;;; gpm.el --- Support the mouse when emacs run on a Linux console.

;; Copyright (C) 1999 Free Software Foundation

;; Author: William Perry <wmperry@gnu.org>
;; Keywords: mouse, terminals

;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

(defvar gpm-enabled-devices (make-hash-table :test 'eq
					     :size 13
					     :weakness 'key)
  "A hash table of devices with GPM currently turned on.")
 
(defun gpm-mode (&optional arg device)
  "Toggle GPM mouse mode.
With prefix arg, turn GPM mouse mode on if and only if arg is positive."
  (interactive (list current-prefix-arg (selected-device)))
  (with-fboundp 'gpm-enable
    (cond
     ((null arg)				; Toggle
      (if (gethash device gpm-enabled-devices)
	  (progn
	    (gpm-enable device nil)
	    (remhash device gpm-enabled-devices))
	(gpm-enable device t)
	(puthash device t gpm-enabled-devices)))
     ((> arg 0)				; Turn on
      (gpm-enable device t)
      (puthash device t gpm-enabled-devices))
     ((gethash device gpm-enabled-devices) ; Turn off
      (gpm-enable device nil)
      (remhash device gpm-enabled-devices)))))

(defun turn-on-gpm-mouse-tracking (&optional device)
  ;; Enable mouse tracking on linux console
  (gpm-mode 5 device))

(defun turn-off-gpm-mouse-tracking (&optional device)
  ;; Disable mouse tracking on linux console
  (gpm-mode -5 device))

(defun gpm-is-supported-p (device)
  "Returns non-nil if GPM is usable right now on DEVICE in this XEmacs session.
This checks whether GPM support was compiled in, TTY support was
compiled in, XEmacs is running on Linux, the current console/device is
TTY, and its terminal type has been set to `linux'."
  (and (not noninteractive)	; Don't want to do this in batch mode
       (fboundp 'gpm-enable)	; Must have C-level GPM support
       (eq system-type 'linux)	; Must be running linux
       (eq (device-type device) 'tty) ; on a tty
       (equal "linux" (declare-fboundp ; an a linux terminal type
		       (console-tty-terminal-type (device-console device))))))
  
(defun gpm-create-device-hook (device)
  (if (gpm-is-supported-p device)
      (turn-on-gpm-mouse-tracking device)))

(defun gpm-delete-device-hook (device)
  (if (gpm-is-supported-p device)
      (turn-off-gpm-mouse-tracking device)))

;; Restore normal mouse behavior outside Emacs

(add-hook 'suspend-hook 'turn-off-gpm-mouse-tracking)
(add-hook 'suspend-resume-hook 'turn-on-gpm-mouse-tracking)
(add-hook 'create-device-hook 'gpm-create-device-hook)
(add-hook 'delete-device-hook 'gpm-delete-device-hook)

(provide 'gpm)