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|
;;; gs.el --- interface to Ghostscript -*- lexical-binding: t; -*-
;; Copyright (C) 1998, 2001-2025 Free Software Foundation, Inc.
;; Maintainer: emacs-devel@gnu.org
;; Keywords: internal
;; Obsolete-since: 26.1
;; 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; This code is experimental. Don't use it. Try imagemagick images instead.
;; When this file is removed from Emacs, associated code in image.c
;; can be removed too (HAVE_GHOSTSCRIPT).
;;; 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 translated 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 translated 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 window-id))
(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 ((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 0.1 t)
(sleep-for 0.05))
(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)
;;; gs.el ends here
|
