lisp/face-remap.el

   1 ;;; face-remap.el --- Functions for managing `face-remapping-alist'  -*- lexical-binding: t -*-
   2 ;;
   3 ;; Copyright (C) 2008-2018 Free Software Foundation, Inc.
   4 ;;
   5 ;; Author: Miles Bader <miles@gnu.org>
   6 ;; Keywords: faces, face remapping, display, user commands
   7 ;;
   8 ;; This file is part of GNU Emacs.
   9 ;;
  10 ;; GNU Emacs is free software: you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation, either version 3 of the License, or
  13 ;; (at your option) any later version.
  14 ;;
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19 ;;
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
  22 ;;
  23
  24 ;;; Commentary:
  25
  26 ;;
  27 ;; This file defines some simple operations that can be used for
  28 ;; maintaining the `face-remapping-alist' in a cooperative way.  This is
  29 ;; especially important for the `default' face.
  30 ;;
  31 ;; Each face-remapping definition in `face-remapping-alist' added by
  32 ;; this code uses the form:
  33 ;;
  34 ;;   (face RELATIVE_SPECS_1 RELATIVE_SPECS_2 ... BASE_SPECS)
  35 ;;
  36 ;; The "specs" values are a lists of face names or face attribute-value
  37 ;; pairs, and are merged together, with earlier values taking precedence.
  38 ;;
  39 ;; The RELATIVE_SPECS_* values are added by `face-remap-add-relative'
  40 ;; (and removed by `face-remap-remove-relative', and are intended for
  41 ;; face "modifications" (such as increasing the size).  Typical users of
  42 ;; relative specs would be minor modes.
  43 ;;
  44 ;; BASE_SPECS is the lowest-priority value, and by default is just the
  45 ;; face name, which causes the global definition of that face to be used.
  46 ;;
  47 ;; A non-default value of BASE_SPECS may also be set using
  48 ;; `face-remap-set-base'.  Because this _overwrites_ the default
  49 ;; value inheriting from the global face definition, it is up to the
  50 ;; caller of face-remap-set-base to add such inheritance if it is
  51 ;; desired.  A typical use of face-remap-set-base would be a major
  52 ;; mode setting face remappings, e.g., of the default face.
  53 ;;
  54 ;; All modifications cause face-remapping-alist to be made buffer-local.
  55 ;;
  56
  57
  58 ;;; Code:
  59
  60 \f
  61 ;; ----------------------------------------------------------------
  62 ;; Utility functions
  63
  64 ;; Names of face attributes corresponding to lisp face-vector positions.
  65 ;; This variable should probably be defined in C code where the actual
  66 ;; definitions are available.
  67 ;;
  68 (defvar internal-lisp-face-attributes
  69   [nil
  70    :family :foundry :swidth :height :weight :slant :underline :inverse
  71    :foreground :background :stipple :overline :strike :box
  72    :font :inherit :fontset :vector])
  73
  74 (defun face-attrs-more-relative-p (attrs1 attrs2)
  75   "Return true if ATTRS1 contains a greater number of relative
  76 face-attributes than ATTRS2.  A face attribute is considered
  77 relative if `face-attribute-relative-p' returns non-nil.
  78
  79 ATTRS1 and ATTRS2 may be any value suitable for a `face' text
  80 property, including face names, lists of face names,
  81 face-attribute plists, etc.
  82
  83 This function can be used as a predicate with `sort', to sort
  84 face lists so that more specific faces are located near the end."
  85   (unless (vectorp attrs1)
  86     (setq attrs1 (face-attributes-as-vector attrs1)))
  87   (unless (vectorp attrs2)
  88     (setq attrs2 (face-attributes-as-vector attrs2)))
  89   (let ((rel1-count 0) (rel2-count 0))
  90     (dotimes (i (length attrs1))
  91       (let ((attr (aref internal-lisp-face-attributes i)))
  92         (when attr
  93           (when (face-attribute-relative-p attr (aref attrs1 i))
  94             (setq rel1-count (+ rel1-count 1)))
  95           (when (face-attribute-relative-p attr (aref attrs2 i))
  96             (setq rel2-count (+ rel2-count 1))))))
  97     (< rel1-count rel2-count)))
  98
  99 (defun face-remap-order (entry)
 100   "Order ENTRY so that more relative face specs are near the beginning.
 101 The list structure of ENTRY may be destructively modified."
 102   (setq entry (nreverse entry))
 103   (setcdr entry (sort (cdr entry) 'face-attrs-more-relative-p))
 104   (nreverse entry))
 105
 106 ;;;###autoload
 107 (defun face-remap-add-relative (face &rest specs)
 108   "Add a face remapping entry of FACE to SPECS in the current buffer.
 109 Return a cookie which can be used to delete this remapping with
 110 `face-remap-remove-relative'.
 111
 112 The remaining arguments, SPECS, should form a list of faces.
 113 Each list element should be either a face name or a property list
 114 of face attribute/value pairs.  If more than one face is listed,
 115 that specifies an aggregate face, in the same way as in a `face'
 116 text property, except for possible priority changes noted below.
 117
 118 The face remapping specified by SPECS takes effect alongside the
 119 remappings from other calls to `face-remap-add-relative' for the
 120 same FACE, as well as the normal definition of FACE (at lowest
 121 priority).  This function tries to sort multiple remappings for
 122 the same face, so that remappings specifying relative face
 123 attributes are applied after remappings specifying absolute face
 124 attributes.
 125
 126 The base (lowest priority) remapping may be set to something
 127 other than the normal definition of FACE via `face-remap-set-base'."
 128   (while (and (consp specs) (null (cdr specs)))
 129     (setq specs (car specs)))
 130   (make-local-variable 'face-remapping-alist)
 131   (let ((entry (assq face face-remapping-alist)))
 132     (when (null entry)
 133       (setq entry (list face face))     ; explicitly merge with global def
 134       (push entry face-remapping-alist))
 135     (let ((faces (cdr entry)))
 136       (if (symbolp faces)
 137           (setq faces (list faces)))
 138       (setcdr entry (face-remap-order (cons specs faces)))
 139       ;; Force redisplay of this buffer.
 140       (force-mode-line-update))
 141     (cons face specs)))
 142
 143 (defun face-remap-remove-relative (cookie)
 144   "Remove a face remapping previously added by `face-remap-add-relative'.
 145 COOKIE should be the return value from that function."
 146   (let ((remapping (assq (car cookie) face-remapping-alist)))
 147     (when remapping
 148       (let ((updated-entries (remq (cdr cookie) (cdr remapping))))
 149         (unless (eq updated-entries (cdr remapping))
 150           (setcdr remapping updated-entries)
 151           (when (or (null updated-entries)
 152                     (and (eq (car-safe updated-entries) (car cookie))
 153                          (null (cdr updated-entries))))
 154             (setq face-remapping-alist
 155                   (remq remapping face-remapping-alist))
 156             ;; Force redisplay of this buffer.
 157             (force-mode-line-update))
 158           (cdr cookie))))))
 159
 160 ;;;###autoload
 161 (defun face-remap-reset-base (face)
 162   "Set the base remapping of FACE to the normal definition of FACE.
 163 This causes the remappings specified by `face-remap-add-relative'
 164 to apply on top of the normal definition of FACE."
 165   (let ((entry (assq face face-remapping-alist)))
 166     (when entry
 167       ;; If there's nothing except a base remapping, we simply remove
 168       ;; the entire remapping entry, as setting the base to the default
 169       ;; would be the same as the global definition.  Otherwise, we
 170       ;; modify the base remapping.
 171       (if (null (cddr entry))           ; nothing except base remapping
 172           (setq face-remapping-alist    ; so remove entire entry
 173                 (remq entry face-remapping-alist))
 174         (setcar (last entry) face))
 175       ;; Force redisplay of this buffer.
 176       (force-mode-line-update))))  ; otherwise, just inherit global def
 177
 178 ;;;###autoload
 179 (defun face-remap-set-base (face &rest specs)
 180   "Set the base remapping of FACE in the current buffer to SPECS.
 181 This causes the remappings specified by `face-remap-add-relative'
 182 to apply on top of the face specification given by SPECS.
 183
 184 The remaining arguments, SPECS, should form a list of faces.
 185 Each list element should be either a face name or a property list
 186 of face attribute/value pairs, like in a `face' text property.
 187
 188 If SPECS is empty, call `face-remap-reset-base' to use the normal
 189 definition of FACE as the base remapping; note that this is
 190 different from SPECS containing a single value nil, which means
 191 not to inherit from the global definition of FACE at all."
 192   (while (and (consp specs) (not (null (car specs))) (null (cdr specs)))
 193     (setq specs (car specs)))
 194   (if (or (null specs)
 195           (and (eq (car specs) face) (null (cdr specs)))) ; default
 196       ;; Set entry back to default
 197       (face-remap-reset-base face)
 198     ;; Set the base remapping
 199     (make-local-variable 'face-remapping-alist)
 200     (let ((entry (assq face face-remapping-alist)))
 201       (if entry
 202           (setcar (last entry) specs)   ; overwrite existing base entry
 203         (push (list face specs) face-remapping-alist)))
 204     ;; Force redisplay of this buffer.
 205     (force-mode-line-update)))
 206
 207 \f
 208 ;; ----------------------------------------------------------------
 209 ;; text-scale-mode
 210
 211 (defcustom text-scale-mode-step 1.2
 212   "Scale factor used by `text-scale-mode'.
 213 Each positive or negative step scales the default face height by this amount."
 214   :group 'display
 215   :type 'number
 216   :version "23.1")
 217
 218 ;; current remapping cookie for text-scale-mode
 219 (defvar text-scale-mode-remapping nil)
 220 (make-variable-buffer-local 'text-scale-mode-remapping)
 221
 222 ;; Lighter displayed for text-scale-mode in mode-line minor-mode list
 223 (defvar text-scale-mode-lighter "+0")
 224 (make-variable-buffer-local 'text-scale-mode-lighter)
 225
 226 ;; Number of steps that text-scale-mode will increase/decrease text height
 227 (defvar text-scale-mode-amount 0)
 228 (make-variable-buffer-local 'text-scale-mode-amount)
 229
 230 (define-minor-mode text-scale-mode
 231   "Minor mode for displaying buffer text in a larger/smaller font.
 232 With a prefix argument ARG, enable the mode if ARG is positive,
 233 and disable it otherwise.  If called from Lisp, enable the mode
 234 if ARG is omitted or nil.
 235
 236 The amount of scaling is determined by the variable
 237 `text-scale-mode-amount': one step scales the global default
 238 face size by the value of the variable `text-scale-mode-step'
 239 \(a negative amount shrinks the text).
 240
 241 The `text-scale-increase', `text-scale-decrease', and
 242 `text-scale-set' functions may be used to interactively modify
 243 the variable `text-scale-mode-amount' (they also enable or
 244 disable `text-scale-mode' as necessary)."
 245   :lighter (" " text-scale-mode-lighter)
 246   (when text-scale-mode-remapping
 247     (face-remap-remove-relative text-scale-mode-remapping))
 248   (setq text-scale-mode-lighter
 249         (format (if (>= text-scale-mode-amount 0) "+%d" "%d")
 250                 text-scale-mode-amount))
 251   (setq text-scale-mode-remapping
 252         (and text-scale-mode
 253              (face-remap-add-relative 'default
 254                                           :height
 255                                           (expt text-scale-mode-step
 256                                                 text-scale-mode-amount))))
 257   (force-window-update (current-buffer)))
 258
 259 (defun text-scale-min-amount ()
 260   "Return the minimum amount of text-scaling we allow."
 261   ;; When the resulting pixel-height of characters will become smaller
 262   ;; than 1 pixel, we can expect trouble from the display engine.
 263   ;; E.g., it requires that the character glyph's ascent is
 264   ;; non-negative.
 265   (log (/ 1.0 (frame-char-height)) text-scale-mode-step))
 266
 267 (defun text-scale-max-amount ()
 268   "Return the maximum amount of text-scaling we allow."
 269   ;; The display engine uses a 16-bit short for pixel-width of
 270   ;; characters, thus the 0xffff limitation.  It also makes no sense
 271   ;; to have characters wider than the display.
 272   (log (/ (min (display-pixel-width) #xffff)
 273           (frame-char-width))
 274        text-scale-mode-step))
 275
 276 ;;;###autoload
 277 (defun text-scale-set (level)
 278   "Set the scale factor of the default face in the current buffer to LEVEL.
 279 If LEVEL is non-zero, `text-scale-mode' is enabled, otherwise it is disabled.
 280
 281 LEVEL is a number of steps, with 0 representing the default size.
 282 Each step scales the height of the default face by the variable
 283 `text-scale-mode-step' (a negative number decreases the height by
 284 the same amount)."
 285   (interactive "p")
 286   (setq text-scale-mode-amount
 287         (max (min level (text-scale-max-amount)) (text-scale-min-amount)))
 288   (text-scale-mode (if (zerop text-scale-mode-amount) -1 1)))
 289
 290 ;;;###autoload
 291 (defun text-scale-increase (inc)
 292   "Increase the height of the default face in the current buffer by INC steps.
 293 If the new height is other than the default, `text-scale-mode' is enabled.
 294
 295 Each step scales the height of the default face by the variable
 296 `text-scale-mode-step' (a negative number of steps decreases the
 297 height by the same amount).  As a special case, an argument of 0
 298 will remove any scaling currently active."
 299   (interactive "p")
 300   (let* ((current-value (if text-scale-mode text-scale-mode-amount 0))
 301          (new-value (if (= inc 0) 0 (+ current-value inc))))
 302     (if (or (> new-value (text-scale-max-amount))
 303             (< new-value (text-scale-min-amount)))
 304         (user-error "Cannot %s the default face height more than it already is"
 305                     (if (> inc 0) "increase" "decrease")))
 306     (setq text-scale-mode-amount new-value))
 307   (text-scale-mode (if (zerop text-scale-mode-amount) -1 1)))
 308
 309 ;;;###autoload
 310 (defun text-scale-decrease (dec)
 311   "Decrease the height of the default face in the current buffer by DEC steps.
 312 See `text-scale-increase' for more details."
 313   (interactive "p")
 314   (text-scale-increase (- dec)))
 315
 316 ;;;###autoload (define-key ctl-x-map [(control ?+)] 'text-scale-adjust)
 317 ;;;###autoload (define-key ctl-x-map [(control ?-)] 'text-scale-adjust)
 318 ;;;###autoload (define-key ctl-x-map [(control ?=)] 'text-scale-adjust)
 319 ;;;###autoload (define-key ctl-x-map [(control ?0)] 'text-scale-adjust)
 320 ;;;###autoload
 321 (defun text-scale-adjust (inc)
 322   "Adjust the height of the default face by INC.
 323
 324 INC may be passed as a numeric prefix argument.
 325
 326 The actual adjustment made depends on the final component of the
 327 key-binding used to invoke the command, with all modifiers removed:
 328
 329    +, =   Increase the default face height by one step
 330    -      Decrease the default face height by one step
 331    0      Reset the default face height to the global default
 332
 333 After adjusting, continue to read input events and further adjust
 334 the face height as long as the input event read
 335 \(with all modifiers removed) is one of the above characters.
 336
 337 Each step scales the height of the default face by the variable
 338 `text-scale-mode-step' (a negative number of steps decreases the
 339 height by the same amount).  As a special case, an argument of 0
 340 will remove any scaling currently active.
 341
 342 This command is a special-purpose wrapper around the
 343 `text-scale-increase' command which makes repetition convenient
 344 even when it is bound in a non-top-level keymap.  For binding in
 345 a top-level keymap, `text-scale-increase' or
 346 `text-scale-decrease' may be more appropriate."
 347   (interactive "p")
 348   (let ((ev last-command-event)
 349         (echo-keystrokes nil))
 350     (let* ((base (event-basic-type ev))
 351            (step
 352             (pcase base
 353               ((or ?+ ?=) inc)
 354               (?- (- inc))
 355               (?0 0)
 356               (_ inc))))
 357       (text-scale-increase step)
 358       ;; (unless (zerop step)
 359       (message "Use +,-,0 for further adjustment")
 360       (set-transient-map
 361        (let ((map (make-sparse-keymap)))
 362          (dolist (mods '(() (control)))
 363            (dolist (key '(?- ?+ ?= ?0)) ;; = is often unshifted +.
 364              (define-key map (vector (append mods (list key)))
 365                (lambda () (interactive) (text-scale-adjust (abs inc))))))
 366          map))))) ;; )
 367
 368 \f
 369 ;; ----------------------------------------------------------------
 370 ;; buffer-face-mode
 371
 372 (defcustom buffer-face-mode-face 'variable-pitch
 373   "The face specification used by `buffer-face-mode'.
 374 It may contain any value suitable for a `face' text property,
 375 including a face name, a list of face names, a face-attribute
 376 plist, etc."
 377   :type '(choice (face)
 378                  (repeat :tag "List of faces" face)
 379                  (plist :tag "Face property list"))
 380   :group 'display
 381   :version "23.1")
 382
 383 ;; current remapping cookie for  buffer-face-mode
 384 (defvar buffer-face-mode-remapping nil)
 385 (make-variable-buffer-local 'buffer-face-mode-remapping)
 386
 387 ;;;###autoload
 388 (define-minor-mode buffer-face-mode
 389   "Minor mode for a buffer-specific default face.
 390 With a prefix argument ARG, enable the mode if ARG is positive,
 391 and disable it otherwise.  If called from Lisp, enable the mode
 392 if ARG is omitted or nil.  When enabled, the face specified by the
 393 variable `buffer-face-mode-face' is used to display the buffer text."
 394   :lighter " BufFace"
 395   (when buffer-face-mode-remapping
 396     (face-remap-remove-relative buffer-face-mode-remapping))
 397   (setq buffer-face-mode-remapping
 398         (and buffer-face-mode
 399              (face-remap-add-relative 'default buffer-face-mode-face)))
 400   (force-window-update (current-buffer)))
 401
 402 ;;;###autoload
 403 (defun buffer-face-set (&rest specs)
 404   "Enable `buffer-face-mode', using face specs SPECS.
 405 Each argument in SPECS should be a face, i.e. either a face name
 406 or a property list of face attributes and values.  If more than
 407 one face is listed, that specifies an aggregate face, like in a
 408 `face' text property.  If SPECS is nil or omitted, disable
 409 `buffer-face-mode'.
 410
 411 This function makes the variable `buffer-face-mode-face' buffer
 412 local, and sets it to FACE."
 413   (interactive (list (read-face-name "Set buffer face" (face-at-point t))))
 414   (while (and (consp specs) (null (cdr specs)))
 415     (setq specs (car specs)))
 416   (if (null specs)
 417       (buffer-face-mode 0)
 418     (set (make-local-variable 'buffer-face-mode-face) specs)
 419     (buffer-face-mode t)))
 420
 421 ;;;###autoload
 422 (defun buffer-face-toggle (&rest specs)
 423   "Toggle `buffer-face-mode', using face specs SPECS.
 424 Each argument in SPECS should be a face, i.e. either a face name
 425 or a property list of face attributes and values.  If more than
 426 one face is listed, that specifies an aggregate face, like in a
 427 `face' text property.
 428
 429 If `buffer-face-mode' is already enabled, and is currently using
 430 the face specs SPECS, then it is disabled; if `buffer-face-mode'
 431 is disabled, or is enabled and currently displaying some other
 432 face, then is left enabled, but the face changed to reflect SPECS.
 433
 434 This function will make the variable `buffer-face-mode-face'
 435 buffer local, and set it to SPECS."
 436   (interactive (list buffer-face-mode-face))
 437   (while (and (consp specs) (null (cdr specs)))
 438     (setq specs (car specs)))
 439   (if (or (null specs)
 440           (and buffer-face-mode (equal buffer-face-mode-face specs)))
 441       (buffer-face-mode 0)
 442     (set (make-local-variable 'buffer-face-mode-face) specs)
 443     (buffer-face-mode t)))
 444
 445 (defun buffer-face-mode-invoke (specs arg &optional interactive)
 446   "Enable or disable `buffer-face-mode' using face specs SPECS.
 447 ARG controls whether the mode is enabled or disabled, and is
 448 interpreted in the usual manner for minor-mode commands.
 449
 450 SPECS can be any value suitable for a `face' text property,
 451 including a face name, a plist of face attributes and values,
 452 or a list of faces.
 453
 454 If INTERACTIVE is non-nil, display a message describing the
 455 result.
 456
 457 This is a wrapper function which calls `buffer-face-set' or
 458 `buffer-face-toggle' (depending on ARG), and prints a status
 459 message in the echo area.  In many cases one of those functions
 460 may be more appropriate."
 461   (let ((last-message (current-message)))
 462     (if (or (eq arg 'toggle) (not arg))
 463         (buffer-face-toggle specs)
 464       (buffer-face-set (and (> (prefix-numeric-value arg) 0) specs)))
 465     (when interactive
 466       (unless (and (current-message)
 467                    (not (equal last-message (current-message))))
 468         (message "Buffer-Face mode %sabled"
 469                  (if buffer-face-mode "en" "dis"))))))
 470
 471 \f
 472 ;; ----------------------------------------------------------------
 473 ;; variable-pitch-mode
 474
 475 ;;;###autoload
 476 (defun variable-pitch-mode (&optional arg)
 477   "Variable-pitch default-face mode.
 478 An interface to `buffer-face-mode' which uses the `variable-pitch' face.
 479 Besides the choice of face, it is the same as `buffer-face-mode'."
 480   (interactive (list (or current-prefix-arg 'toggle)))
 481   (buffer-face-mode-invoke 'variable-pitch arg
 482                            (called-interactively-p 'interactive)))
 483
 484
 485 (provide 'face-remap)
 486
 487 ;;; face-remap.el ends here