lisp/xwidget.el

   1 ;;; xwidget.el --- api functions for xwidgets  -*- lexical-binding: t -*-
   2 ;;
   3 ;; Copyright (C) 2011-2017 Free Software Foundation, Inc.
   4 ;;
   5 ;; Author: Joakim Verona (joakim@verona.se)
   6 ;;
   7 ;; This file is part of GNU Emacs.
   8 ;;
   9 ;; GNU Emacs is free software: you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation, either version 3 of the License, or
  12 ;; (at your option) any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  21 ;;
  22 ;; --------------------------------------------------------------------
  23
  24 ;;; Commentary:
  25 ;;
  26 ;; See xwidget.c for more api functions.
  27
  28 ;; This breaks compilation when we don't have xwidgets.
  29 ;; And is pointless when we do, since it's in C and so preloaded.
  30 ;;(require 'xwidget-internal)
  31
  32 ;;; Code:
  33
  34 (require 'cl-lib)
  35 (require 'bookmark)
  36
  37 (declare-function make-xwidget "xwidget.c"
  38                   (type title width height arguments &optional buffer))
  39 (declare-function xwidget-buffer "xwidget.c" (xwidget))
  40 (declare-function xwidget-size-request "xwidget.c" (xwidget))
  41 (declare-function xwidget-resize "xwidget.c" (xwidget new-width new-height))
  42 (declare-function xwidget-webkit-execute-script "xwidget.c"
  43                   (xwidget script &optional callback))
  44 (declare-function xwidget-webkit-goto-uri "xwidget.c" (xwidget uri))
  45 (declare-function xwidget-webkit-zoom "xwidget.c" (xwidget factor))
  46 (declare-function xwidget-plist "xwidget.c" (xwidget))
  47 (declare-function set-xwidget-plist "xwidget.c" (xwidget plist))
  48 (declare-function xwidget-view-window "xwidget.c" (xwidget-view))
  49 (declare-function xwidget-view-model "xwidget.c" (xwidget-view))
  50 (declare-function delete-xwidget-view "xwidget.c" (xwidget-view))
  51 (declare-function get-buffer-xwidgets "xwidget.c" (buffer))
  52 (declare-function xwidget-query-on-exit-flag "xwidget.c" (xwidget))
  53
  54 (defun xwidget-insert (pos type title width height &optional args)
  55   "Insert an xwidget at position POS.
  56 Supply the xwidget's TYPE, TITLE, WIDTH, and HEIGHT.
  57 See `make-xwidget' for the possible TYPE values.
  58 The usage of optional argument ARGS depends on the xwidget.
  59 This returns the result of `make-xwidget'."
  60   (goto-char pos)
  61   (let ((id (make-xwidget type title width height args)))
  62     (put-text-property (point) (+ 1 (point))
  63                        'display (list 'xwidget ':xwidget id))
  64     id))
  65
  66 (defun xwidget-at (pos)
  67   "Return xwidget at POS."
  68   ;; TODO this function is a bit tedious because the C layer isn't well
  69   ;; protected yet and xwidgetp apparently doesn't work yet.
  70   (let* ((disp (get-text-property pos 'display))
  71          (xw (car (cdr (cdr  disp)))))
  72     ;;(if (xwidgetp  xw) xw nil)
  73     (if (equal 'xwidget (car disp)) xw)))
  74
  75
  76
  77 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  78 ;;; webkit support
  79 (require 'browse-url)
  80 (require 'image-mode);;for some image-mode alike functionality
  81
  82 ;;;###autoload
  83 (defun xwidget-webkit-browse-url (url &optional new-session)
  84   "Ask xwidget-webkit to browse URL.
  85 NEW-SESSION specifies whether to create a new xwidget-webkit session.
  86 Interactively, URL defaults to the string looking like a url around point."
  87   (interactive (progn
  88                  (require 'browse-url)
  89                  (browse-url-interactive-arg "xwidget-webkit URL: "
  90                                              ;;(xwidget-webkit-current-url)
  91                                              )))
  92   (or (featurep 'xwidget-internal)
  93       (user-error "Your Emacs was not compiled with xwidgets support"))
  94   (when (stringp url)
  95     (if new-session
  96         (xwidget-webkit-new-session url)
  97       (xwidget-webkit-goto-url url))))
  98
  99 ;;todo.
 100 ;; - check that the webkit support is compiled in
 101 (defvar xwidget-webkit-mode-map
 102   (let ((map (make-sparse-keymap)))
 103     (define-key map "g" 'xwidget-webkit-browse-url)
 104     (define-key map "a" 'xwidget-webkit-adjust-size-dispatch)
 105     (define-key map "b" 'xwidget-webkit-back)
 106     (define-key map "r" 'xwidget-webkit-reload)
 107     (define-key map "t" (lambda () (interactive) (message "o"))) ;FIXME: ?!?
 108     (define-key map "\C-m" 'xwidget-webkit-insert-string)
 109     (define-key map "w" 'xwidget-webkit-current-url)
 110     (define-key map "+" 'xwidget-webkit-zoom-in)
 111     (define-key map "-" 'xwidget-webkit-zoom-out)
 112
 113     ;;similar to image mode bindings
 114     (define-key map (kbd "SPC")                 'xwidget-webkit-scroll-up)
 115     (define-key map (kbd "DEL")                 'xwidget-webkit-scroll-down)
 116
 117     (define-key map [remap scroll-up]           'xwidget-webkit-scroll-up)
 118     (define-key map [remap scroll-up-command]   'xwidget-webkit-scroll-up)
 119
 120     (define-key map [remap scroll-down]         'xwidget-webkit-scroll-down)
 121     (define-key map [remap scroll-down-command] 'xwidget-webkit-scroll-down)
 122
 123     (define-key map [remap forward-char]        'xwidget-webkit-scroll-forward)
 124     (define-key map [remap backward-char]       'xwidget-webkit-scroll-backward)
 125     (define-key map [remap right-char]          'xwidget-webkit-scroll-forward)
 126     (define-key map [remap left-char]           'xwidget-webkit-scroll-backward)
 127     (define-key map [remap previous-line]       'xwidget-webkit-scroll-down)
 128     (define-key map [remap next-line]           'xwidget-webkit-scroll-up)
 129
 130     ;; (define-key map [remap move-beginning-of-line] 'image-bol)
 131     ;; (define-key map [remap move-end-of-line]       'image-eol)
 132     (define-key map [remap beginning-of-buffer] 'xwidget-webkit-scroll-top)
 133     (define-key map [remap end-of-buffer]       'xwidget-webkit-scroll-bottom)
 134     map)
 135   "Keymap for `xwidget-webkit-mode'.")
 136
 137 (defun xwidget-webkit-zoom-in ()
 138   "Increase webkit view zoom factor."
 139   (interactive)
 140   (xwidget-webkit-zoom (xwidget-webkit-current-session) 0.1))
 141
 142 (defun xwidget-webkit-zoom-out ()
 143   "Decrease webkit view zoom factor."
 144   (interactive)
 145   (xwidget-webkit-zoom (xwidget-webkit-current-session) -0.1))
 146
 147 (defun xwidget-webkit-scroll-up ()
 148   "Scroll webkit up."
 149   (interactive)
 150   (xwidget-webkit-execute-script
 151    (xwidget-webkit-current-session)
 152    "window.scrollBy(0, 50);"))
 153
 154 (defun xwidget-webkit-scroll-down ()
 155   "Scroll webkit down."
 156   (interactive)
 157   (xwidget-webkit-execute-script
 158    (xwidget-webkit-current-session)
 159    "window.scrollBy(0, -50);"))
 160
 161 (defun xwidget-webkit-scroll-forward ()
 162   "Scroll webkit forwards."
 163   (interactive)
 164   (xwidget-webkit-execute-script
 165    (xwidget-webkit-current-session)
 166    "window.scrollBy(50, 0);"))
 167
 168 (defun xwidget-webkit-scroll-backward ()
 169   "Scroll webkit backwards."
 170   (interactive)
 171   (xwidget-webkit-execute-script
 172    (xwidget-webkit-current-session)
 173    "window.scrollBy(-50, 0);"))
 174
 175 (defun xwidget-webkit-scroll-top ()
 176   "Scroll webkit to the very top."
 177   (interactive)
 178   (xwidget-webkit-execute-script
 179    (xwidget-webkit-current-session)
 180    "window.scrollTo(pageXOffset, 0);"))
 181
 182 (defun xwidget-webkit-scroll-bottom ()
 183   "Scroll webkit to the very bottom."
 184   (interactive)
 185   (xwidget-webkit-execute-script
 186    (xwidget-webkit-current-session)
 187    "window.scrollTo(pageXOffset, window.document.body.clientHeight);"))
 188
 189 ;; The xwidget event needs to go into a higher level handler
 190 ;; since the xwidget can generate an event even if it's offscreen.
 191 ;; TODO this needs to use callbacks and consider different xwidget event types.
 192 (define-key (current-global-map) [xwidget-event] #'xwidget-event-handler)
 193 (defun xwidget-log (&rest msg)
 194   "Log MSG to a buffer."
 195   (let ((buf (get-buffer-create " *xwidget-log*")))
 196     (with-current-buffer buf
 197       (insert (apply #'format msg))
 198       (insert "\n"))))
 199
 200 (defun xwidget-event-handler ()
 201   "Receive xwidget event."
 202   (interactive)
 203   (xwidget-log "stuff happened to xwidget %S" last-input-event)
 204   (let*
 205       ((xwidget-event-type (nth 1 last-input-event))
 206        (xwidget (nth 2 last-input-event))
 207        ;;(xwidget-callback (xwidget-get xwidget 'callback))
 208        ;;TODO stopped working for some reason
 209        )
 210     ;;(funcall  xwidget-callback xwidget xwidget-event-type)
 211     (message "xw callback %s" xwidget)
 212     (funcall  'xwidget-webkit-callback xwidget xwidget-event-type)))
 213
 214 (defun xwidget-webkit-callback (xwidget xwidget-event-type)
 215   "Callback for xwidgets.
 216 XWIDGET instance, XWIDGET-EVENT-TYPE depends on the originating xwidget."
 217   (if (not (buffer-live-p (xwidget-buffer xwidget)))
 218       (xwidget-log
 219        "error: callback called for xwidget with dead buffer")
 220     (with-current-buffer (xwidget-buffer xwidget)
 221       (cond ((eq xwidget-event-type 'load-changed)
 222              (xwidget-webkit-execute-script
 223               xwidget "document.title"
 224               (lambda (title)
 225                 (xwidget-log "webkit finished loading: '%s'" title)
 226                 ;;TODO - check the native/internal scroll
 227                 ;;(xwidget-adjust-size-to-content xwidget)
 228                 (xwidget-webkit-adjust-size-to-window xwidget)
 229                 (rename-buffer (format "*xwidget webkit: %s *" title))))
 230              (pop-to-buffer (current-buffer)))
 231             ((eq xwidget-event-type 'decide-policy)
 232              (let ((strarg  (nth 3 last-input-event)))
 233                (if (string-match ".*#\\(.*\\)" strarg)
 234                    (xwidget-webkit-show-id-or-named-element
 235                     xwidget
 236                     (match-string 1 strarg)))))
 237             ((eq xwidget-event-type 'javascript-callback)
 238              (let ((proc (nth 3 last-input-event))
 239                    (arg  (nth 4 last-input-event)))
 240                (funcall proc arg)))
 241             (t (xwidget-log "unhandled event:%s" xwidget-event-type))))))
 242
 243 (defvar bookmark-make-record-function)
 244 (define-derived-mode xwidget-webkit-mode
 245     special-mode "xwidget-webkit" "Xwidget webkit view mode."
 246     (setq buffer-read-only t)
 247     (setq-local bookmark-make-record-function
 248                 #'xwidget-webkit-bookmark-make-record)
 249     ;; Keep track of [vh]scroll when switching buffers
 250     (image-mode-setup-winprops))
 251
 252 (defun xwidget-webkit-bookmark-make-record ()
 253   "Integrate Emacs bookmarks with the webkit xwidget."
 254   (nconc (bookmark-make-record-default t t)
 255          `((page     . ,(xwidget-webkit-current-url))
 256            (handler  . (lambda (bmk) (browse-url
 257                                  (bookmark-prop-get bmk 'page)))))))
 258
 259
 260 (defvar xwidget-webkit-last-session-buffer nil)
 261
 262 (defun xwidget-webkit-last-session ()
 263   "Last active webkit, or nil."
 264   (if (buffer-live-p xwidget-webkit-last-session-buffer)
 265       (with-current-buffer xwidget-webkit-last-session-buffer
 266         (xwidget-at (point-min)))
 267     nil))
 268
 269 (defun xwidget-webkit-current-session ()
 270   "Either the webkit in the current buffer, or the last one used.
 271 The latter might be nil."
 272   (or (xwidget-at (point-min)) (xwidget-webkit-last-session)))
 273
 274 (defun xwidget-adjust-size-to-content (xw)
 275   "Resize XW to content."
 276   ;; xwidgets doesn't support widgets that have their own opinions about
 277   ;; size well, yet this reads the desired size and resizes the Emacs
 278   ;; allocated area accordingly.
 279   (let ((size (xwidget-size-request xw)))
 280     (xwidget-resize xw (car size) (cadr size))))
 281
 282
 283 (defvar xwidget-webkit-activeelement-js"
 284 function findactiveelement(doc){
 285 //alert(doc.activeElement.value);
 286    if(doc.activeElement.value != undefined){
 287       return doc.activeElement;
 288    }else{
 289         // recurse over the child documents:
 290         var frames = doc.getElementsByTagName('frame');
 291         for (var i = 0; i < frames.length; i++)
 292         {
 293                 var d = frames[i].contentDocument;
 294                  var rv = findactiveelement(d);
 295                  if(rv != undefined){
 296                     return rv;
 297                  }
 298         }
 299     }
 300     return undefined;
 301 };
 302
 303
 304 "
 305
 306   "javascript that finds the active element."
 307   ;; Yes it's ugly, because:
 308   ;; - there is apparently no way to find the active frame other than recursion
 309   ;; - the js "for each" construct misbehaved on the "frames" collection
 310   ;; - a window with no frameset still has frames.length == 1, but
 311   ;; frames[0].document.activeElement != document.activeElement
 312   ;;TODO the activeelement type needs to be examined, for iframe, etc.
 313   )
 314
 315 (defun xwidget-webkit-insert-string ()
 316   "Prompt for a string and insert it in the active field in the
 317 current webkit widget."
 318   ;; Read out the string in the field first and provide for edit.
 319   (interactive)
 320   (let ((xww (xwidget-webkit-current-session)))
 321     (xwidget-webkit-execute-script
 322      xww
 323      (concat xwidget-webkit-activeelement-js "
 324 (function () {
 325   var res = findactiveelement(document);
 326   return [res.value, res.type];
 327 })();")
 328      (lambda (field)
 329        (let ((str (pcase field
 330                     (`[,val "text"]
 331                      (read-string "Text: " val))
 332                     (`[,val "password"]
 333                      (read-passwd "Password: " nil val))
 334                     (`[,val "textarea"]
 335                      (xwidget-webkit-begin-edit-textarea xww val)))))
 336          (xwidget-webkit-execute-script
 337           xww
 338           (format "findactiveelement(document).value='%s'" str)))))))
 339
 340 (defvar xwidget-xwbl)
 341 (defun xwidget-webkit-begin-edit-textarea (xw text)
 342   "Start editing of a webkit text area.
 343 XW is the xwidget identifier, TEXT is retrieved from the webkit."
 344   (switch-to-buffer
 345    (generate-new-buffer "textarea"))
 346   (set (make-local-variable 'xwidget-xwbl) xw)
 347   (insert text))
 348
 349 (defun xwidget-webkit-end-edit-textarea ()
 350   "End editing of a webkit text area."
 351   (interactive)
 352   (goto-char (point-min))
 353   (while (search-forward "\n" nil t)
 354     (replace-match "\\n" nil t))
 355   (xwidget-webkit-execute-script
 356    xwidget-xwbl
 357    (format "findactiveelement(document).value='%s'"
 358            (buffer-substring (point-min) (point-max))))
 359   ;;TODO convert linefeed to \n
 360   )
 361
 362 (defun xwidget-webkit-show-element (xw element-selector)
 363   "Make webkit xwidget XW show a named element ELEMENT-SELECTOR.
 364 The ELEMENT-SELECTOR must be a valid CSS selector.  For example,
 365 use this to display an anchor."
 366   (interactive (list (xwidget-webkit-current-session)
 367                      (read-string "Element selector: ")))
 368   (xwidget-webkit-execute-script
 369    xw
 370    (format "
 371 (function (query) {
 372   var el = document.querySelector(query);
 373   if (el !== null) {
 374     window.scrollTo(0, el.offsetTop);
 375   }
 376 })('%s');"
 377     element-selector)))
 378
 379 (defun xwidget-webkit-show-named-element (xw element-name)
 380   "Make webkit xwidget XW show a named element ELEMENT-NAME.
 381 For example, use this to display an anchor."
 382   (interactive (list (xwidget-webkit-current-session)
 383                      (read-string "Element name: ")))
 384   ;; TODO: This needs to be interfaced into browse-url somehow.  The
 385   ;; tricky part is that we need to do this in two steps: A: load the
 386   ;; base url, wait for load signal to arrive B: navigate to the
 387   ;; anchor when the base url is finished rendering
 388   (xwidget-webkit-execute-script
 389    xw
 390    (format "
 391 (function (query) {
 392   var el = document.getElementsByName(query)[0];
 393   if (el !== undefined) {
 394     window.scrollTo(0, el.offsetTop);
 395   }
 396 })('%s');"
 397     element-name)))
 398
 399 (defun xwidget-webkit-show-id-element (xw element-id)
 400   "Make webkit xwidget XW show an id-element ELEMENT-ID.
 401 For example, use this to display an anchor."
 402   (interactive (list (xwidget-webkit-current-session)
 403                      (read-string "Element id: ")))
 404   (xwidget-webkit-execute-script
 405    xw
 406    (format "
 407 (function (query) {
 408   var el = document.getElementById(query);
 409   if (el !== null) {
 410     window.scrollTo(0, el.offsetTop);
 411   }
 412 })('%s');"
 413     element-id)))
 414
 415 (defun xwidget-webkit-show-id-or-named-element (xw element-id)
 416    "Make webkit xwidget XW show a name or element id ELEMENT-ID.
 417 For example, use this to display an anchor."
 418   (interactive (list (xwidget-webkit-current-session)
 419                      (read-string "Name or element id: ")))
 420   (xwidget-webkit-execute-script
 421    xw
 422    (format "
 423 (function (query) {
 424   var el = document.getElementById(query) ||
 425            document.getElementsByName(query)[0];
 426   if (el !== undefined) {
 427     window.scrollTo(0, el.offsetTop);
 428   }
 429 })('%s');"
 430     element-id)))
 431
 432 (defun xwidget-webkit-adjust-size-to-content ()
 433   "Adjust webkit to content size."
 434   (interactive)
 435   (xwidget-adjust-size-to-content (xwidget-webkit-current-session)))
 436
 437 (defun xwidget-webkit-adjust-size-dispatch ()
 438   "Adjust size according to mode."
 439   (interactive)
 440   (xwidget-webkit-adjust-size-to-window (xwidget-webkit-current-session))
 441   ;; The recenter is intended to correct a visual glitch.
 442   ;; It errors out if the buffer isn't visible, but then we don't get
 443   ;; the glitch, so silence errors.
 444   (ignore-errors
 445     (recenter-top-bottom)))
 446
 447 (defun xwidget-webkit-adjust-size-to-window (xwidget &optional window)
 448   "Adjust the size of the webkit XWIDGET to fit the WINDOW."
 449   (xwidget-resize xwidget
 450                   (window-pixel-width window)
 451                   (window-pixel-height window)))
 452
 453 (defun xwidget-webkit-adjust-size (w h)
 454   "Manually set webkit size to width W, height H."
 455   ;; TODO shouldn't be tied to the webkit xwidget
 456   (interactive "nWidth:\nnHeight:\n")
 457   (xwidget-resize (xwidget-webkit-current-session) w h))
 458
 459 (defun xwidget-webkit-fit-width ()
 460   "Adjust width of webkit to window width."
 461   (interactive)
 462   (xwidget-webkit-adjust-size (- (nth 2 (window-inside-pixel-edges))
 463                                  (car (window-inside-pixel-edges)))
 464                               1000))
 465
 466 (defun xwidget-webkit-auto-adjust-size (window)
 467   "Adjust the size of the webkit widget in the given WINDOW."
 468   (with-current-buffer (window-buffer window)
 469     (when (eq major-mode 'xwidget-webkit-mode)
 470       (let ((xwidget (xwidget-webkit-current-session)))
 471         (xwidget-webkit-adjust-size-to-window xwidget window)))))
 472
 473 (defun xwidget-webkit-adjust-size-in-frame (frame)
 474   "Dynamically adjust webkit widget for all windows of the FRAME."
 475   (walk-windows 'xwidget-webkit-auto-adjust-size 'no-minibuf frame))
 476
 477 (eval-after-load 'xwidget-webkit-mode
 478   (add-to-list 'window-size-change-functions
 479                'xwidget-webkit-adjust-size-in-frame))
 480
 481 (defun xwidget-webkit-new-session (url)
 482   "Create a new webkit session buffer with URL."
 483   (let*
 484       ((bufname (generate-new-buffer-name "*xwidget-webkit*"))
 485        xw)
 486     (setq xwidget-webkit-last-session-buffer (switch-to-buffer
 487                                               (get-buffer-create bufname)))
 488     ;; The xwidget id is stored in a text property, so we need to have
 489     ;; at least character in this buffer.
 490     (insert " ")
 491     (setq xw (xwidget-insert 1 'webkit bufname
 492                              (window-pixel-width)
 493                              (window-pixel-height)))
 494     (xwidget-put xw 'callback 'xwidget-webkit-callback)
 495     (xwidget-webkit-mode)
 496     (xwidget-webkit-goto-uri (xwidget-webkit-last-session) url)))
 497
 498
 499 (defun xwidget-webkit-goto-url (url)
 500   "Goto URL."
 501   (if (xwidget-webkit-current-session)
 502       (progn
 503         (xwidget-webkit-goto-uri (xwidget-webkit-current-session) url))
 504     (xwidget-webkit-new-session url)))
 505
 506 (defun xwidget-webkit-back ()
 507   "Go back in history."
 508   (interactive)
 509   (xwidget-webkit-execute-script (xwidget-webkit-current-session)
 510                                  "history.go(-1);"))
 511
 512 (defun xwidget-webkit-reload ()
 513   "Reload current url."
 514   (interactive)
 515   (xwidget-webkit-execute-script (xwidget-webkit-current-session)
 516                                  "history.go(0);"))
 517
 518 (defun xwidget-webkit-current-url ()
 519   "Get the webkit url and place it on the kill-ring."
 520   (interactive)
 521   (xwidget-webkit-execute-script
 522    (xwidget-webkit-current-session)
 523    "document.URL" (lambda (rv)
 524                     (let ((url (kill-new (or rv ""))))
 525                       (message "url: %s" url)))))
 526
 527 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 528 (defun xwidget-webkit-get-selection (proc)
 529   "Get the webkit selection and pass it to PROC."
 530   (xwidget-webkit-execute-script
 531    (xwidget-webkit-current-session)
 532    "window.getSelection().toString();"
 533    proc))
 534
 535 (defun xwidget-webkit-copy-selection-as-kill ()
 536   "Get the webkit selection and put it on the kill-ring."
 537   (interactive)
 538   (xwidget-webkit-get-selection (lambda (selection) (kill-new selection))))
 539
 540
 541 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 542 ;; Xwidget plist management (similar to the process plist functions)
 543
 544 (defun xwidget-get (xwidget propname)
 545   "Get an xwidget's property value.
 546 XWIDGET is an xwidget, PROPNAME a property.
 547 Returns the last value stored with `xwidget-put'."
 548   (plist-get (xwidget-plist xwidget) propname))
 549
 550 (defun xwidget-put (xwidget propname value)
 551   "Set an xwidget's property value.
 552 XWIDGET is an xwidget, PROPNAME a property to be set to specified VALUE.
 553 You can retrieve the value with `xwidget-get'."
 554   (set-xwidget-plist xwidget
 555                      (plist-put (xwidget-plist xwidget) propname value)))
 556
 557
 558 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 559
 560 (defvar xwidget-view-list)              ; xwidget.c
 561 (defvar xwidget-list)                   ; xwidget.c
 562
 563 (defun xwidget-delete-zombies ()
 564   "Helper for `xwidget-cleanup'."
 565   (dolist (xwidget-view xwidget-view-list)
 566     (when (or (not (window-live-p (xwidget-view-window xwidget-view)))
 567               (not (memq (xwidget-view-model xwidget-view)
 568                          xwidget-list)))
 569       (delete-xwidget-view xwidget-view))))
 570
 571 (defun xwidget-cleanup ()
 572   "Delete zombie xwidgets."
 573   ;; During development it was sometimes easy to wind up with zombie
 574   ;; xwidget instances.
 575   ;; This function tries to implement a workaround should it occur again.
 576   (interactive)
 577   ;; Kill xviews that should have been deleted but still linger.
 578   (xwidget-delete-zombies)
 579   ;; Redraw display otherwise ghost of zombies will remain to haunt the screen
 580   (redraw-display))
 581
 582 (defun xwidget-kill-buffer-query-function ()
 583   "Ask before killing a buffer that has xwidgets."
 584   (let ((xwidgets (get-buffer-xwidgets (current-buffer))))
 585     (or (not xwidgets)
 586         (not (memq t (mapcar #'xwidget-query-on-exit-flag xwidgets)))
 587         (yes-or-no-p
 588          (format "Buffer %S has xwidgets; kill it? " (buffer-name))))))
 589
 590 (when (featurep 'xwidget-internal)
 591   (add-hook 'kill-buffer-query-functions #'xwidget-kill-buffer-query-function)
 592   ;; This would have felt better in C, but this seems to work well in
 593   ;; practice though.
 594   (add-hook 'window-configuration-change-hook #'xwidget-delete-zombies))
 595
 596 (provide 'xwidget)
 597 ;;; xwidget.el ends here