This is Info file ../../info/lispref.info, produced by Makeinfo-1.63
from the input file lispref.texi.

   Edition History:

   GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU
Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid
Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994
XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995
GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp
Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp
Reference Manual (for 19.14 and 20.0) v3.1, March 1996

   Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software
Foundation, Inc.  Copyright (C) 1994, 1995 Sun Microsystems, Inc.
Copyright (C) 1995, 1996 Ben Wing.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the section entitled "GNU General Public License" is included
exactly as in the original, and provided that the entire resulting
derived work is distributed under the terms of a permission notice
identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the section entitled "GNU General Public License"
may be included in a translation approved by the Free Software
Foundation instead of in the original English.


File: lispref.info,  Node: Adding Specifications,  Next: Retrieving Specifications,  Prev: Specifier Types,  Up: Specifiers

Adding specifications to a Specifier
====================================

 - Function: add-spec-to-specifier SPECIFIER INSTANTIATOR &optional
          LOCALE TAG-SET HOW-TO-ADD
     This function adds a specification to SPECIFIER.  The
     specification maps from LOCALE (which should be a buffer, window,
     frame, device, or the symbol `global', and defaults to `global')
     to INSTANTIATOR, whose allowed values depend on the type of the
     specifier.  Optional argument TAG-SET limits the instantiator to
     apply only to the specified tag set, which should be a list of
     tags all of which must match the device being instantiated over
     (tags are a device type, a device class, or tags defined with
     `define-specifier-tag').  Specifying a single symbol for TAG-SET
     is equivalent to specifying a one-element list containing that
     symbol.  Optional argument HOW-TO-ADD specifies what to do if
     there are already specifications in the specifier.  It should be
     one of

    `prepend'
          Put at the beginning of the current list of instantiators for
          LOCALE.

    `append'
          Add to the end of the current list of instantiators for
          LOCALE.

    `remove-tag-set-prepend'
          This is the default.  Remove any existing instantiators whose
          tag set is the same as TAG-SET; then put the new instantiator
          at the beginning of the current list.

    `remove-tag-set-append'
          Remove any existing instantiators whose tag set is the same as
          TAG-SET; then put the new instantiator at the end of the
          current list.

    `remove-locale'
          Remove all previous instantiators for this locale before
          adding the new spec.

    `remove-locale-type'
          Remove all specifications for all locales of the same type as
          LOCALE (this includes LOCALE itself) before adding the new
          spec.

    `remove-all'
          Remove all specifications from the specifier before adding
          the new spec.

     `remove-tag-set-prepend' is the default.

     You can retrieve the specifications for a particular locale or
     locale type with the function `specifier-spec-list' or
     `specifier-specs'.

 - Function: add-spec-list-to-specifier SPECIFIER SPEC-LIST &optional
          HOW-TO-ADD
     This function adds a "spec-list" (a list of specifications) to
     SPECIFIER.  The format of a spec-list is

            `((LOCALE (TAG-SET . INSTANTIATOR) ...) ...)'

     where

        * LOCALE := a buffer, a window, a frame, a device, or `global'

        * TAG-SET := an unordered list of zero or more TAGS, each of
          which is a symbol

        * TAG := a device class (*note Consoles and Devices::.), a
          device type, or a tag defined with `define-specifier-tag'

        * INSTANTIATOR := format determined by the type of specifier

     The pair `(TAG-SET . INSTANTIATOR)' is called an "inst-pair".  A
     list of inst-pairs is called an "inst-list".  The pair `(LOCALE .
     INST-LIST)' is called a "specification".  A spec-list, then, can
     be viewed as a list of specifications.

     HOW-TO-ADD specifies how to combine the new specifications with
     the existing ones, and has the same semantics as for
     `add-spec-to-specifier'.

     In many circumstances, the higher-level function `set-specifier' is
     more convenient and should be used instead.

 - Function: set-specifier SPECIFIER VALUE &optional HOW-TO-ADD
     This function adds some specifications to SPECIFIER.  VALUE can be
     a single instantiator or tagged instantiator (added as a global
     specification), a list of tagged and/or untagged instantiators
     (added as a global specification), a cons of a locale and
     instantiator or locale and instantiator list, a list of such
     conses, or nearly any other reasonable form.  More specifically,
     VALUE can be anything accepted by `canonicalize-spec-list'.

     HOW-TO-ADD is the same as in `add-spec-to-specifier'.

     Note that `set-specifier' is exactly complementary to
     `specifier-specs' except in the case where SPECIFIER has no specs
     at all in it but `nil' is a valid instantiator (in that case,
     `specifier-specs' will return `nil' (meaning no specs) and
     `set-specifier' will interpret the `nil' as meaning "I'm adding a
     global instantiator and its value is `nil'"), or in strange cases
     where there is an ambiguity between a spec-list and an inst-list,
     etc. (The built-in specifier types are designed in such a way as
     to avoid any such ambiguities.)

     If you want to work with spec-lists, you should probably not use
     these functions, but should use the lower-level functions
     `specifier-spec-list' and `add-spec-list-to-specifier'.  These
     functions always work with fully-qualified spec-lists; thus, there
     is no ambiguity.

 - Function: canonicalize-inst-pair INST-PAIR SPECIFIER-TYPE &optional
          NOERROR
     This function canonicalizes the given INST-PAIR.

     SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
     will be used for.

     Canonicalizing means converting to the full form for an inst-pair,
     i.e.  `(TAG-SET . INSTANTIATOR)'.  A single, untagged instantiator
     is given a tag set of `nil' (the empty set), and a single tag is
     converted into a tag set consisting only of that tag.

     If NOERROR is non-`nil', signal an error if the inst-pair is
     invalid; otherwise return `t'.

 - Function: canonicalize-inst-list INST-LIST SPECIFIER-TYPE &optional
          NOERROR
     This function canonicalizes the given INST-LIST (a list of
     inst-pairs).

     SPECIFIER-TYPE specifies the type of specifier that this INST-LIST
     will be used for.

     Canonicalizing means converting to the full form for an inst-list,
     i.e.  `((TAG-SET . INSTANTIATOR) ...)'.  This function accepts a
     single inst-pair or any abbrevation thereof or a list of (possibly
     abbreviated) inst-pairs. (See `canonicalize-inst-pair'.)

     If NOERROR is non-`nil', signal an error if the inst-list is
     invalid; otherwise return `t'.

 - Function: canonicalize-spec SPEC SPECIFIER-TYPE &optional NOERROR
     This function canonicalizes the given SPEC (a specification).

     SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
     will be used for.

     Canonicalizing means converting to the full form for a spec, i.e.
     `(LOCALE (TAG-SET . INSTANTIATOR) ...)'.  This function accepts a
     possibly abbreviated inst-list or a cons of a locale and a
     possibly abbreviated inst-list. (See `canonicalize-inst-list'.)

     If NOERROR is `nil', signal an error if the specification is
     invalid; otherwise return `t'.

 - Function: canonicalize-spec-list SPEC-LIST SPECIFIER-TYPE &optional
          NOERROR
     This function canonicalizes the given SPEC-LIST (a list of
     specifications).

     SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
     will be used for.

     Canonicalizing means converting to the full form for a spec-list,
     i.e.  `((LOCALE (TAG-SET . INSTANTIATOR) ...) ...)'.  This
     function accepts a possibly abbreviated specification or a list of
     such things. (See `canonicalize-spec'.) This is the function used
     to convert spec-lists accepted by `set-specifier' and such into a
     form suitable for `add-spec-list-to-specifier'.

     This function tries extremely hard to resolve any ambiguities, and
     the built-in specifier types (font, image, toolbar, etc.) are
     designed so that there won't be any ambiguities.

     If NOERROR is `nil', signal an error if the spec-list is invalid;
     otherwise return `t'.


File: lispref.info,  Node: Retrieving Specifications,  Next: Specifier Tag Functions,  Prev: Adding Specifications,  Up: Specifiers

Retrieving the Specifications from a Specifier
==============================================

 - Function: specifier-spec-list SPECIFIER &optional LOCALE TAG-SET
          EXACT-P
     This function returns the spec-list of specifications for
     SPECIFIER in LOCALE.

     If LOCALE is a particular locale (a buffer, window, frame, device,
     or the symbol `global'), a spec-list consisting of the
     specification for that locale will be returned.

     If LOCALE is a locale type (i.e. a symbol `buffer', `window',
     `frame', or `device'), a spec-list of the specifications for all
     locales of that type will be returned.

     If LOCALE is `nil' or the symbol `all', a spec-list of all
     specifications in SPECIFIER will be returned.

     LOCALE can also be a list of locales, locale types, and/or `all';
     the result is as if `specifier-spec-list' were called on each
     element of the list and the results concatenated together.

     Only instantiators where TAG-SET (a list of zero or more tags) is
     a subset of (or possibly equal to) the instantiator's tag set are
     returned.  (The default value of` nil' is a subset of all tag sets,
     so in this case no instantiators will be screened out.) If EXACT-P
     is non-`nil', however, TAG-SET must be equal to an instantiator's
     tag set for the instantiator to be returned.

 - Function: specifier-specs SPECIFIER &optional LOCALE TAG-SET EXACT-P
     This function returns the specification(s) for SPECIFIER in LOCALE.

     If LOCALE is a single locale or is a list of one element
     containing a single locale, then a "short form" of the
     instantiators for that locale will be returned.  Otherwise, this
     function is identical to `specifier-spec-list'.

     The "short form" is designed for readability and not for ease of
     use in Lisp programs, and is as follows:

       1. If there is only one instantiator, then an inst-pair (i.e.
          cons of tag and instantiator) will be returned; otherwise a
          list of inst-pairs will be returned.

       2. For each inst-pair returned, if the instantiator's tag is
          `any', the tag will be removed and the instantiator itself
          will be returned instead of the inst-pair.

       3. If there is only one instantiator, its value is `nil', and
          its tag is `any', a one-element list containing `nil' will be
          returned rather than just `nil', to distinguish this case
          from there being no instantiators at all.


 - Function: specifier-fallback SPECIFIER
     This function returns the fallback value for SPECIFIER.  Fallback
     values are provided by the C code for certain built-in specifiers
     to make sure that instancing won't fail even if all specs are
     removed from the specifier, or to implement simple inheritance
     behavior (e.g. this method is used to ensure that faces other than
     `default' inherit their attributes from `default').  By design,
     you cannot change the fallback value, and specifiers created with
     `make-specifier' will never have a fallback (although a similar,
     Lisp-accessible capability may be provided in the future to allow
     for inheritance).

     The fallback value will be an inst-list that is instanced like any
     other inst-list, a specifier of the same type as SPECIFIER
     (results in inheritance), or `nil' for no fallback.

     When you instance a specifier, you can explicitly request that the
     fallback not be consulted. (The C code does this, for example, when
     merging faces.) See `specifier-instance'.


File: lispref.info,  Node: Specifier Tag Functions,  Next: Specifier Instancing Functions,  Prev: Retrieving Specifications,  Up: Specifiers

Working With Specifier Tags
===========================

   A specifier tag set is an entity that is attached to an instantiator
and can be used to restrict the scope of that instantiator to a
particular device class or device type and/or to mark instantiators
added by a particular package so that they can be later removed.

   A specifier tag set consists of a list of zero of more specifier
tags, each of which is a symbol that is recognized by XEmacs as a tag.
(The valid device types and device classes are always tags, as are any
tags defined by `define-specifier-tag'.) It is called a "tag set" (as
opposed to a list) because the order of the tags or the number of times
a particular tag occurs does not matter.

   Each tag has a predicate associated with it, which specifies whether
that tag applies to a particular device.  The tags which are device
types and classes match devices of that type or class.  User-defined
tags can have any predicate, or none (meaning that all devices match).
When attempting to instance a specifier, a particular instantiator is
only considered if the device of the domain being instanced over matches
all tags in the tag set attached to that instantiator.

   Most of the time, a tag set is not specified, and the instantiator
gets a null tag set, which matches all devices.

 - Function: valid-specifier-tag-p TAG
     This function returns non-`nil' if TAG is a valid specifier tag.

 - Function: valid-specifier-tag-set-p TAG-SET
     This function returns non-`nil' if TAG-SET is a valid specifier
     tag set.

 - Function: canonicalize-tag-set TAG-SET
     This function canonicalizes the given tag set.  Two canonicalized
     tag sets can be compared with `equal' to see if they represent the
     same tag set. (Specifically, canonicalizing involves sorting by
     symbol name and removing duplicates.)

 - Function: device-matches-specifier-tag-set-p DEVICE TAG-SET
     This function returns non-`nil' if DEVICE matches specifier tag
     set TAG-SET.  This means that DEVICE matches each tag in the tag
     set.

 - Function: define-specifier-tag TAG &optional PREDICATE
     This function defines a new specifier tag.  If PREDICATE is
     specified, it should be a function of one argument (a device) that
     specifies whether the tag matches that particular device.  If
     PREDICATE is omitted, the tag matches all devices.

     You can redefine an existing user-defined specifier tag.  However,
     you cannot redefine the built-in specifier tags (the device types
     and classes) or the symbols `nil', `t', `all', or `global'.

 - Function: device-matching-specifier-tag-list &optional DEVICE
     This function returns a list of all specifier tags matching
     DEVICE.  DEVICE defaults to the selected device if omitted.

 - Function: specifier-tag-list
     This function returns a list of all currently-defined specifier
     tags.  This includes the built-in ones (the device types and
     classes).

 - Function: specifier-tag-predicate TAG
     This function returns the predicate for the given specifier tag.


File: lispref.info,  Node: Specifier Instancing Functions,  Next: Specifier Example,  Prev: Specifier Tag Functions,  Up: Specifiers

Functions for Instancing a Specifier
====================================

 - Function: specifier-instance SPECIFIER &optional DOMAIN DEFAULT
          NO-FALLBACK
     This function instantiates SPECIFIER (return its value) in DOMAIN.
     If no instance can be generated for this domain, return DEFAULT.

     DOMAIN should be a window, frame, or device.  Other values that
     are legal as a locale (e.g. a buffer) are not valid as a domain
     because they do not provide enough information to identify a
     particular device (see `valid-specifier-domain-p').  DOMAIN
     defaults to the selected window if omitted.

     "Instantiating" a specifier in a particular domain means
     determining the specifier's "value" in that domain.  This is
     accomplished by searching through the specifications in the
     specifier that correspond to all locales that can be derived from
     the given domain, from specific to general.  In most cases, the
     domain is an Emacs window.  In that case specifications are
     searched for as follows:

       1. A specification whose locale is the window's buffer;

       2. A specification whose locale is the window itself;

       3. A specification whose locale is the window's frame;

       4. A specification whose locale is the window's frame's device;

       5. A specification whose locale is the symbol `global'.

     If all of those fail, then the C-code-provided fallback value for
     this specifier is consulted (see `specifier-fallback').  If it is
     an inst-list, then this function attempts to instantiate that list
     just as when a specification is located in the first five steps
     above.  If the fallback is a specifier, `specifier-instance' is
     called recursively on this specifier and the return value used.
     Note, however, that if the optional argument NO-FALLBACK is
     non-`nil', the fallback value will not be consulted.

     Note that there may be more than one specification matching a
     particular locale; all such specifications are considered before
     looking for any specifications for more general locales.  Any
     particular specification that is found may be rejected because it
     is tagged to a particular device class (e.g. `color') or device
     type (e.g. `x') or both and the device for the given domain does
     not match this, or because the specification is not valid for the
     device of the given domain (e.g.  the font or color name does not
     exist for this particular X server).

     The returned value is dependent on the type of specifier.  For
     example, for a font specifier (as returned by the `face-font'
     function), the returned value will be a font-instance object.  For
     images, the returned value will be a string, pixmap, or subwindow.

 - Function: specifier-instance-from-inst-list SPECIFIER DOMAIN
          INST-LIST &optional DEFAULT
     This function attempts to convert a particular inst-list into an
     instance.  This attempts to instantiate INST-LIST in the given
     DOMAIN, as if INST-LIST existed in a specification in SPECIFIER.
     If the instantiation fails, DEFAULT is returned.  In most
     circumstances, you should not use this function; use
     `specifier-instance' instead.


File: lispref.info,  Node: Specifier Example,  Next: Creating Specifiers,  Prev: Specifier Instancing Functions,  Up: Specifiers

Example of Specifier Usage
==========================

   Now let us present an example to clarify the theoretical discussions
we have been through.  In this example, we will use the general
specifier functions for clarity.  Keep in mind that many types of
specifiers, and some other types of objects that are associated with
specifiers (e.g. faces), provide convenience functions making it easier
to work with objects of that type.

   Let us consider the background color of the default face.  A
specifier is used to specify how that color will appear in different
domains.  First, let's retrieve the specifier:

     (setq sp (face-property 'default 'background))
         =>   #<color-specifier 0x3da>

     (specifier-specs sp)
         =>   ((#<buffer "device.c"> (nil . "forest green"))
                      (#<window on "Makefile" 0x8a2b> (nil . "hot pink"))
                      (#<x-frame "emacs" 0x4ac> (nil . "puke orange")
     					   (nil . "moccasin"))
                      (#<x-frame "VM" 0x4ac> (nil . "magenta"))
     		 (global ((tty) . "cyan") (nil . "white"))
                     )

   Then, say we want to determine what the background color of the
default face is for the window currently displaying the buffer
`*scratch*'.  We call

     (get-buffer-window "*scratch*")
         => #<window on "*scratch*" 0x4ad>
     (window-frame (get-buffer-window "*scratch*"))
         => #<x-frame "emacs" 0x4ac>
     (specifier-instance sp (get-buffer-window "*scratch*"))
         => #<color-instance moccasin 47=(FFFF,E4E4,B5B5) 0x6309>

   Note that we passed a window to `specifier-instance', not a buffer.
We cannot pass a buffer because a buffer by itself does not provide
enough information.  The buffer might not be displayed anywhere at all,
or could be displayed in many different frames on different devices.

   The result is arrived at like this:

  1. First, we look for a specification matching the buffer displayed
     in the window, i.e. `*scratch'.  There are none, so we proceed.

  2. Then, we look for a specification matching the window itself.
     Again, there are none.

  3. Then, we look for a specification matching the window's frame.  The
     specification `(#<x-frame "emacs" 0x4ac> . "puke orange")' is
     found.  We call the instantiation method for colors, passing it the
     locale we were searching over (i.e. the window, in this case) and
     the instantiator (`"puke orange"').  However, the particular device
     which this window is on (let's say it's an X connection) doesn't
     recognize the color `"puke orange"', so the specification is
     rejected.

  4. So we continue looking for a specification matching the window's
     frame.  We find `(#<x-frame "emacs" 0x4ac> . "moccasin")'.  Again,
     we call the instantiation method for colors.  This time, the X
     server our window is on recognizes the color `moccasin', and so the
     instantiation method succeeds and returns a color instance.


File: lispref.info,  Node: Creating Specifiers,  Next: Specifier Validation Functions,  Prev: Specifier Example,  Up: Specifiers

Creating New Specifier Objects
==============================

 - Function: make-specifier TYPE
     This function creates a new specifier.

     A specifier is an object that can be used to keep track of a
     property whose value can be per-buffer, per-window, per-frame, or
     per-device, and can further be restricted to a particular
     device-type or device-class.  Specifiers are used, for example,
     for the various built-in properties of a face; this allows a face
     to have different values in different frames, buffers, etc.  For
     more information, see `specifier-instance', `specifier-specs', and
     `add-spec-to-specifier'; or, for a detailed description of
     specifiers, including how they are instantiated over a particular
     domain (i.e. how their value in that domain is determined), see
     the chapter on specifiers in the XEmacs Lisp Reference Manual.

     TYPE specifies the particular type of specifier, and should be one
     of the symbols `generic', `integer', `natnum', `boolean', `color',
     `font', `image', `face-boolean', or `toolbar'.

     For more information on particular types of specifiers, see the
     functions `generic-specifier-p', `integer-specifier-p',
     `natnum-specifier-p', `boolean-specifier-p', `color-specifier-p',
     `font-specifier-p', `image-specifier-p',
     `face-boolean-specifier-p', and `toolbar-specifier-p'.

 - Function: make-specifier-and-init TYPE SPEC-LIST &optional
          DONT-CANONICALIZE
     This function creates and initialize a new specifier.

     This is a front-end onto `make-specifier' that allows you to create
     a specifier and add specs to it at the same time.  TYPE specifies
     the specifier type.  SPEC-LIST supplies the specification(s) to be
     added to the specifier. Normally, almost any reasonable
     abbreviation of the full spec-list form is accepted, and is
     converted to the full form; however, if optional argument
     DONT-CANONICALIZE is non-`nil', this conversion is not performed,
     and the SPEC-LIST must already be in full form.  See
     `canonicalize-spec-list'.


File: lispref.info,  Node: Specifier Validation Functions,  Next: Other Specification Functions,  Prev: Creating Specifiers,  Up: Specifiers

Functions for Checking the Validity of Specifier Components
===========================================================

 - Function: valid-specifier-domain-p DOMAIN
     This function returns non-`nil' if DOMAIN is a valid specifier
     domain.  A domain is used to instance a specifier (i.e. determine
     the specifier's value in that domain).  Valid domains are a
     window, frame, or device.  (`nil' is not valid.)

 - Function: valid-specifier-locale-p LOCALE
     This function returns non-`nil' if LOCALE is a valid specifier
     locale.  Valid locales are a device, a frame, a window, a buffer,
     and `global'.  (`nil' is not valid.)

 - Function: valid-specifier-locale-type-p LOCALE-TYPE
     Given a specifier LOCALE-TYPE, this function returns non-nil if it
     is valid.  Valid locale types are the symbols `global', `device',
     `frame', `window', and `buffer'. (Note, however, that in functions
     that accept either a locale or a locale type, `global' is
     considered an individual locale.)

 - Function: valid-specifier-type-p SPECIFIER-TYPE
     Given a SPECIFIER-TYPE, this function returns non-`nil' if it is
     valid.  Valid types are `generic', `integer', `boolean', `color',
     `font', `image', `face-boolean', and `toolbar'.

 - Function: valid-specifier-tag-p TAG
     This function returns non-`nil' if TAG is a valid specifier tag.

 - Function: valid-instantiator-p INSTANTIATOR SPECIFIER-TYPE
     This function returns non-`nil' if INSTANTIATOR is valid for
     SPECIFIER-TYPE.

 - Function: valid-inst-list-p INST-LIST TYPE
     This function returns non-`nil' if INST-LIST is valid for
     specifier type TYPE.

 - Function: valid-spec-list-p SPEC-LIST TYPE
     This function returns non-`nil' if SPEC-LIST is valid for
     specifier type TYPE.

 - Function: check-valid-instantiator INSTANTIATOR SPECIFIER-TYPE
     This function signals an error if INSTANTIATOR is invalid for
     SPECIFIER-TYPE.

 - Function: check-valid-inst-list INST-LIST TYPE
     This function signals an error if INST-LIST is invalid for
     specifier type TYPE.

 - Function: check-valid-spec-list SPEC-LIST TYPE
     This function signals an error if SPEC-LIST is invalid for
     specifier type TYPE.


File: lispref.info,  Node: Other Specification Functions,  Prev: Specifier Validation Functions,  Up: Specifiers

Other Functions for Working with Specifications in a Specifier
==============================================================

 - Function: copy-specifier SPECIFIER &optional DEST LOCALE TAG-SET
          EXACT-P HOW-TO-ADD
     This function copies SPECIFIER to DEST, or creates a new one if
     DEST is `nil'.

     If DEST is `nil' or omitted, a new specifier will be created and
     the specifications copied into it.  Otherwise, the specifications
     will be copied into the existing specifier in DEST.

     If LOCALE is `nil' or the symbol `all', all specifications will be
     copied.  If LOCALE is a particular locale, the specification for
     that particular locale will be copied.  If LOCALE is a locale
     type, the specifications for all locales of that type will be
     copied.  LOCALE can also be a list of locales, locale types,
     and/or `all'; this is equivalent to calling `copy-specifier' for
     each of the elements of the list.  See `specifier-spec-list' for
     more information about LOCALE.

     Only instantiators where TAG-SET (a list of zero or more tags) is
     a subset of (or possibly equal to) the instantiator's tag set are
     copied.  (The default value of `nil' is a subset of all tag sets,
     so in this case no instantiators will be screened out.) If EXACT-P
     is non-`nil', however, TAG-SET must be equal to an instantiator's
     tag set for the instantiator to be copied.

     Optional argument HOW-TO-ADD specifies what to do with existing
     specifications in DEST.  If nil, then whichever locales or locale
     types are copied will first be completely erased in DEST.
     Otherwise, it is the same as in `add-spec-to-specifier'.

 - Function: remove-specifier SPECIFIER &optional LOCALE TAG-SET EXACT-P
     This function removes specification(s) for SPECIFIER.

     If LOCALE is a particular locale (a buffer, window, frame, device,
     or the symbol `global'), the specification for that locale will be
     removed.

     If instead, LOCALE is a locale type (i.e. a symbol `buffer',
     `window', `frame', or `device'), the specifications for all
     locales of that type will be removed.

     If LOCALE is `nil' or the symbol `all', all specifications will be
     removed.

     LOCALE can also be a list of locales, locale types, and/or `all';
     this is equivalent to calling `remove-specifier' for each of the
     elements in the list.

     Only instantiators where TAG-SET (a list of zero or more tags) is
     a subset of (or possibly equal to) the instantiator's tag set are
     removed.  (The default value of `nil' is a subset of all tag sets,
     so in this case no instantiators will be screened out.) If EXACT-P
     is non-`nil', however, TAG-SET must be equal to an instantiator's
     tag set for the instantiator to be removed.

 - Function: map-specifier SPECIFIER FUNC &optional LOCALE MAPARG
     This function applies FUNC to the specification(s) for LOCALE in
     SPECIFIER.

     If LOCALE is a locale, FUNC will be called for that locale.  If
     LOCALE is a locale type, FUNC will be mapped over all locales of
     that type.  If LOCALE is `nil' or the symbol `all', FUNC will be
     mapped over all locales in SPECIFIER.

     FUNC is called with four arguments: the SPECIFIER, the locale
     being mapped over, the inst-list for that locale, and the optional
     MAPARG.  If any invocation of FUNC returns non-`nil', the mapping
     will stop and the returned value becomes the value returned from
     `map-specifier'.  Otherwise, `map-specifier' returns `nil'.

 - Function: specifier-locale-type-from-locale LOCALE
     Given a specifier LOCALE, this function returns its type.


File: lispref.info,  Node: Faces and Window-System Objects,  Next: Glyphs,  Prev: Specifiers,  Up: Top

Faces and Window-System Objects
*******************************

* Menu:

* Faces::		Controlling the way text looks.
* Fonts::		Controlling the typeface of text.
* Colors::		Controlling the color of text and pixmaps.


File: lispref.info,  Node: Faces,  Next: Fonts,  Up: Faces and Window-System Objects

Faces
=====

   A "face" is a named collection of graphical properties: font,
foreground color, background color, background pixmap, optional
underlining, and (on TTY devices) whether the text is to be highlighted,
dimmed, blinking, or displayed in reverse video.  Faces control the
display of text on the screen.  Every face has a name, which is a symbol
such as `default' or `modeline'.

   Each built-in property of a face is controlled using a specifier,
which allows it to have separate values in particular buffers, frames,
windows, and devices and to further vary according to device type (X or
TTY) and device class (color, mono, or grayscale).  *Note Specifiers::
for more information.

   The face named `default' is used for ordinary text.  The face named
`modeline' is used for displaying the modeline.  The face named
`highlight' is used for highlighted extents (*note Extents::.).  The
faces named `left-margin' and `right-margin' are used for the left and
right margin areas, respectively (*note Annotations::.).  The face
named `zmacs-region' is used for the highlighted region between point
and mark.

* Menu:

* Merging Faces::		How XEmacs decides which face to use
				  for a character.
* Basic Face Functions::	How to define and examine faces.
* Face Properties::		How to access and modify a face's properties.
* Face Convenience Functions::	Convenience functions for accessing
				  particular properties of a face.
* Other Face Display Functions:: Other functions pertaining to how a
				  a face appears.


File: lispref.info,  Node: Merging Faces,  Next: Basic Face Functions,  Up: Faces

Merging Faces for Display
-------------------------

   Here are all the ways to specify which face to use for display of
text:

   * With defaults.  Each frame has a "default face", which is used for
     all text that doesn't somehow specify another face.  The face named
     `default' applies to the text area, while the faces `left-margin'
     and `right-margin' apply to the left and right margin areas.

   * With text properties.  A character may have a `face' property; if
     so, it's displayed with that face. (Text properties are actually
     implemented in terms of extents.) *Note Text Properties::.

   * With extents.  An extent may have a `face' property, which applies
     to all the text covered by the extent; in addition, if the
     `highlight' property is set, the `highlight' property applies when
     the mouse moves over the extent or if the extent is explicitly
     highlighted.  *Note Extents::.

   * With annotations.  Annotations that are inserted into a buffer can
     specify their own face. (Annotations are actually implemented in
     terms of extents.) *Note Annotations::.

   If these various sources together specify more than one face for a
particular character, XEmacs merges the properties of the various faces
specified.  Extents, text properties, and annotations all use the same
underlying representation (as extents).  When multiple extents cover one
character, an extent with higher priority overrides those with lower
priority.  *Note Extents::.  If no extent covers a particular character,
the `default' face is used.

   If a background pixmap is specified, it determines what will be
displayed in the background of text characters.  If the background
pixmap is actually a pixmap, with its colors specified, those colors are
used; if it is a bitmap, the face's foreground and background colors are
used to color it.


File: lispref.info,  Node: Basic Face Functions,  Next: Face Properties,  Prev: Merging Faces,  Up: Faces

Basic Functions for Working with Faces
--------------------------------------

   The properties a face can specify include the font, the foreground
color, the background color, the background pixmap, the underlining,
the display table, and (for TTY devices) whether the text is to be
highlighted, dimmed, blinking, or displayed in reverse video.  The face
can also leave these unspecified, causing them to assume the value of
the corresponding property of the `default' face.

   Here are the basic primitives for working with faces.

 - Function: make-face NAME &optional DOC-STRING TEMPORARY
     This function defines and returns a new face named NAME, initially
     with all properties unspecified.  It does nothing if there is
     already a face named NAME.  Optional argument DOC-STRING specifies
     an explanatory string used for descriptive purposes.  If optional
     argument TEMPORARY is non-`nil', the face will automatically
     disappear when there are no more references to it anywhere in text
     or Lisp code (otherwise, the face will continue to exist
     indefinitely even if it is not used).

 - Function: face-list &optional TEMPORARY
     This function returns a list of the names of all defined faces.  If
     TEMPORARY is `nil', only the permanent faces are included.  If it
     is `t', only the temporary faces are included.  If it is any other
     non-`nil' value both permanent and temporary are included.

 - Function: facep OBJECT
     This function returns whether the given object is a face.

 - Function: copy-face OLD-FACE NEW-NAME &optional LOCALE HOW-TO-ADD
     This function defines a new face named NEW-NAME which is a copy of
     the existing face named OLD-FACE.  If there is already a face
     named NEW-NAME, then it alters the face to have the same
     properties as OLD-FACE.  LOCALE and HOW-TO-ADD let you copy just
     parts of the old face rather than the whole face, and are as in
     `copy-specifier' (*note Specifiers::.).


File: lispref.info,  Node: Face Properties,  Next: Face Convenience Functions,  Prev: Basic Face Functions,  Up: Faces

Face Properties
---------------

   You can examine and modify the properties of an existing face with
the following functions.

   The following symbols have predefined meanings:

`foreground'
     The foreground color of the face.

`background'
     The background color of the face.

`font'
     The font used to display text covered by this face.

`display-table'
     The display table of the face.

`background-pixmap'
     The pixmap displayed in the background of the face.  Only used by
     faces on X devices.

`underline'
     Underline all text covered by this face.

`highlight'
     Highlight all text covered by this face.  Only used by faces on TTY
     devices.

`dim'
     Dim all text covered by this face.  Only used by faces on TTY
     devices.

`blinking'
     Blink all text covered by this face.  Only used by faces on TTY
     devices.

`reverse'
     Reverse the foreground and background colors.  Only used by faces
     on TTY devices.

`doc-string'
     Description of what the face's normal use is.  NOTE: This is not a
     specifier, unlike all the other built-in properties, and cannot
     contain locale-specific values.

 - Function: set-face-property FACE PROPERTY VALUE &optional LOCALE TAG
          HOW-TO-ADD
     This function changes a property of a FACE.

     For built-in properties, the actual value of the property is a
     specifier and you cannot change this; but you can change the
     specifications within the specifier, and that is what this
     function will do.  For user-defined properties, you can use this
     function to either change the actual value of the property or, if
     this value is a specifier, change the specifications within it.

     If PROPERTY is a built-in property, the specifications to be added
     to this property can be supplied in many different ways:

          If VALUE is a simple instantiator (e.g. a string naming a
          font or color) or a list of instantiators, then the
          instantiator(s) will be added as a specification of the
          property for the given LOCALE (which defaults to `global' if
          omitted).

          If VALUE is a list of specifications (each of which is a cons
          of a locale and a list of instantiators), then LOCALE must be
          `nil' (it does not make sense to explicitly specify a locale
          in this case), and specifications will be added as given.

          If VALUE is a specifier (as would be returned by
          `face-property' if no LOCALE argument is given), then some or
          all of the specifications in the specifier will be added to
          the property.  In this case, the function is really
          equivalent to `copy-specifier' and LOCALE has the same
          semantics (if it is a particular locale, the specification
          for the locale will be copied; if a locale type,
          specifications for all locales of that type will be copied;
          if `nil' or `all', then all specifications will be copied).

     HOW-TO-ADD should be either `nil' or one of the symbols `prepend',
     `append', `remove-tag-set-prepend', `remove-tag-set-append',
     `remove-locale', `remove-locale-type', or `remove-all'.  See
     `copy-specifier' and `add-spec-to-specifier' for a description of
     what each of these means.  Most of the time, you do not need to
     worry about this argument; the default behavior usually is fine.

     In general, it is OK to pass an instance object (e.g. as returned
     by `face-property-instance') as an instantiator in place of an
     actual instantiator.  In such a case, the instantiator used to
     create that instance object will be used (for example, if you set
     a font-instance object as the value of the `font' property, then
     the font name used to create that object will be used instead).
     If some cases, however, doing this conversion does not make sense,
     and this will be noted in the documentation for particular types
     of instance objects.

     If PROPERTY is not a built-in property, then this function will
     simply set its value if LOCALE is `nil'.  However, if LOCALE is
     given, then this function will attempt to add VALUE as the
     instantiator for the given LOCALE, using `add-spec-to-specifier'.
     If the value of the property is not a specifier, it will
     automatically be converted into a `generic' specifier.

 - Function: face-property FACE PROPERTY &optional LOCALE
     This function returns FACE's value of the given PROPERTY.

     If LOCALE is omitted, the FACE's actual value for PROPERTY will be
     returned.  For built-in properties, this will be a specifier
     object of a type appropriate to the property (e.g. a font or color
     specifier).  For other properties, this could be anything.

     If LOCALE is supplied, then instead of returning the actual value,
     the specification(s) for the given locale or locale type will be
     returned.  This will only work if the actual value of PROPERTY is
     a specifier (this will always be the case for built-in properties,
     but not or not may apply to user-defined properties).  If the
     actual value of PROPERTY is not a specifier, this value will
     simply be returned regardless of LOCALE.

     The return value will be a list of instantiators (e.g. strings
     specifying a font or color name), or a list of specifications,
     each of which is a cons of a locale and a list of instantiators.
     Specifically, if LOCALE is a particular locale (a buffer, window,
     frame, device, or `global'), a list of instantiators for that
     locale will be returned.  Otherwise, if LOCALE is a locale type
     (one of the symbols `buffer', `window', `frame', or `device'), the
     specifications for all locales of that type will be returned.
     Finally, if LOCALE is `all', the specifications for all locales of
     all types will be returned.

     The specifications in a specifier determine what the value of
     PROPERTY will be in a particular "domain" or set of circumstances,
     which is typically a particular Emacs window along with the buffer
     it contains and the frame and device it lies within.  The value is
     derived from the instantiator associated with the most specific
     locale (in the order buffer, window, frame, device, and `global')
     that matches the domain in question.  In other words, given a
     domain (i.e. an Emacs window, usually), the specifier for PROPERTY
     will first be searched for a specification whose locale is the
     buffer contained within that window; then for a specification
     whose locale is the window itself; then for a specification whose
     locale is the frame that the window is contained within; etc.  The
     first instantiator that is valid for the domain (usually this
     means that the instantiator is recognized by the device [i.e. the
     X server or TTY device] that the domain is on).  The function
     `face-property-instance' actually does all this, and is used to
     determine how to display the face.

 - Function: face-property-instance FACE PROPERTY &optional DOMAIN
          DEFAULT NO-FALLBACK
     This function returns the instance of FACE's PROPERTY in the
     specified DOMAIN.

     Under most circumstances, DOMAIN will be a particular window, and
     the returned instance describes how the specified property
     actually is displayed for that window and the particular buffer in
     it.  Note that this may not be the same as how the property
     appears when the buffer is displayed in a different window or
     frame, or how the property appears in the same window if you
     switch to another buffer in that window; and in those cases, the
     returned instance would be different.

     The returned instance will typically be a color-instance,
     font-instance, or pixmap-instance object, and you can query it
     using the appropriate object-specific functions.  For example, you
     could use `color-instance-rgb-components' to find out the RGB
     (red, green, and blue) components of how the `background' property
     of the `highlight' face is displayed in a particular window.  The
     results might be different from the results you would get for
     another window (perhaps the user specified a different color for
     the frame that window is on; or perhaps the same color was
     specified but the window is on a different X server, and that X
     server has different RGB values for the color from this one).

     DOMAIN defaults to the selected window if omitted.

     DOMAIN can be a frame or device, instead of a window.  The value
     returned for a such a domain is used in special circumstances when
     a more specific domain does not apply; for example, a frame value
     might be used for coloring a toolbar, which is conceptually
     attached to a frame rather than a particular window.  The value is
     also useful in determining what the value would be for a
     particular window within the frame or device, if it is not
     overridden by a more specific specification.

     If PROPERTY does not name a built-in property, its value will
     simply be returned unless it is a specifier object, in which case
     it will be instanced using `specifier-instance'.

     Optional arguments DEFAULT and NO-FALLBACK are the same as in
     `specifier-instance'.  *Note Specifiers::.


File: lispref.info,  Node: Face Convenience Functions,  Next: Other Face Display Functions,  Prev: Face Properties,  Up: Faces

Face Convenience Functions
--------------------------

 - Function: set-face-foreground FACE COLOR &optional LOCALE TAG
          HOW-TO-ADD
 - Function: set-face-background FACE COLOR &optional LOCALE TAG
          HOW-TO-ADD
     These functions set the foreground (respectively, background)
     color of face FACE to COLOR.  The argument COLOR should be a
     string (the name of a color) or a color object as returned by
     `make-color' (*note Colors::.).

 - Function: set-face-background-pixmap FACE PIXMAP &optional LOCALE
          TAG HOW-TO-ADD
     This function sets the background pixmap of face FACE to PIXMAP.
     The argument PIXMAP should be a string (the name of a bitmap or
     pixmap file; the directories listed in the variable
     `x-bitmap-file-path' will be searched) or a glyph object as
     returned by `make-glyph' (*note Glyphs::.).  The argument may also
     be a list of the form `(WIDTH HEIGHT DATA)' where WIDTH and HEIGHT
     are the size in pixels, and DATA is a string, containing the raw
     bits of the bitmap.

 - Function: set-face-font FACE FONT &optional LOCALE TAG HOW-TO-ADD
     This function sets the font of face FACE.  The argument FONT
     should be a string or a font object as returned by `make-font'
     (*note Fonts::.).

 - Function: set-face-underline-p FACE UNDERLINE-P &optional LOCALE TAG
          HOW-TO-ADD
     This function sets the underline property of face FACE.

 - Function: face-foreground FACE &optional LOCALE
 - Function: face-background FACE &optional LOCALE
     These functions return the foreground (respectively, background)
     color specifier of face FACE.  *Note Colors::.

 - Function: face-background-pixmap FACE &optional LOCALE
     This function return the background-pixmap glyph object of face
     FACE.

 - Function: face-font FACE &optional LOCALE
     This function returns the font specifier of face FACE.  (Note:
     This is not the same as the function `face-font' in FSF Emacs.)
     *Note Fonts::.

 - Function: face-font-name FACE &optional DOMAIN
     This function returns the name of the font of face FACE, or `nil'
     if it is unspecified.  This is basically equivalent to `(font-name
     (face-font FACE) DOMAIN)' except that it does not cause an error
     if FACE's font is `nil'. (This function is named `face-font' in
     FSF Emacs.)

 - Function: face-underline-p FACE &optional LOCALE
     This function returns the underline property of face FACE.

 - Function: face-foreground-instance FACE &optional DOMAIN
 - Function: face-background-instance FACE &optional DOMAIN
     These functions return the foreground (respectively, background)
     color specifier of face FACE.  *Note Colors::.

 - Function: face-background-pixmap-instance FACE &optional DOMAIN
     This function return the background-pixmap glyph object of face
     FACE.

 - Function: face-font-instance FACE &optional DOMAIN
     This function returns the font specifier of face FACE.  *Note
     Fonts::.


File: lispref.info,  Node: Other Face Display Functions,  Prev: Face Convenience Functions,  Up: Faces

Other Face Display Functions
----------------------------

 - Function: invert-face FACE &optional LOCALE
     Swap the foreground and background colors of face FACE.  If the
     face doesn't specify both foreground and background, then its
     foreground and background are set to the default background and
     foreground.

 - Function: face-equal FACE1 FACE2 &optional DOMAIN
     This returns `t' if the faces FACE1 and FACE2 will display in the
     same way.  DOMAIN is as in `face-property-instance'.

 - Function: face-differs-from-default-p FACE &optional DOMAIN
     This returns `t' if the face FACE displays differently from the
     default face.  DOMAIN is as in `face-property-instance'.

