927cd7 CY |
1448 | screen line. |
1449 | ||
1450 | To move by logical lines, use the commands @kbd{M-x | |
1451 | next-logical-line} and @kbd{M-x previous-logical-line}. These move | |
1452 | point to the next logical line and the previous logical line | |
1453 | respectively, regardless of whether Visual Line mode is enabled. If | |
1454 | you use these commands frequently, it may be convenient to assign key | |
1455 | bindings to them. @xref{Init Rebinding}. | |
458db4b6 CY |
1456 | |
1457 | By default, word-wrapped lines do not display fringe indicators. | |
1458 | Visual Line mode is often used to edit files that contain many long | |
1459 | logical lines, so having a fringe indicator for each wrapped line | |
1460 | would be visually distracting. You can change this by customizing the | |
1461 | variable @code{visual-line-fringe-indicators}. | |
1462 | ||
9d2908a6 RS |
1463 | @node Display Custom |
1464 | @section Customization of Display | |
80174a97 | 1465 | |
939db9ac CY |
1466 | This section describes variables that control miscellaneous aspects |
1467 | of the appearance of the Emacs screen. Beginning users can skip it. | |
62ea61af | 1468 | |
9d2908a6 RS |
1469 | @vindex visible-bell |
1470 | If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts | |
1471 | to make the whole screen blink when it would normally make an audible bell | |
1472 | sound. This variable has no effect if your terminal does not have a way | |
1473 | to make the screen blink. | |
80174a97 | 1474 | |
9d2908a6 RS |
1475 | @vindex echo-keystrokes |
1476 | The variable @code{echo-keystrokes} controls the echoing of multi-character | |
1477 | keys; its value is the number of seconds of pause required to cause echoing | |
1478 | to start, or zero, meaning don't echo at all. The value takes effect when | |
bfd779dd | 1479 | there is something to echo. @xref{Echo Area}. |
80174a97 | 1480 | |
b4a1a8b2 | 1481 | @cindex mouse pointer |
62095f01 | 1482 | @cindex hourglass pointer display |
b4a1a8b2 | 1483 | @vindex display-hourglass |
62095f01 | 1484 | @vindex hourglass-delay |
b4a1a8b2 CY |
1485 | On graphical displays, Emacs displays the mouse pointer as an |
1486 | hourglass if Emacs is busy. To disable this feature, set the variable | |
1487 | @code{display-hourglass} to @code{nil}. The variable | |
1488 | @code{hourglass-delay} determines the number of seconds of ``busy | |
1489 | time'' before the hourglass is shown; the default is 1. | |
1490 | ||
1491 | @vindex make-pointer-invisible | |
1492 | If the mouse pointer lies inside an Emacs frame, Emacs makes it | |
1493 | invisible each time you type a character to insert text, to prevent it | |
1494 | from obscuring the text. (To be precise, the hiding occurs when you | |
1495 | type a ``self-inserting'' character. @xref{Inserting Text}.) Moving | |
1496 | the mouse pointer makes it visible again. To disable this feature, | |
1497 | set the variable @code{make-pointer-invisible} to @code{nil}. | |
1498 | ||
1499 | @vindex underline-minimum-offset | |
1500 | @vindex x-underline-at-descent-line | |
1501 | On graphical displays, the variable @code{underline-minimum-offset} | |
1502 | determines the minimum distance between the baseline and underline, in | |
1503 | pixels, for underlined text. By default, the value is 1; increasing | |
1504 | it may improve the legibility of underlined text for certain fonts. | |
1505 | (However, Emacs will never draw the underline below the current line | |
1506 | area.) The variable @code{x-underline-at-descent-line} determines how | |
1507 | to draw underlined text. The default is @code{nil}, which means to | |
1508 | draw it at the baseline level of the font; if you change it to | |
1509 | @code{nil}, Emacs draws the underline at the same height as the font's | |
1510 | descent line. | |
099bfef9 | 1511 | |
9d2908a6 | 1512 | @vindex overline-margin |
b4a1a8b2 CY |
1513 | The variable @code{overline-margin} specifies the vertical position |
1514 | of an overline above the text, including the height of the overline | |
1515 | itself, in pixels; the default is 2. | |
9d2908a6 | 1516 | |
a66b12be RS |
1517 | @findex tty-suppress-bold-inverse-default-colors |
1518 | On some text-only terminals, bold face and inverse video together | |
1519 | result in text that is hard to read. Call the function | |
1520 | @code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil} | |
1521 | argument to suppress the effect of bold-face in this case. |