lisp/gs.el

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