lisp/emacs-lisp/levents.el

   1 ;;; levents.el --- emulate the Lucid event data type and associated functions
   2
   3 ;; Copyright (C) 1993, 2001 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: emulations
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; Things we cannot emulate in Lisp:
  28 ;; It is not possible to emulate current-mouse-event as a variable,
  29 ;; though it is not hard to obtain the data from (this-command-keys).
  30
  31 ;; We do not have a variable unread-command-event;
  32 ;; instead, we have the more general unread-command-events.
  33
  34 ;; Our read-key-sequence and read-char are not precisely
  35 ;; compatible with those in Lucid Emacs, but they should work ok.
  36
  37 ;;; Code:
  38
  39 (defun next-command-event (event)
  40   (error "You must rewrite to use `read-command-event' instead of `next-command-event'"))
  41
  42 (defun next-event (event)
  43   (error "You must rewrite to use `read-event' instead of `next-event'"))
  44
  45 (defun dispatch-event (event)
  46   (error "`dispatch-event' not supported"))
  47
  48 ;; Make events of type eval, menu and timeout
  49 ;; execute properly.
  50
  51 (define-key global-map [menu] 'execute-eval-event)
  52 (define-key global-map [timeout] 'execute-eval-event)
  53 (define-key global-map [eval] 'execute-eval-event)
  54
  55 (defun execute-eval-event (event)
  56   (interactive "e")
  57   (funcall (nth 1 event) (nth 2 event)))
  58
  59 (put 'eval 'event-symbol-elements '(eval))
  60 (put 'menu 'event-symbol-elements '(eval))
  61 (put 'timeout 'event-symbol-elements '(eval))
  62
  63 (defun allocate-event ()
  64   "Returns an empty event structure.
  65 In this emulation, it returns nil."
  66   nil)
  67
  68 (defun button-press-event-p (obj)
  69   "True if the argument is a mouse-button-press event object."
  70   (and (consp obj) (symbolp (car obj))
  71        (memq 'down (get (car obj) 'event-symbol-elements))))
  72
  73 (defun button-release-event-p (obj)
  74   "True if the argument is a mouse-button-release event object."
  75   (and (consp obj) (symbolp (car obj))
  76        (or (memq 'click (get (car obj) 'event-symbol-elements))
  77            (memq 'drag (get (car obj) 'event-symbol-elements)))))
  78
  79 (defun button-event-p (obj)
  80   "True if the argument is a mouse-button press or release event object."
  81   (and (consp obj) (symbolp (car obj))
  82        (or (memq 'click (get (car obj) 'event-symbol-elements))
  83            (memq 'down (get (car obj) 'event-symbol-elements))
  84            (memq 'drag (get (car obj) 'event-symbol-elements)))))
  85
  86 (defun mouse-event-p (obj)
  87   "True if the argument is a mouse-button press or release event object."
  88   (and (consp obj) (symbolp (car obj))
  89        (or (eq (car obj) 'mouse-movement)
  90            (memq 'click (get (car obj) 'event-symbol-elements))
  91            (memq 'down (get (car obj) 'event-symbol-elements))
  92            (memq 'drag (get (car obj) 'event-symbol-elements)))))
  93
  94 (defun character-to-event (ch &optional event)
  95   "Converts a numeric ASCII value to an event structure, replete with
  96 bucky bits.  The character is the first argument, and the event to fill
  97 in is the second.  This function contains knowledge about what the codes
  98 mean -- for example, the number 9 is converted to the character Tab,
  99 not the distinct character Control-I.
 100
 101 Beware that character-to-event and event-to-character are not strictly
 102 inverse functions, since events contain much more information than the
 103 ASCII character set can encode."
 104   ch)
 105
 106 (defun copy-event (event1 &optional event2)
 107   "Make a copy of the given event object.
 108 In this emulation, `copy-event' just returns its argument."
 109   event1)
 110
 111 (defun deallocate-event (event)
 112   "Allow the given event structure to be reused.
 113 In actual Lucid Emacs, you MUST NOT use this event object after
 114 calling this function with it.  You will lose.  It is not necessary to
 115 call this function, as event objects are garbage- collected like all
 116 other objects; however, it may be more efficient to explicitly
 117 deallocate events when you are sure that that is safe.
 118
 119 This emulation does not actually deallocate or reuse events
 120 except via garbage collection and `cons'."
 121   nil)
 122
 123 (defun enqueue-eval-event: (function object)
 124   "Add an eval event to the back of the queue.
 125 It will be the next event read after all pending events."
 126   (setq unread-command-events
 127         (nconc unread-command-events
 128                (list (list 'eval function object)))))
 129
 130 (defun eval-event-p (obj)
 131   "True if the argument is an eval or menu event object."
 132   (eq (car-safe obj) 'eval))
 133
 134 (defun event-button (event)
 135   "Return the button-number of the given mouse-button-press event."
 136   (let ((sym (car (get (car event) 'event-symbol-elements))))
 137     (cdr (assq sym '((mouse-1 . 1) (mouse-2 . 2) (mouse-3 . 3)
 138                      (mouse-4 . 4) (mouse-5 . 5))))))
 139
 140 (defun event-function (event)
 141   "Return the callback function of the given timeout, menu, or eval event."
 142   (nth 1 event))
 143
 144 (defun event-key (event)
 145   "Returns the KeySym of the given key-press event.
 146 The value is an ASCII printing character (not upper case) or a symbol."
 147   (if (symbolp event)
 148       (car (get event 'event-symbol-elements))
 149     (let ((base (logand event (1- (lsh 1 18)))))
 150       (downcase (if (< base 32) (logior base 64) base)))))
 151
 152 (defun event-object (event)
 153   "Returns the function argument of the given timeout, menu, or eval event."
 154   (nth 2 event))
 155
 156 (defun event-point (event)
 157   "Returns the character position of the given mouse-related event.
 158 If the event did not occur over a window, or did
 159 not occur over text, then this returns nil.  Otherwise, it returns an index
 160 into the buffer visible in the event's window."
 161   (posn-point (event-end event)))
 162
 163 ;; Return position of start of line LINE in WINDOW.
 164 ;; If LINE is nil, return the last position
 165 ;; visible in WINDOW.
 166 (defun event-closest-point-1 (window &optional line)
 167   (let* ((total (- (window-height window)
 168                    (if (window-minibuffer-p window)
 169                        0 1)))
 170          (distance (or line total)))
 171     (save-excursion
 172       (goto-char (window-start window))
 173       (if (= (vertical-motion distance) distance)
 174           (if (not line)
 175               (forward-char -1)))
 176       (point))))
 177
 178 (defun event-closest-point (event &optional start-window)
 179   "Return the nearest position to where EVENT ended its motion.
 180 This is computed for the window where EVENT's motion started,
 181 or for window WINDOW if that is specified."
 182   (or start-window (setq start-window (posn-window (event-start event))))
 183   (if (eq start-window (posn-window (event-end event)))
 184       (if (eq (event-point event) 'vertical-line)
 185           (event-closest-point-1 start-window
 186                                  (cdr (posn-col-row (event-end event))))
 187         (if (eq (event-point event) 'mode-line)
 188             (event-closest-point-1 start-window)
 189           (event-point event)))
 190     ;; EVENT ended in some other window.
 191     (let* ((end-w (posn-window (event-end event)))
 192            (end-w-top)
 193            (w-top (nth 1 (window-edges start-window))))
 194       (setq end-w-top
 195             (if (windowp end-w)
 196                 (nth 1 (window-edges end-w))
 197               (/ (cdr (posn-x-y (event-end event)))
 198                  (frame-char-height end-w))))
 199       (if (>= end-w-top w-top)
 200           (event-closest-point-1 start-window)
 201         (window-start start-window)))))
 202
 203 (defun event-process (event)
 204   "Returns the process of the given process-output event."
 205   (nth 1 event))
 206
 207 (defun event-timestamp (event)
 208   "Returns the timestamp of the given event object.
 209 In Lucid Emacs, this works for any kind of event.
 210 In this emulation, it returns nil for non-mouse-related events."
 211   (and (listp event)
 212        (posn-timestamp (event-end event))))
 213
 214 (defun event-to-character (event &optional lenient)
 215   "Returns the closest ASCII approximation to the given event object.
 216 If the event isn't a keypress, this returns nil.
 217 If the second argument is non-nil, then this is lenient in its
 218 translation; it will ignore modifier keys other than control and meta,
 219 and will ignore the shift modifier on those characters which have no
 220 shifted ASCII equivalent (Control-Shift-A for example, will be mapped to
 221 the same ASCII code as Control-A.)  If the second arg is nil, then nil
 222 will be returned for events which have no direct ASCII equivalent."
 223   (if (symbolp event)
 224       (and lenient
 225            (cdr (assq event '((backspace . 8) (delete . 127) (tab . 9)
 226                               (return . 10) (enter . 10)))))
 227     ;; Our interpretation is, ASCII means anything a number can represent.
 228     (if (integerp event)
 229         event nil)))
 230
 231 (defun event-window (event)
 232   "Returns the window of the given mouse-related event object."
 233   (posn-window (event-end event)))
 234
 235 (defun event-x (event)
 236   "Returns the X position in characters of the given mouse-related event."
 237   (/ (car (posn-col-row (event-end event)))
 238      (frame-char-width (window-frame (event-window event)))))
 239
 240 (defun event-x-pixel (event)
 241   "Returns the X position in pixels of the given mouse-related event."
 242   (car (posn-col-row (event-end event))))
 243
 244 (defun event-y (event)
 245   "Returns the Y position in characters of the given mouse-related event."
 246   (/ (cdr (posn-col-row (event-end event)))
 247      (frame-char-height (window-frame (event-window event)))))
 248
 249 (defun event-y-pixel (event)
 250   "Returns the Y position in pixels of the given mouse-related event."
 251   (cdr (posn-col-row (event-end event))))
 252
 253 (defun key-press-event-p (obj)
 254   "True if the argument is a keyboard event object."
 255   (or (integerp obj)
 256       (and (symbolp obj)
 257            (get obj 'event-symbol-elements))))
 258
 259 (defun menu-event-p (obj)
 260   "True if the argument is a menu event object."
 261   (eq (car-safe obj) 'menu))
 262
 263 (defun motion-event-p (obj)
 264   "True if the argument is a mouse-motion event object."
 265   (eq (car-safe obj) 'mouse-movement))
 266
 267 (defun read-command-event ()
 268   "Return the next keyboard or mouse event; execute other events.
 269 This is similar to the function `next-command-event' of Lucid Emacs,
 270 but different in that it returns the event rather than filling in
 271 an existing event object."
 272   (let (event)
 273     (while (progn
 274              (setq event (read-event))
 275              (not (or (key-press-event-p event)
 276                       (button-press-event-p event)
 277                       (button-release-event-p event)
 278                       (menu-event-p event))))
 279       (let ((type (car-safe event)))
 280         (cond ((eq type 'eval)
 281                (funcall (nth 1 event) (nth 2 event)))
 282               ((eq type 'switch-frame)
 283                (select-frame (nth 1 event))))))
 284     event))
 285
 286 (defun process-event-p (obj)
 287   "True if the argument is a process-output event object.
 288 GNU Emacs 19 does not currently generate process-output events."
 289   (eq (car-safe obj) 'process))
 290
 291 (provide 'levents)
 292
 293 ;;; levents.el ends here