1;;; gs.el --- interface to Ghostscript
2
3;; Copyright (C) 1998, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 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 2, or (at your option)
14;; 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; see the file COPYING.  If not, write to the
23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27
28;; This code is experimental.  Don't use it.
29
30;;; Code:
31
32(defvar gs-program "gs"
33  "The name of the Ghostscript interpreter.")
34
35
36(defvar gs-device "x11"
37  "The Ghostscript device to use to produce images.")
38
39
40(defvar gs-options
41  '("-q"
42    ;"-dNOPAUSE"
43    "-dSAFER"
44    "-dBATCH"
45    "-sDEVICE=<device>"
46    "<file>")
47  "List of command line arguments to pass to Ghostscript.
48Arguments may contain place-holders `<file>' for the name of the
49input file, and `<device>' for the device to use.")
50(put 'gs-options 'risky-local-variable t)
51
52(defun gs-options (device file)
53  "Return a list of command line options with place-holders replaced.
54DEVICE is the value to substitute for the place-holder `<device>',
55FILE is the value to substitute for the place-holder `<file>'."
56  (mapcar #'(lambda (option)
57	      (setq option (replace-regexp-in-string "<device>" device option)
58		    option (replace-regexp-in-string "<file>" file option)))
59	  gs-options))
60
61;; The GHOSTVIEW property (taken from gv 3.5.8).
62;;
63;; Type:
64;;
65;; STRING
66;;
67;; Parameters:
68;;
69;; BPIXMAP ORIENT LLX LLY URX URY XDPI YDPI [LEFT BOTTOM TOP RIGHT]
70;;
71;; Scanf format: "%d %d %d %d %d %d %f %f %d %d %d %d"
72;;
73;; Explanation of parameters:
74;;
75;; BPIXMAP: pixmap id of the backing pixmap for the window.  If no
76;; pixmap is to be used, this parameter should be zero.  This
77;; parameter must be zero when drawing on a pixmap.
78;;
79;; ORIENT: orientation of the page.  The number represents clockwise
80;; rotation of the paper in degrees.  Permitted values are 0, 90, 180,
81;; 270.
82;;
83;; LLX, LLY, URX, URY: Bounding box of the drawable.  The bounding box
84;; is specified in PostScript points in default user coordinates.
85;;
86;; XDPI, YDPI: Resolution of window.  (This can be derived from the
87;; other parameters, but not without roundoff error.  These values are
88;; included to avoid this error.)
89;;
90;; LEFT, BOTTOM, TOP, RIGHT: (optional) Margins around the window.
91;; The margins extend the imageable area beyond the boundaries of the
92;; window.  This is primarily used for popup zoom windows.  I have
93;; encountered several instances of PostScript programs that position
94;; themselves with respect to the imageable area.  The margins are
95;; specified in PostScript points.  If omitted, the margins are
96;; assumed to be 0.
97
98(defun gs-width-in-pt (frame pixel-width)
99  "Return, on FRAME, pixel width PIXEL-WIDTH tranlated 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
106(defun gs-height-in-pt (frame pixel-height)
107  "Return, on FRAME, pixel height PIXEL-HEIGHT tranlated to pt."
108  (let ((mm (* (float pixel-height)
109	       (/ (float (x-display-mm-height frame))
110		  (float (x-display-pixel-height frame))))))
111    (/ (* 25.4 mm) 72.0)))
112
113
114(defun gs-set-ghostview-window-prop (frame spec img-width img-height)
115  "Set the `GHOSTVIEW' window property of FRAME.
116SPEC is a GS image specification.  IMG-WIDTH is the width of the
117requested image, and IMG-HEIGHT is the height of the requested
118image in pixels."
119  (let* ((box (plist-get (cdr spec) :bounding-box))
120	 (llx (elt box 0))
121	 (lly (elt box 1))
122	 (urx (elt box 2))
123	 (ury (elt box 3))
124	 (rotation (or (plist-get (cdr spec) :rotate) 0))
125	 ;; The pixel width IMG-WIDTH of the pixmap gives the
126	 ;; dots, URX - LLX give the inch.
127	 (in-width (/ (- urx llx) 72.0))
128	 (in-height (/ (- ury lly) 72.0))
129	 (xdpi (/ img-width in-width))
130	 (ydpi (/ img-height in-height)))
131    (x-change-window-property "GHOSTVIEW"
132			      (format "0 %d %d %d %d %d %g %g"
133				      rotation llx lly urx ury xdpi ydpi)
134			      frame)))
135
136
137(defun gs-set-ghostview-colors-window-prop (frame pixel-colors)
138  "Set the `GHOSTVIEW_COLORS' environment variable depending on FRAME."
139  (let ((mode (cond ((x-display-color-p frame) "Color")
140		    ((x-display-grayscale-p frame) "Grayscale")
141		    (t "Monochrome"))))
142    (x-change-window-property "GHOSTVIEW_COLORS"
143			      (format "%s %s" mode pixel-colors)
144			      frame)))
145
146
147;
148;;;###autoload
149(defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
150			    pixel-colors)
151  "Load a PS image for display on FRAME.
152SPEC is an image specification, IMG-HEIGHT and IMG-WIDTH are width
153and height of the image in pixels.  WINDOW-AND-PIXMAP-ID is a string of
154the form \"WINDOW-ID PIXMAP-ID\".  Value is non-nil if successful."
155  (unwind-protect
156      (let ((file (plist-get (cdr spec) :file))
157	    gs
158 	    (timeout 40))
159 	;; Wait while property gets freed from a previous ghostscript process
160 	;; sit-for returns nil as soon as input starts being
161	;; available, so if we want to give GhostScript a reasonable
162 	;; chance of starting up, we better use sleep-for.  We let
163 	;; sleep-for wait only half the time because if input is
164 	;; available, it is more likely that we don't care that much
165 	;; about garbled redisplay and are in a hurry.
166 	(while (and
167 		;; Wait while the property is not yet available
168 		(not (zerop (length (x-window-property "GHOSTVIEW"
169 						       frame))))
170 		;; The following was an alternative condition: wait
171 		;; while there is still a process running.  The idea
172 		;; was to avoid contention between processes.  Turned
173 		;; out even more sluggish.
174 		;; (get-buffer-process "*GS*")
175 		(not (zerop timeout)))
176 	  (unless (sit-for 0 100 t)
177 	    (sleep-for 0 50))
178 	  (setq timeout (1- timeout)))
179
180 	;; No use waiting longer.  We might want to try killing off
181 	;; stuck processes, but there is no point in doing so: either
182 	;; they are stuck for good, in which case the user would
183 	;; probably be responsible for that, and killing them off will
184 	;; make debugging harder, or they are not.  In that case, they
185 	;; will cause incomplete displays.  But the same will happen
186 	;; if they are killed, anyway. The whole is rather
187 	;; disconcerting, and fast scrolling through a dozen images
188 	;; will make Emacs freeze for a while.  The alternatives are a)
189 	;; proper implementation not waiting at all but creating
190 	;; appropriate queues, or b) permanently bad display due to
191 	;; bad cached images.  So remember that this
192 	;; is just a hack and if people don't like the behaviour, they
193 	;; will most likely like the easy alternatives even less.
194 	;; And at least the image cache will make the delay apparent
195 	;; just once.
196	(gs-set-ghostview-window-prop frame spec img-width img-height)
197	(gs-set-ghostview-colors-window-prop frame pixel-colors)
198	(setenv "GHOSTVIEW" window-and-pixmap-id)
199	(setq gs (apply 'start-process "gs" "*GS*" gs-program
200			(gs-options gs-device file)))
201	(set-process-query-on-exit-flag gs nil)
202	gs)
203    nil))
204
205
206;(defun gs-put-tiger ()
207;  (let* ((ps-file "/usr/local/share/ghostscript/5.10/examples/tiger.ps")
208;	  (spec `(image :type postscript
209;			:pt-width 200 :pt-height 200
210;			:bounding-box (22 171 567 738)
211;			:file ,ps-file)))
212;    (put-text-property 1 2 'display spec)))
213;
214
215(provide 'gs)
216
217;;; arch-tag: 06ab51b8-4932-4cfe-9f60-b924a8edb3f0
218;;; gs.el ends here
219