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802b0ea7 | 1 | @c This is part of the Emacs manual. |
73b0cd50 | 2 | @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011 |
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 | ||
9 | Since only part of a large buffer fits in the window, Emacs tries to | |
43d67313 | 10 | show a part that is likely to be interesting. Display-control |
956c76ef CY |
11 | commands and variables allow you to specify which part of the text you |
12 | want to see, and how to display it. | |
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13 | |
14 | @menu | |
8838673e | 15 | * Scrolling:: Commands to move text up and down in a window. |
43d67313 | 16 | * Auto Scrolling:: Redisplay scrolls text automatically when needed. |
54952612 | 17 | * Horizontal Scrolling:: Moving text left and right in a window. |
f404f8bc CY |
18 | * Narrowing:: Restricting display and editing to a portion |
19 | of the buffer. | |
54952612 | 20 | * Follow Mode:: Follow mode lets two windows scroll as one. |
8838673e | 21 | * Faces:: How to change the display style using faces. |
43d08eb9 | 22 | * Standard Faces:: Emacs' predefined faces. |
956c76ef | 23 | * Temporary Face Changes:: Commands to temporarily modify the default text face |
b8f3a9e3 | 24 | * Font Lock:: Minor mode for syntactic highlighting using faces. |
b8f3a9e3 | 25 | * Highlight Interactively:: Tell Emacs what text to highlight. |
fad78d58 | 26 | * Fringes:: Enabling or disabling window fringes. |
9d2908a6 | 27 | * Displaying Boundaries:: Displaying top and bottom of the buffer. |
fad78d58 | 28 | * Useless Whitespace:: Showing possibly-spurious trailing whitespace. |
6bf7aab6 DL |
29 | * Selective Display:: Hiding lines with lots of indentation. |
30 | * Optional Mode Line:: Optional mode line display features. | |
31 | * Text Display:: How text characters are normally displayed. | |
099bfef9 | 32 | * Cursor Display:: Features for displaying the cursor. |
9d2908a6 RS |
33 | * Line Truncation:: Truncating lines to fit the screen width instead |
34 | of continuing them to multiple screen lines. | |
458db4b6 | 35 | * Visual Line Mode:: Word wrap and screen line-based editing. |
0015d677 | 36 | * Display Custom:: Information on variables for customizing display. |
6bf7aab6 DL |
37 | @end menu |
38 | ||
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39 | @node Scrolling |
40 | @section Scrolling | |
41 | ||
42 | If a buffer contains text that is too large to fit entirely within a | |
43 | window that is displaying the buffer, Emacs shows a contiguous portion of | |
44 | the text. The portion shown always contains point. | |
45 | ||
46 | @cindex scrolling | |
47 | @dfn{Scrolling} means moving text up or down in the window so that | |
48 | different parts of the text are visible. Scrolling ``forward'' or | |
49 | ``up'' means that text moves up, and new text appears at the bottom. | |
50 | Scrolling ``backward'' or ``down'' moves text down, and new text | |
51 | appears at the top. | |
52 | ||
53 | Scrolling happens automatically if you move point past the bottom or | |
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54 | top of the window. You can also scroll explicitly with these |
55 | commands: | |
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56 | |
57 | @table @kbd | |
58 | @item C-l | |
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59 | Scroll the selected window so that the current line is the center-most |
60 | text line; on subsequent consecutive invocations, make the current | |
61 | line the top-most line, the bottom-most line, and so forth in cyclic | |
62 | order; also, maybe redisplay the screen (@code{recenter-top-bottom}). | |
dc917bd9 | 63 | @item C-v |
b5700de6 CY |
64 | @itemx @key{next} |
65 | @itemx @key{PageDown} | |
61436e9f | 66 | Scroll forward by nearly a full window (@code{scroll-up-command}). |
dc917bd9 | 67 | @item M-v |
b5700de6 CY |
68 | @itemx @key{prior} |
69 | @itemx @key{PageUp} | |
61436e9f | 70 | Scroll backward (@code{scroll-down-command}). |
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71 | @item C-M-l |
72 | Scroll heuristically to bring useful information onto the screen | |
73 | (@code{reposition-window}). | |
74 | @end table | |
75 | ||
76 | @kindex C-l | |
956c76ef | 77 | @findex recenter-top-bottom |
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78 | @kbd{C-l} (@code{recenter-top-bottom}) is a basic scrolling command. |
79 | It @dfn{recenters} the selected window, scrolling it so that the | |
80 | current screen line is exactly in the center of the window, or as | |
81 | close to the center as possible. | |
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82 | |
83 | Typing @kbd{C-l} twice in a row (@kbd{C-l C-l}) scrolls the window | |
84 | so that point is on the topmost screen line. Typing a third @kbd{C-l} | |
85 | scrolls the window so that point is on the bottom-most screen line. | |
86 | Each successive @kbd{C-l} cycles through these three screen positions. | |
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87 | |
88 | @vindex recenter-positions | |
89 | You can change the cycling order by customizing the list variable | |
90 | @code{recenter-positions}. Each list element should be the symbol | |
91 | @code{top}, @code{middle}, or @code{bottom}, or a number; an integer | |
92 | number means to move the line to the specified screen line, while a | |
93 | floating-point number between 0.0 and 1.0 specifies a percentage of | |
94 | the screen space from the top. The default, @code{(middle top | |
95 | bottom)}, is the cycling order described above. Furthermore, if you | |
96 | change the variable @code{scroll-margin} to a non-zero value @var{n}, | |
97 | Emacs always leaves @var{n} screen lines between point and the top or | |
98 | bottom of the window (@pxref{Auto Scrolling}). | |
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99 | |
100 | You can also supply @kbd{C-l} with a prefix argument. With a plain | |
101 | prefix argument, @kbd{C-u C-l}, Emacs simply recenters point. With a | |
102 | positive argument @var{n}, it scrolls to place point @var{n} lines | |
103 | down from the top of the window. An argument of zero puts point on | |
104 | the topmost line. A negative argument @var{-n} puts point @var{n} | |
105 | lines from the bottom of the window. For example, @kbd{C-u - 1 C-l} | |
106 | puts point on the bottom line, and @kbd{C-u - 5 C-l} puts it five | |
107 | lines from the bottom. When given an argument, @kbd{C-l} does not | |
108 | clear the screen or cycle through different screen positions. | |
dc917bd9 | 109 | |
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110 | The more primitive command @code{recenter} behaves like |
111 | @code{recenter-top-bottom}, but does not cycle among screen positions. | |
112 | Prior to Emacs 23, @kbd{C-l} was bound to @code{recenter}. | |
113 | ||
666e158e | 114 | @vindex recenter-redisplay |
91ed7ea8 CY |
115 | If the variable @code{recenter-redisplay} has a non-@code{nil} |
116 | value, Emacs clears and redisplays the screen each time @kbd{C-l} | |
117 | recenters the window; the special value @code{tty} (the default) says | |
118 | to do this on text-terminal frames only. Redisplaying is useful in | |
119 | case the screen becomes garbled for any reason (@pxref{Screen | |
120 | Garbled}). | |
666e158e | 121 | |
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122 | @kindex C-v |
123 | @kindex M-v | |
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124 | @kindex next |
125 | @kindex prior | |
126 | @kindex PageDown | |
127 | @kindex PageUp | |
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128 | @findex scroll-up |
129 | @findex scroll-down | |
91ed7ea8 | 130 | To read the buffer a windowful at a time, type @kbd{C-v} |
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131 | (@code{scroll-up}). This scrolls forward by nearly the whole window |
132 | height. The effect is to take the two lines at the bottom of the | |
133 | window and put them at the top, followed by lines that were not | |
134 | previously visible. If point was in the text that scrolled off the | |
135 | top, it ends up at the new top of the window. | |
136 | ||
137 | @kbd{M-v} (@code{scroll-down}) scrolls backward in a similar way. | |
dc917bd9 | 138 | |
43d67313 | 139 | @vindex next-screen-context-lines |
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140 | The variable @code{next-screen-context-lines} controls the number of |
141 | lines of overlap left by @kbd{C-v} or @kbd{M-v}; by default, it is 2. | |
b5700de6 | 142 | The function keys @key{next} and @key{prior}, or @key{PageDown} and |
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143 | @key{PageUp}, are equivalent to @kbd{C-v} and @kbd{M-v} respectively. |
144 | ||
145 | You can supply @kbd{C-v} or @kbd{M-v} with a numeric prefix argument | |
146 | @var{n}. This scrolls the window by @var{n} lines, while attempting | |
147 | to leave point unchanged (so that the text and point move up or down | |
148 | together). @kbd{C-v} with a negative argument is like @kbd{M-v} and | |
149 | vice versa. | |
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150 | |
151 | The names of scroll commands are based on the direction that the | |
152 | text moves in the window. Thus, the command to scroll forward is | |
153 | called @code{scroll-up} because it moves the text upward on the | |
956c76ef | 154 | screen. The keys @key{PageUp} and @key{PageDown} derive their names |
dc917bd9 | 155 | and customary meanings from a different convention that developed |
956c76ef | 156 | elsewhere; hence the strange result that @key{PageDown} runs |
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157 | @code{scroll-up}. |
158 | ||
159 | @vindex scroll-preserve-screen-position | |
160 | Some users like the full-screen scroll commands to keep point at the | |
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161 | same screen position. To enable this behavior, set the variable |
162 | @code{scroll-preserve-screen-position} to a non-@code{nil} value. | |
163 | Then, whenever a command scrolls the text around point offscreen (or | |
164 | within @code{scroll-margin} lines of the edge), Emacs moves point to | |
165 | keep it at the same vertical and horizontal position within the | |
166 | window. This mode is convenient for browsing through a file by | |
167 | scrolling by screenfuls; if you come back to the screen where you | |
168 | started, point goes back to the line where it started. | |
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169 | |
170 | @kindex C-M-l | |
171 | @findex reposition-window | |
172 | The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current | |
173 | window heuristically in a way designed to get useful information onto | |
174 | the screen. For example, in a Lisp file, this command tries to get the | |
175 | entire current defun onto the screen if possible. | |
176 | ||
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177 | @node Auto Scrolling |
178 | @section Automatic Scrolling | |
179 | ||
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180 | Emacs performs @dfn{automatic scrolling} when point moves out of the |
181 | visible portion of the text. | |
182 | ||
dc917bd9 | 183 | @vindex scroll-conservatively |
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184 | Normally, this centers point vertically within the window. However, |
185 | if you set @code{scroll-conservatively} to a small number @var{n}, | |
186 | then if you move point just a little off the screen (less than @var{n} | |
187 | lines), Emacs scrolls the text just far enough to bring point back on | |
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188 | screen. By default, @code{scroll-conservatively} is@tie{}0. If you |
189 | set @code{scroll-conservatively} to a large number (larger than 100), | |
190 | Emacs will never center point as result of scrolling, even if point | |
191 | moves far away from the text previously displayed in the window. With | |
192 | such a large value, Emacs will always scroll text just enough for | |
193 | bringing point into view, so point will end up at the top or bottom of | |
194 | the window, depending on the scroll direction. | |
195 | ||
196 | @vindex scroll-step | |
197 | The variable @code{scroll-step} determines how many lines to scroll | |
198 | the window when point moves off the screen. If moving by that number | |
199 | of lines fails to bring point back into view, point is centered | |
200 | instead. The default value is zero, which causes point to always be | |
201 | centered after scrolling. | |
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202 | |
203 | @cindex aggressive scrolling | |
204 | @vindex scroll-up-aggressively | |
205 | @vindex scroll-down-aggressively | |
206 | When the window does scroll by a longer distance, you can control | |
956c76ef | 207 | how aggressively it scrolls by setting the variables |
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208 | @code{scroll-up-aggressively} and @code{scroll-down-aggressively}. |
209 | The value of @code{scroll-up-aggressively} should be either | |
210 | @code{nil}, or a fraction @var{f} between 0 and 1. A fraction | |
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211 | specifies where on the screen to put point when scrolling upward, |
212 | i.e.@: when point moves forward in the buffer, and therefore text | |
213 | scrolls up in the window. When point goes off the window end, the new | |
956c76ef | 214 | start position is chosen to put point @var{f} parts of the window |
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215 | height from the bottom. Thus, larger @var{f} means more aggressive |
216 | scrolling: more new text is brought into view. The default value, | |
217 | @code{nil}, is equivalent to 0.5. | |
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218 | |
219 | Likewise, @code{scroll-down-aggressively} is used for scrolling | |
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220 | down, i.e.@: moving point back in the buffer. The value specifies how |
221 | far point should be placed from the top of the window; thus, as with | |
222 | @code{scroll-up-aggressively}, a larger value is more aggressive. | |
dc917bd9 | 223 | |
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224 | These two variables are ignored if either @code{scroll-step} or |
225 | @code{scroll-conservatively} are set to a non-zero value. | |
226 | ||
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227 | @vindex scroll-margin |
228 | The variable @code{scroll-margin} restricts how close point can come | |
229 | to the top or bottom of a window. Its value is a number of screen | |
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230 | lines; if point comes within that many lines of the top or bottom of |
231 | the window, Emacs performs automatic scrolling. By default, | |
232 | @code{scroll-margin} is 0. | |
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233 | |
234 | @node Horizontal Scrolling | |
235 | @section Horizontal Scrolling | |
236 | @cindex horizontal scrolling | |
237 | ||
956c76ef | 238 | @vindex auto-hscroll-mode |
dc917bd9 | 239 | @dfn{Horizontal scrolling} means shifting all the lines sideways |
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240 | within a window, so that some of the text near the left margin is not |
241 | displayed. When the text in a window is scrolled horizontally, text | |
242 | lines are truncated rather than continued (@pxref{Line Truncation}). | |
243 | If a window shows truncated lines, Emacs performs automatic horizontal | |
244 | scrolling whenever point moves off the left or right edge of the | |
245 | screen. To disable automatic horizontal scrolling, set the variable | |
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246 | @code{auto-hscroll-mode} to @code{nil}. Note that when the automatic |
247 | horizontal scrolling is turned off, if point moves off the edge of the | |
248 | screen, the cursor disappears to indicate that. (On text-mode | |
249 | terminals, the cursor is left at the edge instead.) | |
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250 | |
251 | @vindex hscroll-margin | |
252 | The variable @code{hscroll-margin} controls how close point can get | |
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253 | to the window's edges before automatic scrolling occurs. It is |
254 | measured in columns. For example, if the value is 5, then moving | |
255 | point within 5 columns of an edge causes horizontal scrolling away | |
256 | from that edge. | |
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257 | |
258 | @vindex hscroll-step | |
259 | The variable @code{hscroll-step} determines how many columns to | |
260 | scroll the window when point gets too close to the edge. Zero, the | |
261 | default value, means to center point horizontally within the window. | |
262 | A positive integer value specifies the number of columns to scroll by. | |
263 | A floating-point number specifies the fraction of the window's width | |
264 | to scroll by. | |
265 | ||
266 | You can also perform explicit horizontal scrolling with the | |
267 | following commands: | |
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268 | |
269 | @table @kbd | |
270 | @item C-x < | |
271 | Scroll text in current window to the left (@code{scroll-left}). | |
272 | @item C-x > | |
273 | Scroll to the right (@code{scroll-right}). | |
274 | @end table | |
275 | ||
276 | @kindex C-x < | |
277 | @kindex C-x > | |
278 | @findex scroll-left | |
279 | @findex scroll-right | |
6308321a EZ |
280 | @kbd{C-x <} (@code{scroll-left}) scrolls text in the selected window |
281 | to the left by the full width of the window, less two columns. (In | |
282 | other words, the text in the window moves left relative to the | |
283 | window.) With a numeric argument @var{n}, it scrolls by @var{n} | |
284 | columns. | |
285 | ||
286 | If the text is scrolled to the left, and point moves off the left | |
287 | edge of the window, the cursor will freeze at the left edge of the | |
288 | window, until point moves back to the displayed portion of the text. | |
289 | This is independent of the current setting of | |
290 | @code{auto-hscroll-mode}, which, for text scrolled to the left, only | |
291 | affects the behavior at the right edge of the window. | |
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292 | |
293 | @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. | |
294 | The window cannot be scrolled any farther to the right once it is | |
295 | displayed normally, with each line starting at the window's left | |
296 | margin; attempting to do so has no effect. This means that you don't | |
297 | have to calculate the argument precisely for @w{@kbd{C-x >}}; any | |
298 | sufficiently large argument will restore the normal display. | |
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299 | |
300 | If you use those commands to scroll a window horizontally, that sets | |
301 | a lower bound for automatic horizontal scrolling. Automatic scrolling | |
302 | will continue to scroll the window, but never farther to the right | |
303 | than the amount you previously set by @code{scroll-left}. | |
304 | ||
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305 | @node Narrowing |
306 | @section Narrowing | |
307 | @cindex widening | |
308 | @cindex restriction | |
309 | @cindex narrowing | |
310 | @cindex accessible portion | |
311 | ||
312 | @dfn{Narrowing} means focusing in on some portion of the buffer, | |
313 | making the rest temporarily inaccessible. The portion which you can | |
314 | still get to is called the @dfn{accessible portion}. Canceling the | |
315 | narrowing, which makes the entire buffer once again accessible, is | |
316 | called @dfn{widening}. The bounds of narrowing in effect in a buffer | |
317 | are called the buffer's @dfn{restriction}. | |
318 | ||
319 | Narrowing can make it easier to concentrate on a single subroutine or | |
320 | paragraph by eliminating clutter. It can also be used to limit the | |
321 | range of operation of a replace command or repeating keyboard macro. | |
322 | ||
323 | @table @kbd | |
324 | @item C-x n n | |
325 | Narrow down to between point and mark (@code{narrow-to-region}). | |
326 | @item C-x n w | |
327 | Widen to make the entire buffer accessible again (@code{widen}). | |
328 | @item C-x n p | |
329 | Narrow down to the current page (@code{narrow-to-page}). | |
330 | @item C-x n d | |
331 | Narrow down to the current defun (@code{narrow-to-defun}). | |
332 | @end table | |
333 | ||
334 | When you have narrowed down to a part of the buffer, that part appears | |
335 | to be all there is. You can't see the rest, you can't move into it | |
336 | (motion commands won't go outside the accessible part), you can't change | |
337 | it in any way. However, it is not gone, and if you save the file all | |
338 | the inaccessible text will be saved. The word @samp{Narrow} appears in | |
339 | the mode line whenever narrowing is in effect. | |
340 | ||
341 | @kindex C-x n n | |
342 | @findex narrow-to-region | |
343 | The primary narrowing command is @kbd{C-x n n} (@code{narrow-to-region}). | |
344 | It sets the current buffer's restrictions so that the text in the current | |
345 | region remains accessible, but all text before the region or after the | |
346 | region is inaccessible. Point and mark do not change. | |
347 | ||
348 | @kindex C-x n p | |
349 | @findex narrow-to-page | |
350 | @kindex C-x n d | |
351 | @findex narrow-to-defun | |
352 | Alternatively, use @kbd{C-x n p} (@code{narrow-to-page}) to narrow | |
353 | down to the current page. @xref{Pages}, for the definition of a page. | |
354 | @kbd{C-x n d} (@code{narrow-to-defun}) narrows down to the defun | |
355 | containing point (@pxref{Defuns}). | |
356 | ||
357 | @kindex C-x n w | |
358 | @findex widen | |
359 | The way to cancel narrowing is to widen with @kbd{C-x n w} | |
360 | (@code{widen}). This makes all text in the buffer accessible again. | |
361 | ||
362 | You can get information on what part of the buffer you are narrowed down | |
363 | to using the @kbd{C-x =} command. @xref{Position Info}. | |
364 | ||
365 | Because narrowing can easily confuse users who do not understand it, | |
366 | @code{narrow-to-region} is normally a disabled command. Attempting to use | |
367 | this command asks for confirmation and gives you the option of enabling it; | |
368 | if you enable the command, confirmation will no longer be required for | |
369 | it. @xref{Disabling}. | |
370 | ||
dc917bd9 RS |
371 | @node Follow Mode |
372 | @section Follow Mode | |
373 | @cindex Follow mode | |
374 | @cindex mode, Follow | |
375 | @findex follow-mode | |
376 | @cindex windows, synchronizing | |
377 | @cindex synchronizing windows | |
378 | ||
379 | @dfn{Follow mode} is a minor mode that makes two windows, both | |
380 | showing the same buffer, scroll as a single tall ``virtual window.'' | |
381 | To use Follow mode, go to a frame with just one window, split it into | |
382 | two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x | |
383 | follow-mode}. From then on, you can edit the buffer in either of the | |
384 | two windows, or scroll either one; the other window follows it. | |
385 | ||
386 | In Follow mode, if you move point outside the portion visible in one | |
387 | window and into the portion visible in the other window, that selects | |
388 | the other window---again, treating the two as if they were parts of | |
389 | one large window. | |
390 | ||
391 | To turn off Follow mode, type @kbd{M-x follow-mode} a second time. | |
392 | ||
b8f3a9e3 | 393 | @node Faces |
b18a8f7f | 394 | @section Faces: Controlling Text Display Style |
b8f3a9e3 GM |
395 | @cindex faces |
396 | ||
956c76ef | 397 | Emacs can display text in several different styles, which are called |
0015d677 | 398 | @dfn{faces}. Each face can specify various @dfn{face attributes}, |
956c76ef CY |
399 | such as the font, height, weight and slant, the foreground and |
400 | background color, and underlining or overlining. A face does not have | |
401 | to specify all of these attributes; often it inherits most of them | |
402 | from another face. | |
306da12e | 403 | |
956c76ef CY |
404 | On a text-only terminal, not all face attributes are meaningful. |
405 | Some text-only terminals support inverse video, bold, and underline | |
406 | attributes; some support colors. Text-only terminals generally do not | |
407 | support changing the height, width or font. | |
c1b45553 | 408 | |
b18a8f7f RS |
409 | Most major modes assign faces to the text automatically through the |
410 | work of Font Lock mode. @xref{Font Lock}, for more information about | |
411 | Font Lock mode and syntactic highlighting. You can print the current | |
412 | buffer with the highlighting that appears on your screen using the | |
413 | command @code{ps-print-buffer-with-faces}. @xref{PostScript}. | |
43d08eb9 | 414 | |
956c76ef | 415 | Enriched mode, the mode for editing formatted text, provides |
0073fd65 | 416 | commands and menus for specifying faces for text in the buffer. |
956c76ef | 417 | @xref{Format Faces}. |
b8f3a9e3 GM |
418 | |
419 | @cindex face colors, setting | |
0073fd65 RS |
420 | To alter the appearance of a face, use the customization buffer. |
421 | @xref{Face Customization}. You can also use X resources to specify | |
956c76ef CY |
422 | attributes of any particular face (@pxref{Resources}). When |
423 | displaying a character, any attribute that isn't specified by its face | |
424 | is taken from the @code{default} face, whose attributes reflect the | |
425 | default settings of the frame itself. | |
426 | ||
427 | @findex set-face-foreground | |
428 | @findex set-face-background | |
429 | You can also change the foreground and background colors of a | |
430 | specific face with @kbd{M-x set-face-foreground} and @kbd{M-x | |
431 | set-face-background}. These commands prompt in the minibuffer for a | |
432 | face name and a color name, with completion, and then set that face to | |
433 | use the specified color. @xref{Face Customization}, for information | |
434 | about color names. These commands affect the face colors on all | |
435 | frames, both existing and those to be created in the future. These | |
436 | changes do not, however, persist for future Emacs sessions; to make | |
437 | lasting changes, use the customization buffer (@pxref{Face | |
438 | Customization}). | |
439 | ||
440 | You can also set foreground and background colors for the current | |
441 | frame only; see @ref{Frame Parameters}. | |
442 | ||
443 | Emacs can display variable-width fonts, but some of the Emacs | |
444 | commands that calculate width and indentation do not know how to | |
445 | calculate variable widths. This can sometimes lead to incorrect | |
446 | results when you use variable-width fonts. In particular, indentation | |
447 | commands can give inconsistent results, so we recommend you avoid | |
448 | variable-width fonts, especially for editing program source code. | |
b8f3a9e3 | 449 | |
43d08eb9 RS |
450 | @node Standard Faces |
451 | @section Standard Faces | |
452 | ||
b8f3a9e3 | 453 | @findex list-faces-display |
43d08eb9 RS |
454 | To see what faces are currently defined, and what they look like, |
455 | type @kbd{M-x list-faces-display}. It's possible for a given face to | |
456 | look different in different frames; this command shows the appearance | |
93339ade CY |
457 | in the frame in which you type it. With a prefix argument, this |
458 | prompts for a regular expression, and displays only faces with names | |
459 | matching that regular expression. | |
3b91a16d | 460 | |
54952612 RS |
461 | Here are the standard faces for specifying text appearance. You can |
462 | apply them to specific text when you want the effects they produce. | |
b8f3a9e3 GM |
463 | |
464 | @table @code | |
465 | @item default | |
54952612 | 466 | This face is used for ordinary text that doesn't specify any face. |
43d08eb9 | 467 | @item bold |
956c76ef | 468 | This face uses a bold variant of the default font. |
43d08eb9 | 469 | @item italic |
956c76ef | 470 | This face uses an italic variant of the default font. |
43d08eb9 | 471 | @item bold-italic |
956c76ef | 472 | This face uses a bold italic variant of the default font. |
43d08eb9 RS |
473 | @item underline |
474 | This face underlines text. | |
475 | @item fixed-pitch | |
956c76ef CY |
476 | This face forces use of a fixed-width font. It's reasonable to |
477 | customize this face to use a different fixed-width font, if you like, | |
478 | but you should not make it a variable-width font. | |
43d08eb9 | 479 | @item variable-pitch |
956c76ef | 480 | This face forces use of a variable-width font. |
3b91a16d JL |
481 | @item shadow |
482 | This face is used for making the text less noticeable than the surrounding | |
483 | ordinary text. Usually this can be achieved by using shades of gray in | |
484 | contrast with either black or white default foreground color. | |
43d08eb9 RS |
485 | @end table |
486 | ||
487 | Here's an incomplete list of faces used to highlight parts of the | |
488 | text temporarily for specific purposes. (Many other modes define | |
489 | their own faces for this purpose.) | |
490 | ||
491 | @table @code | |
492 | @item highlight | |
493 | This face is used for highlighting portions of text, in various modes. | |
494 | For example, mouse-sensitive text is highlighted using this face. | |
43d08eb9 | 495 | @item isearch |
956c76ef CY |
496 | This face is used for highlighting the current Isearch match |
497 | (@pxref{Incremental Search}). | |
54952612 | 498 | @item query-replace |
956c76ef CY |
499 | This face is used for highlighting the current Query Replace match |
500 | (@pxref{Replace}). | |
43d08eb9 RS |
501 | @item lazy-highlight |
502 | This face is used for lazy highlighting of Isearch and Query Replace | |
503 | matches other than the current one. | |
504 | @item region | |
04eaab7d | 505 | This face is used for displaying a selected region (@pxref{Mark}). |
43d08eb9 RS |
506 | @item secondary-selection |
507 | This face is used for displaying a secondary X selection (@pxref{Secondary | |
508 | Selection}). | |
509 | @item trailing-whitespace | |
3b91a16d JL |
510 | The face for highlighting excess spaces and tabs at the end of a line |
511 | when @code{show-trailing-whitespace} is non-@code{nil}; see | |
512 | @ref{Useless Whitespace}. | |
43d08eb9 | 513 | @item nobreak-space |
5a7f4c1b | 514 | The face for displaying the character ``nobreak space.'' |
43d08eb9 RS |
515 | @item escape-glyph |
516 | The face for highlighting the @samp{\} or @samp{^} that indicates | |
517 | a control character. It's also used when @samp{\} indicates a | |
518 | nobreak space or nobreak (soft) hyphen. | |
43d08eb9 RS |
519 | @end table |
520 | ||
43d08eb9 RS |
521 | These faces control the appearance of parts of the Emacs frame. |
522 | They exist as faces to provide a consistent way to customize the | |
523 | appearance of these parts of the frame. | |
524 | ||
525 | @table @code | |
b8f3a9e3 | 526 | @item mode-line |
3b91a16d JL |
527 | This face is used for the mode line of the currently selected window, |
528 | and for menu bars when toolkit menus are not used. By default, it's | |
54952612 | 529 | drawn with shadows for a ``raised'' effect on graphical displays, and |
3b91a16d | 530 | drawn as the inverse of the default face on non-windowed terminals. |
b9e58bf2 EZ |
531 | @item mode-line-inactive |
532 | Like @code{mode-line}, but used for mode lines of the windows other | |
533 | than the selected one (if @code{mode-line-in-non-selected-windows} is | |
ac6875fc RS |
534 | non-@code{nil}). This face inherits from @code{mode-line}, so changes |
535 | in that face affect mode lines in all windows. | |
d545c9fd JL |
536 | @item mode-line-highlight |
537 | Like @code{highlight}, but used for portions of text on mode lines. | |
538 | @item mode-line-buffer-id | |
539 | This face is used for buffer identification parts in the mode line. | |
b8f3a9e3 | 540 | @item header-line |
54952612 RS |
541 | Similar to @code{mode-line} for a window's header line, which appears |
542 | at the top of a window just as the mode line appears at the bottom. | |
543 | Most windows do not have a header line---only some special modes, such | |
544 | Info mode, create one. | |
53abc3bf | 545 | @item vertical-border |
58f1b4d8 JL |
546 | This face is used for the vertical divider between windows. |
547 | By default this face inherits from the @code{mode-line-inactive} face | |
54952612 | 548 | on character terminals. On graphical displays the foreground color of |
58f1b4d8 JL |
549 | this face is used for the vertical line between windows without |
550 | scrollbars. | |
3094ad7a | 551 | @item minibuffer-prompt |
3b91a16d JL |
552 | @cindex @code{minibuffer-prompt} face |
553 | @vindex minibuffer-prompt-properties | |
3094ad7a | 554 | This face is used for the prompt strings displayed in the minibuffer. |
3b91a16d JL |
555 | By default, Emacs automatically adds this face to the value of |
556 | @code{minibuffer-prompt-properties}, which is a list of text | |
43d67313 RS |
557 | properties used to display the prompt text. (This variable takes |
558 | effect when you enter the minibuffer.) | |
b8f3a9e3 | 559 | @item fringe |
3b91a16d | 560 | @cindex @code{fringe} face |
b8f3a9e3 GM |
561 | The face for the fringes to the left and right of windows on graphic |
562 | displays. (The fringes are the narrow portions of the Emacs frame | |
940627fe | 563 | between the text area and the window's right and left borders.) |
43d08eb9 | 564 | @xref{Fringes}. |
b8f3a9e3 GM |
565 | @item scroll-bar |
566 | This face determines the visual appearance of the scroll bar. | |
43d08eb9 | 567 | @xref{Scroll Bars}. |
b8f3a9e3 GM |
568 | @item border |
569 | This face determines the color of the frame border. | |
570 | @item cursor | |
571 | This face determines the color of the cursor. | |
572 | @item mouse | |
573 | This face determines the color of the mouse pointer. | |
574 | @item tool-bar | |
54952612 | 575 | This face determines the color of tool bar icons. @xref{Tool Bars}. |
b8f3a9e3 | 576 | @item tooltip |
43d08eb9 | 577 | This face is used for tooltips. @xref{Tooltips}. |
b8f3a9e3 | 578 | @item menu |
9e6bb19f EZ |
579 | @cindex menu bar appearance |
580 | @cindex @code{menu} face, no effect if customized | |
581 | @cindex customization of @code{menu} face | |
582 | This face determines the colors and font of Emacs's menus. @xref{Menu | |
956c76ef CY |
583 | Bars}. This has no effect in Emacs built with GTK and in the |
584 | MS-Windows/Mac ports; you need to use system-wide styles and options | |
585 | to change the appearance of GTK, Windows, or Mac menus. Setting the | |
586 | font of LessTif/Motif menus is currently not supported; attempts to | |
587 | set the font are ignored in this case. | |
b8f3a9e3 GM |
588 | @end table |
589 | ||
956c76ef CY |
590 | @node Temporary Face Changes |
591 | @section Temporary Face Changes | |
592 | ||
593 | The following commands change the default face within a buffer. | |
594 | ||
595 | @cindex adjust buffer face height | |
596 | @findex text-scale-adjust | |
597 | @kindex C-x C-+ | |
598 | @kindex C-x C-- | |
599 | @kindex C-x C-= | |
600 | @kindex C-x C-0 | |
601 | To increase the height of the default face in the current buffer, | |
602 | type @kbd{C-x C-+} or @kbd{C-x C-=}. To decrease it, type @kbd{C-x | |
603 | C--}. To restore the default (global) face height, type @kbd{C-x | |
604 | C-0}. These keys are all bound to the same command, | |
605 | @code{text-scale-adjust}, which looks at the last key typed to | |
606 | determine which action to take. | |
607 | ||
608 | The final key of these commands may be repeated without the leading | |
609 | @kbd{C-x}. For instance, @kbd{C-x C-= C-= C-=} increases the face | |
610 | height by three steps. Each step scales the height of the default | |
611 | face by the value of the variable @code{text-scale-mode-step}. As a | |
612 | special case, an argument of 0 removes any scaling currently active. | |
613 | ||
614 | @cindex increase buffer face height | |
615 | @findex text-scale-increase | |
616 | @cindex decrease buffer face height | |
617 | @findex text-scale-decrease | |
618 | The commands @code{text-scale-increase} and | |
619 | @code{text-scale-decrease} increase or decrease the height of the | |
620 | default face, just like @kbd{C-x C-+} and @kbd{C-x C--} respectively. | |
621 | You may find it convenient to bind to these commands, rather than | |
622 | @code{text-scale-adjust}. | |
623 | ||
05fbc4a9 MB |
624 | @cindex set buffer face height |
625 | @findex text-scale-set | |
626 | The command @code{text-scale-set} sets the height of the default face | |
627 | in the current buffer to an absolute level specified by its prefix | |
628 | argument. | |
629 | ||
956c76ef CY |
630 | @findex text-scale-mode |
631 | The above commands automatically enable or disable the minor mode | |
632 | @code{text-scale-mode}, depending on whether the current font scaling | |
633 | is other than 1 or not. | |
634 | ||
635 | @cindex variable pitch mode | |
636 | @findex variable-pitch-mode | |
637 | To temporarily change the face in the current buffer to a | |
638 | variable-pitch (``proportional'') font, use the command @kbd{M-x | |
639 | variable-pitch-mode} to enable or disable the Variable Pitch minor | |
640 | mode. | |
641 | ||
b8f3a9e3 GM |
642 | @node Font Lock |
643 | @section Font Lock mode | |
644 | @cindex Font Lock mode | |
645 | @cindex mode, Font Lock | |
646 | @cindex syntax highlighting and coloring | |
647 | ||
8cc11660 | 648 | Font Lock mode is a minor mode, always local to a particular buffer, |
0015d677 | 649 | which highlights (or ``fontifies'') the buffer contents according to |
8cc11660 | 650 | the syntax of the text you are editing. It can recognize comments and |
956c76ef CY |
651 | strings in most programming languages; in several languages, it can |
652 | also recognize and properly highlight various other important | |
653 | constructs, such as names of functions being defined or reserved | |
654 | keywords. Some special modes, such as Occur mode and Info mode, have | |
655 | completely specialized ways of assigning fonts for Font Lock mode. | |
b8f3a9e3 GM |
656 | |
657 | @findex font-lock-mode | |
c4e8acbc CY |
658 | Font Lock mode is turned on by default in all modes which support it. |
659 | You can toggle font-lock for each buffer with the command @kbd{M-x | |
660 | font-lock-mode}. Using a positive argument unconditionally turns Font | |
661 | Lock mode on, and a negative or zero argument turns it off. | |
b8f3a9e3 GM |
662 | |
663 | @findex global-font-lock-mode | |
664 | @vindex global-font-lock-mode | |
c4e8acbc CY |
665 | If you do not wish Font Lock mode to be turned on by default, |
666 | customize the variable @code{global-font-lock-mode} using the Customize | |
667 | interface (@pxref{Easy Customization}), or use the function | |
d239287a | 668 | @code{global-font-lock-mode} in your @file{.emacs} file, like this: |
b8f3a9e3 GM |
669 | |
670 | @example | |
c4e8acbc | 671 | (global-font-lock-mode 0) |
b8f3a9e3 GM |
672 | @end example |
673 | ||
43d67313 RS |
674 | @noindent |
675 | This variable, like all the variables that control Font Lock mode, | |
676 | take effect whenever fontification is done; that is, potentially at | |
677 | any time. | |
678 | ||
c4e8acbc | 679 | @findex turn-on-font-lock |
54952612 RS |
680 | If you have disabled Global Font Lock mode, you can still enable Font |
681 | Lock for specific major modes by adding the function | |
c4e8acbc CY |
682 | @code{turn-on-font-lock} to the mode hooks (@pxref{Hooks}). For |
683 | example, to enable Font Lock mode for editing C files, you can do this: | |
684 | ||
685 | @example | |
686 | (add-hook 'c-mode-hook 'turn-on-font-lock) | |
687 | @end example | |
0015d677 | 688 | |
b8f3a9e3 GM |
689 | Font Lock mode uses several specifically named faces to do its job, |
690 | including @code{font-lock-string-face}, @code{font-lock-comment-face}, | |
54952612 RS |
691 | and others. The easiest way to find them all is to use @kbd{M-x |
692 | customize-group @key{RET} font-lock-faces @key{RET}}. You can then | |
693 | use that customization buffer to customize the appearance of these | |
694 | faces. @xref{Face Customization}. | |
b8f3a9e3 | 695 | |
b8f3a9e3 GM |
696 | @vindex font-lock-maximum-decoration |
697 | The variable @code{font-lock-maximum-decoration} specifies the | |
698 | preferred level of fontification, for modes that provide multiple | |
699 | levels. Level 1 is the least amount of fontification; some modes | |
700 | support levels as high as 3. The normal default is ``as high as | |
701 | possible.'' You can specify an integer, which applies to all modes, or | |
702 | you can specify different numbers for particular major modes; for | |
703 | example, to use level 1 for C/C++ modes, and the default level | |
704 | otherwise, use this: | |
705 | ||
706 | @example | |
707 | (setq font-lock-maximum-decoration | |
708 | '((c-mode . 1) (c++-mode . 1))) | |
709 | @end example | |
710 | ||
711 | @vindex font-lock-maximum-size | |
712 | Fontification can be too slow for large buffers, so you can suppress | |
54952612 RS |
713 | it for buffers above a certain size. The variable |
714 | @code{font-lock-maximum-size} specifies a buffer size, beyond which | |
715 | buffer fontification is suppressed. | |
b8f3a9e3 GM |
716 | |
717 | @c @w is used below to prevent a bad page-break. | |
718 | @vindex font-lock-beginning-of-syntax-function | |
e07e854d EZ |
719 | @cindex incorrect fontification |
720 | @cindex parenthesis in column zero and fontification | |
721 | @cindex brace in column zero and fontification | |
b8f3a9e3 GM |
722 | Comment and string fontification (or ``syntactic'' fontification) |
723 | relies on analysis of the syntactic structure of the buffer text. For | |
174862cf RS |
724 | the sake of speed, some modes, including Lisp mode, rely on a special |
725 | convention: an open-parenthesis or open-brace in the leftmost column | |
726 | always defines the @w{beginning} of a defun, and is thus always | |
727 | outside any string or comment. (@xref{Left Margin Paren}.) If you | |
728 | don't follow this convention, Font Lock mode can misfontify the text | |
729 | that follows an open-parenthesis or open-brace in the leftmost column | |
730 | that is inside a string or comment. | |
b8f3a9e3 | 731 | |
6bb2ed9b | 732 | @cindex slow display during scrolling |
ae742cb5 CY |
733 | The variable @code{font-lock-beginning-of-syntax-function}, which is |
734 | always buffer-local, specifies how Font Lock mode can find a position | |
735 | guaranteed to be outside any comment or string. In modes which use | |
736 | the leftmost column parenthesis convention, the default value of the | |
737 | variable is @code{beginning-of-defun}---that tells Font Lock mode to | |
738 | use the convention. If you set this variable to @code{nil}, Font Lock | |
739 | no longer relies on the convention. This avoids incorrect results, | |
740 | but the price is that, in some cases, fontification for a changed text | |
741 | must rescan buffer text from the beginning of the buffer. This can | |
742 | considerably slow down redisplay while scrolling, particularly if you | |
743 | are close to the end of a large buffer. | |
b8f3a9e3 GM |
744 | |
745 | @findex font-lock-add-keywords | |
746 | Font Lock highlighting patterns already exist for many modes, but you | |
747 | may want to fontify additional patterns. You can use the function | |
748 | @code{font-lock-add-keywords}, to add your own highlighting patterns for | |
749 | a particular mode. For example, to highlight @samp{FIXME:} words in C | |
750 | comments, use this: | |
751 | ||
752 | @example | |
a152877d SM |
753 | (add-hook 'c-mode-hook |
754 | (lambda () | |
755 | (font-lock-add-keywords nil | |
ae742cb5 CY |
756 | '(("\\<\\(FIXME\\):" 1 |
757 | font-lock-warning-face t))))) | |
b8f3a9e3 GM |
758 | @end example |
759 | ||
4063fff3 EZ |
760 | @findex font-lock-remove-keywords |
761 | To remove keywords from the font-lock highlighting patterns, use the | |
cd77ce13 | 762 | function @code{font-lock-remove-keywords}. @xref{Search-based |
956c76ef | 763 | Fontification,,, elisp, The Emacs Lisp Reference Manual}. |
4063fff3 | 764 | |
3be9b0ca EZ |
765 | @cindex just-in-time (JIT) font-lock |
766 | @cindex background syntax highlighting | |
767 | Fontifying large buffers can take a long time. To avoid large | |
768 | delays when a file is visited, Emacs fontifies only the visible | |
769 | portion of a buffer. As you scroll through the buffer, each portion | |
956c76ef CY |
770 | that becomes visible is fontified as soon as it is displayed; this |
771 | type of Font Lock is called @dfn{Just-In-Time} (or @dfn{JIT}) Lock. | |
772 | You can control how JIT Lock behaves, including telling it to perform | |
773 | fontification while idle, by customizing variables in the | |
774 | customization group @samp{jit-lock}. @xref{Specific Customization}. | |
3be9b0ca | 775 | |
b8f3a9e3 | 776 | @node Highlight Interactively |
54952612 | 777 | @section Interactive Highlighting |
b8f3a9e3 GM |
778 | @cindex highlighting by matching |
779 | @cindex interactive highlighting | |
54952612 | 780 | @cindex Highlight Changes mode |
b8f3a9e3 | 781 | |
54952612 | 782 | @findex highlight-changes-mode |
956c76ef CY |
783 | Highlight Changes mode is a minor mode that @dfn{highlights} the parts |
784 | of the buffer were changed most recently, by giving that text a | |
785 | different face. To enable or disable Highlight Changes mode, use | |
786 | @kbd{M-x highlight-changes-mode}. | |
b8f3a9e3 | 787 | |
54952612 | 788 | @cindex Hi Lock mode |
b8f3a9e3 | 789 | @findex hi-lock-mode |
956c76ef CY |
790 | Hi Lock mode is a minor mode that highlights text that matches |
791 | regular expressions you specify. For example, you can use it to | |
792 | highlight all the references to a certain variable in a program source | |
793 | file, highlight certain parts in a voluminous output of some program, | |
794 | or highlight certain names in an article. To enable or disable Hi | |
795 | Lock mode, use the command @kbd{M-x hi-lock-mode}. To enable Hi Lock | |
796 | mode for all buffers, use @kbd{M-x global-hi-lock-mode} or place | |
797 | @code{(global-hi-lock-mode 1)} in your @file{.emacs} file. | |
54952612 RS |
798 | |
799 | Hi Lock mode works like Font Lock mode (@pxref{Font Lock}), except | |
800 | that you specify explicitly the regular expressions to highlight. You | |
801 | control them with these commands: | |
b8f3a9e3 GM |
802 | |
803 | @table @kbd | |
804 | @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET} | |
805 | @kindex C-x w h | |
806 | @findex highlight-regexp | |
cedf175b | 807 | Highlight text that matches @var{regexp} using face @var{face} |
54952612 RS |
808 | (@code{highlight-regexp}). The highlighting will remain as long as |
809 | the buffer is loaded. For example, to highlight all occurrences of | |
810 | the word ``whim'' using the default face (a yellow background) | |
811 | @kbd{C-x w h whim @key{RET} @key{RET}}. Any face can be used for | |
812 | highlighting, Hi Lock provides several of its own and these are | |
29a483ac JL |
813 | pre-loaded into a list of default values. While being prompted |
814 | for a face use @kbd{M-n} and @kbd{M-p} to cycle through them. | |
54952612 RS |
815 | |
816 | You can use this command multiple times, specifying various regular | |
817 | expressions to highlight in different ways. | |
b8f3a9e3 GM |
818 | |
819 | @item C-x w r @var{regexp} @key{RET} | |
820 | @kindex C-x w r | |
821 | @findex unhighlight-regexp | |
630acdcc | 822 | Unhighlight @var{regexp} (@code{unhighlight-regexp}). |
54952612 RS |
823 | |
824 | If you invoke this from the menu, you select the expression to | |
825 | unhighlight from a list. If you invoke this from the keyboard, you | |
826 | use the minibuffer. It will show the most recently added regular | |
827 | expression; use @kbd{M-p} to show the next older expression and | |
828 | @kbd{M-n} to select the next newer expression. (You can also type the | |
829 | expression by hand, with completion.) When the expression you want to | |
830 | unhighlight appears in the minibuffer, press @kbd{@key{RET}} to exit | |
831 | the minibuffer and unhighlight it. | |
b8f3a9e3 GM |
832 | |
833 | @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET} | |
834 | @kindex C-x w l | |
835 | @findex highlight-lines-matching-regexp | |
836 | @cindex lines, highlighting | |
837 | @cindex highlighting lines of text | |
04d0b662 | 838 | Highlight entire lines containing a match for @var{regexp}, using face |
b8f3a9e3 GM |
839 | @var{face} (@code{highlight-lines-matching-regexp}). |
840 | ||
841 | @item C-x w b | |
842 | @kindex C-x w b | |
843 | @findex hi-lock-write-interactive-patterns | |
844 | Insert all the current highlighting regexp/face pairs into the buffer | |
845 | at point, with comment delimiters to prevent them from changing your | |
54952612 RS |
846 | program. (This key binding runs the |
847 | @code{hi-lock-write-interactive-patterns} command.) | |
b8f3a9e3 | 848 | |
3173ce7e RS |
849 | These patterns are extracted from the comments, if appropriate, if you |
850 | invoke @kbd{M-x hi-lock-find-patterns}, or if you visit the file while | |
851 | Hi Lock mode is enabled (since that runs @code{hi-lock-find-patterns}). | |
b8f3a9e3 GM |
852 | |
853 | @item C-x w i | |
854 | @kindex C-x w i | |
855 | @findex hi-lock-find-patterns | |
3173ce7e RS |
856 | Extract regexp/face pairs from comments in the current buffer |
857 | (@code{hi-lock-find-patterns}). Thus, you can enter patterns | |
858 | interactively with @code{highlight-regexp}, store them into the file | |
859 | with @code{hi-lock-write-interactive-patterns}, edit them (perhaps | |
cedf175b | 860 | including different faces for different parenthesized parts of the |
3173ce7e RS |
861 | match), and finally use this command (@code{hi-lock-find-patterns}) to |
862 | have Hi Lock highlight the edited patterns. | |
b8f3a9e3 | 863 | |
3173ce7e | 864 | @vindex hi-lock-file-patterns-policy |
d439bcd8 | 865 | The variable @code{hi-lock-file-patterns-policy} controls whether Hi |
0419b8d6 GM |
866 | Lock mode should automatically extract and highlight patterns found in a |
867 | file when it is visited. Its value can be @code{nil} (never highlight), | |
868 | @code{ask} (query the user), or a function. If it is a function, | |
869 | @code{hi-lock-find-patterns} calls it with the patterns as argument; if | |
870 | the function returns non-@code{nil}, the patterns are used. The default | |
871 | is @code{ask}. Note that patterns are always highlighted if you call | |
872 | @code{hi-lock-find-patterns} directly, regardless of the value of this | |
873 | variable. | |
3173ce7e RS |
874 | |
875 | @vindex hi-lock-exclude-modes | |
876 | Also, @code{hi-lock-find-patterns} does nothing if the current major | |
877 | mode's symbol is a member of the list @code{hi-lock-exclude-modes}. | |
b8f3a9e3 GM |
878 | @end table |
879 | ||
fad78d58 RS |
880 | @node Fringes |
881 | @section Window Fringes | |
882 | @cindex fringes | |
883 | ||
884 | On a graphical display, each Emacs window normally has narrow | |
956c76ef CY |
885 | @dfn{fringes} on the left and right edges. The fringes are used to |
886 | display symbols that provide information about the text in the window. | |
fad78d58 RS |
887 | |
888 | The most common use of the fringes is to indicate a continuation | |
889 | line, when one line of text is split into multiple lines on the | |
890 | screen. The left fringe shows a curving arrow for each screen line | |
891 | except the first, indicating that ``this is not the real beginning.'' | |
892 | The right fringe shows a curving arrow for each screen line except the | |
34313041 EZ |
893 | last, indicating that ``this is not the real end.'' If the line's |
894 | direction is right-to-left (@pxref{Bidirectional Editing}), the | |
895 | meaning of the curving arrows in the left and right fringes are | |
896 | swapped. | |
fad78d58 | 897 | |
566da2e7 | 898 | The fringes indicate line truncation with short horizontal arrows |
fad78d58 | 899 | meaning ``there's more text on this line which is scrolled |
566da2e7 EZ |
900 | horizontally out of view;'' clicking the mouse on one of the arrows |
901 | scrolls the display horizontally in the direction of the arrow. The | |
d239287a | 902 | fringes can also indicate other things, such as empty lines, or where a |
566da2e7 | 903 | program you are debugging is executing (@pxref{Debuggers}). |
fad78d58 RS |
904 | |
905 | @findex set-fringe-style | |
906 | @findex fringe-mode | |
907 | You can enable and disable the fringes for all frames using | |
908 | @kbd{M-x fringe-mode}. To enable and disable the fringes | |
909 | for the selected frame, use @kbd{M-x set-fringe-style}. | |
910 | ||
9d2908a6 RS |
911 | @node Displaying Boundaries |
912 | @section Displaying Boundaries | |
913 | ||
914 | @vindex indicate-buffer-boundaries | |
915 | On a graphical display, Emacs can indicate the buffer boundaries in | |
916 | the fringes. It indicates the first line and the last line with | |
917 | angle images in the fringes. This can be combined with up and down | |
918 | arrow images which say whether it is possible to scroll the window up | |
919 | and down. | |
920 | ||
921 | The buffer-local variable @code{indicate-buffer-boundaries} controls | |
922 | how the buffer boundaries and window scrolling is indicated in the | |
923 | fringes. If the value is @code{left} or @code{right}, both angle and | |
924 | arrow bitmaps are displayed in the left or right fringe, respectively. | |
925 | ||
926 | If value is an alist, each element @code{(@var{indicator} . | |
927 | @var{position})} specifies the position of one of the indicators. | |
928 | The @var{indicator} must be one of @code{top}, @code{bottom}, | |
929 | @code{up}, @code{down}, or @code{t} which specifies the default | |
930 | position for the indicators not present in the alist. | |
931 | The @var{position} is one of @code{left}, @code{right}, or @code{nil} | |
932 | which specifies not to show this indicator. | |
933 | ||
934 | For example, @code{((top . left) (t . right))} places the top angle | |
935 | bitmap in left fringe, the bottom angle bitmap in right fringe, and | |
936 | both arrow bitmaps in right fringe. To show just the angle bitmaps in | |
937 | the left fringe, but no arrow bitmaps, use @code{((top . left) | |
938 | (bottom . left))}. | |
939 | ||
fad78d58 RS |
940 | @node Useless Whitespace |
941 | @section Useless Whitespace | |
942 | ||
943 | @cindex trailing whitespace | |
944 | @cindex whitespace, trailing | |
945 | @vindex show-trailing-whitespace | |
946 | It is easy to leave unnecessary spaces at the end of a line, or | |
947 | empty lines at the end of a file, without realizing it. In most | |
948 | cases, this @dfn{trailing whitespace} has no effect, but there are | |
956c76ef | 949 | special circumstances where it matters, and it can be a nuisance. |
fad78d58 | 950 | |
956c76ef CY |
951 | You can make trailing whitespace at the end of a line visible by |
952 | setting the buffer-local variable @code{show-trailing-whitespace} to | |
953 | @code{t}. Then Emacs displays trailing whitespace, using the face | |
954 | @code{trailing-whitespace}. | |
fad78d58 RS |
955 | |
956 | This feature does not apply when point is at the end of the line | |
957 | containing the whitespace. Strictly speaking, that is ``trailing | |
958 | whitespace'' nonetheless, but displaying it specially in that case | |
959 | looks ugly while you are typing in new text. In this special case, | |
960 | the location of point is enough to show you that the spaces are | |
961 | present. | |
962 | ||
963 | @findex delete-trailing-whitespace | |
ae742cb5 CY |
964 | Type @kbd{M-x delete-trailing-whitespace @key{RET}} to delete all |
965 | trailing whitespace within the buffer's accessible portion | |
966 | (@pxref{Narrowing}). This command does not remove newline characters. | |
fad78d58 | 967 | |
23e3383d | 968 | @vindex indicate-empty-lines |
877db12e RS |
969 | @cindex unused lines |
970 | @cindex fringes, and unused line indication | |
971 | Emacs can indicate unused lines at the end of the window with a | |
972 | small image in the left fringe (@pxref{Fringes}). The image appears | |
973 | for window lines that do not correspond to any buffer text. Blank | |
974 | lines at the end of the buffer then stand out because they do not have | |
975 | this image in the fringe. | |
976 | ||
977 | To enable this feature, set the buffer-local variable | |
cd61af01 SM |
978 | @code{indicate-empty-lines} to a non-@code{nil} value. You can enable |
979 | or disable this feature for all new buffers by setting the default | |
980 | value of this variable, e.g.@: @code{(setq-default | |
981 | indicate-empty-lines t)};. (This feature currently doesn't work on | |
982 | text-only terminals.) | |
fad78d58 | 983 | |
6bf7aab6 DL |
984 | @node Selective Display |
985 | @section Selective Display | |
4946337d | 986 | @cindex selective display |
6bf7aab6 DL |
987 | @findex set-selective-display |
988 | @kindex C-x $ | |
989 | ||
956c76ef CY |
990 | Emacs has the ability to hide lines indented more than a given |
991 | number of columns. You can use this to get an overview of a part of a | |
992 | program. | |
6bf7aab6 | 993 | |
d239287a LT |
994 | To hide lines in the current buffer, type @kbd{C-x $} |
995 | (@code{set-selective-display}) with a numeric argument @var{n}. Then | |
996 | lines with at least @var{n} columns of indentation disappear from the | |
997 | screen. The only indication of their presence is that three dots | |
998 | (@samp{@dots{}}) appear at the end of each visible line that is | |
999 | followed by one or more hidden ones. | |
6bf7aab6 DL |
1000 | |
1001 | The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as | |
1002 | if they were not there. | |
1003 | ||
1004 | The hidden lines are still present in the buffer, and most editing | |
1005 | commands see them as usual, so you may find point in the middle of the | |
1006 | hidden text. When this happens, the cursor appears at the end of the | |
1007 | previous line, after the three dots. If point is at the end of the | |
1008 | visible line, before the newline that ends it, the cursor appears before | |
1009 | the three dots. | |
1010 | ||
1011 | To make all lines visible again, type @kbd{C-x $} with no argument. | |
1012 | ||
1013 | @vindex selective-display-ellipses | |
1014 | If you set the variable @code{selective-display-ellipses} to | |
1015 | @code{nil}, the three dots do not appear at the end of a line that | |
1016 | precedes hidden lines. Then there is no visible indication of the | |
1017 | hidden lines. This variable becomes local automatically when set. | |
1018 | ||
0015d677 RS |
1019 | See also @ref{Outline Mode} for another way to hide part of |
1020 | the text in a buffer. | |
1021 | ||
6bf7aab6 DL |
1022 | @node Optional Mode Line |
1023 | @section Optional Mode Line Features | |
1024 | ||
b213b767 LK |
1025 | @cindex buffer size display |
1026 | @cindex display of buffer size | |
1027 | @findex size-indication-mode | |
1028 | The buffer percentage @var{pos} indicates the percentage of the | |
1029 | buffer above the top of the window. You can additionally display the | |
1030 | size of the buffer by typing @kbd{M-x size-indication-mode} to turn on | |
1031 | Size Indication mode. The size will be displayed immediately | |
1032 | following the buffer percentage like this: | |
1033 | ||
1034 | @example | |
1035 | @var{POS} of @var{SIZE} | |
1036 | @end example | |
1037 | ||
1038 | @noindent | |
1039 | Here @var{SIZE} is the human readable representation of the number of | |
1040 | characters in the buffer, which means that @samp{k} for 10^3, @samp{M} | |
1041 | for 10^6, @samp{G} for 10^9, etc., are used to abbreviate. | |
1042 | ||
e598186c RS |
1043 | @cindex line number display |
1044 | @cindex display of line number | |
6bf7aab6 DL |
1045 | @findex line-number-mode |
1046 | The current line number of point appears in the mode line when Line | |
1047 | Number mode is enabled. Use the command @kbd{M-x line-number-mode} to | |
1048 | turn this mode on and off; normally it is on. The line number appears | |
b213b767 | 1049 | after the buffer percentage @var{pos}, with the letter @samp{L} to |
79199dd2 AM |
1050 | indicate what it is. |
1051 | ||
1052 | @cindex Column Number mode | |
1053 | @cindex mode, Column Number | |
1054 | @findex column-number-mode | |
1055 | Similarly, you can display the current column number by turning on | |
1056 | Column number mode with @kbd{M-x column-number-mode}. The column | |
1057 | number is indicated by the letter @samp{C}. However, when both of | |
1058 | these modes are enabled, the line and column numbers are displayed in | |
1059 | parentheses, the line number first, rather than with @samp{L} and | |
1060 | @samp{C}. For example: @samp{(561,2)}. @xref{Minor Modes}, for more | |
1061 | information about minor modes and about how to use these commands. | |
6bf7aab6 | 1062 | |
43f971ab EZ |
1063 | @cindex narrowing, and line number display |
1064 | If you have narrowed the buffer (@pxref{Narrowing}), the displayed | |
1065 | line number is relative to the accessible portion of the buffer. | |
54952612 RS |
1066 | Thus, it isn't suitable as an argument to @code{goto-line}. (Use |
1067 | @code{what-line} command to see the line number relative to the whole | |
1068 | file.) | |
43f971ab | 1069 | |
6bf7aab6 DL |
1070 | @vindex line-number-display-limit |
1071 | If the buffer is very large (larger than the value of | |
956c76ef CY |
1072 | @code{line-number-display-limit}), Emacs won't compute the line |
1073 | number, because that would be too slow; therefore, the line number | |
1074 | won't appear on the mode-line. To remove this limit, set | |
1075 | @code{line-number-display-limit} to @code{nil}. | |
43f971ab EZ |
1076 | |
1077 | @vindex line-number-display-limit-width | |
1078 | Line-number computation can also be slow if the lines in the buffer | |
956c76ef CY |
1079 | are too long. For this reason, Emacs doesn't display line numbers if |
1080 | the average width, in characters, of lines near point is larger than | |
1081 | the value of @code{line-number-display-limit-width}. The default | |
1082 | value is 200 characters. | |
6bf7aab6 | 1083 | |
6bf7aab6 DL |
1084 | @findex display-time |
1085 | @cindex time (on mode line) | |
1086 | Emacs can optionally display the time and system load in all mode | |
4f00b8c1 DL |
1087 | lines. To enable this feature, type @kbd{M-x display-time} or customize |
1088 | the option @code{display-time-mode}. The information added to the mode | |
bb3865e8 | 1089 | line looks like this: |
6bf7aab6 DL |
1090 | |
1091 | @example | |
1092 | @var{hh}:@var{mm}pm @var{l.ll} | |
1093 | @end example | |
1094 | ||
1095 | @noindent | |
1096 | @vindex display-time-24hr-format | |
1097 | Here @var{hh} and @var{mm} are the hour and minute, followed always by | |
4f1948eb EZ |
1098 | @samp{am} or @samp{pm}. @var{l.ll} is the average number, collected |
1099 | for the last few minutes, of processes in the whole system that were | |
1100 | either running or ready to run (i.e.@: were waiting for an available | |
1101 | processor). (Some fields may be missing if your operating system | |
1102 | cannot support them.) If you prefer time display in 24-hour format, | |
1103 | set the variable @code{display-time-24hr-format} to @code{t}. | |
6bf7aab6 DL |
1104 | |
1105 | @cindex mail (on mode line) | |
72bd7b7b DL |
1106 | @vindex display-time-use-mail-icon |
1107 | @vindex display-time-mail-face | |
fad78d58 RS |
1108 | @vindex display-time-mail-file |
1109 | @vindex display-time-mail-directory | |
6bf7aab6 | 1110 | The word @samp{Mail} appears after the load level if there is mail |
72bd7b7b DL |
1111 | for you that you have not read yet. On a graphical display you can use |
1112 | an icon instead of @samp{Mail} by customizing | |
1113 | @code{display-time-use-mail-icon}; this may save some space on the mode | |
1114 | line. You can customize @code{display-time-mail-face} to make the mail | |
fad78d58 RS |
1115 | indicator prominent. Use @code{display-time-mail-file} to specify |
1116 | the mail file to check, or set @code{display-time-mail-directory} | |
1117 | to specify the directory to check for incoming mail (any nonempty regular | |
1118 | file in the directory is considered as ``newly arrived mail''). | |
6bf7aab6 | 1119 | |
956c76ef CY |
1120 | @cindex mail (on mode line) |
1121 | @findex display-battery-mode | |
1122 | @vindex display-battery-mode | |
1123 | @vindex battery-mode-line-format | |
1124 | When running Emacs on a laptop computer, you can display the battery | |
1125 | charge on the mode-line, by using the command | |
1126 | @code{display-battery-mode} or customizing the variable | |
1127 | @code{display-battery-mode}. The variable | |
1128 | @code{battery-mode-line-format} determines the way the battery charge | |
1129 | is displayed; the exact mode-line message depends on the operating | |
1130 | system, and it usually shows the current battery charge as a | |
1131 | percentage of the total charge. | |
1132 | ||
47d7776c | 1133 | @cindex mode line, 3D appearance |
bd3ead08 EZ |
1134 | @cindex attributes of mode line, changing |
1135 | @cindex non-integral number of lines in a window | |
04d0b662 RS |
1136 | By default, the mode line is drawn on graphics displays with |
1137 | 3D-style highlighting, like that of a button when it is not being | |
1138 | pressed. If you don't like this effect, you can disable the 3D | |
1139 | highlighting of the mode line, by customizing the attributes of the | |
54952612 | 1140 | @code{mode-line} face. @xref{Face Customization}. |
bd3ead08 | 1141 | |
b9e58bf2 | 1142 | @cindex non-selected windows, mode line appearance |
ac6875fc | 1143 | By default, the mode line of nonselected windows is displayed in a |
1c9f5f23 | 1144 | different face, called @code{mode-line-inactive}. Only the selected |
ac6875fc RS |
1145 | window is displayed in the @code{mode-line} face. This helps show |
1146 | which window is selected. When the minibuffer is selected, since | |
1147 | it has no mode line, the window from which you activated the minibuffer | |
1148 | has its mode line displayed using @code{mode-line}; as a result, | |
1149 | ordinary entry to the minibuffer does not change any mode lines. | |
1150 | ||
1151 | @vindex mode-line-in-non-selected-windows | |
1152 | You can disable use of @code{mode-line-inactive} by setting variable | |
1c9f5f23 KS |
1153 | @code{mode-line-in-non-selected-windows} to @code{nil}; then all mode |
1154 | lines are displayed in the @code{mode-line} face. | |
b9e58bf2 | 1155 | |
589a3f9f RS |
1156 | @vindex eol-mnemonic-unix |
1157 | @vindex eol-mnemonic-dos | |
1158 | @vindex eol-mnemonic-mac | |
1159 | @vindex eol-mnemonic-undecided | |
1160 | You can customize the mode line display for each of the end-of-line | |
1161 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
1162 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
54952612 | 1163 | @code{eol-mnemonic-undecided} to the strings you prefer. |
589a3f9f | 1164 | |
6bf7aab6 DL |
1165 | @node Text Display |
1166 | @section How Text Is Displayed | |
1167 | @cindex characters (in text) | |
1168 | ||
76dd3692 | 1169 | @acronym{ASCII} printing characters (octal codes 040 through 0176) in Emacs |
06723f0f | 1170 | buffers are displayed with their graphics, as are non-@acronym{ASCII} multibyte |
6bf7aab6 DL |
1171 | printing characters (octal codes above 0400). |
1172 | ||
956c76ef | 1173 | @vindex tab-width |
956c76ef CY |
1174 | Some @acronym{ASCII} control characters are displayed in special |
1175 | ways. The newline character (octal code 012) is displayed by starting | |
1176 | a new line. The tab character (octal code 011) is displayed by moving | |
1177 | to the next tab stop column (normally every 8 columns). The number of | |
1178 | spaces per tab is controlled by the variable @code{tab-width}, which | |
1179 | must have an integer value between 1 and 1000, inclusive, and is made | |
cd61af01 | 1180 | buffer-local by changing it. Note that how the tab character in the buffer |
956c76ef | 1181 | is displayed has nothing to do with the definition of @key{TAB} as a |
cd61af01 | 1182 | command. |
6bf7aab6 | 1183 | |
76dd3692 | 1184 | Other @acronym{ASCII} control characters are normally displayed as a caret |
6bf7aab6 | 1185 | (@samp{^}) followed by the non-control version of the character; thus, |
54952612 RS |
1186 | control-A is displayed as @samp{^A}. The caret appears in face |
1187 | @code{escape-glyph}. | |
1188 | ||
1189 | Non-@acronym{ASCII} characters 0200 through 0237 (octal) are | |
1190 | displayed with octal escape sequences; thus, character code 0230 | |
1191 | (octal) is displayed as @samp{\230}. The backslash appears in face | |
1192 | @code{escape-glyph}. | |
1193 | ||
1194 | @vindex ctl-arrow | |
1195 | If the variable @code{ctl-arrow} is @code{nil}, control characters in | |
1196 | the buffer are displayed with octal escape sequences, except for newline | |
1197 | and tab. Altering the value of @code{ctl-arrow} makes it local to the | |
1198 | current buffer; until that time, the default value is in effect. The | |
1199 | default is initially @code{t}. | |
1200 | ||
1201 | The display of character codes 0240 through 0377 (octal) may be | |
1202 | either as escape sequences or as graphics. They do not normally occur | |
1203 | in multibyte buffers, but if they do, they are displayed as Latin-1 | |
1204 | graphics. In unibyte mode, if you enable European display they are | |
1205 | displayed using their graphics (assuming your terminal supports them), | |
662286c3 | 1206 | otherwise as escape sequences. @xref{Unibyte Mode}. |
6bf7aab6 | 1207 | |
470a11a3 | 1208 | @vindex nobreak-char-display |
367aa52c RS |
1209 | @cindex no-break space, display |
1210 | @cindex no-break hyphen, display | |
1211 | @cindex soft hyphen, display | |
470a11a3 RS |
1212 | Some character sets define ``no-break'' versions of the space and |
1213 | hyphen characters, which are used where a line should not be broken. | |
1214 | Emacs normally displays these characters with special faces | |
1215 | (respectively, @code{nobreak-space} and @code{escape-glyph}) to | |
1216 | distinguish them from ordinary spaces and hyphens. You can turn off | |
1217 | this feature by setting the variable @code{nobreak-char-display} to | |
1218 | @code{nil}. If you set the variable to any other value, that means to | |
1219 | prefix these characters with an escape character. | |
b5cced4b | 1220 | |
54952612 RS |
1221 | You can customize the way any particular character code is displayed |
1222 | by means of a display table. @xref{Display Tables,, Display Tables, | |
1223 | elisp, The Emacs Lisp Reference Manual}. | |
1224 | ||
0eb025fb EZ |
1225 | @cindex glyphless characters |
1226 | @cindex characters with no font glyphs | |
1227 | On graphics displays, some characters could have no glyphs in any of | |
1228 | the fonts available to Emacs. On text terminals, some characters | |
1229 | could be impossible to encode with the terminal coding system | |
1230 | (@pxref{Terminal Coding}). Emacs can display such @dfn{glyphless} | |
1231 | characters using one of the following methods: | |
1232 | ||
1233 | @table @code | |
1234 | @item zero-width | |
1235 | Don't display the character. | |
1236 | ||
1237 | @item thin-space | |
1238 | Display a thin space, 1-pixel wide on graphics displays or 1-character | |
1239 | wide on text terminals. | |
1240 | ||
1241 | @item empty-box | |
1242 | Display an empty box. | |
1243 | ||
1244 | @item acronym | |
1245 | Display the acronym of the character's name (such as @sc{zwnj} or | |
1246 | @sc{rlm}) in a box. | |
1247 | ||
1248 | @item hex-code | |
1249 | Display the Unicode codepoint of the character in hexadecimal | |
1250 | notation, in a box. | |
1251 | @end table | |
1252 | ||
1253 | @noindent | |
1254 | @cindex @code{glyphless-char} face | |
1255 | With the exception of @code{zero-width}, all other methods draw these | |
1256 | characters in a special face @code{glyphless-char}, which you can | |
1257 | customize. | |
1258 | ||
1259 | @vindex glyphless-char-display-control | |
1260 | @vindex char-acronym-table | |
1261 | To control what glyphless characters are displayed using which method, | |
1262 | customize the variable @code{glyphless-char-display-control}; see its | |
1263 | doc string for the details. For even finer control, set the elements | |
1264 | of 2 char-tables: @code{glyphless-char-display} and | |
1265 | @code{char-acronym-table}. | |
1266 | ||
0015d677 RS |
1267 | @node Cursor Display |
1268 | @section Displaying the Cursor | |
1269 | ||
1270 | @findex blink-cursor-mode | |
1271 | @vindex blink-cursor-alist | |
1272 | @cindex cursor, locating visually | |
1273 | @cindex cursor, blinking | |
1274 | You can customize the cursor's color, and whether it blinks, using | |
1275 | the @code{cursor} Custom group (@pxref{Easy Customization}). On | |
098199b1 | 1276 | a graphical display, the command @kbd{M-x blink-cursor-mode} enables |
0015d677 RS |
1277 | or disables the blinking of the cursor. (On text terminals, the |
1278 | terminal itself blinks the cursor, and Emacs has no control over it.) | |
1279 | You can control how the cursor appears when it blinks off by setting | |
1280 | the variable @code{blink-cursor-alist}. | |
1281 | ||
4cb4f3ba LMI |
1282 | @vindex cursor-type |
1283 | You can change the shape of the cursor from the default ``box'' look | |
1284 | to a bar by altering the @code{cursor-type} variable. | |
1285 | ||
468160b7 SM |
1286 | @vindex visible-cursor |
1287 | Some text terminals offer two different cursors: the normal cursor | |
1288 | and the very visible cursor, where the latter may be e.g. bigger or | |
43d67313 RS |
1289 | blinking. By default Emacs uses the very visible cursor, and switches |
1290 | to it when you start or resume Emacs. If the variable | |
1291 | @code{visible-cursor} is @code{nil} when Emacs starts or resumes, it | |
1292 | doesn't switch, so it uses the normal cursor. | |
468160b7 | 1293 | |
0015d677 RS |
1294 | @cindex cursor in non-selected windows |
1295 | @vindex cursor-in-non-selected-windows | |
93870ce2 RS |
1296 | Normally, the cursor appears in non-selected windows without |
1297 | blinking, with the same appearance as when the blinking cursor blinks | |
5a7f4c1b | 1298 | ``off.'' For a box cursor, this is a hollow box; for a bar cursor, |
0015d677 | 1299 | this is a thinner bar. To turn off cursors in non-selected windows, |
93870ce2 RS |
1300 | customize the variable @code{cursor-in-non-selected-windows} and |
1301 | assign it a @code{nil} value. | |
0015d677 RS |
1302 | |
1303 | @vindex x-stretch-cursor | |
1304 | @cindex wide block cursor | |
098199b1 | 1305 | On graphical displays, Emacs can optionally draw the block cursor |
0015d677 RS |
1306 | as wide as the character under the cursor---for example, if the cursor |
1307 | is on a tab character, it would cover the full width occupied by that | |
1308 | tab character. To enable this feature, set the variable | |
1309 | @code{x-stretch-cursor} to a non-@code{nil} value. | |
1310 | ||
1311 | @findex hl-line-mode | |
1312 | @findex global-hl-line-mode | |
1313 | @cindex highlight current line | |
54952612 RS |
1314 | To make the cursor even more visible, you can use HL Line mode, a |
1315 | minor mode that highlights the line containing point. Use @kbd{M-x | |
0015d677 RS |
1316 | hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x |
1317 | global-hl-line-mode} enables or disables the same mode globally. | |
1318 | ||
9d2908a6 RS |
1319 | @node Line Truncation |
1320 | @section Truncation of Lines | |
0015d677 RS |
1321 | |
1322 | @cindex truncation | |
1323 | @cindex line truncation, and fringes | |
9c6361c9 MR |
1324 | As an alternative to continuation (@pxref{Continuation Lines}), Emacs |
1325 | can display long lines by @dfn{truncation}. This means that all the | |
1326 | characters that do not fit in the width of the screen or window do not | |
1327 | appear at all. On graphical displays, a small straight arrow in the | |
1328 | fringe indicates truncation at either end of the line. On text-only | |
34313041 EZ |
1329 | terminals, @samp{$} appears in the leftmost column when there is text |
1330 | truncated to the left, and in the rightmost column when there is text | |
9c6361c9 | 1331 | truncated to the right. |
0015d677 RS |
1332 | |
1333 | @vindex truncate-lines | |
1334 | @findex toggle-truncate-lines | |
1335 | Horizontal scrolling automatically causes line truncation | |
1336 | (@pxref{Horizontal Scrolling}). You can explicitly enable line | |
1337 | truncation for a particular buffer with the command @kbd{M-x | |
1338 | toggle-truncate-lines}. This works by locally changing the variable | |
1339 | @code{truncate-lines}. If that variable is non-@code{nil}, long lines | |
1340 | are truncated; if it is @code{nil}, they are continued onto multiple | |
1341 | screen lines. Setting the variable @code{truncate-lines} in any way | |
1342 | makes it local to the current buffer; until that time, the default | |
1343 | value is in effect. The default value is normally @code{nil}. | |
6bf7aab6 DL |
1344 | |
1345 | @c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows. | |
1346 | If the variable @code{truncate-partial-width-windows} is | |
1347 | non-@code{nil}, it forces truncation rather than continuation in any | |
1348 | window less than the full width of the screen or frame, regardless of | |
956c76ef | 1349 | the value of @code{truncate-lines}. See also @ref{Display,, Display, |
6bf7aab6 DL |
1350 | elisp, The Emacs Lisp Reference Manual}. |
1351 | ||
80174a97 KS |
1352 | @vindex overflow-newline-into-fringe |
1353 | If the variable @code{overflow-newline-into-fringe} is | |
54952612 RS |
1354 | non-@code{nil} on a graphical display, then Emacs does not continue or |
1355 | truncate a line which is exactly as wide as the window. Instead, the | |
1356 | newline overflows into the right fringe, and the cursor appears in the | |
1357 | fringe when positioned on that newline. | |
80174a97 | 1358 | |
458db4b6 CY |
1359 | @node Visual Line Mode |
1360 | @section Visual Line Mode | |
1361 | ||
1362 | @cindex word wrap | |
1363 | Another alternative to ordinary line continuation is to use | |
1364 | @dfn{word wrap}. Here, each long logical line is divided into two or | |
1365 | more screen lines, like in ordinary line continuation. However, Emacs | |
1366 | attempts to wrap the line at word boundaries near the right window | |
1367 | edge. This makes the text easier to read, as wrapping does not occur | |
1368 | in the middle of words. | |
1369 | ||
1370 | @cindex Visual Line mode | |
1371 | @findex visual-line-mode | |
1372 | @findex global-visual-line-mode | |
1373 | Word wrap is enabled by Visual Line mode, an optional minor mode. | |
1374 | To turn on Visual Line mode in the current buffer, type @kbd{M-x | |
1375 | visual-line-mode}; repeating this command turns it off. You can also | |
1376 | turn on Visual Line mode using the menu bar: in the Options menu, | |
1377 | select the @samp{Line Wrapping in this Buffer} submenu, followed by | |
1378 | the @samp{Word Wrap (Visual Line Mode)} menu item. While Visual Line | |
1379 | mode is enabled, the mode-line shows the string @samp{wrap} in the | |
1380 | mode display. The command @kbd{M-x global-visual-line-mode} toggles | |
1381 | Visual Line mode in all buffers. | |
1382 | ||
1383 | @findex beginning-of-visual-line | |
1384 | @findex end-of-visual-line | |
1385 | @findex next-logical-line | |
1386 | @findex previous-logical-line | |
1387 | In Visual Line mode, some editing commands work on screen lines | |
1388 | instead of logical lines: @kbd{C-a} (@code{beginning-of-visual-line}) | |
1389 | moves to the beginning of the screen line, @kbd{C-e} | |
1390 | (@code{end-of-visual-line}) moves to the end of the screen line, and | |
1391 | @kbd{C-k} (@code{kill-visual-line}) kills text to the end of the | |
21927cd7 CY |
1392 | screen line. |
1393 | ||
1394 | To move by logical lines, use the commands @kbd{M-x | |
1395 | next-logical-line} and @kbd{M-x previous-logical-line}. These move | |
1396 | point to the next logical line and the previous logical line | |
1397 | respectively, regardless of whether Visual Line mode is enabled. If | |
1398 | you use these commands frequently, it may be convenient to assign key | |
1399 | bindings to them. @xref{Init Rebinding}. | |
458db4b6 CY |
1400 | |
1401 | By default, word-wrapped lines do not display fringe indicators. | |
1402 | Visual Line mode is often used to edit files that contain many long | |
1403 | logical lines, so having a fringe indicator for each wrapped line | |
1404 | would be visually distracting. You can change this by customizing the | |
1405 | variable @code{visual-line-fringe-indicators}. | |
1406 | ||
9d2908a6 RS |
1407 | @node Display Custom |
1408 | @section Customization of Display | |
80174a97 | 1409 | |
9d2908a6 RS |
1410 | This section describes variables (@pxref{Variables}) that you can |
1411 | change to customize how Emacs displays. Beginning users can skip | |
1412 | it. | |
1413 | @c the reason for that pxref is because an xref early in the | |
1414 | @c ``echo area'' section leads here. | |
62ea61af | 1415 | |
9d2908a6 RS |
1416 | @vindex visible-bell |
1417 | If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts | |
1418 | to make the whole screen blink when it would normally make an audible bell | |
1419 | sound. This variable has no effect if your terminal does not have a way | |
1420 | to make the screen blink. | |
80174a97 | 1421 | |
9d2908a6 RS |
1422 | @vindex echo-keystrokes |
1423 | The variable @code{echo-keystrokes} controls the echoing of multi-character | |
1424 | keys; its value is the number of seconds of pause required to cause echoing | |
1425 | to start, or zero, meaning don't echo at all. The value takes effect when | |
1426 | there is someting to echo. @xref{Echo Area}. | |
80174a97 | 1427 | |
6bf7aab6 | 1428 | @vindex baud-rate |
54952612 | 1429 | The variable @anchor{baud-rate}@code{baud-rate} holds the output |
b4a1a8b2 CY |
1430 | speed of the terminal. Setting this variable does not change the |
1431 | speed of actual data transmission, but the value is used for | |
1432 | calculations. On text-only terminals, it affects padding, and | |
1433 | decisions about whether to scroll part of the screen or redraw it | |
1434 | instead. It also affects the behavior of incremental search. On | |
1435 | graphical displays, @code{baud-rate} is only used to determine how | |
1436 | frequently to look for pending input during display updating. A | |
e598186c RS |
1437 | higher value of @code{baud-rate} means that check for pending input |
1438 | will be done less frequently. | |
6bf7aab6 | 1439 | |
b4a1a8b2 | 1440 | @cindex mouse pointer |
62095f01 | 1441 | @cindex hourglass pointer display |
b4a1a8b2 | 1442 | @vindex display-hourglass |
62095f01 | 1443 | @vindex hourglass-delay |
b4a1a8b2 CY |
1444 | On graphical displays, Emacs displays the mouse pointer as an |
1445 | hourglass if Emacs is busy. To disable this feature, set the variable | |
1446 | @code{display-hourglass} to @code{nil}. The variable | |
1447 | @code{hourglass-delay} determines the number of seconds of ``busy | |
1448 | time'' before the hourglass is shown; the default is 1. | |
1449 | ||
1450 | @vindex make-pointer-invisible | |
1451 | If the mouse pointer lies inside an Emacs frame, Emacs makes it | |
1452 | invisible each time you type a character to insert text, to prevent it | |
1453 | from obscuring the text. (To be precise, the hiding occurs when you | |
1454 | type a ``self-inserting'' character. @xref{Inserting Text}.) Moving | |
1455 | the mouse pointer makes it visible again. To disable this feature, | |
1456 | set the variable @code{make-pointer-invisible} to @code{nil}. | |
1457 | ||
1458 | @vindex underline-minimum-offset | |
1459 | @vindex x-underline-at-descent-line | |
1460 | On graphical displays, the variable @code{underline-minimum-offset} | |
1461 | determines the minimum distance between the baseline and underline, in | |
1462 | pixels, for underlined text. By default, the value is 1; increasing | |
1463 | it may improve the legibility of underlined text for certain fonts. | |
1464 | (However, Emacs will never draw the underline below the current line | |
1465 | area.) The variable @code{x-underline-at-descent-line} determines how | |
1466 | to draw underlined text. The default is @code{nil}, which means to | |
1467 | draw it at the baseline level of the font; if you change it to | |
1468 | @code{nil}, Emacs draws the underline at the same height as the font's | |
1469 | descent line. | |
099bfef9 | 1470 | |
9d2908a6 | 1471 | @vindex overline-margin |
b4a1a8b2 CY |
1472 | The variable @code{overline-margin} specifies the vertical position |
1473 | of an overline above the text, including the height of the overline | |
1474 | itself, in pixels; the default is 2. | |
9d2908a6 | 1475 | |
a66b12be RS |
1476 | @findex tty-suppress-bold-inverse-default-colors |
1477 | On some text-only terminals, bold face and inverse video together | |
1478 | result in text that is hard to read. Call the function | |
1479 | @code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil} | |
1480 | argument to suppress the effect of bold-face in this case. | |
1481 | ||
54952612 RS |
1482 | @vindex no-redraw-on-reenter |
1483 | On a text-only terminal, when you reenter Emacs after suspending, Emacs | |
1484 | normally clears the screen and redraws the entire display. On some | |
1485 | terminals with more than one page of memory, it is possible to arrange | |
1486 | the termcap entry so that the @samp{ti} and @samp{te} strings (output | |
1487 | to the terminal when Emacs is entered and exited, respectively) switch | |
1488 | between pages of memory so as to use one page for Emacs and another | |
43d67313 | 1489 | page for other output. On such terminals, you might want to set the variable |
54952612 RS |
1490 | @code{no-redraw-on-reenter} non-@code{nil}; this tells Emacs to |
1491 | assume, when resumed, that the screen page it is using still contains | |
1492 | what Emacs last wrote there. |