* gs.el: Undo removal.

lisp/gs.el

+;;; gs.el --- interface to Ghostscript
+
+;; Copyright (C) 1998, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
+;;   2008, 2009 Free Software Foundation, Inc.
+
+;; Maintainer: FSF
+;; Keywords: internal
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This code is experimental.  Don't use it.
+
+;;; Code:
+
+(defvar gs-program "gs"
+  "The name of the Ghostscript interpreter.")
+
+
+(defvar gs-device "x11"
+  "The Ghostscript device to use to produce images.")
+
+
+(defvar gs-options
+  '("-q"
+    ;"-dNOPAUSE"
+    "-dSAFER"
+    "-dBATCH"
+    "-sDEVICE=<device>"
+    "<file>")
+  "List of command line arguments to pass to Ghostscript.
+Arguments may contain place-holders `<file>' for the name of the
+input file, and `<device>' for the device to use.")
+(put 'gs-options 'risky-local-variable t)
+
+(defun gs-options (device file)
+  "Return a list of command line options with place-holders replaced.
+DEVICE is the value to substitute for the place-holder `<device>',
+FILE is the value to substitute for the place-holder `<file>'."
+  (mapcar #'(lambda (option)
+	      (setq option (replace-regexp-in-string "<device>" device option)
+		    option (replace-regexp-in-string "<file>" file option)))
+	  gs-options))
+
+;; The GHOSTVIEW property (taken from gv 3.5.8).
+;;
+;; Type:
+;;
+;; STRING
+;;
+;; Parameters:
+;;
+;; BPIXMAP ORIENT LLX LLY URX URY XDPI YDPI [LEFT BOTTOM TOP RIGHT]
+;;
+;; Scanf format: "%d %d %d %d %d %d %f %f %d %d %d %d"
+;;
+;; Explanation of parameters:
+;;
+;; BPIXMAP: pixmap id of the backing pixmap for the window.  If no
+;; pixmap is to be used, this parameter should be zero.  This
+;; parameter must be zero when drawing on a pixmap.
+;;
+;; ORIENT: orientation of the page.  The number represents clockwise
+;; rotation of the paper in degrees.  Permitted values are 0, 90, 180,
+;; 270.
+;;
+;; LLX, LLY, URX, URY: Bounding box of the drawable.  The bounding box
+;; is specified in PostScript points in default user coordinates.
+;;
+;; XDPI, YDPI: Resolution of window.  (This can be derived from the
+;; other parameters, but not without roundoff error.  These values are
+;; included to avoid this error.)
+;;
+;; LEFT, BOTTOM, TOP, RIGHT: (optional) Margins around the window.
+;; The margins extend the imageable area beyond the boundaries of the
+;; window.  This is primarily used for popup zoom windows.  I have
+;; encountered several instances of PostScript programs that position
+;; themselves with respect to the imageable area.  The margins are
+;; specified in PostScript points.  If omitted, the margins are
+;; assumed to be 0.
+
+(declare-function x-display-mm-width "xfns.c" (&optional terminal))
+(declare-function x-display-pixel-width "xfns.c" (&optional terminal))
+
+(defun gs-width-in-pt (frame pixel-width)
+  "Return, on FRAME, pixel width PIXEL-WIDTH tranlated to pt."
+  (let ((mm (* (float pixel-width)
+	       (/ (float (x-display-mm-width frame))
+		  (float (x-display-pixel-width frame))))))
+    (/ (* 25.4 mm) 72.0)))
+
+(declare-function x-display-mm-height "xfns.c" (&optional terminal))
+(declare-function x-display-pixel-height "xfns.c" (&optional terminal))
+
+(defun gs-height-in-pt (frame pixel-height)
+  "Return, on FRAME, pixel height PIXEL-HEIGHT tranlated to pt."
+  (let ((mm (* (float pixel-height)
+	       (/ (float (x-display-mm-height frame))
+		  (float (x-display-pixel-height frame))))))
+    (/ (* 25.4 mm) 72.0)))
+
+(declare-function x-change-window-property "xfns.c"
+		  (prop value &optional frame type format outer-p))
+
+(defun gs-set-ghostview-window-prop (frame spec img-width img-height)
+  "Set the `GHOSTVIEW' window property of FRAME.
+SPEC is a GS image specification.  IMG-WIDTH is the width of the
+requested image, and IMG-HEIGHT is the height of the requested
+image in pixels."
+  (let* ((box (plist-get (cdr spec) :bounding-box))
+	 (llx (elt box 0))
+	 (lly (elt box 1))
+	 (urx (elt box 2))
+	 (ury (elt box 3))
+	 (rotation (or (plist-get (cdr spec) :rotate) 0))
+	 ;; The pixel width IMG-WIDTH of the pixmap gives the
+	 ;; dots, URX - LLX give the inch.
+	 (in-width (/ (- urx llx) 72.0))
+	 (in-height (/ (- ury lly) 72.0))
+	 (xdpi (/ img-width in-width))
+	 (ydpi (/ img-height in-height)))
+    (x-change-window-property "GHOSTVIEW"
+			      (format "0 %d %d %d %d %d %g %g"
+				      rotation llx lly urx ury xdpi ydpi)
+			      frame)))
+
+(declare-function x-display-grayscale-p "xfns.c" (&optional terminal))
+
+(defun gs-set-ghostview-colors-window-prop (frame pixel-colors)
+  "Set the `GHOSTVIEW_COLORS' environment variable depending on FRAME."
+  (let ((mode (cond ((x-display-color-p frame) "Color")
+		    ((x-display-grayscale-p frame) "Grayscale")
+		    (t "Monochrome"))))
+    (x-change-window-property "GHOSTVIEW_COLORS"
+			      (format "%s %s" mode pixel-colors)
+			      frame)))
+
+(declare-function x-window-property "xfns.c"
+		  (prop &optional frame type source delete-p vector-ret-p))
+
+;;;###autoload
+(defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
+			    pixel-colors)
+  "Load a PS image for display on FRAME.
+SPEC is an image specification, IMG-HEIGHT and IMG-WIDTH are width
+and height of the image in pixels.  WINDOW-AND-PIXMAP-ID is a string of
+the form \"WINDOW-ID PIXMAP-ID\".  Value is non-nil if successful."
+  (unwind-protect
+      (let ((file (plist-get (cdr spec) :file))
+	    gs
+ 	    (timeout 40))
+ 	;; Wait while property gets freed from a previous ghostscript process
+ 	;; sit-for returns nil as soon as input starts being
+	;; available, so if we want to give GhostScript a reasonable
+ 	;; chance of starting up, we better use sleep-for.  We let
+ 	;; sleep-for wait only half the time because if input is
+ 	;; available, it is more likely that we don't care that much
+ 	;; about garbled redisplay and are in a hurry.
+ 	(while (and
+ 		;; Wait while the property is not yet available
+ 		(not (zerop (length (x-window-property "GHOSTVIEW"
+ 						       frame))))
+ 		;; The following was an alternative condition: wait
+ 		;; while there is still a process running.  The idea
+ 		;; was to avoid contention between processes.  Turned
+ 		;; out even more sluggish.
+ 		;; (get-buffer-process "*GS*")
+ 		(not (zerop timeout)))
+ 	  (unless (sit-for 0 100 t)
+ 	    (sleep-for 0 50))
+ 	  (setq timeout (1- timeout)))
+
+ 	;; No use waiting longer.  We might want to try killing off
+ 	;; stuck processes, but there is no point in doing so: either
+ 	;; they are stuck for good, in which case the user would
+ 	;; probably be responsible for that, and killing them off will
+ 	;; make debugging harder, or they are not.  In that case, they
+ 	;; will cause incomplete displays.  But the same will happen
+ 	;; if they are killed, anyway. The whole is rather
+ 	;; disconcerting, and fast scrolling through a dozen images
+ 	;; will make Emacs freeze for a while.  The alternatives are a)
+ 	;; proper implementation not waiting at all but creating
+ 	;; appropriate queues, or b) permanently bad display due to
+ 	;; bad cached images.  So remember that this
+ 	;; is just a hack and if people don't like the behavior, they
+ 	;; will most likely like the easy alternatives even less.
+ 	;; And at least the image cache will make the delay apparent
+ 	;; just once.
+	(gs-set-ghostview-window-prop frame spec img-width img-height)
+	(gs-set-ghostview-colors-window-prop frame pixel-colors)
+	(setenv "GHOSTVIEW" window-and-pixmap-id)
+	(setq gs (apply 'start-process "gs" "*GS*" gs-program
+			(gs-options gs-device file)))
+	(set-process-query-on-exit-flag gs nil)
+	gs)
+    nil))
+
+
+;(defun gs-put-tiger ()
+;  (let* ((ps-file "/usr/local/share/ghostscript/5.10/examples/tiger.ps")
+;	  (spec `(image :type postscript
+;			:pt-width 200 :pt-height 200
+;			:bounding-box (22 171 567 738)
+;			:file ,ps-file)))
+;    (put-text-property 1 2 'display spec)))
+;
+
+(provide 'gs)
+
+;; arch-tag: 06ab51b8-4932-4cfe-9f60-b924a8edb3f0
+;;; gs.el ends here