;;; gs.el --- interface to Ghostscript
;; Copyright (C) 1998, 2001, 2002, 2003, 2004,
;; 2005, 2006 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 2, 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; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;; This code is experimental. Don't use it.
(defvar gs-program "gs"
"The name of the Ghostscript interpreter.")
(defvar gs-device "x11"
"The Ghostscript device to use to produce images.")
"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)))
;; The GHOSTVIEW property (taken from gv 3.5.8).
;; 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,
;; 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.
(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)))
(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)))
(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)))
(format "0 %d %d %d %d %d %g %g"
rotation llx lly urx ury xdpi ydpi)
(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")
(format "%s %s" mode pixel-colors)
(defun gs-load-image (frame spec img-width img-height window-and-pixmap-id
"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."
(let ((file (plist-get (cdr spec) :file))
;; 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.
;; Wait while the property is not yet available
(not (zerop (length (x-window-property "GHOSTVIEW"
;; 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 behaviour, 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)
;(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)))
;;; arch-tag: 06ab51b8-4932-4cfe-9f60-b924a8edb3f0
;;; gs.el ends here