lisp/gs.el

   1 ;;; gs.el --- interface to Ghostscript
   2
   3 ;; Copyright (C) 1998, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
   4 ;;   2009, 2010, 2011  Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7 ;; Keywords: internal
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; This code is experimental.  Don't use it.
  27
  28 ;;; Code:
  29
  30 (defvar gs-program "gs"
  31   "The name of the Ghostscript interpreter.")
  32
  33
  34 (defvar gs-device "x11"
  35   "The Ghostscript device to use to produce images.")
  36
  37
  38 (defvar gs-options
  39   '("-q"
  40     ;"-dNOPAUSE"
  41     "-dSAFER"
  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 (put 'gs-options 'risky-local-variable t)
  49
  50 (defun gs-options (device file)
  51   "Return a list of command line options with place-holders replaced.
  52 DEVICE is the value to substitute for the place-holder `<device>',
  53 FILE is the value to substitute for the place-holder `<file>'."
  54   (mapcar #'(lambda (option)
  55               (setq option (replace-regexp-in-string "<device>" device option)
  56                     option (replace-regexp-in-string "<file>" file option)))
  57           gs-options))
  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 (declare-function x-display-mm-width "xfns.c" (&optional terminal))
  97 (declare-function x-display-pixel-width "xfns.c" (&optional terminal))
  98
  99 (defun gs-width-in-pt (frame pixel-width)
 100   "Return, on FRAME, pixel width PIXEL-WIDTH tranlated to pt."
 101   (let ((mm (* (float pixel-width)
 102                (/ (float (x-display-mm-width frame))
 103                   (float (x-display-pixel-width frame))))))
 104     (/ (* 25.4 mm) 72.0)))
 105
 106 (declare-function x-display-mm-height "xfns.c" (&optional terminal))
 107 (declare-function x-display-pixel-height "xfns.c" (&optional terminal))
 108
 109 (defun gs-height-in-pt (frame pixel-height)
 110   "Return, on FRAME, pixel height PIXEL-HEIGHT tranlated to pt."
 111   (let ((mm (* (float pixel-height)
 112                (/ (float (x-display-mm-height frame))
 113                   (float (x-display-pixel-height frame))))))
 114     (/ (* 25.4 mm) 72.0)))
 115
 116 (declare-function x-change-window-property "xfns.c"
 117                   (prop value &optional frame type format outer-p))
 118
 119 (defun gs-set-ghostview-window-prop (frame spec img-width img-height)
 120   "Set the `GHOSTVIEW' window property of FRAME.
 121 SPEC is a GS image specification.  IMG-WIDTH is the width of the
 122 requested image, and IMG-HEIGHT is the height of the requested
 123 image in pixels."
 124   (let* ((box (plist-get (cdr spec) :bounding-box))
 125          (llx (elt box 0))
 126          (lly (elt box 1))
 127          (urx (elt box 2))
 128          (ury (elt box 3))
 129          (rotation (or (plist-get (cdr spec) :rotate) 0))
 130          ;; The pixel width IMG-WIDTH of the pixmap gives the
 131          ;; dots, URX - LLX give the inch.
 132          (in-width (/ (- urx llx) 72.0))
 133          (in-height (/ (- ury lly) 72.0))
 134          (xdpi (/ img-width in-width))
 135          (ydpi (/ img-height in-height)))
 136     (x-change-window-property "GHOSTVIEW"
 137                               (format "0 %d %d %d %d %d %g %g"
 138                                       rotation llx lly urx ury xdpi ydpi)
 139                               frame)))
 140
 141 (declare-function x-display-grayscale-p "xfns.c" (&optional terminal))
 142
 143 (defun gs-set-ghostview-colors-window-prop (frame pixel-colors)
 144   "Set the `GHOSTVIEW_COLORS' environment variable depending on FRAME."
 145   (let ((mode (cond ((x-display-color-p frame) "Color")
 146                     ((x-display-grayscale-p frame) "Grayscale")
 147                     (t "Monochrome"))))
 148     (x-change-window-property "GHOSTVIEW_COLORS"
 149                               (format "%s %s" mode pixel-colors)
 150                               frame)))
 151
 152 (declare-function x-window-property "xfns.c"
 153                   (prop &optional frame type source delete-p vector-ret-p))
 154
 155 ;;;###autoload
 156 (defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
 157                             pixel-colors)
 158   "Load a PS image for display on FRAME.
 159 SPEC is an image specification, IMG-HEIGHT and IMG-WIDTH are width
 160 and height of the image in pixels.  WINDOW-AND-PIXMAP-ID is a string of
 161 the form \"WINDOW-ID PIXMAP-ID\".  Value is non-nil if successful."
 162   (unwind-protect
 163       (let ((file (plist-get (cdr spec) :file))
 164             gs
 165             (timeout 40))
 166         ;; Wait while property gets freed from a previous ghostscript process
 167         ;; sit-for returns nil as soon as input starts being
 168         ;; available, so if we want to give GhostScript a reasonable
 169         ;; chance of starting up, we better use sleep-for.  We let
 170         ;; sleep-for wait only half the time because if input is
 171         ;; available, it is more likely that we don't care that much
 172         ;; about garbled redisplay and are in a hurry.
 173         (while (and
 174                 ;; Wait while the property is not yet available
 175                 (not (zerop (length (x-window-property "GHOSTVIEW"
 176                                                        frame))))
 177                 ;; The following was an alternative condition: wait
 178                 ;; while there is still a process running.  The idea
 179                 ;; was to avoid contention between processes.  Turned
 180                 ;; out even more sluggish.
 181                 ;; (get-buffer-process "*GS*")
 182                 (not (zerop timeout)))
 183           (unless (sit-for 0.1 t)
 184             (sleep-for 0.05))
 185           (setq timeout (1- timeout)))
 186
 187         ;; No use waiting longer.  We might want to try killing off
 188         ;; stuck processes, but there is no point in doing so: either
 189         ;; they are stuck for good, in which case the user would
 190         ;; probably be responsible for that, and killing them off will
 191         ;; make debugging harder, or they are not.  In that case, they
 192         ;; will cause incomplete displays.  But the same will happen
 193         ;; if they are killed, anyway. The whole is rather
 194         ;; disconcerting, and fast scrolling through a dozen images
 195         ;; will make Emacs freeze for a while.  The alternatives are a)
 196         ;; proper implementation not waiting at all but creating
 197         ;; appropriate queues, or b) permanently bad display due to
 198         ;; bad cached images.  So remember that this
 199         ;; is just a hack and if people don't like the behavior, they
 200         ;; will most likely like the easy alternatives even less.
 201         ;; And at least the image cache will make the delay apparent
 202         ;; just once.
 203         (gs-set-ghostview-window-prop frame spec img-width img-height)
 204         (gs-set-ghostview-colors-window-prop frame pixel-colors)
 205         (setenv "GHOSTVIEW" window-and-pixmap-id)
 206         (setq gs (apply 'start-process "gs" "*GS*" gs-program
 207                         (gs-options gs-device file)))
 208         (set-process-query-on-exit-flag gs nil)
 209         gs)
 210     nil))
 211
 212
 213 ;(defun gs-put-tiger ()
 214 ;  (let* ((ps-file "/usr/local/share/ghostscript/5.10/examples/tiger.ps")
 215 ;         (spec `(image :type postscript
 216 ;                       :pt-width 200 :pt-height 200
 217 ;                       :bounding-box (22 171 567 738)
 218 ;                       :file ,ps-file)))
 219 ;    (put-text-property 1 2 'display spec)))
 220 ;
 221
 222 (provide 'gs)
 223
 224 ;;; gs.el ends here