lisp/gs.el

   1 ;;; gs.el --- interface to Ghostscript
   2
   3 ;; Copyright (C) 1998, 2001-2016 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: emacs-devel@gnu.org
   6 ;; Keywords: internal
   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 <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; This code is experimental.  Don't use it.
  26
  27 ;;; Code:
  28
  29 (defvar gs-program "gs"
  30   "The name of the Ghostscript interpreter.")
  31
  32
  33 (defvar gs-device "x11"
  34   "The Ghostscript device to use to produce images.")
  35
  36
  37 (defvar gs-options
  38   '("-q"
  39     ;"-dNOPAUSE"
  40     "-dSAFER"
  41     "-dBATCH"
  42     "-sDEVICE=<device>"
  43     "<file>")
  44   "List of command line arguments to pass to Ghostscript.
  45 Arguments may contain place-holders `<file>' for the name of the
  46 input file, and `<device>' for the device to use.")
  47 (put 'gs-options 'risky-local-variable t)
  48
  49 (defun gs-options (device file)
  50   "Return a list of command line options with place-holders replaced.
  51 DEVICE is the value to substitute for the place-holder `<device>',
  52 FILE is the value to substitute for the place-holder `<file>'."
  53   (mapcar #'(lambda (option)
  54               (setq option (replace-regexp-in-string "<device>" device option)
  55                     option (replace-regexp-in-string "<file>" file option)))
  56           gs-options))
  57
  58 ;; The GHOSTVIEW property (taken from gv 3.5.8).
  59 ;;
  60 ;; Type:
  61 ;;
  62 ;; STRING
  63 ;;
  64 ;; Parameters:
  65 ;;
  66 ;; BPIXMAP ORIENT LLX LLY URX URY XDPI YDPI [LEFT BOTTOM TOP RIGHT]
  67 ;;
  68 ;; Scanf format: "%d %d %d %d %d %d %f %f %d %d %d %d"
  69 ;;
  70 ;; Explanation of parameters:
  71 ;;
  72 ;; BPIXMAP: pixmap id of the backing pixmap for the window.  If no
  73 ;; pixmap is to be used, this parameter should be zero.  This
  74 ;; parameter must be zero when drawing on a pixmap.
  75 ;;
  76 ;; ORIENT: orientation of the page.  The number represents clockwise
  77 ;; rotation of the paper in degrees.  Permitted values are 0, 90, 180,
  78 ;; 270.
  79 ;;
  80 ;; LLX, LLY, URX, URY: Bounding box of the drawable.  The bounding box
  81 ;; is specified in PostScript points in default user coordinates.
  82 ;;
  83 ;; XDPI, YDPI: Resolution of window.  (This can be derived from the
  84 ;; other parameters, but not without roundoff error.  These values are
  85 ;; included to avoid this error.)
  86 ;;
  87 ;; LEFT, BOTTOM, TOP, RIGHT: (optional) Margins around the window.
  88 ;; The margins extend the imageable area beyond the boundaries of the
  89 ;; window.  This is primarily used for popup zoom windows.  I have
  90 ;; encountered several instances of PostScript programs that position
  91 ;; themselves with respect to the imageable area.  The margins are
  92 ;; specified in PostScript points.  If omitted, the margins are
  93 ;; assumed to be 0.
  94
  95 (declare-function x-display-mm-width "xfns.c" (&optional terminal))
  96 (declare-function x-display-pixel-width "xfns.c" (&optional terminal))
  97
  98 (defun gs-width-in-pt (frame pixel-width)
  99   "Return, on FRAME, pixel width PIXEL-WIDTH translated to pt."
 100   (let ((mm (* (float pixel-width)
 101                (/ (float (x-display-mm-width frame))
 102                   (float (x-display-pixel-width frame))))))
 103     (/ (* 25.4 mm) 72.0)))
 104
 105 (declare-function x-display-mm-height "xfns.c" (&optional terminal))
 106 (declare-function x-display-pixel-height "xfns.c" (&optional terminal))
 107
 108 (defun gs-height-in-pt (frame pixel-height)
 109   "Return, on FRAME, pixel height PIXEL-HEIGHT translated to pt."
 110   (let ((mm (* (float pixel-height)
 111                (/ (float (x-display-mm-height frame))
 112                   (float (x-display-pixel-height frame))))))
 113     (/ (* 25.4 mm) 72.0)))
 114
 115 (declare-function x-change-window-property "xfns.c"
 116                   (prop value &optional frame type format outer-p))
 117
 118 (defun gs-set-ghostview-window-prop (frame spec img-width img-height)
 119   "Set the `GHOSTVIEW' window property of FRAME.
 120 SPEC is a GS image specification.  IMG-WIDTH is the width of the
 121 requested image, and IMG-HEIGHT is the height of the requested
 122 image in pixels."
 123   (let* ((box (plist-get (cdr spec) :bounding-box))
 124          (llx (elt box 0))
 125          (lly (elt box 1))
 126          (urx (elt box 2))
 127          (ury (elt box 3))
 128          (rotation (or (plist-get (cdr spec) :rotate) 0))
 129          ;; The pixel width IMG-WIDTH of the pixmap gives the
 130          ;; dots, URX - LLX give the inch.
 131          (in-width (/ (- urx llx) 72.0))
 132          (in-height (/ (- ury lly) 72.0))
 133          (xdpi (/ img-width in-width))
 134          (ydpi (/ img-height in-height)))
 135     (x-change-window-property "GHOSTVIEW"
 136                               (format "0 %d %d %d %d %d %g %g"
 137                                       rotation llx lly urx ury xdpi ydpi)
 138                               frame)))
 139
 140 (declare-function x-display-grayscale-p "xfns.c" (&optional terminal))
 141
 142 (defun gs-set-ghostview-colors-window-prop (frame pixel-colors)
 143   "Set the `GHOSTVIEW_COLORS' environment variable depending on FRAME."
 144   (let ((mode (cond ((x-display-color-p frame) "Color")
 145                     ((x-display-grayscale-p frame) "Grayscale")
 146                     (t "Monochrome"))))
 147     (x-change-window-property "GHOSTVIEW_COLORS"
 148                               (format "%s %s" mode pixel-colors)
 149                               frame)))
 150
 151 (declare-function x-window-property "xfns.c"
 152                   (prop &optional frame type source delete-p vector-ret-p))
 153
 154 ;;;###autoload
 155 (defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
 156                             pixel-colors)
 157   "Load a PS image for display on FRAME.
 158 SPEC is an image specification, IMG-HEIGHT and IMG-WIDTH are width
 159 and height of the image in pixels.  WINDOW-AND-PIXMAP-ID is a string of
 160 the form \"WINDOW-ID PIXMAP-ID\".  Value is non-nil if successful."
 161   (unwind-protect
 162       (let ((file (plist-get (cdr spec) :file))
 163             gs
 164             (timeout 40))
 165         ;; Wait while property gets freed from a previous ghostscript process
 166         ;; sit-for returns nil as soon as input starts being
 167         ;; available, so if we want to give GhostScript a reasonable
 168         ;; chance of starting up, we better use sleep-for.  We let
 169         ;; sleep-for wait only half the time because if input is
 170         ;; available, it is more likely that we don't care that much
 171         ;; about garbled redisplay and are in a hurry.
 172         (while (and
 173                 ;; Wait while the property is not yet available
 174                 (not (zerop (length (x-window-property "GHOSTVIEW"
 175                                                        frame))))
 176                 ;; The following was an alternative condition: wait
 177                 ;; while there is still a process running.  The idea
 178                 ;; was to avoid contention between processes.  Turned
 179                 ;; out even more sluggish.
 180                 ;; (get-buffer-process "*GS*")
 181                 (not (zerop timeout)))
 182           (unless (sit-for 0.1 t)
 183             (sleep-for 0.05))
 184           (setq timeout (1- timeout)))
 185
 186         ;; No use waiting longer.  We might want to try killing off
 187         ;; stuck processes, but there is no point in doing so: either
 188         ;; they are stuck for good, in which case the user would
 189         ;; probably be responsible for that, and killing them off will
 190         ;; make debugging harder, or they are not.  In that case, they
 191         ;; will cause incomplete displays.  But the same will happen
 192         ;; if they are killed, anyway. The whole is rather
 193         ;; disconcerting, and fast scrolling through a dozen images
 194         ;; will make Emacs freeze for a while.  The alternatives are a)
 195         ;; proper implementation not waiting at all but creating
 196         ;; appropriate queues, or b) permanently bad display due to
 197         ;; bad cached images.  So remember that this
 198         ;; is just a hack and if people don't like the behavior, they
 199         ;; will most likely like the easy alternatives even less.
 200         ;; And at least the image cache will make the delay apparent
 201         ;; just once.
 202         (gs-set-ghostview-window-prop frame spec img-width img-height)
 203         (gs-set-ghostview-colors-window-prop frame pixel-colors)
 204         (setenv "GHOSTVIEW" window-and-pixmap-id)
 205         (setq gs (apply 'start-process "gs" "*GS*" gs-program
 206                         (gs-options gs-device file)))
 207         (set-process-query-on-exit-flag gs nil)
 208         gs)
 209     nil))
 210
 211
 212 ;(defun gs-put-tiger ()
 213 ;  (let* ((ps-file "/usr/local/share/ghostscript/5.10/examples/tiger.ps")
 214 ;         (spec `(image :type postscript
 215 ;                       :pt-width 200 :pt-height 200
 216 ;                       :bounding-box (22 171 567 738)
 217 ;                       :file ,ps-file)))
 218 ;    (put-text-property 1 2 'display spec)))
 219 ;
 220
 221 (provide 'gs)
 222
 223 ;;; gs.el ends here