lisp/fringe.el

   1 ;;; fringe.el --- fringe setup and control  -*- coding: utf-8 -*-
   2
   3 ;; Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008,
   4 ;;   2009, 2010, 2011 Free Software Foundation, Inc.
   5
   6 ;; Author: Simon Josefsson <simon@josefsson.org>
   7 ;; Maintainer: FSF
   8 ;; Keywords: frames
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file contains code to initialize the built-in fringe bitmaps
  28 ;; as well as helpful functions for customizing the appearance of the
  29 ;; fringe.
  30
  31 ;; The code is influenced by scroll-bar.el and avoid.el.  The author
  32 ;; gratefully acknowledge comments and suggestions made by Miles
  33 ;; Bader, Eli Zaretski, Richard Stallman, Pavel Janík and others which
  34 ;; improved this package.
  35
  36 ;;; Code:
  37
  38 (defgroup fringe nil
  39   "Window fringes."
  40   :version "22.1"
  41   :group 'frames)
  42
  43 ;; Define the built-in fringe bitmaps and setup default mappings
  44
  45 (when (boundp 'fringe-bitmaps)
  46   (let ((bitmaps '(question-mark
  47                    left-arrow right-arrow up-arrow down-arrow
  48                    left-curly-arrow right-curly-arrow
  49                    left-triangle right-triangle
  50                    top-left-angle top-right-angle
  51                    bottom-left-angle bottom-right-angle
  52                    left-bracket right-bracket
  53                    filled-rectangle hollow-rectangle
  54                    filled-square hollow-square
  55                    vertical-bar horizontal-bar
  56                    empty-line))
  57         (bn 1))
  58     (while bitmaps
  59       (push (car bitmaps) fringe-bitmaps)
  60       (put (car bitmaps) 'fringe bn)
  61       (setq bitmaps (cdr bitmaps)
  62             bn (1+ bn))))
  63
  64   (setq-default fringe-indicator-alist
  65                 '((truncation . (left-arrow right-arrow))
  66                   (continuation . (left-curly-arrow right-curly-arrow))
  67                   (overlay-arrow . right-triangle)
  68                   (up . up-arrow)
  69                   (down . down-arrow)
  70                   (top . (top-left-angle top-right-angle))
  71                   (bottom . (bottom-left-angle bottom-right-angle
  72                              top-right-angle top-left-angle))
  73                   (top-bottom . (left-bracket right-bracket
  74                                  top-right-angle top-left-angle))
  75                   (empty-line . empty-line)
  76                   (unknown . question-mark)))
  77
  78   (setq-default fringe-cursor-alist
  79                 '((box . filled-rectangle)
  80                   (hollow . hollow-rectangle)
  81                   (bar . vertical-bar)
  82                   (hbar . horizontal-bar)
  83                   (hollow-small . hollow-square))))
  84
  85
  86 (defmacro fringe-bitmap-p (symbol)
  87   "Return non-nil if SYMBOL is a fringe bitmap."
  88   `(get ,symbol 'fringe))
  89
  90
  91 ;; Control presence of fringes
  92
  93 (defvar fringe-mode)
  94
  95 (defvar fringe-mode-explicit nil
  96   "Non-nil means `set-fringe-mode' should really do something.
  97 This is nil while loading `fringe.el', and t afterward.")
  98
  99 (defun set-fringe-mode-1 (ignore value)
 100   "Call `set-fringe-mode' with VALUE.
 101 See `fringe-mode' for valid values and their effect.
 102 This is usually invoked when setting `fringe-mode' via customize."
 103   (set-fringe-mode value))
 104
 105 (defun set-fringe-mode (value)
 106   "Set `fringe-mode' to VALUE and put the new value into effect.
 107 See `fringe-mode' for possible values and their effect."
 108   (setq fringe-mode value)
 109
 110   (when fringe-mode-explicit
 111     (modify-all-frames-parameters
 112      (list (cons 'left-fringe (if (consp fringe-mode)
 113                                   (car fringe-mode)
 114                                 fringe-mode))
 115            (cons 'right-fringe (if (consp fringe-mode)
 116                                    (cdr fringe-mode)
 117                                  fringe-mode))))))
 118
 119 ;; For initialization of fringe-mode, take account of changes
 120 ;; made explicitly to default-frame-alist.
 121 (defun fringe-mode-initialize (symbol value)
 122   (let* ((left-pair (assq 'left-fringe default-frame-alist))
 123          (right-pair (assq 'right-fringe default-frame-alist))
 124          (left (cdr left-pair))
 125          (right (cdr right-pair)))
 126     (if (or left-pair right-pair)
 127         ;; If there's something in default-frame-alist for fringes,
 128         ;; don't change it, but reflect that into the value of fringe-mode.
 129         (progn
 130           (setq fringe-mode (cons left right))
 131           (if (equal fringe-mode '(nil . nil))
 132               (setq fringe-mode nil))
 133           (if (equal fringe-mode '(0 . 0))
 134               (setq fringe-mode 0)))
 135       ;; Otherwise impose the user-specified value of fringe-mode.
 136       (custom-initialize-reset symbol value))))
 137
 138 (defcustom fringe-mode nil
 139   "Specify appearance of fringes on all frames.
 140 This variable can be nil (the default) meaning the fringes should have
 141 the default width (8 pixels), it can be an integer value specifying
 142 the width of both left and right fringe (where 0 means no fringe), or
 143 a cons cell where car indicates width of left fringe and cdr indicates
 144 width of right fringe (where again 0 can be used to indicate no
 145 fringe).
 146 To set this variable in a Lisp program, use `set-fringe-mode' to make
 147 it take real effect.
 148 Setting the variable with a customization buffer also takes effect.
 149 If you only want to modify the appearance of the fringe in one frame,
 150 you can use the interactive function `set-fringe-style'."
 151   :type '(choice (const :tag "Default width" nil)
 152                  (const :tag "No fringes" 0)
 153                  (const :tag "Only right" (0 . nil))
 154                  (const :tag "Only left" (nil . 0))
 155                  (const :tag "Half width" (5 . 5))
 156                  (const :tag "Minimal" (1 . 1))
 157                  (integer :tag "Specific width")
 158                  (cons :tag "Different left/right sizes"
 159                        (integer :tag "Left width")
 160                        (integer :tag "Right width")))
 161   :group 'fringe
 162   :require 'fringe
 163   :initialize 'fringe-mode-initialize
 164   :set 'set-fringe-mode-1)
 165
 166 ;; We just set fringe-mode, but that was the default.
 167 ;; If it is set again, that is for real.
 168 (setq fringe-mode-explicit t)
 169
 170 (defun fringe-query-style (&optional all-frames)
 171   "Query user for fringe style.
 172 Returns values suitable for left-fringe and right-fringe frame parameters.
 173 If ALL-FRAMES, the negation of the fringe values in
 174 `default-frame-alist' is used when user enters the empty string.
 175 Otherwise the negation of the fringe value in the currently selected
 176 frame parameter is used."
 177   (let ((mode (intern (completing-read
 178                        (concat
 179                         "Select fringe mode for "
 180                         (if all-frames "all frames" "selected frame")
 181                         " (type ? for list): ")
 182                        '(("none") ("default") ("left-only")
 183                          ("right-only") ("half") ("minimal"))
 184                        nil t))))
 185     (cond ((eq mode 'none) 0)
 186           ((eq mode 'default) nil)
 187           ((eq mode 'left-only) '(nil . 0))
 188           ((eq mode 'right-only) '(0 . nil))
 189           ((eq mode 'half) '(5 . 5))
 190           ((eq mode 'minimal) '(1 . 1))
 191           ((eq mode (intern ""))
 192            (if (eq 0 (cdr (assq 'left-fringe
 193                                 (if all-frames
 194                                     default-frame-alist
 195                                   (frame-parameters (selected-frame))))))
 196                nil
 197              0)))))
 198
 199 (defun fringe-mode (&optional mode)
 200   "Set the default appearance of fringes on all frames.
 201
 202 When called interactively, query the user for MODE.  Valid values
 203 for MODE include `none', `default', `left-only', `right-only',
 204 `minimal' and `half'.
 205
 206 When used in a Lisp program, MODE can be a cons cell where the
 207 integer in car specifies the left fringe width and the integer in
 208 cdr specifies the right fringe width.  MODE can also be a single
 209 integer that specifies both the left and the right fringe width.
 210 If a fringe width specification is nil, that means to use the
 211 default width (8 pixels).  This command may round up the left and
 212 right width specifications to ensure that their sum is a multiple
 213 of the character width of a frame.  It never rounds up a fringe
 214 width of 0.
 215
 216 Fringe widths set by `set-window-fringes' override the default
 217 fringe widths set by this command.  This command applies to all
 218 frames that exist and frames to be created in the future.  If you
 219 want to set the default appearance of fringes on the selected
 220 frame only, see the command `set-fringe-style'."
 221   (interactive (list (fringe-query-style 'all-frames)))
 222   (set-fringe-mode mode))
 223
 224 (defun set-fringe-style (&optional mode)
 225   "Set the default appearance of fringes on the selected frame.
 226
 227 When called interactively, query the user for MODE.  Valid values
 228 for MODE include `none', `default', `left-only', `right-only',
 229 `minimal' and `half'.
 230
 231 When used in a Lisp program, MODE can be a cons cell where the
 232 integer in car specifies the left fringe width and the integer in
 233 cdr specifies the right fringe width.  MODE can also be a single
 234 integer that specifies both the left and the right fringe width.
 235 If a fringe width specification is nil, that means to use the
 236 default width (8 pixels).  This command may round up the left and
 237 right width specifications to ensure that their sum is a multiple
 238 of the character width of a frame.  It never rounds up a fringe
 239 width of 0.
 240
 241 Fringe widths set by `set-window-fringes' override the default
 242 fringe widths set by this command.  If you want to set the
 243 default appearance of fringes on all frames, see the command
 244 `fringe-mode'."
 245   (interactive (list (fringe-query-style)))
 246   (modify-frame-parameters
 247    (selected-frame)
 248    (list (cons 'left-fringe (if (consp mode) (car mode) mode))
 249          (cons 'right-fringe (if (consp mode) (cdr mode) mode)))))
 250
 251 (defsubst fringe-columns (side &optional real)
 252   "Return the width, measured in columns, of the fringe area on SIDE.
 253 If optional argument REAL is non-nil, return a real floating point
 254 number instead of a rounded integer value.
 255 SIDE must be the symbol `left' or `right'."
 256   (funcall (if real '/ 'ceiling)
 257            (or (funcall (if (eq side 'left) 'car 'cadr)
 258                         (window-fringes))
 259                0)
 260            (float (frame-char-width))))
 261
 262 (provide 'fringe)
 263
 264 ;; arch-tag: 6611ef60-0869-47ed-8b93-587ee7d3ff5d
 265 ;;; fringe.el ends here