;;; mode-motion.el --- Mode-specific mouse-highlighting of text.
;; Copyright (C) 1992, 1993, 1997 Free Software Foundation, Inc.
;; Maintainer: XEmacs Development Team
;; Keywords: internal, mouse, dumped
;; This file is part of XEmacs.
;; XEmacs 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.
;; XEmacs 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 XEmacs; see the file COPYING. If not, write to the
;; Free Software Foundation, 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Synched up with: Not in FSF.
;; This file is dumped with XEmacs (when window system support is compiled in).
(defvar mode-motion-hook nil
"Function or functions which are called whenever the mouse moves.
Each function must take a single argument of the motion event.
You should normally use this rather than `mouse-motion-handler', which
does some additional window-system-dependent things. This hook is local
to every buffer, and should normally be set up by major-modes which want
to use special highlighting. Every time the mouse moves over a window,
the mode-motion-hook of the buffer of that window is run.")
(defvar mode-motion-extent nil)
(defvar mode-motion-help-echo-string nil
"String to be added as the 'help-echo property of the mode-motion extent.
In order for this to work, you need to add the hook function
`mode-motion-add-help-echo' to the mode-motion hook. If this is a function,
it will be called with one argument (the event) and should return a string
to be added. This variable is local to every buffer.")
(defun mode-motion-ensure-extent-ok (event)
(let ((buffer (event-buffer event)))
(if (and (extent-live-p mode-motion-extent)
(eq buffer (extent-object mode-motion-extent)))
(setq mode-motion-extent (make-extent nil nil buffer))
(set-extent-property mode-motion-extent 'mouse-face 'highlight))))
(defun mode-motion-highlight-internal (event backward forward)
(let* ((buffer (event-buffer event))
(point (and buffer (event-point event))))
(if (and buffer
(not (eq buffer mouse-grabbed-buffer)))
;; #### ack!! Too many calls to save-window-excursion /
;; save-excursion (x-track-pointer calls, so does
;; minibuf-mouse-tracker ...) This needs to be looked
;; into. It's complicated by the fact that sometimes
;; a mode-motion-hook might really want to change
;; the point.
;; #### The save-excursion must come before the
;; save-window-excursion in order to function properly. I
;; haven't given this much thought. Is it a bug that this
;; ordering is necessary or is it correct behavior?
;; Use save-excursion here to avoid
;; save-window-excursion seeing a change in
;; window point's value which would make the
;; display code do a whole lot of useless work
;; and making the display flicker horribly.
(condition-case nil (funcall backward) (error nil))
(setq point (point))
(condition-case nil (funcall forward) (error nil))
(if (eq point (point))
(set-extent-endpoints mode-motion-extent point (point))))
;; not over text; zero the extent.
(defun mode-motion-highlight-line (event)
"For use as the value of `mode-motion-hook' -- highlight line under mouse."
(mode-motion-highlight-internal event 'beginning-of-line 'end-of-line))
(defun mode-motion-highlight-word (event)
"For use as the value of `mode-motion-hook' -- highlight word under mouse."
#'(lambda () (default-mouse-track-beginning-of-word nil))
#'(lambda () (default-mouse-track-end-of-word nil))))
(defun mode-motion-highlight-symbol (event)
"For use as the value of `mode-motion-hook' -- highlight symbol under mouse."
#'(lambda () (default-mouse-track-beginning-of-word t))
#'(lambda () (default-mouse-track-end-of-word t))))
(defun mode-motion-highlight-sexp (event)
"For use as the value of `mode-motion-hook' -- highlight form under mouse."
(if (= (char-syntax (following-char)) ?\()
(goto-char (scan-sexps (point) -1))))
(if (= (char-syntax (following-char)) ?\))
(goto-char (scan-sexps (point) 1)))))
(defun mode-motion-add-help-echo (event)
"For use as the value of `mode-motion-hook' -- add a 'help-echo property.
This causes the string in the 'help-echo property to be displayed when the
mouse moves over the extent. See `mode-motion-help-echo-string' for
documentation on how to control the string that is added."
(let ((string (cond ((null mode-motion-help-echo-string) nil)
(t (funcall mode-motion-help-echo-string event)))))
(if (stringp string)
(set-extent-property mode-motion-extent 'help-echo string))))
;;; mode-motion.el ends here