@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
+@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/display
@node Display, Calendar, Processes, Top
@menu
* Refresh Screen:: Clearing the screen and redrawing everything on it.
+* Forcing Redisplay:: Forcing redisplay.
* Truncation:: Folding or wrapping long text lines.
* The Echo Area:: Where messages are displayed.
* Invisible Text:: Hiding part of the buffer text.
* Overlay Arrow:: Display of an arrow to indicate position.
* Temporary Displays:: Displays that go away automatically.
* Overlays:: Use overlays to highlight parts of the buffer.
-* Width:: How wide is a character or string.
-* Faces:: A face defines a graphics appearance: font, color, etc.
+* Width:: How wide a character or string is on the screen.
+* Faces:: A face defines a graphics style for text characters:
+ font, colors, etc.
+* Display Property:: Enabling special display features.
+* Images:: Displaying images in Emacs buffers.
* Blinking:: How Emacs shows the matching open parenthesis.
* Inverse Video:: Specifying how the screen looks.
* Usual Display:: The usual conventions for displaying nonprinting chars.
to redraw, @code{nil} means redrawing is needed. The default is @code{nil}.
@end defvar
+@node Forcing Redisplay
+@section Forcing Redisplay
+@cindex forcing redisplay
+
+ Emacs redisplay normally stops if input arrives, and does not happen
+at all if input is available before it starts. Most of the time, this
+is exactly what you want. However, you can prevent preemption by
+binding @code{redisplay-dont-pause} to a non-@code{nil} value.
+
+@tindex redisplay-dont-pause
+@defvar redisplay-dont-pause
+If this variable is non-@code{nil}, pending input does not
+prevent or halt redisplay; redisplay occurs, and finishes,
+regardless of whether input is available. This feature is available
+as of Emacs 21.
+@end defvar
+
+ You can request a display update, but only if no input is pending,
+with @code{(sit-for 0)}. To force a display update even when input is
+pending, do this:
+
+@example
+(let ((redisplay-dont-pause t))
+ (sit-for 0))
+@end example
+
@node Truncation
@section Truncation
@cindex line wrapping
In batch mode, @code{message} prints the message text on the standard
error stream, followed by a newline.
+If @var{string}, or strings among the @var{arguments}, have @code{face}
+text properties, these affect the way the message is displayed.
+
@c Emacs 19 feature
-If @var{string} is @code{nil}, @code{message} clears the echo area. If
-the minibuffer is active, this brings the minibuffer contents back onto
-the screen immediately.
+If @var{string} is @code{nil}, @code{message} clears the echo area; if
+the echo area has been expanded automatically, this brings it back to
+its normal size. If the minibuffer is active, this brings the
+minibuffer contents back onto the screen immediately.
@example
@group
@end defun
@defun current-message
-@tindex current-message
This function returns the message currently being displayed in the
echo area, or @code{nil} if there is none.
@end defun
@end defvar
@defvar echo-area-clear-hook
-@tindex echo-area-clear-hook
This normal hook is run whenever the echo area is cleared---either by
@code{(message nil)} or for any other reason.
@end defvar
@defvar echo-keystrokes
This variable determines how much time should elapse before command
-characters echo. Its value must be an integer, which specifies the
+characters echo. Its value must be an integer or floating point number,
+which specifies the
number of seconds to wait before echoing. If the user types a prefix
key (such as @kbd{C-x}) and then delays this many seconds before
continuing, the prefix key is echoed in the echo area. (Once echoing
value of @code{buffer-invisibility-spec}.
Controlling visibility with @code{buffer-invisibility-spec} is
-especially useful in a program to display the list of entries in a data
-base. It permits the implementation of convenient filtering commands to
-view just a part of the entries in the data base. Setting this variable
-is very fast, much faster than scanning all the text in the buffer
-looking for properties to change.
+especially useful in a program to display the list of entries in a
+database. It permits the implementation of convenient filtering
+commands to view just a part of the entries in the database. Setting
+this variable is very fast, much faster than scanning all the text in
+the buffer looking for properties to change.
@defvar buffer-invisibility-spec
This variable specifies which kinds of @code{invisible} properties
@code{buffer-invisibility-spec} and removing elements from it.
@defun add-to-invisibility-spec element
-@tindex add-to-invisibility-spec
Add the element @var{element} to @code{buffer-invisibility-spec}
(if it is not already present in that list).
@end defun
@defun remove-from-invisibility-spec element
-@tindex remove-from-invisibility-spec
Remove the element @var{element} from @code{buffer-invisibility-spec}.
+This does nothing if @var{element} is not in the list.
@end defun
One convention about the use of @code{buffer-invisibility-spec} is
want this to be done differently for a certain overlay, give it an
@code{isearch-open-invisible-temporary} property which is a function.
The function is called with two arguments: the first is the overlay, and
-the second is @code{t} to make the overlay visible, or @code{nil} to
+the second is @code{nil} to make the overlay visible, or @code{t} to
make it invisible again.
@node Selective Display
@itemize @bullet
@item
-If the value of @code{selective-display} is @code{t}, then any portion
-of a line that follows a control-m is not displayed. This is explicit
-selective display.
+If the value of @code{selective-display} is @code{t}, then the character
+control-m marks the start of invisible text; the control-m, and the rest
+of the line following it, are not displayed. This is explicit selective
+display.
@item
If the value of @code{selective-display} is a positive integer, then
@defvar overlay-arrow-string
This variable holds the string to display to call attention to a
particular line, or @code{nil} if the arrow feature is not in use.
+On a graphical display the contents of the string are ignored; instead a
+glyph is displayed in the fringe area to the left of the display area.
@end defvar
@defvar overlay-arrow-position
This variable holds a marker that indicates where to display the overlay
-arrow. It should point at the beginning of a line. The arrow text
+arrow. It should point at the beginning of a line. On a non-graphical
+display the arrow text
appears at the beginning of that line, overlaying any text that would
otherwise appear. Since the arrow is usually short, and the line
usually begins with indentation, normally nothing significant is
@menu
* Overlay Properties:: How to read and set properties.
What properties do to the screen display.
-* Managing Overlays:: Creating, moving, finding overlays.
+* Managing Overlays:: Creating and moving overlays.
+* Finding Overlays:: Searching for overlays.
@end menu
@node Overlay Properties
@subsection Overlay Properties
-Overlay properties are like text properties in that the properties that
+ Overlay properties are like text properties in that the properties that
alter how a character is displayed can come from either source. But in
most respects they are different. Text properties are considered a part
of the text; overlays are specifically considered not to be part of the
changes, overlay changes are not recorded in the buffer's undo list.
@xref{Text Properties}, for comparison.
+ These functions are used for reading and writing the properties of an
+overlay:
+
+@defun overlay-get overlay prop
+This function returns the value of property @var{prop} recorded in
+@var{overlay}, if any. If @var{overlay} does not record any value for
+that property, but it does have a @code{category} property which is a
+symbol, that symbol's @var{prop} property is used. Otherwise, the value
+is @code{nil}.
+@end defun
+
+@defun overlay-put overlay prop value
+This function sets the value of property @var{prop} recorded in
+@var{overlay} to @var{value}. It returns @var{value}.
+@end defun
+
+ See also the function @code{get-char-property} which checks both
+overlay properties and text properties for a given character.
+@xref{Examining Properties}.
+
+ Many overlay properties have special meanings; here is a table
+of them:
+
@table @code
@item priority
@kindex priority @r{(overlay property)}
@item face
@kindex face @r{(overlay property)}
This property controls the way text is displayed---for example, which
-font and which colors. Its value is a face name or a list of face
-names. @xref{Faces}, for more information.
+font and which colors. @xref{Faces}, for more information.
+
+In the simplest case, the value is a face name. It can also be a list;
+then each element can be any of these possibilities:
+
+@itemize @bullet
+@item
+A face name (a symbol or string).
+
+@item
+Starting in Emacs 21, a property list of face attributes. This has the
+form (@var{keyword} @var{value} @dots{}), where each @var{keyword} is a
+face attribute name and @var{value} is a meaningful value for that
+attribute. With this feature, you do not need to create a face each
+time you want to specify a particular attribute for certain text.
+@xref{Face Attributes}.
+
+@item
+A cons cell of the form @code{(foreground-color . @var{color-name})} or
+@code{(background-color . @var{color-name})}. These elements specify
+just the foreground color or just the background color.
-If the property value is a list, elements may also have the form
-@code{(foreground-color . @var{color-name})} or @code{(background-color
-. @var{color-name})}. These elements specify just the foreground color
-or just the background color; therefore, there is no need to create a
-face for each color that you want to use.
+@code{(foreground-color . @var{color-name})} is equivalent to
+@code{(:foreground @var{color-name})}, and likewise for the background.
+@end itemize
@item mouse-face
@kindex mouse-face @r{(overlay property)}
This property is used instead of @code{face} when the mouse is within
the range of the overlay.
+@item display
+@kindex display @r{(overlay property)}
+This property activates various features that change the
+way text is displayed. For example, it can make text appear taller
+or shorter, higher or lower, wider or narror, or replaced with an image.
+@xref{Display Property}.
+
+@item help-echo
+@kindex help-echo @r{(text property)}
+If an overlay has a string as its @code{help-echo} property, then when
+you move the mouse onto the text in the overlay, Emacs displays that
+string in the echo area, or in the tooltip window. This feature is
+available starting in Emacs 21.
+
@item modification-hooks
@kindex modification-hooks @r{(overlay property)}
This property's value is a list of functions to be called if any
@kindex before-string @r{(overlay property)}
This property's value is a string to add to the display at the beginning
of the overlay. The string does not appear in the buffer in any
-sense---only on the screen. The string should contain only characters
-that display as a single column---control characters, including tabs or
-newlines, will give strange results.
+sense---only on the screen.
@item after-string
@kindex after-string @r{(overlay property)}
This property's value is a string to add to the display at the end of
the overlay. The string does not appear in the buffer in any
-sense---only on the screen. The string should contain only characters
-that display as a single column---control characters, including tabs or
-newlines, will give strange results.
+sense---only on the screen.
@item evaporate
@kindex evaporate @r{(overlay property)}
the character after point is within the overlay. @xref{Active Keymaps}.
@end table
- These are the functions for reading and writing the properties of an
-overlay.
-
-@defun overlay-get overlay prop
-This function returns the value of property @var{prop} recorded in
-@var{overlay}, if any. If @var{overlay} does not record any value for
-that property, but it does have a @code{category} property which is a
-symbol, that symbol's @var{prop} property is used. Otherwise, the value
-is @code{nil}.
-@end defun
-
-@defun overlay-put overlay prop value
-This function sets the value of property @var{prop} recorded in
-@var{overlay} to @var{value}. It returns @var{value}.
-@end defun
-
- See also the function @code{get-char-property} which checks both
-overlay properties and text properties for a given character.
-@xref{Examining Properties}.
-
@node Managing Overlays
@subsection Managing Overlays
The arguments @var{front-advance} and @var{rear-advance} specify the
insertion type for the start of the overlay and for the end of the
-overlay. @xref{Marker Insertion Types}.
+overlay, respectively. @xref{Marker Insertion Types}.
@end defun
@defun overlay-start overlay
@defun delete-overlay overlay
This function deletes @var{overlay}. The overlay continues to exist as
-a Lisp object, but ceases to be attached to the buffer it belonged to,
-and ceases to have any effect on display.
+a Lisp object, and its property list is unchanged, but it ceases to be
+attached to the buffer it belonged to, and ceases to have any effect on
+display.
-A deleted overlay is not permanently useless. You can give it
-a new buffer position by calling @code{move-overlay}.
+A deleted overlay is not permanently disconnected. You can give it a
+position in a buffer again by calling @code{move-overlay}.
@end defun
@defun move-overlay overlay start end &optional buffer
This function moves @var{overlay} to @var{buffer}, and places its bounds
at @var{start} and @var{end}. Both arguments @var{start} and @var{end}
-must specify buffer positions; they may be integers or markers. If
-@var{buffer} is omitted, the overlay stays in the same buffer.
+must specify buffer positions; they may be integers or markers.
+
+If @var{buffer} is omitted, @var{overlay} stays in the same buffer it
+was already associated with; if @var{overlay} was deleted, it goes into
+the current buffer.
The return value is @var{overlay}.
``lost''.
@end defun
+ Here are some examples:
+
+@example
+;; @r{Create an overlay.}
+(setq foo (make-overlay 1 10))
+ @result{} #<overlay from 1 to 10 in display.texi>
+(overlay-start foo)
+ @result{} 1
+(overlay-end foo)
+ @result{} 10
+(overlay-buffer foo)
+ @result{} #<buffer display.texi>
+;; @r{Give it a property we can check later.}
+(overlay-put foo 'happy t)
+ @result{} t
+;; @r{Verify the property is present.}
+(overlay-get foo 'happy)
+ @result{} t
+;; @r{Move the overlay.}
+(move-overlay foo 5 20)
+ @result{} #<overlay from 5 to 20 in display.texi>
+(overlay-start foo)
+ @result{} 5
+(overlay-end foo)
+ @result{} 20
+;; @r{Delete the overlay.}
+(delete-overlay foo)
+ @result{} nil
+;; @r{Verify it is deleted.}
+foo
+ @result{} #<overlay in no buffer>
+;; @r{A deleted overlay has no position.}
+(overlay-start foo)
+ @result{} nil
+(overlay-end foo)
+ @result{} nil
+(overlay-buffer foo)
+ @result{} nil
+;; @r{Undelete the overlay.}
+(move-overlay foo 1 20)
+ @result{} #<overlay from 1 to 20 in display.texi>
+;; @r{Verify the results.}
+(overlay-start foo)
+ @result{} 1
+(overlay-end foo)
+ @result{} 20
+(overlay-buffer foo)
+ @result{} #<buffer display.texi>
+;; @r{Moving and deleting the overlay does not change its properties.}
+(overlay-get foo 'happy)
+ @result{} t
+@end example
+
+@node Finding Overlays
+@subsection Searching for Overlays
+
@defun overlays-at pos
-This function returns a list of all the overlays that contain position
-@var{pos} in the current buffer. The list is in no particular order.
-An overlay contains position @var{pos} if it begins at or before
-@var{pos}, and ends after @var{pos}.
+This function returns a list of all the overlays that cover the
+character at position @var{pos} in the current buffer. The list is in
+no particular order. An overlay contains position @var{pos} if it
+begins at or before @var{pos}, and ends after @var{pos}.
+
+To illustrate usage, here is a Lisp function that returns a list of the
+overlays that specify property @var{prop} for the character at point:
+
+@smallexample
+(defun find-overlays-specifying (prop)
+ (let ((overlays (overlays-at (point)))
+ found)
+ (while overlays
+ (let ((overlay (cdr overlays)))
+ (if (overlay-get overlay prop)
+ (setq found (cons overlay found))))
+ (setq overlays (cdr overlays)))
+ found))
+@end smallexample
@end defun
@defun overlays-in beg end
-@tindex overlays-in
This function returns a list of the overlays that overlap the region
@var{beg} through @var{end}. ``Overlap'' means that at least one
character is contained within the overlay and also contained within the
specified region; however, empty overlays are included in the result if
-they are located at @var{beg} or between @var{beg} and @var{end}.
+they are located at @var{beg}, or strictly between @var{beg} and @var{end}.
@end defun
@defun next-overlay-change pos
end of an overlay, before @var{pos}.
@end defun
+ Here's an easy way to use @code{next-overlay-change} to search for the
+next character which gets a non-@code{nil} @code{happy} property from
+either its overlays or its text properties (@pxref{Property Search}):
+
+@smallexample
+(defun find-overlay-prop (prop)
+ (save-excursion
+ (while (and (not (eobp))
+ (not (get-char-property (point) 'happy)))
+ (goto-char (min (next-overlay-change (point))
+ (next-single-property-change (point) 'happy))))
+ (point)))
+@end smallexample
+
@node Width
@section Width
@ref{Screen Lines}, for related functions.
@defun char-width char
-@tindex char-width
This function returns the width in columns of the character @var{char},
if it were displayed in the current buffer and the selected window.
@end defun
@defun string-width string
-@tindex string-width
This function returns the width in columns of the string @var{string},
if it were displayed in the current buffer and the selected window.
@end defun
@defun truncate-string-to-width string width &optional start-column padding
-@tindex truncate-string-to-width
This function returns the part of @var{string} that fits within
@var{width} columns, as a new string.
@section Faces
@cindex face
-A @dfn{face} is a named collection of graphical attributes: font,
-foreground color, background color, and optional underlining. Faces
-control the display of text on the screen.
+ A @dfn{face} is a named collection of graphical attributes: font
+family, foreground color, background color, optional underlining, and
+many others. Faces are used in Emacs to control the style of display of
+particular parts of the text or the frame.
@cindex face id
Each face has its own @dfn{face number}, which distinguishes faces at
-low levels within Emacs. However, for most purposes, you can refer to
+low levels within Emacs. However, for most purposes, you refer to
faces in Lisp programs by their names.
@defun facep object
@menu
* Standard Faces:: The faces Emacs normally comes with.
* Defining Faces:: How to define a face with @code{defface}.
-* Merging Faces:: How Emacs decides which face to use for a character.
+* Face Attributes:: What is in a face?
+* Attribute Functions:: Functions to examine and set face attributes.
+* Merging Faces:: How Emacs combines the faces specified for a character.
+* Font Selection:: Finding the best available font for a face.
* Face Functions:: How to define and examine faces.
+* Auto Faces:: Hook for automatic face assignment.
+* Font Lookup:: Looking up the names of available fonts
+ and information about them.
+* Fontsets:: A fontset is a collection of fonts
+ that handle a range of character sets.
@end menu
@node Standard Faces
@subsection Standard Faces
- This table lists all the standard faces and their uses.
+ This table lists all the standard faces and their uses. Most of them
+are used for displaying certain parts of the frames or certain kinds of
+text; you can control how those places look by customizing these faces.
@table @code
@item default
@kindex default @r{(face name)}
This face is used for ordinary text.
+@item mode-line
+@kindex mode-line @r{(face name)}
+This face is used for mode lines, and for menu bars when toolkit menus
+are not used---but only if @code{mode-line-inverse-video} is
+non-@code{nil}.
+
@item modeline
@kindex modeline @r{(face name)}
-This face is used for mode lines and menu bars.
+This is an alias for the @code{mode-line} face, for compatibility with
+old Emacs versions.
+
+@item header-line
+@kindex header-line @r{(face name)}
+This face is used for the header lines of windows that have them.
+
+@item menu
+This face controls the display of menus, both their colors and their
+font. (This works only on certain systems.)
+
+@item fringe
+@kindex fringe @r{(face name)}
+This face controls the colors of window fringes, the thin areas on
+either side that are used to display continuation and truncation glyphs.
+
+@item scroll-bar
+@kindex scroll-bar @r{(face name)}
+This face controls the colors for display of scroll bars.
+
+@item tool-bar
+@kindex tool-bar @r{(face name)}
+This face is used for display of the tool bar, if any.
@item region
@kindex region @r{(face name)}
@kindex highlight @r{(face name)}
This face is meant to be used for highlighting for various purposes.
-@item underline
-@kindex underline @r{(face name)}
-This face underlines text.
+@item trailing-whitespace
+@kindex trailing-whitespace @r{(face name)}
+This face is used to display excess whitespace at the end of a line,
+if @code{show-trailing-whitespace} is non-@code{nil}.
+@end table
+
+ In contrast, these faces are provided to change the appearance of text
+in specific ways. You can use them on specific text, when you want
+the effects they produce.
+@table @code
@item bold
@kindex bold @r{(face name)}
This face uses a bold font, if possible. It uses the bold variant of
@kindex bold-italic @r{(face name)}
This face uses the bold italic variant of the frame's font, if it has
one.
+
+@item underline
+@kindex underline @r{(face name)}
+This face underlines text.
+
+@item fixed-patch
+@kindex fixed-patch @r{(face name)}
+This face forces use of a particular fixed-width font.
+
+@item variable-patch
+@kindex variable-patch @r{(face name)}
+This face forces use of a particular variable-width font. It's
+reasonable to customize this to use a different variable-width font, if
+you like, but you should not make it a fixed-width font.
@end table
+@defvar show-trailing-whitespace
+@tindex show-trailing-whitespace
+If this variable is non-@code{nil}, Emacs uses the
+@code{trailing-whitespace} face to display any spaces and tabs at the
+end of a line.
+@end defvar
+
@node Defining Faces
@subsection Defining Faces
emacs, The GNU Emacs Manual}).
@defmac defface face spec doc [keyword value]...
-@tindex defface
-Declare @var{face} as a customizable face that defaults according to
-@var{spec}. Do not quote the symbol @var{face}. The argument @var{doc}
-specifies the face documentation.
+This declares @var{face} as a customizable face that defaults according
+to @var{spec}. You should not quote the symbol @var{face}. The
+argument @var{doc} specifies the face documentation. The keywords you
+can use in @code{defface} are the same ones that are meaningful in both
+@code{defgroup} and @code{defcustom} (@pxref{Common Keywords}).
When @code{defface} executes, it defines the face according to
@var{spec}, then uses any customizations that were read from the
-@file{.emacs} file to override that specification.
+init file (@pxref{Init File}) to override that specification.
The purpose of @var{spec} is to specify how the face should appear on
different kinds of terminals. It should be an alist whose elements have
-the form @code{(@var{display} @var{atts})}. The element's @sc{car},
-@var{display}, specifies a class of terminals. The @sc{cdr},
+the form @code{(@var{display} @var{atts})}. Each element's @sc{car},
+@var{display}, specifies a class of terminals. The element's second element,
@var{atts}, is a list of face attributes and their values; it specifies
what the face should look like on that kind of terminal. The possible
attributes are defined in the value of @code{custom-face-attributes}.
@end table
@end defmac
- Here's how the standard face @code{region} could be defined
-with @code{defface}:
+ Here's how the standard face @code{region} is defined:
@example
+@group
(defface region
- ((((class color) (background dark))
- (:background "blue"))
- (t (:background "gray")))
- "Used for displaying the region.")
+ `((((type tty) (class color))
+ (:background "blue" :foreground "white"))
+@end group
+ (((type tty) (class mono))
+ (:inverse-video t))
+ (((class color) (background dark))
+ (:background "blue"))
+ (((class color) (background light))
+ (:background "lightblue"))
+ (t (:background "gray")))
+@group
+ "Basic face for highlighting the region."
+ :group 'basic-faces)
+@end group
@end example
Internally, @code{defface} uses the symbol property
with the customization buffer, and @code{face-documentation} for the
documentation string.
-@tindex frame-background-mode
@defopt frame-background-mode
This option, if non-@code{nil}, specifies the background type to use for
interpreting face definitions. If it is @code{dark}, then Emacs treats
as if they had a light background.
@end defopt
-@node Merging Faces
-@subsection Merging Faces for Display
+@node Face Attributes
+@subsection Face Attributes
+@cindex face attributes
- Here are all the ways to specify which face to use for display of text:
+ The effect of using a face is determined by a fixed set of @dfn{face
+attributes}. This table lists all the face attributes, and what they
+mean. Note that in general, more than one face can be specified for a
+given piece of text; when that happens, the attributes of all the faces
+are merged to specify how to display the text. @xref{Merging Faces}.
-@itemize @bullet
-@item
-With defaults. Each frame has a @dfn{default face}, which is used for
-all text that doesn't somehow specify another face. (We may change this
-in a forthcoming Emacs version to serve as a default for all text.)
+ In Emacs 21, any attribute in a face can have the value
+@code{unspecified}. This means the face doesn't specify that attribute.
+In face merging, when the first face fails to specify a particular
+attribute, that means the next face gets a chance. However, the
+@code{default} face must specify all attributes.
-@item
-With text properties. A character may have a @code{face} property; if so,
-it is displayed with that face. @xref{Special Properties}.
+ Some of these font attributes are meaningful only on certain kinds of
+displays---if your display cannot handle a certain attribute, the
+attribute is ignored. (The attributes @code{:family}, @code{:width},
+@code{:height}, @code{:weight}, and @code{:slant} correspond to parts of
+an X Logical Font Descriptor.)
-If the character has a @code{mouse-face} property, that is used instead
-of the @code{face} property when the mouse is ``near enough'' to the
-character.
+@table @code
+@item :family
+Font family name, or fontset name (@pxref{Fontsets}). If you specify a
+font family name, the wild-card characters @samp{*} and @samp{?} are
+allowed.
+
+@item :width
+Relative proportionate width, also known as the character set width or
+set width. This should be one of the symbols @code{ultra-condensed},
+@code{extra-condensed}, @code{condensed}, @code{semi-condensed},
+@code{normal}, @code{semi-expanded}, @code{expanded},
+@code{extra-expanded}, or @code{ultra-expanded}.
+
+@item :height
+Font height, an integer in units of 1/10 point.
+
+@item :weight
+Font weight---a symbol from this series (from most dense to most faint):
+@code{ultra-bold}, @code{extra-bold}, @code{bold}, @code{semi-bold},
+@code{normal}, @code{semi-light}, @code{light}, @code{extra-light},
+or @code{ultra-light}.
+
+On a text-only terminal, any weight greater than normal is displayed as
+extra bright, and any weight less than normal is displayed as
+half-bright (provided the terminal supports the feature).
+
+@item :slant
+Font slant---one of the symbols @code{italic}, @code{oblique}, @code{normal},
+@code{reverse-italic}, or @code{reverse-oblique}.
+
+On a text-only terminal, slanted text is displayed as half-bright, if
+the terminal supports the feature.
+
+@item :foreground
+Foreground color, a string.
+
+@item :background
+Background color, a string.
+
+@item :inverse-video
+Whether or not characters should be displayed in inverse video. The
+value should be @code{t} (yes) or @code{nil} (no).
+
+@item :stipple
+The background stipple, a bitmap.
+
+The value can be a string; that should be the name of a file containing
+external-format X bitmap data. The file is found in the directories
+listed in the variable @code{x-bitmap-file-path}.
+
+Alternatively, the value can specify the bitmap directly, with a list of
+the form @code{(@var{width} @var{height} @var{data})}. Here,
+@var{width} and @var{height} specify the size in pixels, and @var{data}
+is a string containing the raw bits of the bitmap, row by row. Each row
+occupies @math{(@var{width} + 7) / 8} consecutie bytes in the string
+(which should be a unibyte string for best results).
+
+If the value is @code{nil}, that means use no stipple pattern.
+
+Normally you do not need to set the stipple attribute, because it is
+used automatically to handle certain shades of gray.
+
+@item :underline
+Whether or not characters should be underlined, and in what color. If
+the value is @code{t}, underlining uses the foreground color of the
+face. If the value is a string, underlining uses that color. The
+value @code{nil} means do not underline.
+
+@item :overline
+Whether or not characters should be overlined, and in what color.
+The value is used like that of @code{:underline}.
+
+@item :strike-through
+Whether or not characters should be strike-through, and in what
+color. The value is used like that of @code{:underline}.
+
+@item :box
+Whether or not a box should be drawn around characters, its color, the
+width of the box lines, and 3D appearance.
+@end table
-@item
-With overlays. An overlay may have @code{face} and @code{mouse-face}
-properties too; they apply to all the text covered by the overlay.
+ Here are the possible values of the @code{:box} attribute, and what
+they mean:
-@item
-With a region that is active. In Transient Mark mode, the region is
-highlighted with a particular face (see @code{region-face}, below).
+@table @asis
+@item @code{nil}
+Don't draw a box.
-@item
-With special glyphs. Each glyph can specify a particular face
-number. @xref{Glyphs}.
-@end itemize
+@item @code{t}
+Draw a box with lines of width 1, in the foreground color.
- If these various sources together specify more than one face for a
-particular character, Emacs merges the attributes of the various faces
-specified. The attributes of the faces of special glyphs come first;
-then comes the face for region highlighting, if appropriate;
-then come attributes of faces from overlays, followed by those from text
-properties, and last the default face.
+@item @var{color}
+Draw a box with lines of width 1, in color @var{color}.
- When multiple overlays cover one character, an overlay with higher
-priority overrides those with lower priority. @xref{Overlays}.
+@item @code{(:line-width @var{width} :color @var{color} :style @var{style})}
+This way you can explicitly specify all aspects of the box. The value
+@var{width} specifies the width of the lines to draw; it defaults to 1.
- If an attribute such as the font or a color is not specified in any of
-the above ways, the frame's own font or color is used.
+The value @var{color} specifies the color to draw with. The default is
+the foreground color of the face for simple boxes, and the background
+color of the face for 3D boxes.
-@node Face Functions
-@subsection Functions for Working with Faces
+The value @var{style} specifies whether to draw a 3D box. If it is
+@code{released-button}, the box looks like a 3D button that is not being
+pressed. If it is @code{pressed-button}, the box looks like a 3D button
+that is being pressed. If it is @code{nil} or omitted, a plain 2D box
+is used.
+@end table
- The attributes a face can specify include the font, the foreground
-color, the background color, and underlining. The face can also leave
-these unspecified by giving the value @code{nil} for them.
+ The attributes @code{:overline}, @code{:strike-through} and
+@code{:box} are new in Emacs 21. The attributes @code{:family},
+@code{:height}, @code{:width}, @code{:weight}, @code{:slant} are also
+new; previous versions used the following attributes, now semi-obsolete,
+to specify some of the same information:
- Here are the primitives for creating and changing faces.
+@table @code
+@item :font
+This attribute specifies the font name.
-@defun make-face name
-This function defines a new face named @var{name}, initially with all
-attributes @code{nil}. It does nothing if there is already a face named
-@var{name}.
-@end defun
+@item :bold
+A non-@code{nil} value specifies a bold font.
-@defun face-list
-This function returns a list of all defined face names.
-@end defun
+@item :italic
+A non-@code{nil} value specifies an italic font.
+@end table
-@defun copy-face old-face new-name &optional frame new-frame
-This function defines the face @var{new-name} as a copy of the existing
-face named @var{old-face}. It creates the face @var{new-name} if that
-doesn't already exist.
+ For compatibility, you can still set these ``attributes'' in Emacs 21,
+even though they are not real face attributes. Here is what that does:
-If the optional argument @var{frame} is given, this function applies
-only to that frame. Otherwise it applies to each frame individually,
-copying attributes from @var{old-face} in each frame to @var{new-face}
-in the same frame.
+@table @code
+@item :font
+You can specify an X font name as the ``value'' of this ``attribute'';
+that sets the @code{:family}, @code{:width}, @code{:height},
+@code{:weight}, and @code{:slant} attributes according to the font name.
-If the optional argument @var{new-frame} is given, then @code{copy-face}
-copies the attributes of @var{old-face} in @var{frame} to @var{new-name}
-in @var{new-frame}.
+If the value is a pattern with wildcards, the first font that matches
+the pattern is used to set these attributes.
+
+@item :bold
+A non-@code{nil} makes the face bold; @code{nil} makes it normal.
+This actually works by setting the @code{:weight} attribute.
+
+@item :italic
+A non-@code{nil} makes the face italic; @code{nil} makes it normal.
+This actually works by setting the @code{:slant} attribute.
+@end table
+
+@defvar x-bitmap-file-path
+This variable specifies a list of directories for searching
+for bitmap files, for the @code{:stipple} attribute.
+@end defvar
+
+@defun bitmap-spec-p object
+This returns @code{t} if @var{object} is a valid bitmap
+specification, suitable for use with @code{:stipple}.
+It returns @code{nil} otherwise.
@end defun
+@node Attribute Functions
+@subsection Face Attribute Functions
+
You can modify the attributes of an existing face with the following
functions. If you specify @var{frame}, they affect just that frame;
otherwise, they affect all frames as well as the defaults that apply to
new frames.
+@tindex set-face-attribute
+@defun set-face-attribute face frame &rest arguments
+This function sets one or more attributes of face @var{face}
+for frame @var{frame}. If @var{frame} is @code{nil}, it sets
+the attribute for all frames, and the defaults for new frames.
+
+The extra arguments @var{arguments} specify the attributes to set, and
+the values for them. They should consist of alternating attribute names
+(such as @code{:family} or @code{:underline}) and corresponding values.
+Thus,
+
+@example
+(set-face-attribute 'foo nil
+ :width :extended
+ :weight :bold
+ :underline "red")
+@end example
+
+@noindent
+sets the attributes @code{:width}, @code{:weight} and @code{:underline}
+to the corresponding values.
+@end defun
+
+@tindex face-attribute
+@defun face-attribute face attribute &optional frame
+This returns the value of the @var{attribute} attribute of face
+@var{face} on @var{frame}. If @var{frame} is @code{nil},
+that means the selected frame.
+
+If @var{frame} is @code{t}, the value is the default for
+@var{face} for new frames.
+
+For example,
+
+@example
+(face-attribute 'bold :weight)
+ @result{} bold
+@end example
+@end defun
+
+ The functions above did not exist before Emacs 21. For compatibility
+with older Emacs versions, you can use the following functions to set
+and examine the face attributes which existed in those versions.
+
@defun set-face-foreground face color &optional frame
@defunx set-face-background face color &optional frame
These functions set the foreground (or background, respectively) color
@end defun
@defun set-face-font face font &optional frame
-This function sets the font of face @var{face}. The argument @var{font}
-should be a string, either a valid font name for your system or the name
-of an Emacs fontset (@pxref{Fontsets}). Note that if you set the font
+This function sets the font of face @var{face}.
+
+In Emacs 21, this actually sets the attributes @code{:family},
+@code{:width}, @code{:height}, @code{:weight}, and @code{:slant}
+according to the font name @var{font}.
+
+In Emacs 20, this sets the font attribute. Once you set the font
explicitly, the bold and italic attributes cease to have any effect,
-because the precise font that you specified is always used.
+because the precise font that you specified is used.
@end defun
@defun set-face-bold-p face bold-p &optional frame
-@tindex set-face-bold-p
-This function sets the bold attribute of face @var{face}.
-Non-@code{nil} means bold; @code{nil} means non-bold.
+This function specifies whether @var{face} should be bold. If
+@var{bold-p} is non-@code{nil}, that means yes; @code{nil} means no.
+
+In Emacs 21, this sets the @code{:weight} attribute.
+In Emacs 20, it sets the @code{:bold} attribute.
@end defun
@defun set-face-italic-p face italic-p &optional frame
-@tindex set-face-italic-p
-This function sets the italic attribute of face @var{face}.
-Non-@code{nil} means italic; @code{nil} means non-italic.
+This function specifies whether @var{face} should be italic. If
+@var{italic-p} is non-@code{nil}, that means yes; @code{nil} means no.
+
+In Emacs 21, this sets the @code{:slant} attribute.
+In Emacs 20, it sets the @code{:italic} attribute.
@end defun
@defun set-face-underline-p face underline-p &optional frame
@end defun
@defun invert-face face &optional frame
-Swap the foreground and background colors of face @var{face}. If the
-face doesn't specify both foreground and background, then its foreground
-and background are set to the default background and foreground,
-respectively.
+This function inverts the @code{:inverse-video} attribute of face
+@var{face}. If the attribute is @code{nil}, this function sets it to
+@code{t}, and vice versa.
@end defun
These functions examine the attributes of a face. If you don't
specify @var{frame}, they refer to the default data for new frames.
+They return the symbol @code{unspecified} if the face doesn't define any
+value for that attribute.
@defun face-foreground face &optional frame
@defunx face-background face &optional frame
@end defun
@defun face-bold-p face &optional frame
-@tindex face-bold-p
-This function returns the bold attribute of face @var{face}.
+This function returns @code{t} if @var{face} is bold---that is, if it is
+bolder than normal. It returns @code{nil} otherwise.
@end defun
@defun face-italic-p face &optional frame
-@tindex face-italic-p
-This function returns the italic attribute of face @var{face}.
+This function returns @code{t} if @var{face} is italic or oblique,
+@code{nil} otherwise.
@end defun
@defun face-underline-p face &optional frame
-This function returns the underline attribute of face @var{face}.
+This function returns the @code{:underline} attribute of face @var{face}.
+@end defun
+
+@defun face-inverse-video-p face &optional frame
+This function returns the @code{:inverse-video} attribute of face @var{face}.
+@end defun
+
+@node Merging Faces
+@subsection Merging Faces for Display
+
+ Here are the ways to specify which faces to use for display of text:
+
+@itemize @bullet
+@item
+With defaults. The @code{default} face is used as the ultimate
+default for all text. (In Emacs 19 and 20, the @code{default}
+face is used only when no other face is specified.)
+
+For a mode line or header line, the face @code{modeline} or
+@code{header-line} is used just before @code{default}.
+
+@item
+With text properties. A character can have a @code{face} property; if
+so, the faces and face attributes specified there apply. @xref{Special
+Properties}.
+
+If the character has a @code{mouse-face} property, that is used instead
+of the @code{face} property when the mouse is ``near enough'' to the
+character.
+
+@item
+With overlays. An overlay can have @code{face} and @code{mouse-face}
+properties too; they apply to all the text covered by the overlay.
+
+@item
+With a region that is active. In Transient Mark mode, the region is
+highlighted with the face @code{region} (@pxref{Standard Faces}).
+
+@item
+With special glyphs. Each glyph can specify a particular face
+number. @xref{Glyphs}.
+@end itemize
+
+ If these various sources together specify more than one face for a
+particular character, Emacs merges the attributes of the various faces
+specified. The attributes of the faces of special glyphs come first;
+then comes the face for region highlighting, if appropriate;
+then come attributes of faces from overlays, followed by those from text
+properties, and last the default face.
+
+ When multiple overlays cover one character, an overlay with higher
+priority overrides those with lower priority. @xref{Overlays}.
+
+ In Emacs 20, if an attribute such as the font or a color is not
+specified in any of the above ways, the frame's own font or color is
+used. In newer Emacs versions, this cannot happen, because the
+@code{default} face specifies all attributes---in fact, the frame's own
+font and colors are synonymous with those of the default face.
+
+@node Font Selection
+@subsection Font Selection
+
+ @dfn{Selecting a font} means mapping the specified face attributes for
+a character to a font that is available on a particular display. The
+face attributes, as determined by face merging, specify most of the
+font choice, but not all. Part of the choice depends on what character
+it is.
+
+ For multibyte characters, typically each font covers only one
+character set. So each character set (@pxref{Character Sets}) specifies
+a registry and encoding to use, with the character set's
+@code{x-charset-registry} property. Its value is a string containing
+the registry and the encoding, with a dash between them:
+
+@example
+(plist-get (charset-plist 'latin-iso8859-1)
+ 'x-charset-registry)
+ @result{} "ISO8859-1"
+@end example
+
+ Unibyte text does not have character sets, so displaying a unibyte
+character takes the registry and encoding from the variable
+@code{face-default-registry}.
+
+@defvar face-default-registry
+This variable specifies which registry and encoding to use in choosing
+fonts for unibyte characters. The value is initialized at Emacs startup
+time from the font the user specified for Emacs.
+@end defvar
+
+ If the face specifies a fontset name, that fontset determines a
+pattern for fonts of the given charset. If the face specifies a font
+family, a font pattern is constructed.
+
+ Emacs tries to find an available font for the given face attributes
+and character's registry and encoding. If there is a font that matches
+exactly, it is used, of course. The hard case is when no available font
+exactly fits the specification. Then Emacs looks for one that is
+``close''---one attribute at a time. You can specify the order to
+consider the attributes. In the case where a specified font family is
+not available, you can specify a set of mappings for alternatives to
+try.
+
+@defvar face-font-selection-order
+@tindex face-font-selection-order
+This variable specifies the order of importance of the face attributes
+@code{:width}, @code{:height}, @code{:weight}, and @code{:slant}. The
+value should be a list containing those four symbols, in order of
+decreasing importance.
+
+Font selection first finds the best available matches for the first
+attribute listed; then, among the fonts which are best in that way, it
+searches for the best matches in the second attribute, and so on.
+
+The attributes @code{:weight} and @code{:width} have symbolic values in
+a range centered around @code{normal}. Matches that are more extreme
+(farther from @code{normal}) are somewhat preferred to matches that are
+less extreme (closer to @code{normal}); this is designed to ensure that
+non-normal faces contrast with normal ones, whenever possible.
+
+The default is @code{(:width :height :weight :slant)}, which means first
+find the fonts closest to the specified @code{:width}, then---among the
+fonts with that width---find a best match for the specified font height,
+and so on.
+
+One example of a case where this variable makes a difference is when the
+default font has no italic equivalent. With the default ordering, the
+@code{italic} face will use a non-italic font that is similar to the
+default one. But if you put @code{:slant} before @code{:height}, the
+@code{italic} face will use an italic font, even if its height is not
+quite right.
+@end defvar
+
+@defvar face-alternative-font-family-alist
+@tindex face-alternative-font-family-alist
+This variable lets you specify alternative font families to try, if a
+given family is specified and doesn't exist. Each element should have
+this form:
+
+@example
+(@var{family} @var{alternate-families}@dots{})
+@end example
+
+If @var{family} is specified but not available, Emacs will try the other
+families given in @var{alternate-families}, one by one, until it finds a
+family that does exist.
+@end defvar
+
+ Emacs can make use of scalable fonts, but by default it does not use
+them, since the use of too many or too big scalable fonts can crash
+XFree86 servers.
+
+@defvar scalable-fonts-allowed
+@tindex scalable-fonts-allowed
+This variable controls which scalable fonts to use. A value of
+@code{nil}, the default, means do not use scalable fonts. @code{t}
+means to use any scalable font that seems appropriate for the text.
+
+Otherwise, the value must be a list of regular expressions. Then a
+scalable font is enabled for use if its name matches any regular
+expression in the list. For example,
+
+@example
+(setq scalable-fonts-allowed '("muleindian-2$"))
+@end example
+
+@noindent
+allows the use of scalable fonts with registry @code{muleindian-2}.
+@end defvar
+
+@defun clear-face-cache &optional unload-p
+@tindex clear-face-cache
+This function clears the face cache for all frames.
+If @var{unload-p} is non-@code{nil}, that means to unload
+all unused fonts as well.
+@end defun
+
+@node Face Functions
+@subsection Functions for Working with Faces
+
+ Here are additional functions for creating and working with faces.
+
+@defun make-face name
+This function defines a new face named @var{name}, initially with all
+attributes @code{nil}. It does nothing if there is already a face named
+@var{name}.
+@end defun
+
+@defun face-list
+This function returns a list of all defined face names.
+@end defun
+
+@defun copy-face old-face new-name &optional frame new-frame
+This function defines the face @var{new-name} as a copy of the existing
+face named @var{old-face}. It creates the face @var{new-name} if that
+doesn't already exist.
+
+If the optional argument @var{frame} is given, this function applies
+only to that frame. Otherwise it applies to each frame individually,
+copying attributes from @var{old-face} in each frame to @var{new-face}
+in the same frame.
+
+If the optional argument @var{new-frame} is given, then @code{copy-face}
+copies the attributes of @var{old-face} in @var{frame} to @var{new-name}
+in @var{new-frame}.
@end defun
@defun face-id face
@end defun
@defun face-documentation face
-@tindex face-documentation
This function returns the documentation string of face @var{face}, or
@code{nil} if none was specified for it.
@end defun
@defun face-differs-from-default-p face &optional frame
This returns @code{t} if the face @var{face} displays differently from
-the default face. A face is considered to be ``the same'' as the normal
-face if each attribute is either the same as that of the default face or
-@code{nil} (meaning to inherit from the default).
+the default face. A face is considered to be ``the same'' as the
+default face if each attribute is either the same as that of the default
+face, or unspecified (meaning to inherit from the default).
+@end defun
+
+@node Auto Faces
+@subsection Automatic Face Assignment
+@cindex automatic face assignment
+@cindex faces, automatic choice
+
+@cindex Font-Lock mode
+ Starting with Emacs 21, a hook is available for automatically
+assigning faces to text in the buffer. This hook is used for part of
+the implementation of Font-Lock mode.
+
+@tindex fontification-functions
+@defvar fontification-functions
+This variable holds a list of functions that are called by Emacs
+redisplay as needed to assign faces automatically to text in the buffer.
+
+The functions are called in the order listed, with one argument, a
+buffer position @var{pos}. Each function should attempt to assign faces
+to the text in the current buffer starting at @var{pos}.
+
+Each function should record the faces they assign by setting the
+@code{face} property. It should also add a non-@code{nil}
+@code{fontified} property for all the text it has assigned faces to.
+That property tells redisplay that faces have been assigned to that text
+already.
+
+It is probably a good idea for each function to do nothing if the
+character after @var{pos} already has a non-@code{nil} @code{fontified}
+property, but this is not required. If one function overrides the
+assignments made by a previous one, the properties as they are
+after the last function finishes are the ones that really matter.
+
+For efficiency, we recommend writing these functions so that they
+usually assign faces to around 400 to 600 characters at each call.
+@end defvar
+
+@node Font Lookup
+@subsection Looking Up Fonts
+
+@defun x-list-fonts pattern &optional face frame maximum
+This function returns a list of available font names that match
+@var{pattern}. If the optional arguments @var{face} and @var{frame} are
+specified, then the list is limited to fonts that are the same size as
+@var{face} currently is on @var{frame}.
+
+The argument @var{pattern} should be a string, perhaps with wildcard
+characters: the @samp{*} character matches any substring, and the
+@samp{?} character matches any single character. Pattern matching
+of font names ignores case.
+
+If you specify @var{face} and @var{frame}, @var{face} should be a face name
+(a symbol) and @var{frame} should be a frame.
+
+The optional argument @var{maximum} sets a limit on how many fonts to
+return. If this is non-@code{nil}, then the return value is truncated
+after the first @var{maximum} matching fonts. Specifying a small value
+for @var{maximum} can make this function much faster, in cases where
+many fonts match the pattern.
+@end defun
+
+ These additional functions are available starting in Emacs 21.
+
+@defun x-family-fonts &optional family frame
+@tindex x-family-fonts
+This function returns a list describing the available fonts for family
+@var{family} on @var{frame}. If @var{family} is omitted or @code{nil},
+this list applies to all families, and therefore, it contains all
+available fonts. Otherwise, @var{family} must be a string; it may
+contain the wildcards @samp{?} and @samp{*}.
+
+The list describes the display that @var{frame} is on; if @var{frame} is
+omitted or @code{nil}, it applies to the selected frame's display.
+
+The list contains a vector of the following form for each font:
+
+@example
+[@var{family} @var{width} @var{point-size} @var{weight} @var{slant}
+ @var{fixed-p} @var{full} @var{registry-and-encoding}]
+@end example
+
+The first five elements correspond to face attributes; if you
+specify these attributes for a face, it will use this font.
+
+The last three elements give additional information about the font.
+@var{fixed-p} is non-nil if the font is fixed-pitch. @var{full} is the
+full name of the font, and @var{registry-and-encoding} is a string
+giving the registry and encoding of the font.
+
+The result list is sorted according to the current face font sort order.
@end defun
-@defvar region-face
-This variable's value specifies the face number to use to display characters
-in the region when it is active (in Transient Mark mode only). The face
-thus specified takes precedence over all faces that come from text
-properties and overlays, for characters in the region. @xref{The Mark},
-for more information about Transient Mark mode.
+@defun x-font-family-list &optional frame
+@tindex x-font-family-list
+This function returns a list of the font families available for
+@var{frame}'s display. If @var{frame} is omitted or @code{nil}, it
+describes the selected frame's display.
+
+The value is a list of elements of this form:
+
+@example
+(@var{family} . @var{fixed-p})
+@end example
-Normally, the value is the face number of the face named @code{region}.
+@noindent
+Here @var{family} is a font family, and @var{fixed-p} is
+non-@code{nil} if fonts of that family are fixed-pitch.
+@end defun
+
+@defvar font-list-limit
+@tindex font-list-limit
+This variable specifies maximum number of fonts to consider in font
+matching. The function @code{x-family-fonts} will not return more than
+that many fonts, and font selection will consider only that many fonts
+when searching a matching font for face attributes. The default is
+currently 100.
@end defvar
-@tindex frame-update-face-colors
-@defun frame-update-face-colors frame
-This function updates the way faces display on @var{frame}, for a change
-in @var{frame}'s foreground or background color.
+@node Fontsets
+@subsection Fontsets
+
+ A @dfn{fontset} is a list of fonts, each assigned to a range of
+character codes. An individual font cannot display the whole range of
+characters that Emacs supports, but a fontset can. Fontsets have names,
+just as fonts do, and you can use a fontset name in place of a font name
+when you specify the ``font'' for a frame or a face. Here is
+information about defining a fontset under Lisp program control.
+
+@defun create-fontset-from-fontset-spec fontset-spec &optional style-variant-p noerror
+This function defines a new fontset according to the specification
+string @var{fontset-spec}. The string should have this format:
+
+@smallexample
+@var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}}
+@end smallexample
+
+@noindent
+Whitespace characters before and after the commas are ignored.
+
+The first part of the string, @var{fontpattern}, should have the form of
+a standard X font name, except that the last two fields should be
+@samp{fontset-@var{alias}}.
+
+The new fontset has two names, one long and one short. The long name is
+@var{fontpattern} in its entirety. The short name is
+@samp{fontset-@var{alias}}. You can refer to the fontset by either
+name. If a fontset with the same name already exists, an error is
+signaled, unless @var{noerror} is non-@code{nil}, in which case this
+function does nothing.
+
+If optional argument @var{style-variant-p} is non-@code{nil}, that says
+to create bold, italic and bold-italic variants of the fontset as well.
+These variant fontsets do not have a short name, only a long one, which
+is made by altering @var{fontpattern} to indicate the bold or italic
+status.
+
+The specification string also says which fonts to use in the fontset.
+See below for the details.
+@end defun
+
+ The construct @samp{@var{charset}:@var{font}} specifies which font to
+use (in this fontset) for one particular character set. Here,
+@var{charset} is the name of a character set, and @var{font} is the font
+to use for that character set. You can use this construct any number of
+times in the specification string.
+
+ For the remaining character sets, those that you don't specify
+explicitly, Emacs chooses a font based on @var{fontpattern}: it replaces
+@samp{fontset-@var{alias}} with a value that names one character set.
+For the @sc{ascii} character set, @samp{fontset-@var{alias}} is replaced
+with @samp{ISO8859-1}.
+
+ In addition, when several consecutive fields are wildcards, Emacs
+collapses them into a single wildcard. This is to prevent use of
+auto-scaled fonts. Fonts made by scaling larger fonts are not usable
+for editing, and scaling a smaller font is not useful because it is
+better to use the smaller font in its own size, which Emacs does.
+
+ Thus if @var{fontpattern} is this,
+
+@example
+-*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
+@end example
+
+@noindent
+the font specification for @sc{ascii} characters would be this:
+
+@example
+-*-fixed-medium-r-normal-*-24-*-ISO8859-1
+@end example
+
+@noindent
+and the font specification for Chinese GB2312 characters would be this:
+
+@example
+-*-fixed-medium-r-normal-*-24-*-gb2312*-*
+@end example
+
+ You may not have any Chinese font matching the above font
+specification. Most X distributions include only Chinese fonts that
+have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In
+such a case, @samp{Fontset-@var{n}} can be specified as below:
+
+@smallexample
+Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
+ chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
+@end smallexample
+
+@noindent
+Then, the font specifications for all but Chinese GB2312 characters have
+@samp{fixed} in the @var{family} field, and the font specification for
+Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
+field.
+
+@node Display Property
+@section The @code{display} Property
+@cindex display specification
+@kindex display @r{(text property)}
+
+ The @code{display} text property (or overlay property) is used to
+insert images into text, and also control other aspects of how text
+displays. These features are available starting in Emacs 21. The value
+of the @code{display} property should be a display specification, or a
+list or vector containing several display specifications. The rest of
+this section describes several kinds of display specifications and what
+they mean.
+
+@menu
+* Specified Space:: Displaying one space with a specified width.
+* Other Display Specs:: Displaying an image; magnifying text; moving it
+ up or down on the page; adjusting the width
+ of spaces within text.
+* Display Margins:: Displaying text or images to the side of the main text.
+* Conditional Display:: Making any of the above features conditional
+ depending on some Lisp expression.
+@end menu
+
+@node Specified Space
+@subsection Specified Spaces
+@cindex spaces, specified height or width
+@cindex specified spaces
+@cindex variable-width spaces
+
+ To display a space of specified width and/or height, use a display
+specification of the form @code{(space . @var{props})}, where
+@var{props} is a property list (a list of alternating properties and
+values). You can put this property on one or more consecutive
+characters; a space of the specified height and width is displayed in
+place of @emph{all} of those characters. These are the properties you
+can use to specify the weight of the space:
+
+@table @code
+@item :width @var{width}
+Specifies that the space width should be @var{width} times the normal
+character width. @var{width} can be an integer or floating point
+number.
+
+@item :relative-width @var{factor}
+Specifies that the width of the stretch should be computed from the
+first character in the group of consecutive characters that have the
+same @code{display} property. The space width is the width of that
+character, multiplied by @var{factor}.
+
+@item :align-to @var{hpos}
+Specifies that the space should be wide enough to reach @var{hpos}. The
+value @var{hpos} is measured in units of the normal character width. It
+may be an interer or a floating point number.
+@end table
+
+ Exactly one of the above properties should be used. You can also
+specify the height of the space, with other properties:
+
+@table @code
+@item :height @var{height}
+Specifies the height of the space, as @var{height},
+measured in terms of the normal line height.
+
+@item :relative-height @var{factor}
+Specifies the height of the space, multiplying the ordinary height
+of the text having this display specification by @var{factor}.
+
+@item :ascent @var{ascent}
+Specifies that @var{ascent} percent of the height of the space should be
+considered as the ascent of the space---that is, the part above the
+baseline. The value of @var{ascent} must be a non-negative number no
+greater than 100.
+@end table
+
+ You should not use both @code{:height} and @code{:relative-height}
+together.
+
+@node Other Display Specs
+@subsection Other Display Specifications
+
+@table @code
+@item (image . @var{image-props})
+This is in fact an image descriptor (@pxref{Images}). When used as a
+display specification, it means to display the image instead of the text
+that has the display specification.
+
+@item (space-width @var{factor})
+This display specification affects all the space characters within the
+text that has the specification. It displays all of these spaces
+@var{factor} times as wide as normal. The element @var{factor} should
+be an integer or float. Characters other than spaces are not affected
+at all; in particular, this has no effect on tab characters.
+
+@item (height @var{height})
+This display specification makes the text taller or shorter.
+Here are the possibilities for @var{height}:
+
+@table @asis
+@item @code{(+ @var{n})}
+This means to use a font that is @var{n} steps larger. A ``step'' is
+defined by the set of available fonts---specifically, those that match
+what was otherwise specified for this text, in all attributes except
+height. Each size for which a suitable font is available counts as
+another step. @var{n} should be an integer.
+
+@item @code{(- @var{n})}
+This means to use a font that is @var{n} steps smaller.
+
+@item a number, @var{factor}
+A number, @var{factor}, means to use a font that is @var{factor} times
+as tall as the default font.
+
+@item a symbol, @var{function}
+A symbol is a function to compute the height. It is called with the
+current height as argument, and should return the new height to use.
+
+@item anything else, @var{form}
+If the @var{height} value doesn't fit the previous possibilities, it is
+a form. Emacs evaluates it to get the new height, with the symbol
+@code{height} bound to the current specified font height.
+@end table
+
+@item (raise @var{factor})
+This kind of display specification raises or lowers the text
+it applies to, relative to the baseline of the line.
+
+@var{factor} must be a number, which is interpreted as a multiple of the
+height of the affected text. If it is positive, that means to display
+the characters raised. If it is negative, that means to display them
+lower down.
+
+If the text also has a @code{height} display specification, that does
+not affect the amount of raising or lowering, which is based on the
+faces used for the text.
+@end table
+
+@node Display Margins
+@subsection Displaying in the Margins
+@cindex display margins
+@cindex margins, display
+
+ A buffer can have blank areas called @dfn{display margins} on the left
+and on the right. Ordinary text never appears in these areas, but you
+can put things into the display margins using the @code{display}
+property.
+
+ To put text in the left or right display margin of the window, use a
+display specification of the form @code{(margin right-margin)} or
+@code{(margin left-margin)} on it. To put an image in a display margin,
+use that display specification along with the display specification for
+the image.
+
+ Before the display margins can display anything, you must give
+them a nonzero width. The usual way to do that is to set these
+variables:
+
+@defvar left-margin-width
+@tindex left-margin-width
+This variable specifies the width of the left margin.
+It is buffer-local in all buffers.
+@end defvar
+
+@defvar right-margin-width
+@tindex right-margin-width
+This variable specifies the width of the right margin.
+It is buffer-local in all buffers.
+@end defvar
+
+ Setting these variables does not immediately affect the window. These
+variables are checked when a new buffer is displayed in the window.
+Thus, you can make changes take effect by calling
+@code{set-window-buffer}.
+
+ You can also set the margin widths immediately.
+
+@defun set-window-margins window left right
+@tindex set-window-margins
+This function specifies the margin widths for window @var{window}.
+The argument @var{left} controls the left margin and
+@var{right} controls the right margin.
+@end defun
+
+@defun window-margins &optional window
+@tindex window-margins
+This function returns the left and right margins of @var{window}
+as a cons cell of the form @code{(@var{left} . @var{right})}.
+If @var{window} is @code{nil}, the selected window is used.
+@end defun
+
+@node Conditional Display
+@subsection Conditional Display Specifications
+@cindex conditional display specifications
+
+ You can make any display specification conditional. To do that,
+package it in another list of the form @code{(when @var{condition} .
+@var{spec})}. Then the specification @var{spec} applies only when
+@var{condition} evaluates to a non-@code{nil} value. During the
+evaluation, point is temporarily set at the end position of the text
+having this conditional display specification.
+
+@node Images
+@section Images
+@cindex images in buffers
+
+ To display an image in an Emacs buffer, you must first create an image
+descriptor, then use it as a display specifier in the @code{display}
+property of text that is displayed (@pxref{Display Property}). Like the
+@code{display} property, this feature is available starting in Emacs 21.
+
+ Emacs can display a number of different image formats; some of them
+are supported only if particular support libraries are installed on your
+machine. The supported image formats include XBM, XPM (needing the
+libraries @code{libXpm} version 3.4k and @code{libz}), GIF (needing
+@code{libungif} 4.1.0), Postscript, PBM, JPEG (needing the
+@code{libjpeg} library version v6a), TIFF (needing @code{libtiff} v3.4),
+and PNG (needing @code{libpng} 1.0.2).
+
+ You specify one of these formats with an image type symbol. The image
+type symbols are @code{xbm}, @code{xpm}, @code{gif}, @code{postscript},
+@code{pbm}, @code{jpeg}, @code{tiff}, and @code{png}.
+
+@defvar image-types
+This variable contains a list of those image type symbols that are
+supported in the current configuration.
+@end defvar
+
+@menu
+* Image Descriptors:: How to specify an image for use in @code{:display}.
+* XBM Images:: Special features for XBM format.
+* XPM Images:: Special features for XPM format.
+* GIF Images:: Special features for GIF format.
+* Postscript Images:: Special features for Postscript format.
+* Other Image Types:: Various other formats are supported.
+* Defining Images:: Convenient ways to define an image for later use.
+* Showing Images:: Convenient ways to display an image once it is defined.
+* Image Cache:: Internal mechanisms of image display.
+@end menu
+
+@node Image Descriptors
+@subsection Image Descriptors
+@cindex image descriptor
+
+ An image description is a list of the form @code{(image
+. @var{props})}, where @var{props} is a property list containing
+alternating keyword symbols (symbols whose names start with a colon) and
+their values. You can use any Lisp object as a property, but the only
+properties that have any special meaning are certain symbols, all of
+them keywords.
+
+ Every image descriptor must contain the property @code{:type
+@var{type}} to specify the format of the image. The value of @var{type}
+should be an image type symbol; for example, @code{xpm} for an image in
+XPM format.
+
+ Here is a list of other properties that are meaningful for all image
+types:
+
+@table @code
+@item :ascent @var{ascent}
+The @code{:ascent} property specifies the amount of the image's
+height to use for its ascent---that is, the part above the baseline.
+The value, @var{ascent}, must be a number in the range 0 to 100, or
+the symbol @code{center}.
+
+If @var{ascent} is a number, that percentage of the image's height is
+used for its ascent.
+
+If @var{ascent} is @code{center}, the image is vertically centered
+around a centerline which would be the vertical centerline of text drawn
+at the position of the image, in the manner specified by the text
+properties and overlays that apply to the image.
+
+If this property is omitted, it defaults to 50.
+
+@item :margin @var{margin}
+The @code{:margin} property specifies how many pixels to add as an extra
+margin around the image. The value, @var{margin}, must be a
+non-negative number; if it is not specified, the default is zero.
+
+@item :relief @var{relief}
+The @code{:relief} property, if non-@code{nil}, adds a shadow rectangle
+around the image. The value, @var{relief}, specifies the width of the
+shadow lines, in pixels. If @var{relief} is negative, shadows are drawn
+so that the image appears as a pressed button; otherwise, it appears as
+an unpressed button.
+
+@item :algorithm @var{algorithm}
+The @code{:algorithm} property, if non-@code{nil}, specifies a
+conversion algorithm that should be applied to the image before it is
+displayed; the value, @var{algorithm}, specifies which algorithm.
+
+Currently, the only meaningful value for @var{algorithm} (aside from
+@code{nil}) is @code{laplace}; this applies the Laplace edge detection
+algorithm, which blurs out small differences in color while highlighting
+larger differences. People sometimes consider this useful for
+displaying the image for a ``disabled'' button.
+
+@item :heuristic-mask @var{transparent-color}
+The @code{:heuristic-mask} property, if non-@code{nil}, specifies that a
+certain color in the image should be transparent. Each pixel where this
+color appears will actually allow the frame's background to show
+through.
+
+If @var{transparent-color} is @code{t}, then determine the transparent
+color by looking at the four corners of the image. This uses the color
+that occurs most frequently near the corners as the transparent color.
+
+Otherwise, @var{heuristic-mask} should specify the transparent color
+directly, as a list of three integers in the form @code{(@var{red}
+@var{green} @var{blue})}.
+
+@item :file @var{file}
+The @code{:file} property specifies to load the image from file
+@var{file}. If @var{file} is not an absolute file name, it is expanded
+in @code{data-directory}.
+
+@item :data @var{data}
+The @code{:data} property specifies the actual contents of the image.
+Each image must use either @code{:data} or @code{:file}, but not both.
+For most image types, the value of the @code{:data} property should be a
+string containing the image data; we recommend using a unibyte string.
+
+Before using @code{:data}, look for further information in the section
+below describing the specific image format. For some image types,
+@code{:data} may not be supported; for some, it allows other data types;
+for some, @code{:data} alone is not enough, so you need to use other
+image properties along with @code{:data}.
+@end table
+
+@node XBM Images
+@subsection XBM Images
+@cindex XBM
+
+ To use XBM format, specify @code{xbm} as the image type. This image
+format doesn't require an external library, so images of this type are
+always supported.
+
+ Additional image properties supported for the @code{xbm} image type are:
+
+@table @code
+@item :foreground @var{foreground}
+The value, @var{foreground}, should be a string specifying the image
+foreground color. This color is used for each pixel in the XBM that is
+1. The default is the frame's foreground color.
+
+@item :background @var{background}
+The value, @var{background}, should be a string specifying the image
+background color. This color is used for each pixel in the XBM that is
+0. The default is the frame's background color.
+@end table
+
+ If you specify an XBM image using data within Emacs instead of an
+external file, use the following three properties:
+
+@table @code
+@item :data @var{data}
+The value, @var{data}, specifies the contents of the image.
+There are three formats you can use for @var{data}:
+
+@itemize @bullet
+@item
+A vector of strings or bool-vectors, each specifying one line of the
+image. Do specify @code{:height} and @code{:width}.
+
+@item
+A string containing the same byte sequence as an XBM file would contain.
+You must not specify @code{:height} and @code{:width} in this case,
+because omitting them is what indicates the data has the format of an
+XBM file. The file contents specify the height and width of the image.
+
+@item
+A string or a bool-vector containing the bits of the image (plus perhaps
+some extra bits at the end that will not be used). It should contain at
+least @var{width} * @code{height} bits. In this case, you must specify
+@code{:height} and @code{:width}, both to indicate that the string
+contains just the bits rather than a whole XBM file, and to specify the
+size of the image.
+@end itemize
+
+@item :width @var{width}
+The value, @var{width}, specifies the width of the image, in pixels.
+
+@item :height @var{height}
+The value, @var{height}, specifies the height of the image, in pixels.
+@end table
+
+@node XPM Images
+@subsection XPM Images
+@cindex XPM
+
+ To use XPM format, specify @code{xpm} as the image type. The
+additional image property @code{:color-symbols} is also meaningful with
+the @code{xpm} image type:
+
+@table @code
+@item :color-symbols @var{symbols}
+The value, @var{symbols}, should be an alist whose elements have the
+form @code{(@var{name} . @var{color})}. In each element, @var{name} is
+the name of a color as it appears in the image file, and @var{color}
+specifies the actual color to use for displaying that name.
+@end table
+
+@node GIF Images
+@subsection GIF Images
+@cindex GIF
+
+ For GIF images, specify image type @code{gif}. Because of the patents
+in the US covering the LZW algorithm, the continued use of GIF format is
+a problem for the whole Internet; to end this problem, it is a good idea
+for everyone, even outside the US, to stop using GIFS right away
+(@uref{http://www.burnallgifs.org/}). But if you still want to use
+them, Emacs can display them.
+
+@table @code
+@item :index @var{index}
+You can use @code{:index} to specify one image from a GIF file that
+contains more than one image. This property specifies use of image
+number @var{index} from the file. An error is signaled if the GIF file
+doesn't contain an image with index @var{index}.
+@end table
+
+@ignore
+This could be used to implement limited support for animated GIFs.
+For example, the following function displays a multi-image GIF file
+at point-min in the current buffer, switching between sub-images
+every 0.1 seconds.
+
+(defun show-anim (file max)
+ "Display multi-image GIF file FILE which contains MAX subimages."
+ (display-anim (current-buffer) file 0 max t))
+
+(defun display-anim (buffer file idx max first-time)
+ (when (= idx max)
+ (setq idx 0))
+ (let ((img (create-image file nil :image idx)))
+ (save-excursion
+ (set-buffer buffer)
+ (goto-char (point-min))
+ (unless first-time (delete-char 1))
+ (insert-image img))
+ (run-with-timer 0.1 nil 'display-anim buffer file (1+ idx) max nil)))
+@end ignore
+
+@node Postscript Images
+@subsection Postscript Images
+@cindex Postscript images
+
+ To use Postscript for an image, specify image type @code{postscript}.
+This works only if you have Ghostscript installed. You must always use
+these three properties:
+
+@table @code
+@item :pt-width @var{width}
+The value, @var{width}, specifies the width of the image measured in
+points (1/72 inch). @var{width} must be an integer.
+
+@item :pt-height @var{height}
+The value, @var{height}, specifies the height of the image in points
+(1/72 inch). @var{height} must be an integer.
+
+@item :bounding-box @var{box}
+The value, @var{box}, must be a list or vector of four integers, which
+specifying the bounding box of the Postscript image, analogous to the
+@samp{BoundingBox} comment found in Postscript files.
+
+@example
+%%BoundingBox: 22 171 567 738
+@end example
+@end table
+
+ Displaying Postscript images from Lisp data is not currently
+implemented, but it may be implemented by the time you read this.
+See the @file{etc/NEWS} file to make sure.
+
+@node Other Image Types
+@subsection Other Image Types
+@cindex PBM
+
+ For PBM images, specify image type @code{pbm}. Color, gray-scale and
+monochromatic images are supported.
+
+ For JPEG images, specify image type @code{jpeg}.
+
+ For TIFF images, specify image type @code{tiff}.
+
+ For PNG images, specify image type @code{png}.
+
+@node Defining Images
+@subsection Defining Images
+
+ The functions @code{create-image} and @code{defimage} provide
+convenient ways to create image descriptors.
+
+@defun create-image file &optional type &rest props
+@tindex create-image
+This function creates and returns an image descriptor which uses the
+data in @var{file}.
+
+The optional argument @var{type} is a symbol specifying the image type.
+If @var{type} is omitted or @code{nil}, @code{create-image} tries to
+determine the image type from the file's first few bytes, or else
+from the file's name.
+
+The remaining arguments, @var{props}, specify additional image
+properties---for example,
+
+@example
+(create-image "foo.xpm" 'xpm :heuristic-mask t)
+@end example
+
+The function returns @code{nil} if images of this type are not
+supported. Otherwise it returns an image descriptor.
+@end defun
+
+@defmac defimage variable doc &rest specs
+@tindex defimage
+This macro defines @var{variable} as an image name. The second argument,
+@var{doc}, is an optional documentation string. The remaining
+arguments, @var{specs}, specify alternative ways to display the image.
+
+Each argument in @var{specs} has the form of a property list, and each
+one should specify at least the @code{:type} property and the
+@code{:file} property. Here is an example:
+
+@example
+(defimage test-image
+ '((:type xpm :file "~/test1.xpm")
+ (:type xbm :file "~/test1.xbm")))
+@end example
+
+@code{defimage} tests each argument, one by one, to see if it is
+usable---that is, if the type is supported and the file exists. The
+first usable argument is used to make an image descriptor which is
+stored in the variable @var{variable}.
+
+If none of the alternatives will work, then @var{variable} is defined
+as @code{nil}.
+@end defmac
+
+@node Showing Images
+@subsection Showing Images
+
+ You can use an image descriptor by setting up the @code{display}
+property yourself, but it is easier to use the functions in this
+section.
+
+@defun insert-image image &optional string area
+This function inserts @var{image} in the current buffer at point. The
+value @var{image} should be an image descriptor; it could be a value
+returned by @code{create-image}, or the value of a symbol defined with
+@code{defimage}. The argument @var{string} specifies the text to put in
+the buffer to hold the image.
+
+The argument @var{area} specifies whether to put the image in a margin.
+If it is @code{left-margin}, the image appears in the left margin;
+@code{right-margin} specifies the right margin. If @var{area} is
+@code{nil} or omitted, the image is displayed at point within the
+buffer's text.
+
+Internally, this function inserts @var{string} in the buffer, and gives
+it a @code{display} property which specifies @var{image}. @xref{Display
+Property}.
+@end defun
+
+@defun put-image image pos &optional string area
+This function puts image @var{image} in front of @var{pos} in the
+current buffer. The argument @var{pos} should be an integer or a
+marker. It specifies the buffer position where the image should appear.
+The argument @var{string} specifies the text that should hold the image
+as an alternative to the default.
+
+The argument @var{image} must be an image descriptor, perhaps returned
+by @code{create-image} or stored by @code{defimage}.
+
+The argument @var{area} specifies whether to put the image in a margin.
+If it is @code{left-margin}, the image appears in the left margin;
+@code{right-margin} specifies the right margin. If @var{area} is
+@code{nil} or omitted, the image is displayed at point within the
+buffer's text.
+
+Internally, this function creates an overlay, and gives it a
+@code{before-string} property containing text that has a @code{display}
+property whose value is the image. (Whew!)
+@end defun
+
+@defun remove-images start end &optional buffer
+This function removes images in @var{buffer} between positions
+@var{start} and @var{end}. If @var{buffer} is omitted or @code{nil},
+images are removed from the current buffer.
+
+This removes only images that were put into @var{buffer} the way
+@code{put-image} does it, not images that were inserted with
+@code{insert-image} or in other ways.
+@end defun
+
+@node Image Cache
+@subsection Image Cache
+
+ Emacs stores images in an image cache when it displays them, so it can
+display them again more efficiently. It removes an image from the cache
+when it hasn't been displayed for a specified period of time.
+
+When an image is looked up in the cache, its specification is compared
+with cached image specifications using @code{equal}. This means that
+all images with equal specifications share the same image in the cache.
+
+@defvar image-cache-eviction-delay
+@tindex image-cache-eviction-delay
+This variable specifies the number of seconds an image can remain in the
+cache without being displayed. When an image is not displayed for this
+length of time, Emacs removes it from the image cache.
+
+If the value is @code{nil}, Emacs does not remove images from the cache
+except when you explicitly clear it. This mode can be useful for
+debugging.
+@end defvar
+
+@defun clear-image-cache &optional frame
+@tindex clear-image-cache
+This function clears the image cache. If @var{frame} is non-@code{nil},
+only the cache for that frame is cleared. Otherwise all frames' caches
+are cleared.
@end defun
@node Blinking
@end defopt
@defopt mode-line-inverse-video
-This variable controls the use of inverse video for mode lines. If it
-is non-@code{nil}, then mode lines are displayed in inverse video.
-Otherwise, mode lines are displayed normally, just like text. The
-default is @code{t}.
-
-For window frames, this displays mode lines using the face named
-@code{modeline}, which is normally the inverse of the default face
-unless you change it.
+This variable controls the use of inverse video for mode lines and menu
+bars. If it is non-@code{nil}, then these lines are displayed in
+inverse video. Otherwise, these lines are displayed normally, just like
+other text. The default is @code{t}.
+
+For window frames, this feature actually applies the face named
+@code{mode-line}; that face is normally set up as the inverse of the
+default face, unless you change it.
@end defopt
@node Usual Display
All other codes in the range 0 through 31, and code 127, display in one
of two ways according to the value of @code{ctl-arrow}. If it is
non-@code{nil}, these codes map to sequences of two glyphs, where the
-first glyph is the @sc{ASCII} code for @samp{^}. (A display table can
+first glyph is the @sc{ascii} code for @samp{^}. (A display table can
specify a glyph to use instead of @samp{^}.) Otherwise, these codes map
just like the codes in the range 128 to 255.
+On MS-DOS terminals, Emacs arranges by default for the character code
+127 to be mapped to the glyph code 127, which normally displays as an
+empty polygon. This glyph is used to display non-@sc{ascii} characters
+that the MS-DOS terminal doesn't support. @xref{MS-DOS and MULE,,,
+emacs, The GNU Emacs Manual}.
+
@item
Character codes 128 through 255 map to sequences of four glyphs, where
-the first glyph is the @sc{ASCII} code for @samp{\}, and the others are
+the first glyph is the @sc{ascii} code for @samp{\}, and the others are
digit characters representing the character code in octal. (A display
table can specify a glyph to use instead of @samp{\}.)
buffers that do not override it. @xref{Default Value}.
@end defvar
+@defopt indicate-empty-lines
+@tindex indicate-empty-lines
+When this is non-@code{nil}, Emacs displays a special glyph in
+each empty line at the end of the buffer, on terminals that
+support it (window systems).
+@end defopt
+
@defopt tab-width
The value of this variable is the spacing between tab stops used for
-displaying tab characters in Emacs buffers. The default is 8. Note
-that this feature is completely independent of the user-settable tab
-stops used by the command @code{tab-to-tab-stop}. @xref{Indent Tabs}.
+displaying tab characters in Emacs buffers. The value is in units of
+columns, and the default is 8. Note that this feature is completely
+independent of the user-settable tab stops used by the command
+@code{tab-to-tab-stop}. @xref{Indent Tabs}.
@end defopt
@node Display Tables
@cindex display table
You can use the @dfn{display table} feature to control how all possible
character codes display on the screen. This is useful for displaying
-European languages that have letters not in the @sc{ASCII} character
+European languages that have letters not in the @sc{ascii} character
set.
The display table maps each character code into a sequence of
-@dfn{glyphs}, each glyph being an image that takes up one character
+@dfn{glyphs}, each glyph being a graphic that takes up one character
position on the screen. You can also define how to display each glyph
on your terminal, using the @dfn{glyph table}.
@table @asis
@item 0
The glyph for the end of a truncated screen line (the default for this
-is @samp{$}). @xref{Glyphs}.
+is @samp{$}). @xref{Glyphs}. Newer Emacs versions, on some platforms,
+display arrows to indicate truncation---the display table has no effect
+in these situations.
@item 1
The glyph for the end of a continued line (the default is @samp{\}).
+Newer Emacs versions, on some platforms, display curved arrows to
+indicate truncation---the display table has no effect in these
+situations.
@item 2
The glyph for indicating a character displayed as an octal character
code (the default is @samp{\}).
default is @samp{...}). @xref{Selective Display}.
@item 5
The glyph used to draw the border between side-by-side windows (the
-default is @samp{|}). @xref{Splitting Windows}.
+default is @samp{|}). @xref{Splitting Windows}. This takes effect only
+when there are no scroll bars; if scroll bars are supported and in use,
+a scroll bar separates the two windows.
@end table
For example, here is how to construct a display table that mimics the
@end example
@defun display-table-slot display-table slot
-@tindex display-table-slot
This function returns the value of the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
5 inclusive, or a slot name (symbol). Valid symbols are
@end defun
@defun set-display-table-slot display-table slot value
-@tindex set-display-table-slot
This function stores @var{value} in the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
5 inclusive, or a slot name (symbol). Valid symbols are
@code{selective-display}, and @code{vertical-border}.
@end defun
+@defun describe-display-table display-table
+@tindex describe-display-table
+This function displays a description of the display table
+@var{display-table} in a help buffer.
+@end defun
+
+@deffn Command describe-current-display-table
+@tindex describe-current-display-table
+This command displays a description of the current display table in a
+help buffer.
+@end deffn
+
@node Active Display Table
@subsection Active Display Table
@cindex active display table
display conventions for all character codes in that window. @xref{Usual
Display}.
+A number of functions for changing the standard display table
+are defined in the library @file{disp-table}.
+
@node Glyphs
@subsection Glyphs
mod 524288 is the character to output, and the glyph code divided by
524288 specifies the face number (@pxref{Face Functions}) to use while
outputting it. (524288 is
-@ifinfo
+@ifnottex
2**19.)
-@end ifinfo
+@end ifnottex
@tex
$2^{19}$.)
@end tex
If a glyph code is greater than or equal to the length of the glyph
table, that code is automatically simple.
+@defun create-glyph string
+@tindex create-glyph
+This function returns a newly-allocated glyph code which is set up to
+display by sending @var{string} to the terminal.
+@end defun
+
@node Beeping
@section Beeping
@cindex beeping
@end defopt
@defvar ring-bell-function
-@tindex ring-bell-function
If this is non-@code{nil}, it specifies how Emacs should ``ring the
-bell.'' Its value should be a function of no arguments.
+bell.'' Its value should be a function of no arguments. If this is
+non-@code{nil}, it takes precedence over the @code{visible-bell}
+variable.
@end defvar
@node Window Systems
@cindex X Window System
Emacs is displaying using X.
@item pc
-Emacs is displaying using MSDOS.
+Emacs is displaying using MS-DOS.
@item w32
-Emacs is displaying using Windows NT or Windows 95.
+Emacs is displaying using Windows.
+@item mac
+Emacs is displaying using a Macintosh.
@item nil
Emacs is using a character-based terminal.
@end table
@defvar window-setup-hook
This variable is a normal hook which Emacs runs after handling the
initialization files. Emacs runs this hook after it has completed
-loading your @file{.emacs} file, the default initialization file (if
+loading your init file, the default initialization file (if
any), and the terminal-specific Lisp code, and running the hook
@code{term-setup-hook}.
HCoop / bpt / emacs.git / blobdiff