lisp/gs.el

   1 ;;; gs.el --- interface to Ghostscript
   2
   3 ;; Copyright (C) 1998, 2001, 2004 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   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 2, or (at your option)
  13 ;; 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; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; This code is experimental.  Don't use it.
  28
  29 ;;; Code:
  30
  31 (defvar gs-program "gs"
  32   "The name of the Ghostscript interpreter.")
  33
  34
  35 (defvar gs-device "x11"
  36   "The Ghostscript device to use to produce images.")
  37
  38
  39 (defvar gs-options
  40   '("-q"
  41     ;"-dNOPAUSE"
  42     "-dSAFER"
  43     "-dBATCH"
  44     "-sDEVICE=<device>"
  45     "<file>")
  46   "List of command line arguments to pass to Ghostscript.
  47 Arguments may contain place-holders `<file>' for the name of the
  48 input file, and `<device>' for the device to use.")
  49 (put 'gs-options 'risky-local-variable t)
  50
  51 (defun gs-options (device file)
  52   "Return a list of command line options with place-holders replaced.
  53 DEVICE is the value to substitute for the place-holder `<device>',
  54 FILE is the value to substitute for the place-holder `<file>'."
  55   (mapcar #'(lambda (option)
  56               (setq option (replace-regexp-in-string "<device>" device option)
  57                     option (replace-regexp-in-string "<file>" file option)))
  58           gs-options))
  59
  60 ;; The GHOSTVIEW property (taken from gv 3.5.8).
  61 ;;
  62 ;; Type:
  63 ;;
  64 ;; STRING
  65 ;;
  66 ;; Parameters:
  67 ;;
  68 ;; BPIXMAP ORIENT LLX LLY URX URY XDPI YDPI [LEFT BOTTOM TOP RIGHT]
  69 ;;
  70 ;; Scanf format: "%d %d %d %d %d %d %f %f %d %d %d %d"
  71 ;;
  72 ;; Explanation of parameters:
  73 ;;
  74 ;; BPIXMAP: pixmap id of the backing pixmap for the window.  If no
  75 ;; pixmap is to be used, this parameter should be zero.  This
  76 ;; parameter must be zero when drawing on a pixmap.
  77 ;;
  78 ;; ORIENT: orientation of the page.  The number represents clockwise
  79 ;; rotation of the paper in degrees.  Permitted values are 0, 90, 180,
  80 ;; 270.
  81 ;;
  82 ;; LLX, LLY, URX, URY: Bounding box of the drawable.  The bounding box
  83 ;; is specified in PostScript points in default user coordinates.
  84 ;;
  85 ;; XDPI, YDPI: Resolution of window.  (This can be derived from the
  86 ;; other parameters, but not without roundoff error.  These values are
  87 ;; included to avoid this error.)
  88 ;;
  89 ;; LEFT, BOTTOM, TOP, RIGHT: (optional) Margins around the window.
  90 ;; The margins extend the imageable area beyond the boundaries of the
  91 ;; window.  This is primarily used for popup zoom windows.  I have
  92 ;; encountered several instances of PostScript programs that position
  93 ;; themselves with respect to the imageable area.  The margins are
  94 ;; specified in PostScript points.  If omitted, the margins are
  95 ;; assumed to be 0.
  96
  97 (defun gs-width-in-pt (frame pixel-width)
  98   "Return, on FRAME, pixel width PIXEL-WIDTH tranlated to pt."
  99   (let ((mm (* (float pixel-width)
 100                (/ (float (x-display-mm-width frame))
 101                   (float (x-display-pixel-width frame))))))
 102     (/ (* 25.4 mm) 72.0)))
 103
 104
 105 (defun gs-height-in-pt (frame pixel-height)
 106   "Return, on FRAME, pixel height PIXEL-HEIGHT tranlated to pt."
 107   (let ((mm (* (float pixel-height)
 108                (/ (float (x-display-mm-height frame))
 109                   (float (x-display-pixel-height frame))))))
 110     (/ (* 25.4 mm) 72.0)))
 111
 112
 113 (defun gs-set-ghostview-window-prop (frame spec img-width img-height)
 114   "Set the `GHOSTVIEW' window property of FRAME.
 115 SPEC is a GS image specification.  IMG-WIDTH is the width of the
 116 requested image, and IMG-HEIGHT is the height of the requested
 117 image in pixels."
 118   (let* ((box (plist-get (cdr spec) :bounding-box))
 119          (llx (elt box 0))
 120          (lly (elt box 1))
 121          (urx (elt box 2))
 122          (ury (elt box 3))
 123          (rotation (or (plist-get (cdr spec) :rotate) 0))
 124          ;; The pixel width IMG-WIDTH of the pixmap gives the
 125          ;; dots, URX - LLX give the inch.
 126          (in-width (/ (- urx llx) 72.0))
 127          (in-height (/ (- ury lly) 72.0))
 128          (xdpi (/ img-width in-width))
 129          (ydpi (/ img-height in-height)))
 130     (x-change-window-property "GHOSTVIEW"
 131                               (format "0 %d %d %d %d %d %g %g"
 132                                       rotation llx lly urx ury xdpi ydpi)
 133                               frame)))
 134
 135
 136 (defun gs-set-ghostview-colors-window-prop (frame pixel-colors)
 137   "Set the `GHOSTVIEW_COLORS' environment variable depending on FRAME."
 138   (let ((mode (cond ((x-display-color-p frame) "Color")
 139                     ((x-display-grayscale-p frame) "Grayscale")
 140                     (t "Monochrome"))))
 141     (x-change-window-property "GHOSTVIEW_COLORS"
 142                               (format "%s %s" mode pixel-colors)
 143                               frame)))
 144
 145
 146 ;
 147 ;;;###autoload
 148 (defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
 149                             pixel-colors)
 150   "Load a PS image for display on FRAME.
 151 SPEC is an image specification, IMG-HEIGHT and IMG-WIDTH are width
 152 and height of the image in pixels.  WINDOW-AND-PIXMAP-ID is a string of
 153 the form \"WINDOW-ID PIXMAP-ID\".  Value is non-nil if successful."
 154   (unwind-protect
 155       (let ((file (plist-get (cdr spec) :file))
 156             gs
 157             (timeout 40))
 158         ;; Wait while property gets freed from a previous ghostscript process
 159         ;; sit-for returns nil as soon as input starts being
 160         ;; available, so if we want to give GhostScript a reasonable
 161         ;; chance of starting up, we better use sleep-for.  We let
 162         ;; sleep-for wait only half the time because if input is
 163         ;; available, it is more likely that we don't care that much
 164         ;; about garbled redisplay and are in a hurry.
 165         (while (and
 166                 ;; Wait while the property is not yet available
 167                 (not (zerop (length (x-window-property "GHOSTVIEW"
 168                                                        frame))))
 169                 ;; The following was an alternative condition: wait
 170                 ;; while there is still a process running.  The idea
 171                 ;; was to avoid contention between processes.  Turned
 172                 ;; out even more sluggish.
 173                 ;; (get-buffer-process "*GS*")
 174                 (not (zerop timeout)))
 175           (unless (sit-for 0 100 t)
 176             (sleep-for 0 50))
 177           (setq timeout (1- timeout)))
 178
 179         ;; No use waiting longer.  We might want to try killing off
 180         ;; stuck processes, but there is no point in doing so: either
 181         ;; they are stuck for good, in which case the user would
 182         ;; probably be responsible for that, and killing them off will
 183         ;; make debugging harder, or they are not.  In that case, they
 184         ;; will cause incomplete displays.  But the same will happen
 185         ;; if they are killed, anyway. The whole is rather
 186         ;; disconcerting, and fast scrolling through a dozen images
 187         ;; will make Emacs freeze for a while.  The alternatives are a)
 188         ;; proper implementation not waiting at all but creating
 189         ;; appropriate queues, or b) permanently bad display due to
 190         ;; bad cached images.  So remember that this
 191         ;; is just a hack and if people don't like the behaviour, they
 192         ;; will most likely like the easy alternatives even less.
 193         ;; And at least the image cache will make the delay apparent
 194         ;; just once.
 195         (gs-set-ghostview-window-prop frame spec img-width img-height)
 196         (gs-set-ghostview-colors-window-prop frame pixel-colors)
 197         (setenv "GHOSTVIEW" window-and-pixmap-id)
 198         (setq gs (apply 'start-process "gs" "*GS*" gs-program
 199                         (gs-options gs-device file)))
 200         (set-process-query-on-exit-flag gs nil)
 201         gs)
 202     nil))
 203
 204
 205 ;(defun gs-put-tiger ()
 206 ;  (let* ((ps-file "/usr/local/share/ghostscript/5.10/examples/tiger.ps")
 207 ;         (spec `(image :type postscript
 208 ;                       :pt-width 200 :pt-height 200
 209 ;                       :bounding-box (22 171 567 738)
 210 ;                       :file ,ps-file)))
 211 ;    (put-text-property 1 2 'display spec)))
 212 ;
 213
 214 (provide 'gs)
 215
 216 ;;; arch-tag: 06ab51b8-4932-4cfe-9f60-b924a8edb3f0
 217 ;;; gs.el ends here