lisp/tree-widget.el

   1 ;;; tree-widget.el --- Tree widget
   2
   3 ;; Copyright (C) 2004, 2005 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 ;; This program is free software; you can redistribute it and/or
  13 ;; modify it under the terms of the GNU General Public License as
  14 ;; published by the Free Software Foundation; either version 2, or (at
  15 ;; your option) any later version.
  16
  17 ;; This program is distributed in the hope that it will be useful, but
  18 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 ;; General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with this program; see the file COPYING.  If not, write to
  24 ;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28 ;;
  29 ;; This library provide a tree widget useful to display data
  30 ;; structures organized in a hierarchical order.
  31 ;;
  32 ;; The following properties are specific to the tree widget:
  33 ;;
  34 ;; :open
  35 ;;    Set to non-nil to expand the tree.  By default the tree is
  36 ;;    collapsed.
  37 ;;
  38 ;; :node
  39 ;;    Specify the widget used to represent the value of a tree node.
  40 ;;    By default this is an `item' widget which displays the
  41 ;;    tree-widget :tag property value if defined, or a string
  42 ;;    representation of the tree-widget value.
  43 ;;
  44 ;; :keep
  45 ;;    Specify a list of properties to keep when the tree is collapsed
  46 ;;    so they can be recovered when the tree is expanded.  This
  47 ;;    property can be used in child widgets too.
  48 ;;
  49 ;; :expander (obsoletes :dynargs)
  50 ;;    Specify a function to be called to dynamically provide the
  51 ;;    tree's children in response to an expand request.  This function
  52 ;;    will be passed the tree widget and must return a list of child
  53 ;;    widgets.
  54 ;;
  55 ;;    *Please note:* Child widgets returned by the :expander function
  56 ;;    are stored in the :args property of the tree widget.  To speed
  57 ;;    up successive expand requests, the :expander function is not
  58 ;;    called again when the :args value is non-nil.  To refresh child
  59 ;;    values, it is necessary to set the :args property to nil, then
  60 ;;    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
 129   (not (or (featurep 'xemacs) (< emacs-major-version 21)))
 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 where to search for the themes sub-directory.
 142 Each element is an expression that will be evaluated to return a
 143 single directory or a list of directories to search.
 144
 145 The default is to search in the `load-path' first, then in the
 146 \"images\" sub directory in the data directory, then in the data
 147 directory.
 148 The data directory is the value of the variable `data-directory' on
 149 Emacs, and what `(locate-data-directory \"tree-widget\")' returns on
 150 XEmacs.")
 151
 152 (defcustom tree-widget-themes-directory "tree-widget"
 153   "*Name of the directory where to look up for image themes.
 154 When nil use the directory where the tree-widget library is located.
 155 When a relative name is specified, try to locate that sub directory in
 156 the locations specified in `tree-widget-themes-load-path'.
 157 The default is to use the \"tree-widget\" relative name."
 158   :type '(choice (const :tag "Default" "tree-widget")
 159                  (const :tag "With the library" nil)
 160                  (directory :format "%{%t%}:\n%v"))
 161   :group 'tree-widget)
 162
 163 (defcustom tree-widget-theme nil
 164   "*Name of the theme where to look up for images.
 165 It must be a sub directory of the directory specified in variable
 166 `tree-widget-themes-directory'.  The default theme is \"default\".
 167 When an image is not found in a theme, it is searched in the default
 168 theme.
 169
 170 A complete theme must at least contain images with these file names
 171 with a supported extension (see also `tree-widget-image-formats'):
 172
 173 \"guide\"
 174   A vertical guide line.
 175 \"no-guide\"
 176   An invisible vertical guide line.
 177 \"end-guide\"
 178   End of a vertical guide line.
 179 \"handle\"
 180   Horizontal guide line that joins the vertical guide line to an icon.
 181 \"no-handle\"
 182   An invisible handle.
 183
 184 Plus images whose name is given by the :glyph-name property of the
 185 icon widgets used to draw the tree.  By default these images are used:
 186
 187 \"open\"
 188   Icon associated to an expanded tree.
 189 \"close\"
 190   Icon associated to a collapsed tree.
 191 \"empty\"
 192   Icon associated to an expanded tree with no child.
 193 \"leaf\"
 194   Icon associated to a leaf node."
 195   :type '(choice (const  :tag "Default" nil)
 196                  (string :tag "Name"))
 197   :group 'tree-widget)
 198
 199 (defcustom tree-widget-image-properties-emacs
 200   '(:ascent center :mask (heuristic t))
 201   "*Default properties of Emacs images."
 202   :type 'plist
 203   :group 'tree-widget)
 204
 205 (defcustom tree-widget-image-properties-xemacs
 206   nil
 207   "*Default properties of XEmacs images."
 208   :type 'plist
 209   :group 'tree-widget)
 210
 211 (defcustom tree-widget-space-width 0.5
 212   "Amount of space between an icon image and a node widget.
 213 Must be a valid space :width display property."
 214   :group 'tree-widget
 215   :type 'sexp)
 216 \f
 217 ;;; Image support
 218 ;;
 219 (eval-and-compile ;; Emacs/XEmacs compatibility stuff
 220   (cond
 221    ;; XEmacs
 222    ((featurep 'xemacs)
 223     (defsubst tree-widget-use-image-p ()
 224       "Return non-nil if image support is currently enabled."
 225       (and tree-widget-image-enable
 226            widget-glyph-enable
 227            (console-on-window-system-p)))
 228     (defsubst tree-widget-create-image (type file &optional props)
 229       "Create an image of type TYPE from FILE, and return it.
 230 Give the image the specified properties PROPS."
 231       (apply 'make-glyph `([,type :file ,file ,@props])))
 232     (defsubst tree-widget-image-formats ()
 233       "Return the alist of image formats/file name extensions.
 234 See also the option `widget-image-file-name-suffixes'."
 235       (delq nil
 236             (mapcar
 237              #'(lambda (fmt)
 238                  (and (valid-image-instantiator-format-p (car fmt)) fmt))
 239              widget-image-file-name-suffixes)))
 240     )
 241    ;; Emacs
 242    (t
 243     (defsubst tree-widget-use-image-p ()
 244       "Return non-nil if image support is currently enabled."
 245       (and tree-widget-image-enable
 246            widget-image-enable
 247            (display-images-p)))
 248     (defsubst tree-widget-create-image (type file &optional props)
 249       "Create an image of type TYPE from FILE, and return it.
 250 Give the image the specified properties PROPS."
 251       (apply 'create-image `(,file ,type nil ,@props)))
 252     (defsubst tree-widget-image-formats ()
 253       "Return the alist of image formats/file name extensions.
 254 See also the option `widget-image-conversion'."
 255       (delq nil
 256             (mapcar
 257              #'(lambda (fmt)
 258                  (and (image-type-available-p (car fmt)) fmt))
 259              widget-image-conversion)))
 260     ))
 261   )
 262
 263 ;; Buffer local cache of theme data.
 264 (defvar tree-widget--theme nil)
 265
 266 (defsubst tree-widget-theme-name ()
 267   "Return the current theme name, or nil if no theme is active."
 268   (and tree-widget--theme (aref tree-widget--theme 0)))
 269
 270 (defsubst tree-widget-set-theme (&optional name)
 271   "In the current buffer, set the theme to use for images.
 272 The current buffer must be where the tree widget is drawn.
 273 Optional argument NAME is the name of the theme to use.  It defaults
 274 to the value of the variable `tree-widget-theme'.
 275 Does nothing if NAME is already the current theme."
 276   (or name (setq name (or tree-widget-theme "default")))
 277   (unless (string-equal name (tree-widget-theme-name))
 278     (set (make-local-variable 'tree-widget--theme)
 279          (make-vector 4 nil))
 280     (aset tree-widget--theme 0 name)))
 281
 282 (defun tree-widget--locate-sub-directory (name path)
 283   "Locate the sub-directory NAME in PATH.
 284 Return the absolute name of the directory found, or nil if not found."
 285   (let (dir elt)
 286     (while (and (not dir) (consp path))
 287       (setq elt  (condition-case nil (eval (car path)) (error nil))
 288             path (cdr path))
 289       (cond
 290        ((stringp elt)
 291         (setq dir (expand-file-name name elt))
 292         (or (file-accessible-directory-p dir)
 293             (setq dir nil)))
 294        ((and elt (not (equal elt (car path))))
 295         (setq dir (tree-widget--locate-sub-directory name elt)))))
 296     dir))
 297
 298 (defun tree-widget-themes-directory ()
 299   "Locate the directory where to search for a theme.
 300 It is defined in variable `tree-widget-themes-directory'.
 301 Return the absolute name of the directory found, or nil if the
 302 specified directory is not accessible."
 303   (let ((found (aref tree-widget--theme 1)))
 304     (cond
 305      ;; The directory was not found.
 306      ((eq found 'void)
 307       (setq found nil))
 308      ;; The directory is available in the cache.
 309      (found)
 310      ;; Use the directory where this library is located.
 311      ((null tree-widget-themes-directory)
 312       (setq found (locate-library "tree-widget"))
 313       (when found
 314         (setq found (file-name-directory found))
 315         (or (file-accessible-directory-p found)
 316             (setq found nil))))
 317      ;; Check accessibility of absolute directory name.
 318      ((file-name-absolute-p tree-widget-themes-directory)
 319       (setq found (expand-file-name tree-widget-themes-directory))
 320       (or (file-accessible-directory-p found)
 321           (setq found nil)))
 322      ;; Locate a sub-directory in `tree-widget-themes-load-path'.
 323      (t
 324       (setq found (tree-widget--locate-sub-directory
 325                    tree-widget-themes-directory
 326                    tree-widget-themes-load-path))))
 327     ;; Store the result in the cache for later use.
 328     (aset tree-widget--theme 1 (or found 'void))
 329     found))
 330
 331 (defsubst tree-widget-set-image-properties (props)
 332   "In current theme, set images properties to PROPS."
 333   (aset tree-widget--theme 2 props))
 334
 335 (defun tree-widget-image-properties (file)
 336   "Return the properties of an image in current theme.
 337 FILE is the absolute file name of an image.
 338
 339 If there is a \"tree-widget-theme-setup\" library in the theme
 340 directory, where is located FILE, load it to setup theme images
 341 properties.  Typically it should contain something like this:
 342
 343   (tree-widget-set-image-properties
 344    (if (featurep 'xemacs)
 345        '(:ascent center)
 346      '(:ascent center :mask (heuristic t))
 347      ))
 348
 349 When there is no \"tree-widget-theme-setup\" library in the current
 350 theme directory, load the one from the default theme, if available.
 351 Default global properties are provided for respectively Emacs and
 352 XEmacs in the variables `tree-widget-image-properties-emacs', and
 353 `tree-widget-image-properties-xemacs'."
 354   ;; If properties are in the cache, use them.
 355   (let ((plist (aref tree-widget--theme 2)))
 356     (unless plist
 357       ;; Load tree-widget-theme-setup if available.
 358       (load (expand-file-name "tree-widget-theme-setup"
 359                               (file-name-directory file)) t t)
 360       ;; If properties have been setup, use them.
 361       (unless (setq plist (aref tree-widget--theme 2))
 362         ;; Try from the default theme.
 363         (load (expand-file-name "../default/tree-widget-theme-setup"
 364                                 (file-name-directory file)) t t)
 365         ;; If properties have been setup, use them.
 366         (unless (setq plist (aref tree-widget--theme 2))
 367           ;; By default, use supplied global properties.
 368           (setq plist (if (featurep 'xemacs)
 369                           tree-widget-image-properties-xemacs
 370                         tree-widget-image-properties-emacs))
 371           ;; Setup the cache.
 372           (tree-widget-set-image-properties plist))))
 373     plist))
 374
 375 (defconst tree-widget--cursors
 376   ;; Pointer shapes when the mouse pointer is over inactive
 377   ;; tree-widget images.  This feature works since Emacs 22, and
 378   ;; ignored on older versions, and XEmacs.
 379   '(
 380     ("guide"     . arrow)
 381     ("no-guide"  . arrow)
 382     ("end-guide" . arrow)
 383     ("handle"    . arrow)
 384     ("no-handle" . arrow)
 385     ))
 386
 387 (defun tree-widget-lookup-image (name)
 388   "Look up in current theme for an image with NAME.
 389 Search first in current theme, then in default theme (see also the
 390 variable `tree-widget-theme').
 391 Return the first image found having a supported format, or nil if not
 392 found."
 393   (let ((default-directory (tree-widget-themes-directory)))
 394     (when default-directory
 395       (let (file (theme (tree-widget-theme-name)))
 396         (catch 'found
 397           (dolist (dir (if (string-equal theme "default")
 398                            '("default") (list theme "default")))
 399             (dolist (fmt (tree-widget-image-formats))
 400               (dolist (ext (cdr fmt))
 401                 (setq file (expand-file-name (concat name ext) dir))
 402                 (and
 403                  (file-readable-p file)
 404                  (file-regular-p file)
 405                  (throw
 406                   'found
 407                   (tree-widget-create-image
 408                    (car fmt) file
 409                    ;; Add the pointer shape
 410                    (cons :pointer
 411                          (cons
 412                           (or (cdr (assoc name tree-widget--cursors))
 413                               'hand)
 414                           (tree-widget-image-properties file)))))))))
 415           nil)))))
 416
 417 (defun tree-widget-find-image (name)
 418   "Find the image with NAME in current theme.
 419 NAME is an image file name sans extension.
 420 Return the image found, or nil if not found."
 421   (when (tree-widget-use-image-p)
 422     ;; Ensure there is an active theme.
 423     (tree-widget-set-theme (tree-widget-theme-name))
 424     (let ((image (assoc name (aref tree-widget--theme 3))))
 425       ;; The image NAME is found in the cache.
 426       (if image
 427           (cdr image)
 428         ;; Search the image in current, and default themes.
 429         (prog1
 430             (setq image (tree-widget-lookup-image name))
 431           ;; Store image reference in the cache for later use.
 432           (push (cons name image) (aref tree-widget--theme 3))))
 433       )))
 434 \f
 435 ;;; Widgets
 436 ;;
 437 (defun tree-widget-button-click (event)
 438   "Move to the position clicked on, and if it is a button, invoke it.
 439 EVENT is the mouse event received."
 440   (interactive "e")
 441   (mouse-set-point event)
 442   (let ((pos (widget-event-point event)))
 443     (if (get-char-property pos 'button)
 444         (widget-button-click event))))
 445
 446 (defvar tree-widget-button-keymap
 447   (let ((km (make-sparse-keymap)))
 448     (if (boundp 'widget-button-keymap)
 449         ;; XEmacs
 450         (progn
 451           (set-keymap-parent km widget-button-keymap)
 452           (define-key km [button1] 'tree-widget-button-click))
 453       ;; Emacs
 454       (set-keymap-parent km widget-keymap)
 455       (define-key km [down-mouse-1] 'tree-widget-button-click))
 456     km)
 457   "Keymap used inside node buttons.
 458 Handle mouse button 1 click on buttons.")
 459
 460 (define-widget 'tree-widget-icon 'push-button
 461   "Basic widget other tree-widget icons are derived from."
 462   :format        "%[%t%]"
 463   :button-keymap tree-widget-button-keymap ; XEmacs
 464   :keymap        tree-widget-button-keymap ; Emacs
 465   :create        'tree-widget-icon-create
 466   :action        'tree-widget-icon-action
 467   :help-echo     'tree-widget-icon-help-echo
 468   )
 469
 470 (define-widget 'tree-widget-open-icon 'tree-widget-icon
 471   "Icon for an expanded tree-widget node."
 472   :tag        "[-]"
 473   :glyph-name "open"
 474   )
 475
 476 (define-widget 'tree-widget-empty-icon 'tree-widget-icon
 477   "Icon for an expanded tree-widget node with no child."
 478   :tag        "[X]"
 479   :glyph-name "empty"
 480   )
 481
 482 (define-widget 'tree-widget-close-icon 'tree-widget-icon
 483   "Icon for a collapsed tree-widget node."
 484   :tag        "[+]"
 485   :glyph-name "close"
 486   )
 487
 488 (define-widget 'tree-widget-leaf-icon 'tree-widget-icon
 489   "Icon for a tree-widget leaf node."
 490   :tag        ""
 491   :glyph-name "leaf"
 492   :button-face 'default
 493   )
 494
 495 (define-widget 'tree-widget-guide 'item
 496   "Vertical guide line."
 497   :tag       " |"
 498   ;;:tag-glyph (tree-widget-find-image "guide")
 499   :format    "%t"
 500   )
 501
 502 (define-widget 'tree-widget-end-guide 'item
 503   "End of a vertical guide line."
 504   :tag       " `"
 505   ;;:tag-glyph (tree-widget-find-image "end-guide")
 506   :format    "%t"
 507   )
 508
 509 (define-widget 'tree-widget-no-guide 'item
 510   "Invisible vertical guide line."
 511   :tag       "  "
 512   ;;:tag-glyph (tree-widget-find-image "no-guide")
 513   :format    "%t"
 514   )
 515
 516 (define-widget 'tree-widget-handle 'item
 517   "Horizontal guide line that joins a vertical guide line to a node."
 518   :tag       "-"
 519   ;;:tag-glyph (tree-widget-find-image "handle")
 520   :format    "%t"
 521   )
 522
 523 (define-widget 'tree-widget-no-handle 'item
 524   "Invisible handle."
 525   :tag       " "
 526   ;;:tag-glyph (tree-widget-find-image "no-handle")
 527   :format    "%t"
 528   )
 529
 530 (define-widget 'tree-widget 'default
 531   "Tree widget."
 532   :format         "%v"
 533   :convert-widget 'widget-types-convert-widget
 534   :value-get      'widget-value-value-get
 535   :value-delete   'widget-children-value-delete
 536   :value-create   'tree-widget-value-create
 537   :action         'tree-widget-action
 538   :help-echo      'tree-widget-help-echo
 539   :open-icon      'tree-widget-open-icon
 540   :close-icon     'tree-widget-close-icon
 541   :empty-icon     'tree-widget-empty-icon
 542   :leaf-icon      'tree-widget-leaf-icon
 543   :guide          'tree-widget-guide
 544   :end-guide      'tree-widget-end-guide
 545   :no-guide       'tree-widget-no-guide
 546   :handle         'tree-widget-handle
 547   :no-handle      'tree-widget-no-handle
 548   )
 549 \f
 550 ;;; Widget support functions
 551 ;;
 552 (defun tree-widget-p (widget)
 553   "Return non-nil if WIDGET is a tree-widget."
 554   (let ((type (widget-type widget)))
 555     (while (and type (not (eq type 'tree-widget)))
 556       (setq type (widget-type (get type 'widget-type))))
 557     (eq type 'tree-widget)))
 558
 559 (defun tree-widget-node (widget)
 560   "Return WIDGET's :node child widget.
 561 If not found, setup an `item' widget as default.
 562 Signal an error if the :node widget is a tree-widget.
 563 WIDGET is, or derives from, a tree-widget."
 564   (let ((node (widget-get widget :node)))
 565     (if node
 566         ;; Check that the :node widget is not a tree-widget.
 567         (and (tree-widget-p node)
 568              (error "Invalid tree-widget :node %S" node))
 569       ;; Setup an item widget as default :node.
 570       (setq node `(item :tag ,(or (widget-get widget :tag)
 571                                   (widget-princ-to-string
 572                                    (widget-value widget)))))
 573       (widget-put widget :node node))
 574     node))
 575
 576 (defun tree-widget-keep (arg widget)
 577   "Save in ARG the WIDGET's properties specified by :keep."
 578   (dolist (prop (widget-get widget :keep))
 579     (widget-put arg prop (widget-get widget prop))))
 580
 581 (defun tree-widget-children-value-save (widget &optional args node)
 582   "Save WIDGET children values.
 583 WIDGET is, or derives from, a tree-widget.
 584 Children properties and values are saved in ARGS if non-nil, else in
 585 WIDGET's :args property value.  Properties and values of the
 586 WIDGET's :node sub-widget are saved in NODE if non-nil, else in
 587 WIDGET's :node sub-widget."
 588   (let ((args (cons (or node (widget-get widget :node))
 589                     (or args (widget-get widget :args))))
 590         (children (widget-get widget :children))
 591         arg child)
 592     (while (and args children)
 593       (setq arg      (car args)
 594             args     (cdr args)
 595             child    (car children)
 596             children (cdr children))
 597        (if (tree-widget-p child)
 598 ;;;; The child is a tree node.
 599            (progn
 600              ;; Backtrack :args and :node properties.
 601              (widget-put arg :args (widget-get child :args))
 602              (widget-put arg :node (widget-get child :node))
 603              ;; Save :open property.
 604              (widget-put arg :open (widget-get child :open))
 605              ;; The node is open.
 606              (when (widget-get child :open)
 607                ;; Save the widget value.
 608                (widget-put arg :value (widget-value child))
 609                ;; Save properties specified in :keep.
 610                (tree-widget-keep arg child)
 611                ;; Save children.
 612                (tree-widget-children-value-save
 613                 child (widget-get arg :args) (widget-get arg :node))))
 614 ;;;; Another non tree node.
 615          ;; Save the widget value.
 616          (widget-put arg :value (widget-value child))
 617          ;; Save properties specified in :keep.
 618          (tree-widget-keep arg child)))))
 619 \f
 620 ;;; Widget creation
 621 ;;
 622 (defvar tree-widget-before-create-icon-functions nil
 623   "Hooks run before to create a tree-widget icon.
 624 Each function is passed the icon widget not yet created.
 625 The value of the icon widget :node property is a tree :node widget or
 626 a leaf node widget, not yet created.
 627 This hook can be used to dynamically change properties of the icon and
 628 associated node widgets.  For example, to dynamically change the look
 629 and feel of the tree-widget by changing the values of the :tag
 630 and :glyph-name properties of the icon widget.
 631 This hook should be local in the buffer setup to display widgets.")
 632
 633 (defun tree-widget-icon-create (icon)
 634   "Create the ICON widget."
 635   (run-hook-with-args 'tree-widget-before-create-icon-functions icon)
 636   (widget-put icon :tag-glyph
 637               (tree-widget-find-image (widget-get icon :glyph-name)))
 638   ;; Ensure there is at least one char to display the image.
 639   (and (widget-get icon :tag-glyph)
 640        (equal "" (or (widget-get icon :tag) ""))
 641        (widget-put icon :tag " "))
 642   (widget-default-create icon)
 643   ;; Insert space between the icon and the node widget.
 644   (insert-char ?  1)
 645   (put-text-property
 646    (1- (point)) (point)
 647    'display (list 'space :width tree-widget-space-width)))
 648
 649 (defun tree-widget-value-create (tree)
 650   "Create the TREE tree-widget."
 651   (let* ((node   (tree-widget-node tree))
 652          (flags  (widget-get tree :tree-widget--guide-flags))
 653          (indent (widget-get tree :indent))
 654          ;; Setup widget's image support.  Looking up for images, and
 655          ;; setting widgets' :tag-glyph is done here, to allow to
 656          ;; dynamically change the image theme.
 657          (widget-image-enable (tree-widget-use-image-p))     ; Emacs
 658          (widget-glyph-enable widget-image-enable)           ; XEmacs
 659          children buttons)
 660     (and indent (not (widget-get tree :parent))
 661          (insert-char ?\  indent))
 662     (if (widget-get tree :open)
 663 ;;;; Expanded node.
 664         (let ((args     (widget-get tree :args))
 665               (xpandr   (or (widget-get tree :expander)
 666                             (widget-get tree :dynargs)))
 667               (guide    (widget-get tree :guide))
 668               (noguide  (widget-get tree :no-guide))
 669               (endguide (widget-get tree :end-guide))
 670               (handle   (widget-get tree :handle))
 671               (nohandle (widget-get tree :no-handle))
 672               (guidi    (tree-widget-find-image "guide"))
 673               (noguidi  (tree-widget-find-image "no-guide"))
 674               (endguidi (tree-widget-find-image "end-guide"))
 675               (handli   (tree-widget-find-image "handle"))
 676               (nohandli (tree-widget-find-image "no-handle")))
 677           ;; Request children at run time, when not already done.
 678           (when (and (not args) xpandr)
 679             (setq args (mapcar 'widget-convert (funcall xpandr tree)))
 680             (widget-put tree :args args))
 681           ;; Defer the node widget creation after icon creation.
 682           (widget-put tree :node (widget-convert node))
 683           ;; Create the icon widget for the expanded tree.
 684           (push (widget-create-child-and-convert
 685                  tree (widget-get tree (if args :open-icon :empty-icon))
 686                  ;; Pass the node widget to child.
 687                  :node (widget-get tree :node))
 688                 buttons)
 689           ;; Create the tree node widget.
 690           (push (widget-create-child tree (widget-get tree :node))
 691                 children)
 692           ;; Update the icon :node with the created node widget.
 693           (widget-put (car buttons) :node (car children))
 694           ;; Create the tree children.
 695           (while args
 696             (setq node (car args)
 697                   args (cdr args))
 698             (and indent (insert-char ?\  indent))
 699             ;; Insert guide lines elements from previous levels.
 700             (dolist (f (reverse flags))
 701               (widget-create-child-and-convert
 702                tree (if f guide noguide)
 703                :tag-glyph (if f guidi noguidi))
 704               (widget-create-child-and-convert
 705                tree nohandle :tag-glyph nohandli))
 706             ;; Insert guide line element for this level.
 707             (widget-create-child-and-convert
 708              tree (if args guide endguide)
 709              :tag-glyph (if args guidi endguidi))
 710             ;; Insert the node handle line
 711             (widget-create-child-and-convert
 712              tree handle :tag-glyph handli)
 713             (if (tree-widget-p node)
 714                 ;; Create a sub-tree node.
 715                 (push (widget-create-child-and-convert
 716                        tree node :tree-widget--guide-flags
 717                        (cons (if args t) flags))
 718                       children)
 719               ;; Create the icon widget for a leaf node.
 720               (push (widget-create-child-and-convert
 721                      tree (widget-get tree :leaf-icon)
 722                      ;; At this point the node widget isn't yet created.
 723                      :node (setq node (widget-convert
 724                                        node :tree-widget--guide-flags
 725                                        (cons (if args t) flags)))
 726                      :tree-widget--leaf-flag t)
 727                     buttons)
 728               ;; Create the leaf node widget.
 729               (push (widget-create-child tree node) children)
 730               ;; Update the icon :node with the created node widget.
 731               (widget-put (car buttons) :node (car children)))))
 732 ;;;; Collapsed node.
 733       ;; Defer the node widget creation after icon creation.
 734       (widget-put tree :node (widget-convert node))
 735       ;; Create the icon widget for the collapsed tree.
 736       (push (widget-create-child-and-convert
 737              tree (widget-get tree :close-icon)
 738              ;; Pass the node widget to child.
 739              :node (widget-get tree :node))
 740             buttons)
 741       ;; Create the tree node widget.
 742       (push (widget-create-child tree (widget-get tree :node))
 743             children)
 744       ;; Update the icon :node with the created node widget.
 745       (widget-put (car buttons) :node (car children)))
 746     ;; Save widget children and buttons.  The tree-widget :node child
 747     ;; is the first element in :children.
 748     (widget-put tree :children (nreverse children))
 749     (widget-put tree :buttons  buttons)))
 750 \f
 751 ;;; Widget callbacks
 752 ;;
 753 (defsubst tree-widget-leaf-node-icon-p (icon)
 754   "Return non-nil if ICON is a leaf node icon.
 755 That is, if its :node property value is a leaf node widget."
 756   (widget-get icon :tree-widget--leaf-flag))
 757
 758 (defun tree-widget-icon-action (icon &optional event)
 759   "Handle the ICON widget :action.
 760 If ICON :node is a leaf node it handles the :action.  The tree-widget
 761 parent of ICON handles the :action otherwise.
 762 Pass the received EVENT to :action."
 763   (let ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 764                                    :node :parent))))
 765     (widget-apply node :action event)))
 766
 767 (defun tree-widget-icon-help-echo (icon)
 768   "Return the help-echo string of ICON.
 769 If ICON :node is a leaf node it handles the :help-echo.  The tree-widget
 770 parent of ICON handles the :help-echo otherwise."
 771   (let* ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 772                                     :node :parent)))
 773          (help-echo (widget-get node :help-echo)))
 774     (if (functionp help-echo)
 775         (funcall help-echo node)
 776       help-echo)))
 777
 778 (defvar tree-widget-after-toggle-functions nil
 779   "Hooks run after toggling a tree-widget expansion.
 780 Each function is passed a tree-widget.  If the value of the :open
 781 property is non-nil the tree has been expanded, else collapsed.
 782 This hook should be local in the buffer setup to display widgets.")
 783
 784 (defun tree-widget-action (tree &optional event)
 785   "Handle the :action of the TREE tree-widget.
 786 That is, toggle expansion of the TREE tree-widget.
 787 Ignore the EVENT argument."
 788   (let ((open (not (widget-get tree :open))))
 789     (or open
 790         ;; Before to collapse the node, save children values so next
 791         ;; open can recover them.
 792         (tree-widget-children-value-save tree))
 793     (widget-put tree :open open)
 794     (widget-value-set tree open)
 795     (run-hook-with-args 'tree-widget-after-toggle-functions tree)))
 796
 797 (defun tree-widget-help-echo (tree)
 798   "Return the help-echo string of the TREE tree-widget."
 799   (if (widget-get tree :open)
 800       "Collapse node"
 801     "Expand node"))
 802
 803 (provide 'tree-widget)
 804
 805 ;; arch-tag: c3a1ada2-1663-41dc-9d16-2479ed8320e8
 806 ;;; tree-widget.el ends here