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Say "graphical displays".
351 lines
17 KiB
Plaintext
351 lines
17 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2001, 2002,
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@c 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node Screen, User Input, Acknowledgments, Top
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@chapter The Organization of the Screen
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@cindex screen
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@cindex parts of the screen
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On a text-only terminal, the Emacs display occupies the whole
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screen. On a graphical display, such as on GNU/Linux using the X
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Window System, Emacs creates its own windows to use. We use the term
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@dfn{frame} to mean the entire text-only screen or an entire
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system-level window used by Emacs. Emacs uses both kinds of frames,
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in the same way, to display your editing. Emacs normally starts out
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with just one frame, but you can create additional frames if you wish.
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@xref{Frames}.
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When you start Emacs, the main central area of the frame, all except
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for the top and bottom and sides, displays the text you are editing.
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This area is called @dfn{the window}. At the top there is normally a
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@dfn{menu bar} where you can access a series of menus; then there may
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be a @dfn{tool bar}, a row of icons that perform editing commands if
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you click on them. Below this, the window begins, often with a
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@dfn{scroll bar} on one side. Below the window comes the last line of
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the frame, a special @dfn{echo area} or @dfn{minibuffer window}, where
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prompts appear and you enter information when Emacs asks for it. See
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following sections for more information about these special lines.
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You can subdivide the window horizontally or vertically to make
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multiple text windows, each of which can independently display some
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file or text (@pxref{Windows}). In this manual, the word ``window''
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refers to the initial large window if not subdivided, or any one of
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the multiple windows you have subdivided it into.
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At any time, one window is the @dfn{selected window}. On graphical
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displays, the selected window normally shows a more prominent cursor
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(usually solid and blinking) while other windows show a weaker cursor
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(such as a hollow box). Text terminals have just one cursor, so it
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always appears in the selected window.
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Most Emacs commands implicitly apply to the text in the selected
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window; the text in unselected windows is mostly visible for
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reference. However, mouse commands generally operate on whatever
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window you click them in, whether selected or not. If you use
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multiple frames on a graphical display, then giving the input focus to
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a particular frame selects a window in that frame.
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Each window's last line is a @dfn{mode line}, which describes what
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is going on in that window. It appears in different color and/or a ``3D''
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box if the terminal supports them; its contents normally begin with
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@w{@samp{--:-- @ *scratch*}} when Emacs starts. The mode line
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displays status information such as what buffer is being displayed
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above it in the window, what major and minor modes are in use, and
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whether the buffer contains unsaved changes.
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@menu
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* Point:: The place in the text where editing commands operate.
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* Echo Area:: Short messages appear at the bottom of the screen.
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* Mode Line:: Interpreting the mode line.
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* Menu Bar:: How to use the menu bar.
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@end menu
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@node Point
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@section Point
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@cindex point
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@cindex cursor
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Within Emacs, the active cursor shows the location at which
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editing commands will take effect. This location is called @dfn{point}.
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Many Emacs commands move point through the text, so that you can edit at
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different places in it. You can also place point by clicking mouse
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button 1 (normally the left button).
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While the cursor appears to be @emph{on} a character, you should
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think of point as @emph{between} two characters; it points @emph{before}
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the character that appears under the cursor. For example, if your text
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looks like @samp{frob} with the cursor over the @samp{b}, then point is
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between the @samp{o} and the @samp{b}. If you insert the character
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@samp{!} at that position, the result is @samp{fro!b}, with point
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between the @samp{!} and the @samp{b}. Thus, the cursor remains over
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the @samp{b}, as before.
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Sometimes people speak of ``the cursor'' when they mean ``point,'' or
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speak of commands that move point as ``cursor motion'' commands.
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If you are editing several files in Emacs, each in its own buffer,
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each buffer has its own point location. A buffer that is not
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currently displayed remembers its point location in case you display
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it again later. When Emacs displays multiple windows, each window has
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its own point location. If the same buffer appears in more than one
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window, each window has its own point position in that buffer, and (when
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possible) its own cursor.
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A text-only terminal has just one cursor, in the selected window.
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The other windows do not show a cursor, even though they do have their
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own position of point. When Emacs updates the screen on a text-only
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terminal, it has to put the cursor temporarily at the place the output
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goes. This doesn't mean point is there, though. Once display
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updating finishes, Emacs puts the cursor where point is.
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On graphical displays, Emacs shows a cursor in each window; the
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selected window's cursor is solid and blinking, and the other cursors
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are just hollow. Thus, the most prominent cursor always shows you the
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selected window, on all kinds of terminals.
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@xref{Cursor Display}, for customizable variables that control display
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of the cursor or cursors.
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The term ``point'' comes from the character @samp{.}, which was the
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command in TECO (the language in which the original Emacs was written)
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for accessing the value now called ``point.''
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@node Echo Area
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@section The Echo Area
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@cindex echo area
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The line at the bottom of the frame (below the mode line) is the
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@dfn{echo area}. It is used to display small amounts of text for
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various purposes.
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@dfn{Echoing} means displaying the characters that you type. At the
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command line, the operating system normally echoes all your input.
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Emacs handles echoing differently.
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Single-character commands do not echo in Emacs, and multi-character
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commands echo only if you pause while typing them. As soon as you pause
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for more than a second in the middle of a command, Emacs echoes all the
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characters of the command so far. This is to @dfn{prompt} you for the
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rest of the command. Once echoing has started, the rest of the command
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echoes immediately as you type it. This behavior is designed to give
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confident users fast response, while giving hesitant users maximum
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feedback. You can change this behavior by setting a variable
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(@pxref{Display Custom}).
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@cindex error message in the echo area
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If a command cannot do its job, it may display an @dfn{error
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message} in the echo area. Error messages are accompanied by beeping
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or by flashing the screen. The error also discards any input you have
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typed ahead.
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Some commands display informative messages in the echo area. These
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messages look much like error messages, but they are not announced
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with a beep and do not throw away input. Sometimes the message tells
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you what the command has done, when this is not obvious from looking
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at the text being edited. Sometimes the sole purpose of a command is
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to show you a message giving you specific information---for example,
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@kbd{C-x =} (hold down @key{CTRL} and type @kbd{x}, then let go of
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@key{CTRL} and type @kbd{=}) displays a message describing the
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character position of point in the text and its current column in the
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window. Commands that take a long time often display messages ending
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in @samp{...} while they are working, and add @samp{done} at the end
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when they are finished. They may also indicate progress with
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percentages.
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@cindex @samp{*Messages*} buffer
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@cindex saved echo area messages
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@cindex messages saved from echo area
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Echo-area informative messages are saved in an editor buffer named
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@samp{*Messages*}. (We have not explained buffers yet; see
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@ref{Buffers}, for more information about them.) If you miss a message
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that appears briefly on the screen, you can switch to the
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@samp{*Messages*} buffer to see it again. (Successive progress messages
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are often collapsed into one in that buffer.)
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@vindex message-log-max
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The size of @samp{*Messages*} is limited to a certain number of
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lines. The variable @code{message-log-max} specifies how many lines.
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Once the buffer has that many lines, adding lines at the end deletes lines
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from the beginning, to keep the size constant. @xref{Variables}, for
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how to set variables such as @code{message-log-max}.
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The echo area is also used to display the @dfn{minibuffer}, a window
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where you can input arguments to commands, such as the name of a file
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to be edited. When the minibuffer is in use, the echo area begins
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with a prompt string that usually ends with a colon; also, the cursor
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appears in that line because it is the selected window. You can
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always get out of the minibuffer by typing @kbd{C-g}.
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@xref{Minibuffer}.
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@node Mode Line
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@section The Mode Line
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@cindex mode line
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@cindex top level
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@c
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Each text window's last line is a @dfn{mode line}, which describes
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what is going on in that window. The mode line starts and ends with
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dashes. When there is only one text window, the mode line appears
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right above the echo area; it is the next-to-last line in the frame.
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On a text-only terminal, the mode line is in inverse video if the
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terminal supports that; on a graphics display, the mode line has a 3D
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box appearance to help it stand out. The mode line of the selected
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window is highlighted if possible; see @ref{Optional Mode Line}, for
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more information.
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Normally, the mode line looks like this:
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@example
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-@var{cs}:@var{ch}-@var{fr} @var{buf} @var{pos} @var{line} (@var{major} @var{minor})------
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@end example
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@noindent
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This gives information about the window and the buffer it displays: the
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buffer's name, what major and minor modes are in use, whether the
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buffer's text has been changed, and how far down the buffer you are
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currently looking.
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@var{ch} contains two stars @samp{**} if the text in the buffer has
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been edited (the buffer is ``modified''), or @samp{--} if the buffer has
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not been edited. For a read-only buffer, it is @samp{%*} if the buffer
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is modified, and @samp{%%} otherwise.
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@var{fr} gives the selected frame name (@pxref{Frames}). It appears
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only on text-only terminals. The initial frame's name is @samp{F1}.
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@var{buf} is the name of the window's @dfn{buffer}. Usually this is
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the same as the name of a file you are editing. @xref{Buffers}.
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The buffer displayed in the selected window (the window with the
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cursor) is the @dfn{current buffer}, where editing happens. When a
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command's effect applies to ``the buffer,'' we mean it does those
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things to the current buffer.
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@var{pos} tells you whether there is additional text above the top of
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the window, or below the bottom. If your buffer is small and it is all
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visible in the window, @var{pos} is @samp{All}. Otherwise, it is
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@samp{Top} if you are looking at the beginning of the buffer, @samp{Bot}
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if you are looking at the end of the buffer, or @samp{@var{nn}%}, where
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@var{nn} is the percentage of the buffer above the top of the window.
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With Size Indication mode, you can display the size of the buffer as
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well. @xref{Optional Mode Line}.
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@var{line} is @samp{L} followed by the current line number of point.
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This is present when Line Number mode is enabled (it normally is).
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You can display the current column number too, by turning on Column
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Number mode. It is not enabled by default because it is somewhat
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slower. @xref{Optional Mode Line}.
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@var{major} is the name of the @dfn{major mode} in effect in the
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buffer. A buffer can only be in one major mode at a time. The major
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modes available include Fundamental mode (the least specialized), Text
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mode, Lisp mode, C mode, Texinfo mode, and many others. @xref{Major
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Modes}, for details of how the modes differ and how to select
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them.
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Some major modes display additional information after the major mode
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name. For example, Rmail buffers display the current message number and
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the total number of messages. Compilation buffers and Shell buffers
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display the status of the subprocess.
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@var{minor} is a list of some of the @dfn{minor modes} that are
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turned on at the moment in the window's chosen buffer. For example,
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@samp{Fill} means that Auto Fill mode is on. @samp{Abbrev} means that
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Word Abbrev mode is on. @samp{Ovwrt} means that Overwrite mode is on.
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@xref{Minor Modes}, for more information.
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@samp{Narrow} means that the buffer being displayed has editing
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restricted to only a portion of its text. (This is not really a minor
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mode, but is like one.) @xref{Narrowing}. @samp{Def} means that a
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keyboard macro is being defined. @xref{Keyboard Macros}.
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In addition, if Emacs is inside a recursive editing level, square
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brackets (@samp{[@dots{}]}) appear around the parentheses that
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surround the modes. If Emacs is in one recursive editing level within
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another, double square brackets appear, and so on. Since recursive
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editing levels affect Emacs globally, not just one buffer, the square
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brackets appear in every window's mode line or not in any of them.
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@xref{Recursive Edit}.@refill
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@var{cs} states the coding system used for the file you are editing.
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A dash indicates the default state of affairs: no code conversion,
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except for end-of-line translation if the file contents call for that.
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@samp{=} means no conversion whatsoever. Nontrivial code conversions
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are represented by various letters---for example, @samp{1} refers to ISO
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Latin-1. @xref{Coding Systems}, for more information.
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On a text-only terminal, @var{cs} includes two additional characters
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which describe the coding system for keyboard input and the coding
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system for terminal output. They come right before the coding system
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used for the file you are editing.
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If you are using an input method, a string of the form
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@samp{@var{i}>} is added to the beginning of @var{cs}; @var{i}
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identifies the input method. (Some input methods show @samp{+} or
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@samp{@@} instead of @samp{>}.) @xref{Input Methods}.
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When multibyte characters are not enabled, @var{cs} does not appear at
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all. @xref{Enabling Multibyte}.
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@cindex end-of-line conversion, mode-line indication
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The colon after @var{cs} changes to another string in some cases.
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Emacs uses newline characters to separate lines in the buffer. Some
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files use different conventions for separating lines: either
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carriage-return linefeed (the MS-DOS convention) or just
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carriage-return (the Macintosh convention). If the buffer's file uses
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carriage-return linefeed, the colon changes to either a backslash
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(@samp{\}) or @samp{(DOS)}, depending on the operating system. If the
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file uses just carriage-return, the colon indicator changes to either
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a forward slash (@samp{/}) or @samp{(Mac)}. On some systems, Emacs
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displays @samp{(Unix)} instead of the colon for files that use newline
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as the line separator.
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@xref{Optional Mode Line}, to add other handy information to the
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mode line, such as the size of the buffer, the current column number
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of point, and whether new mail for you has arrived.
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The mode line is mouse-sensitive; when you move the mouse across
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various parts of it, Emacs displays help text to say what a click in
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that place will do. @xref{Mode Line Mouse}.
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@node Menu Bar
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@section The Menu Bar
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@cindex menu bar
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Each Emacs frame normally has a @dfn{menu bar} at the top which you
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can use to perform common operations. There's no need to list them
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here, as you can more easily see them yourself.
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@kindex M-`
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@kindex F10
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@findex tmm-menubar
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On a graphical display, you can use the mouse to choose a command
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from the menu bar. A right-arrow at the end of the menu item means it
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leads to a subsidiary menu; @samp{...} at the end means that the
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command invoked will read arguments (further input from you) before it
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actually does anything.
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To view the full command name and documentation for a menu item, type
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@kbd{C-h k}, and then select the menu bar with the mouse in the usual
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way (@pxref{Key Help}).
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On text-only terminals with no mouse, you can use the menu bar by
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typing @kbd{M-`} or @key{F10} (these run the command
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@code{tmm-menubar}). This lets you select a menu item with the
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keyboard. A provisional choice appears in the echo area. You can use
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the up and down arrow keys to move through the menu to different
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items, and then you can type @key{RET} to select the item.
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Each menu item also has an assigned letter or digit which designates
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that item; it is usually the initial of some word in the item's name.
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This letter or digit is separated from the item name by @samp{=>}. You
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can type the item's letter or digit to select the item.
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Some of the commands in the menu bar have ordinary key bindings as
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well; one such binding is shown in parentheses after the item itself.
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@ignore
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arch-tag: 104ba40e-d972-4866-a542-a98be94bdf2f
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@end ignore
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