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Since only part of a large buffer fits in the window, Emacs tries to show the part that is likely to be
interesting. The display control commands allow you to specify which part of the text you want to see.
- C-l Clear screen and redisplay, scrolling the selected window
to center point vertically within it (
recenter).
C-v Scroll forward (a windowful or a specified number of lines) (scroll-up).
NEXT Likewise, scroll forward. M-v Scroll backward (scroll-down).
PRIOR Likewise, scroll backward. arg C-l Scroll so point is on screen line arg (recenter).
C-x Scroll text in current window to the left (scroll-left). C-x >
Scroll to the right (scroll-right). C-x $ Make deeply indented lines
invisible (set-selective-display).
The names of all scroll commands are based on the direction that the text moves in the window.
Thus, the command to scrolling
forward is called scroll-up, since the text
moves up.
If a buffer contains text
that is too large to fit entirely within a window that
is displaying the buffer, Emacs shows a contiguous
portion of the text. The portion shown always contains
point.
Scrolling means moving text up or down in the window
so that different parts of the text are visible. Scrolling forward means that text moves up, and new text
appears at the bottom. Scrolling backward moves text down and new text
appears at the top.
Scrolling happens automatically if you move point past the bottom or top of the window. You can also explicitly request scrolling with the commands in this section.
- C-l Clear screen and redisplay, scrolling the selected window
to center point vertically within it (
recenter).
C-v Scroll forward (a windowful or a specified number of lines) (scroll-up).
NEXT Likewise, scroll forward. M-v Scroll backward (scroll-down).
PRIOR Likewise, scroll backward. arg C-l Scroll so point is on line arg (recenter). C-M-l
Scroll heuristically to bring useful information onto the screen (reposition-window).
The most basic scrolling command is C-l (recenter) with no
argument. It clears the entire screen and redisplays all windows. In addition, it scrolls
the selected window so that point is halfway down from the top of the window.
The scrolling commands C-v and M-v
let you move all the text in the window up or down a few lines. C-v (scroll-up)
with an argument shows you that many more lines at the bottom of the window, moving the text
and point up together as C-l might. C-v
with a negative argument shows you more lines at the top of the window. M-v (scroll-down) is like
C-v, but moves in the opposite direction. The function keys NEXT and
PRIOR are equivalent to C-v and M-v.
To read the buffer a windowful at a time, use C-v
with no argument. It takes the last two lines at the bottom of the window and puts them at the top, followed by nearly a
whole windowful of lines not previously visible. If point
was in the text scrolled off the top, it moves to the
new top of the window. M-v with no argument
moves backward with overlap similarly. The number of lines of overlap across a C-v
or M-v is controlled by the variable next-screen-context-lines;
by default, it is two.
Another way to do scrolling is with C-l
with a numeric argument. C-l does not clear the screen when given an argument;
it only scrolls the selected window. With a positive
argument n, it repositions text to put point n lines down from the top. An argument
of zero puts point on the very top line. Point does not move with respect to the text; rather, the text
and point move rigidly on the screen. C-l
with a negative argument puts point that many lines
from the bottom of the window. For example, C-u -
1 C-l puts point on the bottom line, and C-u
- 5 C-l puts it five lines from the bottom. Just C-u as argument, as in C-u
C-l, scrolls point to the center of the screen.
The C-M-l command (reposition-window) scrolls the current window heuristically in a way designed to get useful
information onto the screen. For example, in a Lisp file, this command tries to get the entire current defun onto the screen if possible.
Scrolling happens automatically if point has moved out of the visible portion of the text when it is time to display. Usually the scrolling is done so as to put point vertically centered within the window. However, if the variable
scroll-step has a nonzero value, an attempt is made to scroll the buffer by that many lines; if that is enough to bring point back into visibility, that is what is done.
- C-x Scroll text in current window to the left (
scroll-left). C-x >
Scroll to the right (scroll-right).
The text in a window
can also be scrolled horizontally. This means that each line of text is shifted sideways in the window, and one or more characters at the beginning of
each line are not displayed at all. When a window has
been scrolled horizontally in this way, text lines are
truncated rather than continued (see section Continuation
Lines), with a $ appearing in the first column when there is text truncated to the left, and in the last column when
there is text truncated to the right.
The command C-x (scroll-left)
scrolls the selected window to the left by n
columns with argument n. This moves part of the beginning of each line off the
left edge of the window. With no argument, it scrolls
by almost the full width of the window (two columns
less, to be precise).
C-x > (scroll-right) scrolls similarly to the right. The window cannot be scrolled any farther to the right once
it is displayed normally (with each line starting at the window's
left margin); attempting to do so has no effect. This means that you don't have to
calculate the argument precisely for C-x >; any sufficiently large argument
will restore normally display.
Emacs has the ability to hide lines indented more than a certain number of columns (you
specify how many columns). You can use this to get an overview of a part of a program.
To hide lines, type C-x $ (set-selective-display) with a
numeric argument n. Then lines with at least n columns of indentation disappear from the screen. The only indication
of their presence is that three dots (...) appear at the end of each visible
line that is followed by one or more invisible ones.
The commands C-n and C-p move across the invisible lines as if
they were not there.
The invisible lines are still present in the buffer,
and most editing commands see them as usual, so you may find point in the middle of invisible text. When this happens, the cursor appears at the end of the previous line, after the
three dots. If point is at the end of the visible
line, before the newline that ends it, the cursor appears before the three dots.
To make all lines visible again, type C-x $ with no argument.
If you set the variable selective-display-ellipses
to nil, the three dots do not appear at the end of a line that precedes
invisible lines. Then there is no visible indication of the invisible lines. This variable becomes local
automatically when set.
Some European languages use accented letters and other special symbols. The ISO 8859
Latin-1 character set defines character codes for many European languages in the range
160 to 255.
Emacs can display those characters according to Latin-1, provided the terminal or font
in use supports them. The M-x standard-display-european command toggles European character
display mode. With a numeric argument, M-x standard-display-european enables
European character display if and only if the argument
is positive. Load the library iso-syntax to specify the correct syntactic
properties and case conversion table for the Latin-1 character
set.
Some operating systems let you specify the language you are using by setting a locale.
Emacs handles one common special case of this: if your locale name for character types contains the string 8859-1 or 88591, Emacs
automatically enables European character display mode
and its syntax.
There are three different ways you can enter Latin-1 characters:
- If your keyboard can generate character codes 128 and
up, representing ISO Latin-1 characters, execute the following expression to enable Emacs
to understand them:
(set-input-mode (car (current-input-mode))
(nth 1 (current-input-mode))
0)
- You can load the library
iso-transl to turn the key C-x 8 into a
``compose character'' prefix for entry of the extra ISO
Latin-1 printing characters. C-x 8 is good for insertion
(in the minibuffer as well as other buffers), for searching, and in any other context where a key sequence
is allowed. The ALT modifier key, if you have one, serves the same purpose as C-x
8; use ALT together with an accent character
to modify the following letter.
- You can use ISO Accents mode. This minor mode is convenient if you enter non-ASCII ISO
Latin-1 characters often. When this minor mode is enabled, the characters `, ',
", ^, / and ~ modify the
following letter by adding the corresponding diacritical mark
to it, if possible. To enable or disable ISO Accents mode, use the command M-x iso-accents-mode. This command affects only the current buffer.
To enter one of those six special characters
while in ISO Accents mode, type the character, followed
by a space. Some of those characters have a corresponding ``dead key'' accent character in the ISO Latin-1 character set; to enter that character, type the corresponding ASCII character twice. For example, '' enters the
Latin-1 character acute-accent (character code 0264).
ISO Accents mode input is available whenever a key sequence is expected: for ordinary insertion, for searching,
for the minibuffer, and for certain command arguments.
In addition to the accented letters, you can use these special sequences in ISO Accents
mode to enter certain other ISO Latin-1 characters:
- /A A with ring.
- ~C C with cedilla.
- ~D D with stroke.
- /E AE ligature.
- /a a with ring.
- ~c c with cedilla.
- ~d d with stroke.
- /e ae ligature.
- "s German sharp s.
- ~ Left guillemet.
- ~> Right guillemet.
- ~! Inverted exclamation mark.
- ~? Inverted question mark.
To add the current line number of point to the mode
line, enable Line Number mode with the command M-x
line-number-mode. The line number appears before the buffer
percentage pos, with the letter L to indicate what it is. See
section Minor Modes, for more information about minor
modes and about how to use this command.
If the buffer is very large (larger than the value
of line-number-display-limit), then the line number doesn't appear. Emacs
doesn't compute the line number when the buffer is
large, because that would be too slow. If you have narrowed the buffer (see section Narrowing),
the displayed line number is relative to the accessible portion of the buffer.
Emacs can optionally display the time and system load in all mode lines. To enable this
feature, type M-x display-time. The information added to the mode line usually
appears after the buffer name, before the mode names
and their parentheses. It looks like this:
hh:mmpm l.ll
Here hh and mm are the hour and minute, followed always by am
or pm. l.ll is the average number of running processes in the
whole system recently. (Some fields may be missing if your operating system cannot support
them.)
The word Mail appears after the load
level if there is mail for you that you have not read
yet.
This section contains information for customization
only. Beginning users should skip it.
The variable mode-line-inverse-video
controls whether the mode line is displayed in inverse video (assuming the terminal
supports it); nil means don't do so. See section The
Mode Line. If you specify the foreground color for the modeline face, and
mode-line-inverse-video is non-nil, then the default background
color for that face is the usual foreground color. See section Using Multiple Typefaces.
If the variable inverse-video is non-nil,
Emacs attempts to invert all the lines of the display from what they normally are.
If the variable visible-bell is non-nil,
Emacs attempts to make the whole screen blink when it would normally make an audible bell
sound. This variable has no effect if your terminal
does not have a way to make the screen blink.
When you reenter Emacs after suspending, Emacs normally clears the screen and redraws
the entire display. On some terminals with more than one page
of memory, it is possible to arrange the termcap entry so that the ti and te
strings (output to the terminal when Emacs is entered and exited, respectively) switch
between pages of memory so as to use one page for
Emacs and another page for other output. Then you
might want to set the variable no-redraw-on-reenter
non-nil; this tells Emacs to assume, when resumed, that the screen page it is using still contains what Emacs last wrote
there.
The variable echo-keystrokes controls
the echoing of multi-character
keys; its value is the number of seconds of pause required to cause echoing to start, or zero meaning don't echo at all. See
section The Echo Area.
If the variable ctl-arrow is nil,
control characters in the buffer are displayed with
octal escape sequences, all except newline and tab.
Altering the value of ctl-arrow makes it local
to the current buffer; until that time, the default
value is in effect. The default is initially t. See section 'Display Tables'
in The Emacs Lisp Reference Manual.
Normally, a tab character in the buffer is displayed as whitespace
which extends to the next display tab stop position, and display tab stops come at
intervals equal to eight spaces. The number of spaces per tab is controlled by the variable tab-width, which is made local by changing it, just like ctl-arrow.
Note that how the tab character in the buffer is displayed has nothing to do with the definition
of TAB as a command. The variable tab-width must have an integer
value between 1 and 1000, inclusive.
If the variable truncate-lines is non-nil,
then each line of text gets just one screen line for
display; if the text line is too long, display shows
only the part that fits. If truncate-lines is nil, then long text lines display as more than one screen line, enough
to show the whole text of the line. See section Continuation Lines. Altering the value of truncate-lines
makes it local to the current buffer; until that time, the default value is in effect.
The default is initially nil.
If the variable truncate-partial-width-windows
is non-nil, it forces truncation rather
than continuation in any window less than the full
width of the screen or frame, regardless of the value
of truncate-lines. For information about side-by-side windows, see section Splitting Windows. See also section 'Display' in The
Emacs Lisp Reference Manual.
The variable baud-rate holds the the
output speed of the terminal, as far as Emacs knows. Setting this variable does not change the speed of actual data
transmission, but the value is used for calculations such as padding. It also affects
decisions about whether to scroll part of the screen or redraw it instead---even when
using a window system. (We designed it this way,
despite the fact that a window system has no true
``output speed'', to give you a way to tune these decisions.)
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