faces.el

;;; faces.el --- Lisp faces

;; Copyright (C) 1992-1996, 1998-2013 Free Software Foundation, Inc.

;; Maintainer: FSF
;; Keywords: internal
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(defcustom term-file-prefix (purecopy "term/")
  "If non-nil, Emacs startup performs terminal-specific initialization.
It does this by: (load (concat term-file-prefix (getenv \"TERM\")))

You may set this variable to nil in your init file if you do not wish
the terminal-initialization file to be loaded."
  :type '(choice (const :tag "No terminal-specific initialization" nil)
		 (string :tag "Name of directory with term files"))
  :group 'terminals)

(declare-function xw-defined-colors "term/common-win" (&optional frame))

(defvar help-xref-stack-item)

(defvar face-name-history nil
  "History list for some commands that read face names.
Maximum length of the history list is determined by the value
of `history-length', which see.")


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Font selection.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defgroup font-selection nil
  "Influencing face font selection."
  :group 'faces)


(defcustom face-font-selection-order
  '(:width :height :weight :slant)
  "A list specifying how face font selection chooses fonts.
Each of the four symbols `:width', `:height', `:weight', and `:slant'
must appear once in the list, and the list must not contain any other
elements.  Font selection first tries to find a best matching font
for those face attributes that appear before in the list.  For
example, if `:slant' appears before `:height', font selection first
tries to find a font with a suitable slant, even if this results in
a font height that isn't optimal."
  :tag "Font selection order"
  :type '(list symbol symbol symbol symbol)
  :group 'font-selection
  :set #'(lambda (symbol value)
	   (set-default symbol value)
	   (internal-set-font-selection-order value)))


;; In the absence of Fontconfig support, Monospace and Sans Serif are
;; unavailable, and we fall back on the courier and helv families,
;; which are generally available.
(defcustom face-font-family-alternatives
  (mapcar (lambda (arg) (mapcar 'purecopy arg))
  '(("Monospace" "courier" "fixed")
    ("courier" "CMU Typewriter Text" "fixed")
    ("Sans Serif" "helv" "helvetica" "arial" "fixed")
    ("helv" "helvetica" "arial" "fixed")))
  "Alist of alternative font family names.
Each element has the form (FAMILY ALTERNATIVE1 ALTERNATIVE2 ...).
If fonts of family FAMILY can't be loaded, try ALTERNATIVE1, then
ALTERNATIVE2 etc."
  :tag "Alternative font families to try"
  :type '(repeat (repeat string))
  :group 'font-selection
  :set #'(lambda (symbol value)
	   (set-default symbol value)
	   (internal-set-alternative-font-family-alist value)))


;; This is defined originally in xfaces.c.
(defcustom face-font-registry-alternatives
  (mapcar (lambda (arg) (mapcar 'purecopy arg))
  (if (featurep 'w32)
      '(("iso8859-1" "ms-oemlatin")
	("gb2312.1980" "gb2312" "gbk" "gb18030")
	("jisx0208.1990" "jisx0208.1983" "jisx0208.1978")
	("ksc5601.1989" "ksx1001.1992" "ksc5601.1987")
	("muletibetan-2" "muletibetan-0"))
    '(("gb2312.1980" "gb2312.80&gb8565.88" "gbk" "gb18030")
      ("jisx0208.1990" "jisx0208.1983" "jisx0208.1978")
      ("ksc5601.1989" "ksx1001.1992" "ksc5601.1987")
      ("muletibetan-2" "muletibetan-0"))))
  "Alist of alternative font registry names.
Each element has the form (REGISTRY ALTERNATIVE1 ALTERNATIVE2 ...).
If fonts of registry REGISTRY can be loaded, font selection
tries to find a best matching font among all fonts of registry
REGISTRY, ALTERNATIVE1, ALTERNATIVE2, and etc."
  :tag "Alternative font registries to try"
  :type '(repeat (repeat string))
  :version "21.1"
  :group 'font-selection
  :set #'(lambda (symbol value)
	   (set-default symbol value)
	   (internal-set-alternative-font-registry-alist value)))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Creation, copying.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


(defun face-list ()
  "Return a list of all defined faces."
  (mapcar #'car face-new-frame-defaults))

(defun make-face (face &optional no-init-from-resources)
  "Define a new face with name FACE, a symbol.
Do not call this directly from Lisp code; use `defface' instead.

If NO-INIT-FROM-RESOURCES is non-nil, don't initialize face
attributes from X resources.  If FACE is already known as a face,
leave it unmodified.  Return FACE."
  (interactive (list (read-from-minibuffer
		      "Make face: " nil nil t 'face-name-history)))
  (unless (facep face)
    ;; Make frame-local faces (this also makes the global one).
    (dolist (frame (frame-list))
      (internal-make-lisp-face face frame))
    ;; Add the face to the face menu.
    (when (fboundp 'facemenu-add-new-face)
      (facemenu-add-new-face face))
    ;; Define frame-local faces for all frames from X resources.
    (unless no-init-from-resources
      (make-face-x-resource-internal face)))
  face)

(defun make-empty-face (face)
  "Define a new, empty face with name FACE.
Do not call this directly from Lisp code; use `defface' instead."
  (interactive (list (read-from-minibuffer
		      "Make empty face: " nil nil t 'face-name-history)))
  (make-face face 'no-init-from-resources))

(defun copy-face (old-face new-face &optional frame new-frame)
  "Define a face named NEW-FACE, which is a copy of OLD-FACE.
This function does not copy face customization data, so NEW-FACE
will not be made customizable.  Most Lisp code should not call
this function; use `defface' with :inherit instead.

If NEW-FACE already exists as a face, modify it to be like
OLD-FACE.  If NEW-FACE doesn't already exist, create it.

If the optional argument FRAME is a frame, change NEW-FACE on
FRAME only.  If FRAME is t, copy the frame-independent default
specification for OLD-FACE to NEW-FACE.  If FRAME is nil, copy
the defaults as well as the faces on each existing frame.

If the optional fourth argument NEW-FRAME is given, copy the
information from face OLD-FACE on frame FRAME to NEW-FACE on
frame NEW-FRAME.  In this case, FRAME must not be nil."
  (let ((inhibit-quit t))
    (if (null frame)
	(progn
	  (when new-frame
	    (error "Copying face %s from all frames to one frame"
		   old-face))
	  (make-empty-face new-face)
	  (dolist (frame (frame-list))
	    (copy-face old-face new-face frame))
	  (copy-face old-face new-face t))
      (make-empty-face new-face)
      (internal-copy-lisp-face old-face new-face frame new-frame))
    new-face))


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;;; Predicates, type checks.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun facep (face)
  "Return non-nil if FACE is a face name; nil otherwise.
A face name can be a string or a symbol."
  (internal-lisp-face-p face))


(defun check-face (face)
  "Signal an error if FACE doesn't name a face.
Value is FACE."
  (unless (facep face)
    (error "Not a face: %s" face))
  face)


;; The ID returned is not to be confused with the internally used IDs
;; of realized faces.  The ID assigned to Lisp faces is used to
;; support faces in display table entries.

(defun face-id (face &optional _frame)
  "Return the internal ID of face with name FACE.
If FACE is a face-alias, return the ID of the target face.
The optional argument FRAME is ignored, since the internal face ID
of a face name is the same for all frames."
  (check-face face)
  (or (get face 'face)
      (face-id (get face 'face-alias))))

(defun face-equal (face1 face2 &optional frame)
  "Non-nil if faces FACE1 and FACE2 are equal.
Faces are considered equal if all their attributes are equal.
If the optional argument FRAME is given, report on FACE1 and FACE2 in that frame.
If FRAME is t, report on the defaults for FACE1 and FACE2 (for new frames).
If FRAME is omitted or nil, use the selected frame."
  (internal-lisp-face-equal-p face1 face2 frame))


(defun face-differs-from-default-p (face &optional frame)
  "Return non-nil if FACE displays differently from the default face.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame."
  (let ((attrs
	 (delq :inherit (mapcar 'car face-attribute-name-alist)))
	(differs nil))
    (while (and attrs (not differs))
      (let* ((attr (pop attrs))
	     (attr-val (face-attribute face attr frame t)))
	(when (and
	       (not (eq attr-val 'unspecified))
	       (display-supports-face-attributes-p (list attr attr-val)
						   frame))
	  (setq differs attr))))
    differs))


(defun face-nontrivial-p (face &optional frame)
  "True if face FACE has some non-nil attribute.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame."
  (not (internal-lisp-face-empty-p face frame)))



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Setting face attributes from X resources.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defcustom face-x-resources
  (mapcar
   (lambda (arg)
     ;; FIXME; can we purecopy some of the conses too?
     (cons (car arg)
	   (cons (purecopy (car (cdr arg))) (purecopy (cdr (cdr arg))))))
  '((:family (".attributeFamily" . "Face.AttributeFamily"))
    (:foundry (".attributeFoundry" . "Face.AttributeFoundry"))
    (:width (".attributeWidth" . "Face.AttributeWidth"))
    (:height (".attributeHeight" . "Face.AttributeHeight"))
    (:weight (".attributeWeight" . "Face.AttributeWeight"))
    (:slant (".attributeSlant" . "Face.AttributeSlant"))
    (:foreground (".attributeForeground" . "Face.AttributeForeground"))
    (:background (".attributeBackground" . "Face.AttributeBackground"))
    (:overline (".attributeOverline" . "Face.AttributeOverline"))
    (:strike-through (".attributeStrikeThrough" . "Face.AttributeStrikeThrough"))
    (:box (".attributeBox" . "Face.AttributeBox"))
    (:underline (".attributeUnderline" . "Face.AttributeUnderline"))
    (:inverse-video (".attributeInverse" . "Face.AttributeInverse"))
    (:stipple
     (".attributeStipple" . "Face.AttributeStipple")
     (".attributeBackgroundPixmap" . "Face.AttributeBackgroundPixmap"))
    (:bold (".attributeBold" . "Face.AttributeBold"))
    (:italic (".attributeItalic" . "Face.AttributeItalic"))
    (:font (".attributeFont" . "Face.AttributeFont"))
    (:inherit (".attributeInherit" . "Face.AttributeInherit"))))
  "List of X resources and classes for face attributes.
Each element has the form (ATTRIBUTE ENTRY1 ENTRY2...) where ATTRIBUTE is
the name of a face attribute, and each ENTRY is a cons of the form
\(RESOURCE . CLASS) with RESOURCE being the resource and CLASS being the
X resource class for the attribute."
  :type '(repeat (cons symbol (repeat (cons string string))))
  :group 'faces)


(declare-function internal-face-x-get-resource "xfaces.c"
		  (resource class frame))

(declare-function internal-set-lisp-face-attribute-from-resource "xfaces.c"
		  (face attr value &optional frame))

(defun set-face-attribute-from-resource (face attribute resource class frame)
  "Set FACE's ATTRIBUTE from X resource RESOURCE, class CLASS on FRAME.
Value is the attribute value specified by the resource, or nil
if not present.  This function displays a message if the resource
specifies an invalid attribute."
  (let* ((face-name (face-name face))
	 (value (internal-face-x-get-resource (concat face-name resource)
					      class frame)))
    (when value
      (condition-case ()
	  (internal-set-lisp-face-attribute-from-resource
	   face attribute (downcase value) frame)
	(error
	 (message "Face %s, frame %s: invalid attribute %s %s from X resource"
		  face-name frame attribute value))))
    value))


(defun set-face-attributes-from-resources (face frame)
  "Set attributes of FACE from X resources for FRAME."
  (when (memq (framep frame) '(x w32))
    (dolist (definition face-x-resources)
      (let ((attribute (car definition)))
	(dolist (entry (cdr definition))
	  (set-face-attribute-from-resource face attribute (car entry)
					    (cdr entry) frame))))))


(defun make-face-x-resource-internal (face &optional frame)
  "Fill frame-local FACE on FRAME from X resources.
FRAME nil or not specified means do it for all frames."
  (if (null frame)
      (dolist (frame (frame-list))
	(set-face-attributes-from-resources face frame))
    (set-face-attributes-from-resources face frame)))



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Retrieving face attributes.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun face-name (face)
  "Return the name of face FACE."
  (symbol-name (check-face face)))


(defun face-all-attributes (face &optional frame)
  "Return an alist stating the attributes of FACE.
Each element of the result has the form (ATTR-NAME . ATTR-VALUE).
If FRAME is omitted or nil the value describes the default attributes,
but if you specify FRAME, the value describes the attributes
of FACE on FRAME."
  (mapcar (lambda (pair)
	    (let ((attr (car pair)))
	      (cons attr (face-attribute face attr (or frame t)))))
  	  face-attribute-name-alist))

(defun face-attribute (face attribute &optional frame inherit)
  "Return the value of FACE's ATTRIBUTE on FRAME.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.

If INHERIT is nil, only attributes directly defined by FACE are considered,
  so the return value may be `unspecified', or a relative value.
If INHERIT is non-nil, FACE's definition of ATTRIBUTE is merged with the
  faces specified by its `:inherit' attribute; however the return value
  may still be `unspecified' or relative.
If INHERIT is a face or a list of faces, then the result is further merged
  with that face (or faces), until it becomes specified and absolute.

To ensure that the return value is always specified and absolute, use a
value of `default' for INHERIT; this will resolve any unspecified or
relative values by merging with the `default' face (which is always
completely specified)."
  (let ((value (internal-get-lisp-face-attribute face attribute frame)))
    (when (and inherit (face-attribute-relative-p attribute value))
      ;; VALUE is relative, so merge with inherited faces
      (let ((inh-from (face-attribute face :inherit frame)))
	(unless (or (null inh-from) (eq inh-from 'unspecified))
          (condition-case nil
              (setq value
                    (face-attribute-merged-with attribute value inh-from frame))
            ;; The `inherit' attribute may point to non existent faces.
            (error nil)))))
    (when (and inherit
	       (not (eq inherit t))
	       (face-attribute-relative-p attribute value))
      ;; We should merge with INHERIT as well
      (setq value (face-attribute-merged-with attribute value inherit frame)))
    value))

(defun face-attribute-merged-with (attribute value faces &optional frame)
  "Merges ATTRIBUTE, initially VALUE, with faces from FACES until absolute.
FACES may be either a single face or a list of faces.
\[This is an internal function.]"
  (cond ((not (face-attribute-relative-p attribute value))
	 value)
	((null faces)
	 value)
	((consp faces)
	 (face-attribute-merged-with
	  attribute
	  (face-attribute-merged-with attribute value (car faces) frame)
	  (cdr faces)
	  frame))
	(t
	 (merge-face-attribute attribute
			       value
			       (face-attribute faces attribute frame t)))))


(defmacro face-attribute-specified-or (value &rest body)
  "Return VALUE, unless it's `unspecified', in which case evaluate BODY and return the result."
  (let ((temp (make-symbol "value")))
    `(let ((,temp ,value))
       (if (not (eq ,temp 'unspecified))
	   ,temp
	 ,@body))))

(defun face-foreground (face &optional frame inherit)
  "Return the foreground color name of FACE, or nil if unspecified.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.

If INHERIT is nil, only a foreground color directly defined by FACE is
  considered, so the return value may be nil.
If INHERIT is t, and FACE doesn't define a foreground color, then any
  foreground color that FACE inherits through its `:inherit' attribute
  is considered as well; however the return value may still be nil.
If INHERIT is a face or a list of faces, then it is used to try to
  resolve an unspecified foreground color.

To ensure that a valid color is always returned, use a value of
`default' for INHERIT; this will resolve any unspecified values by
merging with the `default' face (which is always completely specified)."
  (face-attribute-specified-or (face-attribute face :foreground frame inherit)
			       nil))

(defun face-background (face &optional frame inherit)
  "Return the background color name of FACE, or nil if unspecified.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.

If INHERIT is nil, only a background color directly defined by FACE is
  considered, so the return value may be nil.
If INHERIT is t, and FACE doesn't define a background color, then any
  background color that FACE inherits through its `:inherit' attribute
  is considered as well; however the return value may still be nil.
If INHERIT is a face or a list of faces, then it is used to try to
  resolve an unspecified background color.

To ensure that a valid color is always returned, use a value of
`default' for INHERIT; this will resolve any unspecified values by
merging with the `default' face (which is always completely specified)."
  (face-attribute-specified-or (face-attribute face :background frame inherit)
			       nil))

(defun face-stipple (face &optional frame inherit)
 "Return the stipple pixmap name of FACE, or nil if unspecified.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.

If INHERIT is nil, only a stipple directly defined by FACE is
  considered, so the return value may be nil.
If INHERIT is t, and FACE doesn't define a stipple, then any stipple
  that FACE inherits through its `:inherit' attribute is considered as
  well; however the return value may still be nil.
If INHERIT is a face or a list of faces, then it is used to try to
  resolve an unspecified stipple.

To ensure that a valid stipple or nil is always returned, use a value of
`default' for INHERIT; this will resolve any unspecified values by merging
with the `default' face (which is always completely specified)."
  (face-attribute-specified-or (face-attribute face :stipple frame inherit)
			       nil))


(defalias 'face-background-pixmap 'face-stipple)


(defun face-underline-p (face &optional frame inherit)
 "Return non-nil if FACE specifies a non-nil underlining.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.
Optional argument INHERIT is passed to `face-attribute'."
 (face-attribute-specified-or
  (face-attribute face :underline frame inherit) nil))


(defun face-inverse-video-p (face &optional frame inherit)
 "Return non-nil if FACE specifies a non-nil inverse-video.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.
Optional argument INHERIT is passed to `face-attribute'."
 (eq (face-attribute face :inverse-video frame inherit) t))


(defun face-bold-p (face &optional frame inherit)
  "Return non-nil if the font of FACE is bold on FRAME.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.
Optional argument INHERIT is passed to `face-attribute'.
Use `face-attribute' for finer control."
  (let ((bold (face-attribute face :weight frame inherit)))
    (memq bold '(semi-bold bold extra-bold ultra-bold))))


(defun face-italic-p (face &optional frame inherit)
  "Return non-nil if the font of FACE is italic on FRAME.
If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame.
Optional argument INHERIT is passed to `face-attribute'.
Use `face-attribute' for finer control."
  (let ((italic (face-attribute face :slant frame inherit)))
    (memq italic '(italic oblique))))



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Face documentation.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun face-documentation (face)
  "Get the documentation string for FACE.
If FACE is a face-alias, get the documentation for the target face."
  (let ((alias (get face 'face-alias))
        doc)
    (if alias
        (progn
          (setq doc (get alias 'face-documentation))
	  (format "%s is an alias for the face `%s'.%s" face alias
                  (if doc (format "\n%s" doc)
                    "")))
      (get face 'face-documentation))))


(defun set-face-documentation (face string)
  "Set the documentation string for FACE to STRING."
  ;; Perhaps the text should go in DOC.
  (put face 'face-documentation (purecopy string)))


(defalias 'face-doc-string 'face-documentation)
(defalias 'set-face-doc-string 'set-face-documentation)



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Setting face attributes.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


(defun set-face-attribute (face frame &rest args)
  "Set attributes of FACE on FRAME from ARGS.
This function overrides the face attributes specified by FACE's
face spec.  It is mostly intended for internal use only.

If FRAME is nil, set the attributes for all existing frames, as
well as the default for new frames.  If FRAME is t, change the
default for new frames only.

ARGS must come in pairs ATTRIBUTE VALUE.  ATTRIBUTE must be a
valid face attribute name.  All attributes can be set to
`unspecified'; this fact is not further mentioned below.

The following attributes are recognized:

`:family'

VALUE must be a string specifying the font family
\(e.g. \"Monospace\") or a fontset.

`:foundry'

VALUE must be a string specifying the font foundry,
e.g. ``adobe''.  If a font foundry is specified, wild-cards `*'
and `?' are allowed.

`:width'

VALUE specifies the relative proportionate width of the font to use.
It must be one of the symbols `ultra-condensed', `extra-condensed',
`condensed', `semi-condensed', `normal', `semi-expanded', `expanded',
`extra-expanded', or `ultra-expanded'.

`:height'

VALUE specifies the relative or absolute height of the font.  An
absolute height is an integer, and specifies font height in units
of 1/10 pt.  A relative height is either a floating point number,
which specifies a scaling factor for the underlying face height;
or a function that takes a single argument (the underlying face
height) and returns the new height.  Note that for the `default'
face, you must specify an absolute height (since there is nothing
for it to be relative to).

`:weight'

VALUE specifies the weight of the font to use.  It must be one of the
symbols `ultra-bold', `extra-bold', `bold', `semi-bold', `normal',
`semi-light', `light', `extra-light', `ultra-light'.

`:slant'

VALUE specifies the slant of the font to use.  It must be one of the
symbols `italic', `oblique', `normal', `reverse-italic', or
`reverse-oblique'.

`:foreground', `:background'

VALUE must be a color name, a string.

`:underline'

VALUE specifies whether characters in FACE should be underlined.
If VALUE is t, underline with foreground color of the face.
If VALUE is a string, underline with that color.
If VALUE is nil, explicitly don't underline.

Otherwise, VALUE must be a property list of the form:

`(:color COLOR :style STYLE)'.

COLOR can be a either a color name string or `foreground-color'.
STYLE can be either `line' or `wave'.
If a keyword/value pair is missing from the property list, a
default value will be used for the value.
The default value of COLOR is the foreground color of the face.
The default value of STYLE is `line'.

`:overline'

VALUE specifies whether characters in FACE should be overlined.  If
VALUE is t, overline with foreground color of the face.  If VALUE is a
string, overline with that color.  If VALUE is nil, explicitly don't
overline.

`:strike-through'

VALUE specifies whether characters in FACE should be drawn with a line
striking through them.  If VALUE is t, use the foreground color of the
face.  If VALUE is a string, strike-through with that color.  If VALUE
is nil, explicitly don't strike through.

`:box'

VALUE specifies whether characters in FACE should have a box drawn
around them.  If VALUE is nil, explicitly don't draw boxes.  If
VALUE is t, draw a box with lines of width 1 in the foreground color
of the face.  If VALUE is a string, the string must be a color name,
and the box is drawn in that color with a line width of 1.  Otherwise,
VALUE must be a property list of the form `(:line-width WIDTH
:color COLOR :style STYLE)'.  If a keyword/value pair is missing from
the property list, a default value will be used for the value, as
specified below.  WIDTH specifies the width of the lines to draw; it
defaults to 1.  If WIDTH is negative, the absolute value is the width
of the lines, and draw top/bottom lines inside the characters area,
not around it.  COLOR is the name of the color to draw in, default is
the foreground color of the face for simple boxes, and the background
color of the face for 3D boxes.  STYLE specifies whether a 3D box
should be draw.  If STYLE is `released-button', draw a box looking
like a released 3D button.  If STYLE is `pressed-button' draw a box
that appears like a pressed button.  If STYLE is nil, the default if
the property list doesn't contain a style specification, draw a 2D
box.

`:inverse-video'

VALUE specifies whether characters in FACE should be displayed in
inverse video.  VALUE must be one of t or nil.

`:stipple'

If VALUE is a string, it must be the name of a file of pixmap data.
The directories listed in the `x-bitmap-file-path' variable are
searched.  Alternatively, VALUE may 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.  VALUE nil means
explicitly don't use a stipple pattern.

For convenience, attributes `:family', `:foundry', `:width',
`:height', `:weight', and `:slant' may also be set in one step
from an X font name:

`:font'

Set font-related face attributes from VALUE.  VALUE must be a
valid font name or font object.  Setting this attribute will also
set the `:family', `:foundry', `:width', `:height', `:weight',
and `:slant' attributes.

`:inherit'

VALUE is the name of a face from which to inherit attributes, or
a list of face names.  Attributes from inherited faces are merged
into the face like an underlying face would be, with higher
priority than underlying faces.

For backward compatibility, the keywords `:bold' and `:italic'
can be used to specify weight and slant respectively.  This usage
is considered obsolete.  For these two keywords, the VALUE must
be either t or nil.  A value of t for `:bold' is equivalent to
setting `:weight' to `bold', and a value of t for `:italic' is
equivalent to setting `:slant' to `italic'.  But if `:weight' is
specified in the face spec, `:bold' is ignored, and if `:slant'
is specified, `:italic' is ignored."
  (setq args (purecopy args))
  (let ((where (if (null frame) 0 frame))
	(spec args)
	family foundry)
    ;; If we set the new-frame defaults, this face is modified outside Custom.
    (if (memq where '(0 t))
	(put (or (get face 'face-alias) face) 'face-modified t))
    ;; If family and/or foundry are specified, set it first.  Certain
    ;; face attributes, e.g. :weight semi-condensed, are not supported
    ;; in every font.  See bug#1127.
    (while spec
      (cond ((eq (car spec) :family)
	     (setq family (cadr spec)))
	    ((eq (car spec) :foundry)
	     (setq foundry (cadr spec))))
      (setq spec (cddr spec)))
    (when (or family foundry)
      (when (and (stringp family)
		 (string-match "\\([^-]*\\)-\\([^-]*\\)" family))
	(unless foundry
	  (setq foundry (match-string 1 family)))
	(setq family (match-string 2 family)))
      (when (or (stringp family) (eq family 'unspecified))
	(internal-set-lisp-face-attribute face :family (purecopy family)
					  where))
      (when (or (stringp foundry) (eq foundry 'unspecified))
	(internal-set-lisp-face-attribute face :foundry (purecopy foundry)
					  where)))
    (while args
      (unless (memq (car args) '(:family :foundry))
	(internal-set-lisp-face-attribute face (car args)
					  (purecopy (cadr args))
					  where))
      (setq args (cddr args)))))

(defun make-face-bold (face &optional frame _noerror)
  "Make the font of FACE be bold, if possible.
FRAME nil or not specified means change face on all frames.
Argument NOERROR is ignored and retained for compatibility.
Use `set-face-attribute' for finer control of the font weight."
  (interactive (list (read-face-name "Make which face bold"
                                     (face-at-point t))))
  (set-face-attribute face frame :weight 'bold))


(defun make-face-unbold (face &optional frame _noerror)
  "Make the font of FACE be non-bold, if possible.
FRAME nil or not specified means change face on all frames.
Argument NOERROR is ignored and retained for compatibility."
  (interactive (list (read-face-name "Make which face non-bold"
                                     (face-at-point t))))
  (set-face-attribute face frame :weight 'normal))


(defun make-face-italic (face &optional frame _noerror)
  "Make the font of FACE be italic, if possible.
FRAME nil or not specified means change face on all frames.
Argument NOERROR is ignored and retained for compatibility.
Use `set-face-attribute' for finer control of the font slant."
  (interactive (list (read-face-name "Make which face italic"
                                     (face-at-point t))))
  (set-face-attribute face frame :slant 'italic))


(defun make-face-unitalic (face &optional frame _noerror)
  "Make the font of FACE be non-italic, if possible.
FRAME nil or not specified means change face on all frames.
Argument NOERROR is ignored and retained for compatibility."
  (interactive (list (read-face-name "Make which face non-italic"
                                     (face-at-point t))))
  (set-face-attribute face frame :slant 'normal))


(defun make-face-bold-italic (face &optional frame _noerror)
  "Make the font of FACE be bold and italic, if possible.
FRAME nil or not specified means change face on all frames.
Argument NOERROR is ignored and retained for compatibility.
Use `set-face-attribute' for finer control of font weight and slant."
  (interactive (list (read-face-name "Make which face bold-italic"
                                     (face-at-point t))))
  (set-face-attribute face frame :weight 'bold :slant 'italic))


(defun set-face-font (face font &optional frame)
  "Change font-related attributes of FACE to those of FONT (a string).
FRAME nil or not specified means change face on all frames.
This sets the attributes `:family', `:foundry', `:width',
`:height', `:weight', and `:slant'.  When called interactively,
prompt for the face and font."
  (interactive (read-face-and-attribute :font))
  (set-face-attribute face frame :font font))


;; Implementation note: Emulating gray background colors with a
;; stipple pattern is now part of the face realization process, and is
;; done in C depending on the frame on which the face is realized.

(defun set-face-background (face color &optional frame)
  "Change the background color of face FACE to COLOR (a string).
FRAME nil or not specified means change face on all frames.
COLOR can be a system-defined color name (see `list-colors-display')
or a hex spec of the form #RRGGBB.
When called interactively, prompts for the face and color."
  (interactive (read-face-and-attribute :background))
  (set-face-attribute face frame :background (or color 'unspecified)))


(defun set-face-foreground (face color &optional frame)
  "Change the foreground color of face FACE to COLOR (a string).
FRAME nil or not specified means change face on all frames.
COLOR can be a system-defined color name (see `list-colors-display')
or a hex spec of the form #RRGGBB.
When called interactively, prompts for the face and color."
  (interactive (read-face-and-attribute :foreground))
  (set-face-attribute face frame :foreground (or color 'unspecified)))


(defun set-face-stipple (face stipple &optional frame)
  "Change the stipple pixmap of face FACE to STIPPLE.
FRAME nil or not specified means change face on all frames.
STIPPLE should be a string, the name of a file of pixmap data.
The directories listed in the `x-bitmap-file-path' variable are searched.

Alternatively, STIPPLE may 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."
  (interactive (read-face-and-attribute :stipple))
  (set-face-attribute face frame :stipple (or stipple 'unspecified)))


(defun set-face-underline (face underline &optional frame)
  "Specify whether face FACE is underlined.
UNDERLINE nil means FACE explicitly doesn't underline.
UNDERLINE t means FACE underlines with its foreground color.
If UNDERLINE is a string, underline with that color.

UNDERLINE may also be a list of the form (:color COLOR :style STYLE),
where COLOR is a string or `foreground-color', and STYLE is either
`line' or `wave'.  :color may be omitted, which means to use the
foreground color.  :style may be omitted, which means to use a line.

FRAME nil or not specified means change face on all frames.
Use `set-face-attribute' to ``unspecify'' underlining."
  (interactive (read-face-and-attribute :underline))
  (set-face-attribute face frame :underline underline))

(define-obsolete-function-alias 'set-face-underline-p
                                'set-face-underline "24.3")


(defun set-face-inverse-video (face inverse-video-p &optional frame)
  "Specify whether face FACE is in inverse video.
INVERSE-VIDEO-P non-nil means FACE displays explicitly in inverse video.
INVERSE-VIDEO-P nil means FACE explicitly is not in inverse video.
FRAME nil or not specified means change face on all frames.
Use `set-face-attribute' to ``unspecify'' the inverse video attribute."
  (interactive
   (let ((list (read-face-and-attribute :inverse-video)))
     (list (car list) (if (cadr list) t))))
  (set-face-attribute face frame :inverse-video inverse-video-p))

(define-obsolete-function-alias 'set-face-inverse-video-p
                                'set-face-inverse-video "24.4")

(defun set-face-bold (face bold-p &optional frame)
  "Specify whether face FACE is bold.
BOLD-P non-nil means FACE should explicitly display bold.
BOLD-P nil means FACE should explicitly display non-bold.
FRAME nil or not specified means change face on all frames.
Use `set-face-attribute' or `modify-face' for finer control."
  (if (null bold-p)
      (make-face-unbold face frame)
    (make-face-bold face frame)))

(define-obsolete-function-alias 'set-face-bold-p 'set-face-bold "24.4")


(defun set-face-italic (face italic-p &optional frame)
  "Specify whether face FACE is italic.
ITALIC-P non-nil means FACE should explicitly display italic.
ITALIC-P nil means FACE should explicitly display non-italic.
FRAME nil or not specified means change face on all frames.
Use `set-face-attribute' or `modify-face' for finer control."
  (if (null italic-p)
      (make-face-unitalic face frame)
    (make-face-italic face frame)))

(define-obsolete-function-alias 'set-face-italic-p 'set-face-italic "24.4")


(defalias 'set-face-background-pixmap 'set-face-stipple)


(defun invert-face (face &optional frame)
  "Swap the foreground and background colors of FACE.
If FRAME is omitted or nil, it means change face on all frames.
If FACE specifies neither foreground nor background color,
set its foreground and background to the background and foreground
of the default face.  Value is FACE."
  (interactive (list (read-face-name "Invert face" (face-at-point t))))
  (let ((fg (face-attribute face :foreground frame))
	(bg (face-attribute face :background frame)))
    (if (not (and (eq fg 'unspecified) (eq bg 'unspecified)))
	(set-face-attribute face frame :foreground bg :background fg)
      (set-face-attribute face frame
			  :foreground
			  (face-attribute 'default :background frame)
			  :background
			  (face-attribute 'default :foreground frame))))
  face)


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Interactively modifying faces.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun read-face-name (prompt &optional default multiple)
  "Read one or more face names, prompting with PROMPT.
PROMPT should not end in a space or a colon.

Return DEFAULT if the user enters the empty string.
If DEFAULT is non-nil, it should be a list of face names (symbols or strings).
In that case, return the `car' of DEFAULT (if MULTIPLE is non-nil),
or DEFAULT (if MULTIPLE is nil).  See below for the meaning of MULTIPLE.
DEFAULT can also be a single face.

This function uses `completing-read-multiple' with \"[ \\t]*,[ \\t]*\"
as the separator regexp.  Thus, the user may enter multiple face names,
separated by commas.

MULTIPLE specifies the form of the return value.  If MULTIPLE is non-nil,
return a list of face names; if the user entered just one face name,
return a list of one face name.  Otherwise, return a single face name;
if the user entered more than one face name, return only the first one."
  (if (and default (not (stringp default)))
      (setq default
            (cond ((symbolp default)
                   (symbol-name default))
                  (multiple
                   (mapconcat (lambda (f) (if (symbolp f) (symbol-name f) f))
                              default ", "))
                  ;; If we only want one, and the default is more than one,
                  ;; discard the unwanted ones.
                  (t (symbol-name (car default))))))

  (let (aliasfaces nonaliasfaces faces)
    ;; Build up the completion tables.
    (mapatoms (lambda (s)
                (if (facep s)
                    (if (get s 'face-alias)
                        (push (symbol-name s) aliasfaces)
                      (push (symbol-name s) nonaliasfaces)))))
    (dolist (face (completing-read-multiple
                   (if default
                       (format "%s (default `%s'): " prompt default)
                     (format "%s: " prompt))
                   (completion-table-in-turn nonaliasfaces aliasfaces)
                   nil t nil 'face-name-history default))
      ;; Ignore elements that are not faces
      ;; (for example, because DEFAULT was "all faces")
      (if (facep face) (push (intern face) faces)))
    ;; Return either a list of faces or just one face.
    (setq faces (nreverse faces))
    (if multiple faces (car faces))))

;; Not defined without X, but behind window-system test.
(defvar x-bitmap-file-path)

(defun face-valid-attribute-values (attribute &optional frame)
  "Return valid values for face attribute ATTRIBUTE.
The optional argument FRAME is used to determine available fonts
and colors.  If it is nil or not specified, the selected frame is used.
Value is an alist of (NAME . VALUE) if ATTRIBUTE expects a value out
of a set of discrete values.  Value is `integerp' if ATTRIBUTE expects
an integer value."
  (let ((valid
         (pcase attribute
           (`:family
            (if (window-system frame)
                (mapcar (lambda (x) (cons x x))
                        (font-family-list))
	      ;; Only one font on TTYs.
	      (list (cons "default" "default"))))
           (`:foundry
	    (list nil))
	   (`:width
	    (mapcar #'(lambda (x) (cons (symbol-name (aref x 1)) (aref x 1)))
		    font-width-table))
           (`:weight
	    (mapcar #'(lambda (x) (cons (symbol-name (aref x 1)) (aref x 1)))
		    font-weight-table))
	   (`:slant
	    (mapcar #'(lambda (x) (cons (symbol-name (aref x 1)) (aref x 1)))
		    font-slant-table))
	   (`:inverse-video
	    (mapcar #'(lambda (x) (cons (symbol-name x) x))
		    (internal-lisp-face-attribute-values attribute)))
           ((or `:underline `:overline `:strike-through `:box)
            (if (window-system frame)
                (nconc (mapcar #'(lambda (x) (cons (symbol-name x) x))
                               (internal-lisp-face-attribute-values attribute))
                       (mapcar #'(lambda (c) (cons c c))
                               (defined-colors frame)))
	      (mapcar #'(lambda (x) (cons (symbol-name x) x))
		      (internal-lisp-face-attribute-values attribute))))
           ((or `:foreground `:background)
            (mapcar #'(lambda (c) (cons c c))
                    (defined-colors frame)))
           (`:height
            'integerp)
           (`:stipple
            (and (memq (window-system frame) '(x ns)) ; No stipple on w32
                 (mapcar #'list
                         (apply #'nconc
                                (mapcar (lambda (dir)
                                          (and (file-readable-p dir)
                                               (file-directory-p dir)
                                               (directory-files dir)))
                                        x-bitmap-file-path)))))
           (`:inherit
            (cons '("none" . nil)
                  (mapcar #'(lambda (c) (cons (symbol-name c) c))
                          (face-list))))
           (_
            (error "Internal error")))))
    (if (and (listp valid) (not (memq attribute '(:inherit))))
	(nconc (list (cons "unspecified" 'unspecified)) valid)
      valid)))


(defconst face-attribute-name-alist
  '((:family . "font family")
    (:foundry . "font foundry")
    (:width . "character set width")
    (:height . "height in 1/10 pt")
    (:weight . "weight")
    (:slant . "slant")
    (:underline . "underline")
    (:overline . "overline")
    (:strike-through . "strike-through")
    (:box . "box")
    (:inverse-video . "inverse-video display")
    (:foreground . "foreground color")
    (:background . "background color")
    (:stipple . "background stipple")
    (:inherit . "inheritance"))
  "An alist of descriptive names for face attributes.
Each element has the form (ATTRIBUTE-NAME . DESCRIPTION) where
ATTRIBUTE-NAME is a face attribute name (a keyword symbol), and
DESCRIPTION is a descriptive name for ATTRIBUTE-NAME.")


(defun face-descriptive-attribute-name (attribute)
  "Return a descriptive name for ATTRIBUTE."
  (cdr (assq attribute face-attribute-name-alist)))


(defun face-read-string (face default name &optional completion-alist)
  "Interactively read a face attribute string value.
FACE is the face whose attribute is read.  If non-nil, DEFAULT is the
default string to return if no new value is entered.  NAME is a
descriptive name of the attribute for prompting.  COMPLETION-ALIST is an
alist of valid values, if non-nil.

Entering nothing accepts the default string DEFAULT.
Value is the new attribute value."
  ;; Capitalize NAME (we don't use `capitalize' because that capitalizes
  ;; each word in a string separately).
  (setq name (concat (upcase (substring name 0 1)) (substring name 1)))
  (let* ((completion-ignore-case t)
	 (value (completing-read
		 (if default
		     (format "%s for face `%s' (default %s): "
			     name face default)
		   (format "%s for face `%s': " name face))
		 completion-alist nil nil nil nil default)))
    (if (equal value "") default value)))


(defun face-read-integer (face default name)
  "Interactively read an integer face attribute value.
FACE is the face whose attribute is read.  DEFAULT is the default
value to return if no new value is entered.  NAME is a descriptive
name of the attribute for prompting.  Value is the new attribute value."
  (let ((new-value
	 (face-read-string face
			   (format "%s" default)
			   name
			   (list (cons "unspecified" 'unspecified)))))
    (cond ((equal new-value "unspecified")
	   'unspecified)
	  ((member new-value '("unspecified-fg" "unspecified-bg"))
	   new-value)
	  (t
	   (string-to-number new-value)))))


;; FIXME this does allow you to enter the list forms of :box,
;; :stipple, or :underline, because face-valid-attribute-values does
;; not return those forms.
(defun read-face-attribute (face attribute &optional frame)
  "Interactively read a new value for FACE's ATTRIBUTE.
Optional argument FRAME nil or unspecified means read an attribute value
of a global face.  Value is the new attribute value."
  (let* ((old-value (face-attribute face attribute frame))
	 (attribute-name (face-descriptive-attribute-name attribute))
	 (valid (face-valid-attribute-values attribute frame))
	 new-value)
    ;; Represent complex attribute values as strings by printing them
    ;; out.  Stipple can be a vector; (WIDTH HEIGHT DATA).  Box can be
    ;; a list `(:width WIDTH :color COLOR)' or `(:width WIDTH :shadow
    ;; SHADOW)'.  Underline can be `(:color COLOR :style STYLE)'.
    (and (memq attribute '(:box :stipple :underline))
	 (or (consp old-value)
	     (vectorp old-value))
	 (setq old-value (prin1-to-string old-value)))
    (cond ((listp valid)
	   (let ((default
		   (or (car (rassoc old-value valid))
		       (format "%s" old-value))))
	     (setq new-value
		   (face-read-string face default attribute-name valid))
	     (if (equal new-value default)
		 ;; Nothing changed, so don't bother with all the stuff
		 ;; below.  In particular, this avoids a non-tty color
		 ;; from being canonicalized for a tty when the user
		 ;; just uses the default.
		 (setq new-value old-value)
	       ;; Terminal frames can support colors that don't appear
	       ;; explicitly in VALID, using color approximation code
	       ;; in tty-colors.el.
	       (when (and (memq attribute '(:foreground :background))
			  (not (memq (window-system frame) '(x w32 ns)))
			  (not (member new-value
				       '("unspecified"
					 "unspecified-fg" "unspecified-bg"))))
		 (setq new-value (car (tty-color-desc new-value frame))))