lisp/emacs-lisp/levents.el

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