lisp/tree-widget.el

   1 ;;; tree-widget.el --- Tree widget
   2
   3 ;; Copyright (C) 2004-2011 Free Software Foundation, Inc.
   4
   5 ;; Author: David Ponce <david@dponce.com>
   6 ;; Maintainer: David Ponce <david@dponce.com>
   7 ;; Created: 16 Feb 2001
   8 ;; Keywords: extensions
   9
  10 ;; This file is part of GNU Emacs
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26 ;;
  27 ;; This library provide a tree widget useful to display data
  28 ;; structures organized in a hierarchical order.
  29 ;;
  30 ;; The following properties are specific to the tree widget:
  31 ;;
  32 ;; :open
  33 ;;    Set to non-nil to expand the tree.  By default the tree is
  34 ;;    collapsed.
  35 ;;
  36 ;; :node
  37 ;;    Specify the widget used to represent the value of a tree node.
  38 ;;    By default this is an `item' widget which displays the
  39 ;;    tree-widget :tag property value if defined, or a string
  40 ;;    representation of the tree-widget value.
  41 ;;
  42 ;; :keep
  43 ;;    Specify a list of properties to keep when the tree is collapsed
  44 ;;    so they can be recovered when the tree is expanded.  This
  45 ;;    property can be used in child widgets too.
  46 ;;
  47 ;; :expander (obsoletes :dynargs)
  48 ;;    Specify a function to be called to dynamically provide the
  49 ;;    tree's children in response to an expand request.  This function
  50 ;;    will be passed the tree widget and must return a list of child
  51 ;;    widgets.  Child widgets returned by the :expander function are
  52 ;;    stored in the :args property of the tree widget.
  53 ;;
  54 ;; :expander-p
  55 ;;    Specify a predicate which must return non-nil to indicate that
  56 ;;    the :expander function above has to be called.  By default, to
  57 ;;    speed up successive expand requests, the :expander-p predicate
  58 ;;    return non-nil when the :args value is nil.  So, by default, to
  59 ;;    refresh child values, it is necessary to set the :args property
  60 ;;    to nil, then redraw the tree.
  61 ;;
  62 ;; :open-icon  (default `tree-widget-open-icon')
  63 ;; :close-icon (default `tree-widget-close-icon')
  64 ;; :empty-icon (default `tree-widget-empty-icon')
  65 ;; :leaf-icon  (default `tree-widget-leaf-icon')
  66 ;;    Those properties define the icon widgets associated to tree
  67 ;;    nodes.  Icon widgets must derive from the `tree-widget-icon'
  68 ;;    widget.  The :tag and :glyph-name property values are
  69 ;;    respectively used when drawing the text and graphic
  70 ;;    representation of the tree.  The :tag value must be a string
  71 ;;    that represent a node icon, like "[+]" for example.  The
  72 ;;    :glyph-name value must the name of an image found in the current
  73 ;;    theme, like "close" for example (see also the variable
  74 ;;    `tree-widget-theme').
  75 ;;
  76 ;; :guide      (default `tree-widget-guide')
  77 ;; :end-guide  (default `tree-widget-end-guide')
  78 ;; :no-guide   (default `tree-widget-no-guide')
  79 ;; :handle     (default `tree-widget-handle')
  80 ;; :no-handle  (default `tree-widget-no-handle')
  81 ;;    Those properties define `item'-like widgets used to draw the
  82 ;;    tree guide lines.  The :tag property value is used when drawing
  83 ;;    the text representation of the tree.  The graphic look and feel
  84 ;;    is given by the images named "guide", "no-guide", "end-guide",
  85 ;;    "handle", and "no-handle" found in the current theme (see also
  86 ;;    the variable `tree-widget-theme').
  87 ;;
  88 ;; These are the default :tag values for icons, and guide lines:
  89 ;;
  90 ;; open-icon    "[-]"
  91 ;; close-icon   "[+]"
  92 ;; empty-icon   "[X]"
  93 ;; leaf-icon    ""
  94 ;; guide        " |"
  95 ;; no-guide     "  "
  96 ;; end-guide    " `"
  97 ;; handle       "-"
  98 ;; no-handle    " "
  99 ;;
 100 ;; The text representation of a tree looks like this:
 101 ;;
 102 ;; [-] 1        (open-icon :node)
 103 ;;  |-[+] 1.0   (guide+handle+close-icon :node)
 104 ;;  |-[X] 1.1   (guide+handle+empty-icon :node)
 105 ;;  `-[-] 1.2   (end-guide+handle+open-icon :node)
 106 ;;     |- 1.2.1 (no-guide+no-handle+guide+handle+leaf-icon leaf)
 107 ;;     `- 1.2.2 (no-guide+no-handle+end-guide+handle+leaf-icon leaf)
 108 ;;
 109 ;; By default, images will be used instead of strings to draw a
 110 ;; nice-looking tree.  See the `tree-widget-image-enable',
 111 ;; `tree-widget-themes-directory', and `tree-widget-theme' options for
 112 ;; more details.
 113
 114 ;;; History:
 115 ;;
 116
 117 ;;; Code:
 118 (eval-when-compile (require 'cl))
 119 (require 'wid-edit)
 120 \f
 121 ;;; Customization
 122 ;;
 123 (defgroup tree-widget nil
 124   "Customization support for the Tree Widget library."
 125   :version "22.1"
 126   :group 'widgets)
 127
 128 (defcustom tree-widget-image-enable (if (fboundp 'display-images-p)
 129                                         (display-images-p))
 130   "Non-nil means that tree-widget will try to use images."
 131   :type  'boolean
 132   :group 'tree-widget)
 133
 134 (defvar tree-widget-themes-load-path
 135   '(load-path
 136     (let ((dir (if (fboundp 'locate-data-directory)
 137                    (locate-data-directory "tree-widget") ;; XEmacs
 138                  data-directory)))
 139       (and dir (list dir (expand-file-name "images" dir))))
 140     )
 141   "List of locations in which to search for the themes sub-directory.
 142 Each element is an expression that will be recursively evaluated until
 143 it returns a single directory or a list of directories.
 144 The default is to search in the `load-path' first, then in the
 145 \"images\" sub directory in the data directory, then in the data
 146 directory.
 147 The data directory is the value of the variable `data-directory' on
 148 Emacs, and what `(locate-data-directory \"tree-widget\")' returns on
 149 XEmacs.")
 150
 151 (defcustom tree-widget-themes-directory "tree-widget"
 152   "Name of the directory in which to look for an image theme.
 153 When nil use the directory where the tree-widget library is located.
 154 When it is a relative name, search in all occurrences of that sub
 155 directory in the path specified by `tree-widget-themes-load-path'.
 156 The default is to use the \"tree-widget\" relative name."
 157   :type '(choice (const :tag "Default" "tree-widget")
 158                  (const :tag "Where is this library" nil)
 159                  (directory :format "%{%t%}:\n%v"))
 160   :group 'tree-widget)
 161
 162 (defcustom tree-widget-theme nil
 163   "Name of the theme in which to look for images.
 164 This is a sub directory of the themes directory specified by the
 165 `tree-widget-themes-directory' option.
 166 The default theme is \"default\".  When an image is not found in a
 167 theme, it is searched in its parent theme.
 168
 169 A complete theme must at least contain images with these file names
 170 with a supported extension (see also `tree-widget-image-formats'):
 171
 172 \"guide\"
 173   A vertical guide line.
 174 \"no-guide\"
 175   An invisible vertical guide line.
 176 \"end-guide\"
 177   End of a vertical guide line.
 178 \"handle\"
 179   Horizontal guide line that joins the vertical guide line to an icon.
 180 \"no-handle\"
 181   An invisible handle.
 182
 183 Plus images whose name is given by the :glyph-name property of the
 184 icon widgets used to draw the tree.  By default these images are used:
 185
 186 \"open\"
 187   Icon associated to an expanded tree.
 188 \"close\"
 189   Icon associated to a collapsed tree.
 190 \"empty\"
 191   Icon associated to an expanded tree with no child.
 192 \"leaf\"
 193   Icon associated to a leaf node."
 194   :type '(choice (const  :tag "Default" nil)
 195                  (string :tag "Name"))
 196   :group 'tree-widget)
 197
 198 (defcustom tree-widget-image-properties-emacs
 199   '(:ascent center :mask (heuristic t))
 200   "Default properties of Emacs images."
 201   :type 'plist
 202   :group 'tree-widget)
 203
 204 (defcustom tree-widget-image-properties-xemacs
 205   nil
 206   "Default properties of XEmacs images."
 207   :type 'plist
 208   :group 'tree-widget)
 209
 210 (defcustom tree-widget-space-width 0.5
 211   "Amount of space between an icon image and a node widget.
 212 Must be a valid space :width display property."
 213   :group 'tree-widget
 214   :type 'sexp)
 215 \f
 216 ;;; Image support
 217 ;;
 218 (eval-and-compile ;; Emacs/XEmacs compatibility stuff
 219   (cond
 220    ;; XEmacs
 221    ((featurep 'xemacs)
 222     (defsubst tree-widget-use-image-p ()
 223       "Return non-nil if image support is currently enabled."
 224       (and tree-widget-image-enable
 225            widget-glyph-enable
 226            (console-on-window-system-p)))
 227     (defsubst tree-widget-create-image (type file &optional props)
 228       "Create an image of type TYPE from FILE, and return it.
 229 Give the image the specified properties PROPS."
 230       (apply 'make-glyph `([,type :file ,file ,@props])))
 231     (defsubst tree-widget-image-formats ()
 232       "Return the alist of image formats/file name extensions.
 233 See also the option `widget-image-file-name-suffixes'."
 234       (delq nil
 235             (mapcar
 236              #'(lambda (fmt)
 237                  (and (valid-image-instantiator-format-p (car fmt)) fmt))
 238              widget-image-file-name-suffixes)))
 239     )
 240    ;; Emacs
 241    (t
 242     (defsubst tree-widget-use-image-p ()
 243       "Return non-nil if image support is currently enabled."
 244       (and tree-widget-image-enable
 245            widget-image-enable
 246            (display-images-p)))
 247     (defsubst tree-widget-create-image (type file &optional props)
 248       "Create an image of type TYPE from FILE, and return it.
 249 Give the image the specified properties PROPS."
 250       (apply 'create-image `(,file ,type nil ,@props)))
 251     (defsubst tree-widget-image-formats ()
 252       "Return the alist of image formats/file name extensions.
 253 See also the option `widget-image-conversion'."
 254       (delq nil
 255             (mapcar
 256              #'(lambda (fmt)
 257                  (and (image-type-available-p (car fmt)) fmt))
 258              widget-image-conversion)))
 259     ))
 260   )
 261
 262 ;; Buffer local cache of theme data.
 263 (defvar tree-widget--theme nil)
 264
 265 (defsubst tree-widget-theme-name ()
 266   "Return the current theme name, or nil if no theme is active."
 267   (and tree-widget--theme (car (aref tree-widget--theme 0))))
 268
 269 (defsubst tree-widget-set-parent-theme (name)
 270   "Set to NAME the parent theme of the current theme.
 271 The default parent theme is the \"default\" theme."
 272   (unless (member name (aref tree-widget--theme 0))
 273     (aset tree-widget--theme 0
 274           (append (aref tree-widget--theme 0) (list name)))
 275     ;; Load the theme setup from the first directory where the theme
 276     ;; is found.
 277     (catch 'found
 278       (dolist (dir (tree-widget-themes-path))
 279         (setq dir (expand-file-name name dir))
 280         (when (file-accessible-directory-p dir)
 281           (throw 'found
 282                  (load (expand-file-name
 283                         "tree-widget-theme-setup" dir) t)))))))
 284
 285 (defun tree-widget-set-theme (&optional name)
 286   "In the current buffer, set the theme to use for images.
 287 The current buffer must be where the tree widget is drawn.
 288 Optional argument NAME is the name of the theme to use.  It defaults
 289 to the value of the variable `tree-widget-theme'.
 290 Does nothing if NAME is already the current theme.
 291
 292 If there is a \"tree-widget-theme-setup\" library in the theme
 293 directory, load it to setup a parent theme or the images properties.
 294 Typically it should contain something like this:
 295
 296   (tree-widget-set-parent-theme \"my-parent-theme\")
 297   (tree-widget-set-image-properties
 298    (if (featurep 'xemacs)
 299        '(:ascent center)
 300      '(:ascent center :mask (heuristic t))
 301      ))"
 302   (or name (setq name (or tree-widget-theme "default")))
 303   (unless (string-equal name (tree-widget-theme-name))
 304     (set (make-local-variable 'tree-widget--theme)
 305          (make-vector 4 nil))
 306       (tree-widget-set-parent-theme name)
 307       (tree-widget-set-parent-theme "default")))
 308
 309 (defun tree-widget--locate-sub-directory (name path &optional found)
 310   "Locate all occurrences of the sub-directory NAME in PATH.
 311 Return a list of absolute directory names in reverse order, or nil if
 312 not found."
 313   (condition-case err
 314       (dolist (elt path)
 315         (setq elt (eval elt))
 316         (cond
 317          ((stringp elt)
 318           (and (file-accessible-directory-p
 319                 (setq elt (expand-file-name name elt)))
 320                (push elt found)))
 321          (elt
 322           (setq found (tree-widget--locate-sub-directory
 323                        name (if (atom elt) (list elt) elt) found)))))
 324     (error
 325      (message "In tree-widget--locate-sub-directory: %s"
 326               (error-message-string err))))
 327   found)
 328
 329 (defun tree-widget-themes-path ()
 330   "Return the path where to search for a theme.
 331 It is specified in variable `tree-widget-themes-directory'.
 332 Return a list of absolute directory names, or nil when no directory
 333 has been found accessible."
 334   (let ((path (aref tree-widget--theme 1)))
 335     (cond
 336      ;; No directory was found.
 337      ((eq path 'void) nil)
 338      ;; The list of directories is available in the cache.
 339      (path)
 340      ;; Use the directory where this library is located.
 341      ((null tree-widget-themes-directory)
 342       (when (setq path (locate-library "tree-widget"))
 343         (setq path (file-name-directory path))
 344         (setq path (and (file-accessible-directory-p path)
 345                         (list path)))
 346         ;; Store the result in the cache for later use.
 347         (aset tree-widget--theme 1 (or path 'void))
 348         path))
 349      ;; Check accessibility of absolute directory name.
 350      ((file-name-absolute-p tree-widget-themes-directory)
 351       (setq path (expand-file-name tree-widget-themes-directory))
 352       (setq path (and (file-accessible-directory-p path)
 353                       (list path)))
 354       ;; Store the result in the cache for later use.
 355       (aset tree-widget--theme 1 (or path 'void))
 356       path)
 357      ;; Locate a sub-directory in `tree-widget-themes-load-path'.
 358      (t
 359       (setq path (nreverse (tree-widget--locate-sub-directory
 360                             tree-widget-themes-directory
 361                             tree-widget-themes-load-path)))
 362       ;; Store the result in the cache for later use.
 363       (aset tree-widget--theme 1 (or path 'void))
 364       path))))
 365
 366 (defconst tree-widget--cursors
 367   ;; Pointer shapes when the mouse pointer is over inactive
 368   ;; tree-widget images.  This feature works since Emacs 22, and
 369   ;; ignored on older versions, and XEmacs.
 370   '(
 371     ("guide"     . arrow)
 372     ("no-guide"  . arrow)
 373     ("end-guide" . arrow)
 374     ("handle"    . arrow)
 375     ("no-handle" . arrow)
 376     ))
 377
 378 (defsubst tree-widget-set-image-properties (props)
 379   "In current theme, set images properties to PROPS.
 380 Does nothing if images properties have already been set for that
 381 theme."
 382   (or (aref tree-widget--theme 2)
 383       (aset tree-widget--theme 2 props)))
 384
 385 (defsubst tree-widget-image-properties (name)
 386   "Return the properties of image NAME in current theme.
 387 Default global properties are provided for respectively Emacs and
 388 XEmacs in the variables `tree-widget-image-properties-emacs', and
 389 `tree-widget-image-properties-xemacs'."
 390   ;; Add the pointer shape
 391   (cons :pointer
 392         (cons (or (cdr (assoc name tree-widget--cursors)) 'hand)
 393               (tree-widget-set-image-properties
 394                (if (featurep 'xemacs)
 395                    tree-widget-image-properties-xemacs
 396                  tree-widget-image-properties-emacs)))))
 397
 398 (defun tree-widget-lookup-image (name)
 399   "Look up in current theme for an image with NAME.
 400 Search first in current theme, then in parent themes (see also the
 401 function `tree-widget-set-parent-theme').
 402 Return the first image found having a supported format, or nil if not
 403 found."
 404   (let (file)
 405     (catch 'found
 406       (dolist (default-directory (tree-widget-themes-path))
 407         (dolist (dir (aref tree-widget--theme 0))
 408           (dolist (fmt (tree-widget-image-formats))
 409             (dolist (ext (cdr fmt))
 410               (setq file (expand-file-name (concat name ext) dir))
 411               (and (file-readable-p file)
 412                    (file-regular-p file)
 413                    (throw 'found
 414                           (tree-widget-create-image
 415                            (car fmt) file
 416                            (tree-widget-image-properties name))))))))
 417       nil)))
 418
 419 (defun tree-widget-find-image (name)
 420   "Find the image with NAME in current theme.
 421 NAME is an image file name sans extension.
 422 Return the image found, or nil if not found."
 423   (when (tree-widget-use-image-p)
 424     ;; Ensure there is an active theme.
 425     (tree-widget-set-theme (tree-widget-theme-name))
 426     (let ((image (assoc name (aref tree-widget--theme 3))))
 427       ;; The image NAME is found in the cache.
 428       (if image
 429           (cdr image)
 430         ;; Search the image in current, and default themes.
 431         (prog1
 432             (setq image (tree-widget-lookup-image name))
 433           ;; Store image reference in the cache for later use.
 434           (push (cons name image) (aref tree-widget--theme 3))))
 435       )))
 436 \f
 437 ;;; Widgets
 438 ;;
 439 (defun tree-widget-button-click (event)
 440   "Move to the position clicked on, and if it is a button, invoke it.
 441 EVENT is the mouse event received."
 442   (interactive "e")
 443   (mouse-set-point event)
 444   (let ((pos (widget-event-point event)))
 445     (if (get-char-property pos 'button)
 446         (widget-button-click event))))
 447
 448 (defvar tree-widget-button-keymap
 449   (let ((km (make-sparse-keymap)))
 450     (if (boundp 'widget-button-keymap)
 451         ;; XEmacs
 452         (progn
 453           (set-keymap-parent km widget-button-keymap)
 454           (define-key km [button1] 'tree-widget-button-click))
 455       ;; Emacs
 456       (set-keymap-parent km widget-keymap)
 457       (define-key km [down-mouse-1] 'tree-widget-button-click))
 458     km)
 459   "Keymap used inside node buttons.
 460 Handle mouse button 1 click on buttons.")
 461
 462 (define-widget 'tree-widget-icon 'push-button
 463   "Basic widget other tree-widget icons are derived from."
 464   :format        "%[%t%]"
 465   :button-keymap tree-widget-button-keymap ; XEmacs
 466   :keymap        tree-widget-button-keymap ; Emacs
 467   :create        'tree-widget-icon-create
 468   :action        'tree-widget-icon-action
 469   :help-echo     'tree-widget-icon-help-echo
 470   )
 471
 472 (define-widget 'tree-widget-open-icon 'tree-widget-icon
 473   "Icon for an expanded tree-widget node."
 474   :tag        "[-]"
 475   :glyph-name "open"
 476   )
 477
 478 (define-widget 'tree-widget-empty-icon 'tree-widget-icon
 479   "Icon for an expanded tree-widget node with no child."
 480   :tag        "[X]"
 481   :glyph-name "empty"
 482   )
 483
 484 (define-widget 'tree-widget-close-icon 'tree-widget-icon
 485   "Icon for a collapsed tree-widget node."
 486   :tag        "[+]"
 487   :glyph-name "close"
 488   )
 489
 490 (define-widget 'tree-widget-leaf-icon 'tree-widget-icon
 491   "Icon for a tree-widget leaf node."
 492   :tag        ""
 493   :glyph-name "leaf"
 494   :button-face 'default
 495   )
 496
 497 (define-widget 'tree-widget-guide 'item
 498   "Vertical guide line."
 499   :tag       " |"
 500   ;;:tag-glyph (tree-widget-find-image "guide")
 501   :format    "%t"
 502   )
 503
 504 (define-widget 'tree-widget-end-guide 'item
 505   "End of a vertical guide line."
 506   :tag       " `"
 507   ;;:tag-glyph (tree-widget-find-image "end-guide")
 508   :format    "%t"
 509   )
 510
 511 (define-widget 'tree-widget-no-guide 'item
 512   "Invisible vertical guide line."
 513   :tag       "  "
 514   ;;:tag-glyph (tree-widget-find-image "no-guide")
 515   :format    "%t"
 516   )
 517
 518 (define-widget 'tree-widget-handle 'item
 519   "Horizontal guide line that joins a vertical guide line to a node."
 520   :tag       "-"
 521   ;;:tag-glyph (tree-widget-find-image "handle")
 522   :format    "%t"
 523   )
 524
 525 (define-widget 'tree-widget-no-handle 'item
 526   "Invisible handle."
 527   :tag       " "
 528   ;;:tag-glyph (tree-widget-find-image "no-handle")
 529   :format    "%t"
 530   )
 531
 532 (define-widget 'tree-widget 'default
 533   "Tree widget."
 534   :format         "%v"
 535   :convert-widget 'tree-widget-convert-widget
 536   :value-get      'widget-value-value-get
 537   :value-delete   'widget-children-value-delete
 538   :value-create   'tree-widget-value-create
 539   :action         'tree-widget-action
 540   :help-echo      'tree-widget-help-echo
 541   :expander-p     'tree-widget-expander-p
 542   :open-icon      'tree-widget-open-icon
 543   :close-icon     'tree-widget-close-icon
 544   :empty-icon     'tree-widget-empty-icon
 545   :leaf-icon      'tree-widget-leaf-icon
 546   :guide          'tree-widget-guide
 547   :end-guide      'tree-widget-end-guide
 548   :no-guide       'tree-widget-no-guide
 549   :handle         'tree-widget-handle
 550   :no-handle      'tree-widget-no-handle
 551   )
 552 \f
 553 ;;; Widget support functions
 554 ;;
 555 (defun tree-widget-p (widget)
 556   "Return non-nil if WIDGET is a tree-widget."
 557   (let ((type (widget-type widget)))
 558     (while (and type (not (eq type 'tree-widget)))
 559       (setq type (widget-type (get type 'widget-type))))
 560     (eq type 'tree-widget)))
 561
 562 (defun tree-widget-node (widget)
 563   "Return WIDGET's :node child widget.
 564 If not found, setup an `item' widget as default.
 565 Signal an error if the :node widget is a tree-widget.
 566 WIDGET is, or derives from, a tree-widget."
 567   (let ((node (widget-get widget :node)))
 568     (if node
 569         ;; Check that the :node widget is not a tree-widget.
 570         (and (tree-widget-p node)
 571              (error "Invalid tree-widget :node %S" node))
 572       ;; Setup an item widget as default :node.
 573       (setq node `(item :tag ,(or (widget-get widget :tag)
 574                                   (widget-princ-to-string
 575                                    (widget-value widget)))))
 576       (widget-put widget :node node))
 577     node))
 578
 579 (defun tree-widget-keep (arg widget)
 580   "Save in ARG the WIDGET's properties specified by :keep."
 581   (dolist (prop (widget-get widget :keep))
 582     (widget-put arg prop (widget-get widget prop))))
 583
 584 (defun tree-widget-children-value-save (widget &optional args node)
 585   "Save WIDGET children values.
 586 WIDGET is, or derives from, a tree-widget.
 587 Children properties and values are saved in ARGS if non-nil, else in
 588 WIDGET's :args property value.  Properties and values of the
 589 WIDGET's :node sub-widget are saved in NODE if non-nil, else in
 590 WIDGET's :node sub-widget."
 591   (let ((args (cons (or node (widget-get widget :node))
 592                     (or args (widget-get widget :args))))
 593         (children (widget-get widget :children))
 594         arg child)
 595     (while (and args children)
 596       (setq arg      (car args)
 597             args     (cdr args)
 598             child    (car children)
 599             children (cdr children))
 600        (if (tree-widget-p child)
 601 ;;;; The child is a tree node.
 602            (progn
 603              ;; Backtrack :args and :node properties.
 604              (widget-put arg :args (widget-get child :args))
 605              (widget-put arg :node (widget-get child :node))
 606              ;; Save :open property.
 607              (widget-put arg :open (widget-get child :open))
 608              ;; The node is open.
 609              (when (widget-get child :open)
 610                ;; Save the widget value.
 611                (widget-put arg :value (widget-value child))
 612                ;; Save properties specified in :keep.
 613                (tree-widget-keep arg child)
 614                ;; Save children.
 615                (tree-widget-children-value-save
 616                 child (widget-get arg :args) (widget-get arg :node))))
 617 ;;;; Another non tree node.
 618          ;; Save the widget value.
 619          (widget-put arg :value (widget-value child))
 620          ;; Save properties specified in :keep.
 621          (tree-widget-keep arg child)))))
 622 \f
 623 ;;; Widget creation
 624 ;;
 625 (defvar tree-widget-before-create-icon-functions nil
 626   "Hooks run before to create a tree-widget icon.
 627 Each function is passed the icon widget not yet created.
 628 The value of the icon widget :node property is a tree :node widget or
 629 a leaf node widget, not yet created.
 630 This hook can be used to dynamically change properties of the icon and
 631 associated node widgets.  For example, to dynamically change the look
 632 and feel of the tree-widget by changing the values of the :tag
 633 and :glyph-name properties of the icon widget.
 634 This hook should be local in the buffer setup to display widgets.")
 635
 636 (defun tree-widget-icon-create (icon)
 637   "Create the ICON widget."
 638   (run-hook-with-args 'tree-widget-before-create-icon-functions icon)
 639   (widget-put icon :tag-glyph
 640               (tree-widget-find-image (widget-get icon :glyph-name)))
 641   ;; Ensure there is at least one char to display the image.
 642   (and (widget-get icon :tag-glyph)
 643        (equal "" (or (widget-get icon :tag) ""))
 644        (widget-put icon :tag " "))
 645   (widget-default-create icon)
 646   ;; Insert space between the icon and the node widget.
 647   (insert-char ?  1)
 648   (put-text-property
 649    (1- (point)) (point)
 650    'display (list 'space :width tree-widget-space-width)))
 651
 652 (defun tree-widget-convert-widget (widget)
 653   "Convert :args as widget types in WIDGET."
 654   (let ((tree (widget-types-convert-widget widget)))
 655     ;; Compatibility
 656     (widget-put tree :expander (or (widget-get tree :expander)
 657                                    (widget-get tree :dynargs)))
 658     tree))
 659
 660 (defvar widget-glyph-enable) ; XEmacs
 661
 662 (defun tree-widget-value-create (tree)
 663   "Create the TREE tree-widget."
 664   (let* ((node   (tree-widget-node tree))
 665          (flags  (widget-get tree :tree-widget--guide-flags))
 666          (indent (widget-get tree :indent))
 667          ;; Setup widget's image support.  Looking up for images, and
 668          ;; setting widgets' :tag-glyph is done here, to allow to
 669          ;; dynamically change the image theme.
 670          (widget-image-enable (tree-widget-use-image-p))     ; Emacs
 671          (widget-glyph-enable widget-image-enable)           ; XEmacs
 672          children buttons)
 673     (and indent (not (widget-get tree :parent))
 674          (insert-char ?\  indent))
 675     (if (widget-get tree :open)
 676 ;;;; Expanded node.
 677         (let ((args     (widget-get tree :args))
 678               (guide    (widget-get tree :guide))
 679               (noguide  (widget-get tree :no-guide))
 680               (endguide (widget-get tree :end-guide))
 681               (handle   (widget-get tree :handle))
 682               (nohandle (widget-get tree :no-handle))
 683               (guidi    (tree-widget-find-image "guide"))
 684               (noguidi  (tree-widget-find-image "no-guide"))
 685               (endguidi (tree-widget-find-image "end-guide"))
 686               (handli   (tree-widget-find-image "handle"))
 687               (nohandli (tree-widget-find-image "no-handle")))
 688           ;; Request children at run time, when requested.
 689           (when (and (widget-get tree :expander)
 690                      (widget-apply tree :expander-p))
 691             (setq args (mapcar 'widget-convert
 692                                (widget-apply tree :expander)))
 693             (widget-put tree :args args))
 694           ;; Defer the node widget creation after icon creation.
 695           (widget-put tree :node (widget-convert node))
 696           ;; Create the icon widget for the expanded tree.
 697           (push (widget-create-child-and-convert
 698                  tree (widget-get tree (if args :open-icon :empty-icon))
 699                  ;; Pass the node widget to child.
 700                  :node (widget-get tree :node))
 701                 buttons)
 702           ;; Create the tree node widget.
 703           (push (widget-create-child tree (widget-get tree :node))
 704                 children)
 705           ;; Update the icon :node with the created node widget.
 706           (widget-put (car buttons) :node (car children))
 707           ;; Create the tree children.
 708           (while args
 709             (setq node (car args)
 710                   args (cdr args))
 711             (and indent (insert-char ?\  indent))
 712             ;; Insert guide lines elements from previous levels.
 713             (dolist (f (reverse flags))
 714               (widget-create-child-and-convert
 715                tree (if f guide noguide)
 716                :tag-glyph (if f guidi noguidi))
 717               (widget-create-child-and-convert
 718                tree nohandle :tag-glyph nohandli))
 719             ;; Insert guide line element for this level.
 720             (widget-create-child-and-convert
 721              tree (if args guide endguide)
 722              :tag-glyph (if args guidi endguidi))
 723             ;; Insert the node handle line
 724             (widget-create-child-and-convert
 725              tree handle :tag-glyph handli)
 726             (if (tree-widget-p node)
 727                 ;; Create a sub-tree node.
 728                 (push (widget-create-child-and-convert
 729                        tree node :tree-widget--guide-flags
 730                        (cons (if args t) flags))
 731                       children)
 732               ;; Create the icon widget for a leaf node.
 733               (push (widget-create-child-and-convert
 734                      tree (widget-get tree :leaf-icon)
 735                      ;; At this point the node widget isn't yet created.
 736                      :node (setq node (widget-convert
 737                                        node :tree-widget--guide-flags
 738                                        (cons (if args t) flags)))
 739                      :tree-widget--leaf-flag t)
 740                     buttons)
 741               ;; Create the leaf node widget.
 742               (push (widget-create-child tree node) children)
 743               ;; Update the icon :node with the created node widget.
 744               (widget-put (car buttons) :node (car children)))))
 745 ;;;; Collapsed node.
 746       ;; Defer the node widget creation after icon creation.
 747       (widget-put tree :node (widget-convert node))
 748       ;; Create the icon widget for the collapsed tree.
 749       (push (widget-create-child-and-convert
 750              tree (widget-get tree :close-icon)
 751              ;; Pass the node widget to child.
 752              :node (widget-get tree :node))
 753             buttons)
 754       ;; Create the tree node widget.
 755       (push (widget-create-child tree (widget-get tree :node))
 756             children)
 757       ;; Update the icon :node with the created node widget.
 758       (widget-put (car buttons) :node (car children)))
 759     ;; Save widget children and buttons.  The tree-widget :node child
 760     ;; is the first element in :children.
 761     (widget-put tree :children (nreverse children))
 762     (widget-put tree :buttons  buttons)))
 763 \f
 764 ;;; Widget callbacks
 765 ;;
 766 (defsubst tree-widget-leaf-node-icon-p (icon)
 767   "Return non-nil if ICON is a leaf node icon.
 768 That is, if its :node property value is a leaf node widget."
 769   (widget-get icon :tree-widget--leaf-flag))
 770
 771 (defun tree-widget-icon-action (icon &optional event)
 772   "Handle the ICON widget :action.
 773 If ICON :node is a leaf node it handles the :action.  The tree-widget
 774 parent of ICON handles the :action otherwise.
 775 Pass the received EVENT to :action."
 776   (let ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 777                                    :node :parent))))
 778     (widget-apply node :action event)))
 779
 780 (defun tree-widget-icon-help-echo (icon)
 781   "Return the help-echo string of ICON.
 782 If ICON :node is a leaf node it handles the :help-echo.  The tree-widget
 783 parent of ICON handles the :help-echo otherwise."
 784   (let* ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 785                                     :node :parent)))
 786          (help-echo (widget-get node :help-echo)))
 787     (if (functionp help-echo)
 788         (funcall help-echo node)
 789       help-echo)))
 790
 791 (defvar tree-widget-after-toggle-functions nil
 792   "Hooks run after toggling a tree-widget expansion.
 793 Each function is passed a tree-widget.  If the value of the :open
 794 property is non-nil the tree has been expanded, else collapsed.
 795 This hook should be local in the buffer setup to display widgets.")
 796
 797 (defun tree-widget-action (tree &optional _event)
 798   "Handle the :action of the TREE tree-widget.
 799 That is, toggle expansion of the TREE tree-widget.
 800 Ignore the EVENT argument."
 801   (let ((open (not (widget-get tree :open))))
 802     (or open
 803         ;; Before to collapse the node, save children values so next
 804         ;; open can recover them.
 805         (tree-widget-children-value-save tree))
 806     (widget-put tree :open open)
 807     (widget-value-set tree open)
 808     (run-hook-with-args 'tree-widget-after-toggle-functions tree)))
 809
 810 (defun tree-widget-help-echo (tree)
 811   "Return the help-echo string of the TREE tree-widget."
 812   (if (widget-get tree :open)
 813       "Collapse node"
 814     "Expand node"))
 815
 816 (defun tree-widget-expander-p (tree)
 817   "Return non-nil if the TREE tree-widget :expander has to be called.
 818 That is, if TREE :args is nil."
 819   (null (widget-get tree :args)))
 820
 821 (provide 'tree-widget)
 822
 823 ;;; tree-widget.el ends here