1;;; tree-widget.el --- Tree widget
2
3;; Copyright (C) 2004, 2005, 2006, 2007 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.  Child widgets returned by the :expander function are
54;;    stored in the :args property of the tree widget.
55;;
56;; :expander-p
57;;    Specify a predicate which must return non-nil to indicate that
58;;    the :expander function above has to be called.  By default, to
59;;    speed up successive expand requests, the :expander-p predicate
60;;    return non-nil when the :args value is nil.  So, by default, to
61;;    refresh child values, it is necessary to set the :args property
62;;    to nil, then redraw the tree.
63;;
64;; :open-icon  (default `tree-widget-open-icon')
65;; :close-icon (default `tree-widget-close-icon')
66;; :empty-icon (default `tree-widget-empty-icon')
67;; :leaf-icon  (default `tree-widget-leaf-icon')
68;;    Those properties define the icon widgets associated to tree
69;;    nodes.  Icon widgets must derive from the `tree-widget-icon'
70;;    widget.  The :tag and :glyph-name property values are
71;;    respectively used when drawing the text and graphic
72;;    representation of the tree.  The :tag value must be a string
73;;    that represent a node icon, like "[+]" for example.  The
74;;    :glyph-name value must the name of an image found in the current
75;;    theme, like "close" for example (see also the variable
76;;    `tree-widget-theme').
77;;
78;; :guide      (default `tree-widget-guide')
79;; :end-guide  (default `tree-widget-end-guide')
80;; :no-guide   (default `tree-widget-no-guide')
81;; :handle     (default `tree-widget-handle')
82;; :no-handle  (default `tree-widget-no-handle')
83;;    Those properties define `item'-like widgets used to draw the
84;;    tree guide lines.  The :tag property value is used when drawing
85;;    the text representation of the tree.  The graphic look and feel
86;;    is given by the images named "guide", "no-guide", "end-guide",
87;;    "handle", and "no-handle" found in the current theme (see also
88;;    the variable `tree-widget-theme').
89;;
90;; These are the default :tag values for icons, and guide lines:
91;;
92;; open-icon    "[-]"
93;; close-icon   "[+]"
94;; empty-icon   "[X]"
95;; leaf-icon    ""
96;; guide        " |"
97;; no-guide     "  "
98;; end-guide    " `"
99;; handle       "-"
100;; no-handle    " "
101;;
102;; The text representation of a tree looks like this:
103;;
104;; [-] 1        (open-icon :node)
105;;  |-[+] 1.0   (guide+handle+close-icon :node)
106;;  |-[X] 1.1   (guide+handle+empty-icon :node)
107;;  `-[-] 1.2   (end-guide+handle+open-icon :node)
108;;     |- 1.2.1 (no-guide+no-handle+guide+handle+leaf-icon leaf)
109;;     `- 1.2.2 (no-guide+no-handle+end-guide+handle+leaf-icon leaf)
110;;
111;; By default, images will be used instead of strings to draw a
112;; nice-looking tree.  See the `tree-widget-image-enable',
113;; `tree-widget-themes-directory', and `tree-widget-theme' options for
114;; more details.
115
116;;; History:
117;;
118
119;;; Code:
120(eval-when-compile (require 'cl))
121(require 'wid-edit)
122
123;;; Customization
124;;
125(defgroup tree-widget nil
126  "Customization support for the Tree Widget library."
127  :version "22.1"
128  :group 'widgets)
129
130(defcustom tree-widget-image-enable
131  (not (or (featurep 'xemacs) (< emacs-major-version 21)))
132  "*Non-nil means that tree-widget will try to use images."
133  :type  'boolean
134  :group 'tree-widget)
135
136(defvar tree-widget-themes-load-path
137  '(load-path
138    (let ((dir (if (fboundp 'locate-data-directory)
139                   (locate-data-directory "tree-widget") ;; XEmacs
140                 data-directory)))
141      (and dir (list dir (expand-file-name "images" dir))))
142    )
143  "List of locations in which to search for the themes sub-directory.
144Each element is an expression that will be recursively evaluated until
145it returns a single directory or a list of directories.
146The default is to search in the `load-path' first, then in the
147\"images\" sub directory in the data directory, then in the data
148directory.
149The data directory is the value of the variable `data-directory' on
150Emacs, and what `(locate-data-directory \"tree-widget\")' returns on
151XEmacs.")
152
153(defcustom tree-widget-themes-directory "tree-widget"
154  "*Name of the directory in which to look for an image theme.
155When nil use the directory where the tree-widget library is located.
156When it is a relative name, search in all occurrences of that sub
157directory in the path specified by `tree-widget-themes-load-path'.
158The default is to use the \"tree-widget\" relative name."
159  :type '(choice (const :tag "Default" "tree-widget")
160                 (const :tag "Where is this library" nil)
161                 (directory :format "%{%t%}:\n%v"))
162  :group 'tree-widget)
163
164(defcustom tree-widget-theme nil
165  "*Name of the theme in which to look for images.
166This is a sub directory of the themes directory specified by the
167`tree-widget-themes-directory' option.
168The default theme is \"default\".  When an image is not found in a
169theme, it is searched in its parent theme.
170
171A complete theme must at least contain images with these file names
172with a supported extension (see also `tree-widget-image-formats'):
173
174\"guide\"
175  A vertical guide line.
176\"no-guide\"
177  An invisible vertical guide line.
178\"end-guide\"
179  End of a vertical guide line.
180\"handle\"
181  Horizontal guide line that joins the vertical guide line to an icon.
182\"no-handle\"
183  An invisible handle.
184
185Plus images whose name is given by the :glyph-name property of the
186icon widgets used to draw the tree.  By default these images are used:
187
188\"open\"
189  Icon associated to an expanded tree.
190\"close\"
191  Icon associated to a collapsed tree.
192\"empty\"
193  Icon associated to an expanded tree with no child.
194\"leaf\"
195  Icon associated to a leaf node."
196  :type '(choice (const  :tag "Default" nil)
197                 (string :tag "Name"))
198  :group 'tree-widget)
199
200(defcustom tree-widget-image-properties-emacs
201  '(:ascent center :mask (heuristic t))
202  "*Default properties of Emacs images."
203  :type 'plist
204  :group 'tree-widget)
205
206(defcustom tree-widget-image-properties-xemacs
207  nil
208  "*Default properties of XEmacs images."
209  :type 'plist
210  :group 'tree-widget)
211
212(defcustom tree-widget-space-width 0.5
213  "Amount of space between an icon image and a node widget.
214Must be a valid space :width display property."
215  :group 'tree-widget
216  :type 'sexp)
217
218;;; Image support
219;;
220(eval-and-compile ;; Emacs/XEmacs compatibility stuff
221  (cond
222   ;; XEmacs
223   ((featurep 'xemacs)
224    (defsubst tree-widget-use-image-p ()
225      "Return non-nil if image support is currently enabled."
226      (and tree-widget-image-enable
227           widget-glyph-enable
228           (console-on-window-system-p)))
229    (defsubst tree-widget-create-image (type file &optional props)
230      "Create an image of type TYPE from FILE, and return it.
231Give the image the specified properties PROPS."
232      (apply 'make-glyph `([,type :file ,file ,@props])))
233    (defsubst tree-widget-image-formats ()
234      "Return the alist of image formats/file name extensions.
235See also the option `widget-image-file-name-suffixes'."
236      (delq nil
237            (mapcar
238             #'(lambda (fmt)
239                 (and (valid-image-instantiator-format-p (car fmt)) fmt))
240             widget-image-file-name-suffixes)))
241    )
242   ;; Emacs
243   (t
244    (defsubst tree-widget-use-image-p ()
245      "Return non-nil if image support is currently enabled."
246      (and tree-widget-image-enable
247           widget-image-enable
248           (display-images-p)))
249    (defsubst tree-widget-create-image (type file &optional props)
250      "Create an image of type TYPE from FILE, and return it.
251Give the image the specified properties PROPS."
252      (apply 'create-image `(,file ,type nil ,@props)))
253    (defsubst tree-widget-image-formats ()
254      "Return the alist of image formats/file name extensions.
255See also the option `widget-image-conversion'."
256      (delq nil
257            (mapcar
258             #'(lambda (fmt)
259                 (and (image-type-available-p (car fmt)) fmt))
260             widget-image-conversion)))
261    ))
262  )
263
264;; Buffer local cache of theme data.
265(defvar tree-widget--theme nil)
266
267(defsubst tree-widget-theme-name ()
268  "Return the current theme name, or nil if no theme is active."
269  (and tree-widget--theme (car (aref tree-widget--theme 0))))
270
271(defsubst tree-widget-set-parent-theme (name)
272  "Set to NAME the parent theme of the current theme.
273The default parent theme is the \"default\" theme."
274  (unless (member name (aref tree-widget--theme 0))
275    (aset tree-widget--theme 0
276          (append (aref tree-widget--theme 0) (list name)))
277    ;; Load the theme setup from the first directory where the theme
278    ;; is found.
279    (catch 'found
280      (dolist (dir (tree-widget-themes-path))
281        (setq dir (expand-file-name name dir))
282        (when (file-accessible-directory-p dir)
283          (throw 'found
284                 (load (expand-file-name
285                        "tree-widget-theme-setup" dir) t)))))))
286
287(defun tree-widget-set-theme (&optional name)
288  "In the current buffer, set the theme to use for images.
289The current buffer must be where the tree widget is drawn.
290Optional argument NAME is the name of the theme to use.  It defaults
291to the value of the variable `tree-widget-theme'.
292Does nothing if NAME is already the current theme.
293
294If there is a \"tree-widget-theme-setup\" library in the theme
295directory, load it to setup a parent theme or the images properties.
296Typically it should contain something like this:
297
298  (tree-widget-set-parent-theme \"my-parent-theme\")
299  (tree-widget-set-image-properties
300   (if (featurep 'xemacs)
301       '(:ascent center)
302     '(:ascent center :mask (heuristic t))
303     ))"
304  (or name (setq name (or tree-widget-theme "default")))
305  (unless (string-equal name (tree-widget-theme-name))
306    (set (make-local-variable 'tree-widget--theme)
307         (make-vector 4 nil))
308      (tree-widget-set-parent-theme name)
309      (tree-widget-set-parent-theme "default")))
310
311(defun tree-widget--locate-sub-directory (name path &optional found)
312  "Locate all occurrences of the sub-directory NAME in PATH.
313Return a list of absolute directory names in reverse order, or nil if
314not found."
315  (condition-case err
316      (dolist (elt path)
317        (setq elt (eval elt))
318        (cond
319         ((stringp elt)
320          (and (file-accessible-directory-p
321                (setq elt (expand-file-name name elt)))
322               (push elt found)))
323         (elt
324          (setq found (tree-widget--locate-sub-directory
325                       name (if (atom elt) (list elt) elt) found)))))
326    (error
327     (message "In tree-widget--locate-sub-directory: %s"
328              (error-message-string err))))
329  found)
330
331(defun tree-widget-themes-path ()
332  "Return the path where to search for a theme.
333It is specified in variable `tree-widget-themes-directory'.
334Return a list of absolute directory names, or nil when no directory
335has been found accessible."
336  (let ((path (aref tree-widget--theme 1)))
337    (cond
338     ;; No directory was found.
339     ((eq path 'void) nil)
340     ;; The list of directories is available in the cache.
341     (path)
342     ;; Use the directory where this library is located.
343     ((null tree-widget-themes-directory)
344      (when (setq path (locate-library "tree-widget"))
345        (setq path (file-name-directory path))
346        (setq path (and (file-accessible-directory-p path)
347                        (list path)))
348        ;; Store the result in the cache for later use.
349        (aset tree-widget--theme 1 (or path 'void))
350        path))
351     ;; Check accessibility of absolute directory name.
352     ((file-name-absolute-p tree-widget-themes-directory)
353      (setq path (expand-file-name tree-widget-themes-directory))
354      (setq path (and (file-accessible-directory-p path)
355                      (list path)))
356      ;; Store the result in the cache for later use.
357      (aset tree-widget--theme 1 (or path 'void))
358      path)
359     ;; Locate a sub-directory in `tree-widget-themes-load-path'.
360     (t
361      (setq path (nreverse (tree-widget--locate-sub-directory
362                            tree-widget-themes-directory
363                            tree-widget-themes-load-path)))
364      ;; Store the result in the cache for later use.
365      (aset tree-widget--theme 1 (or path 'void))
366      path))))
367
368(defconst tree-widget--cursors
369  ;; Pointer shapes when the mouse pointer is over inactive
370  ;; tree-widget images.  This feature works since Emacs 22, and
371  ;; ignored on older versions, and XEmacs.
372  '(
373    ("guide"     . arrow)
374    ("no-guide"  . arrow)
375    ("end-guide" . arrow)
376    ("handle"    . arrow)
377    ("no-handle" . arrow)
378    ))
379
380(defsubst tree-widget-set-image-properties (props)
381  "In current theme, set images properties to PROPS.
382Does nothing if images properties have already been set for that
383theme."
384  (or (aref tree-widget--theme 2)
385      (aset tree-widget--theme 2 props)))
386
387(defsubst tree-widget-image-properties (name)
388  "Return the properties of image NAME in current theme.
389Default global properties are provided for respectively Emacs and
390XEmacs in the variables `tree-widget-image-properties-emacs', and
391`tree-widget-image-properties-xemacs'."
392  ;; Add the pointer shape
393  (cons :pointer
394        (cons (or (cdr (assoc name tree-widget--cursors)) 'hand)
395              (tree-widget-set-image-properties
396               (if (featurep 'xemacs)
397                   tree-widget-image-properties-xemacs
398                 tree-widget-image-properties-emacs)))))
399
400(defun tree-widget-lookup-image (name)
401  "Look up in current theme for an image with NAME.
402Search first in current theme, then in parent themes (see also the
403function `tree-widget-set-parent-theme').
404Return the first image found having a supported format, or nil if not
405found."
406  (catch 'found
407    (dolist (default-directory (tree-widget-themes-path))
408      (dolist (dir (aref tree-widget--theme 0))
409        (dolist (fmt (tree-widget-image-formats))
410          (dolist (ext (cdr fmt))
411            (setq file (expand-file-name (concat name ext) dir))
412            (and (file-readable-p file)
413                 (file-regular-p file)
414                 (throw 'found
415                        (tree-widget-create-image
416                         (car fmt) file
417                         (tree-widget-image-properties name))))))))
418    nil))
419
420(defun tree-widget-find-image (name)
421  "Find the image with NAME in current theme.
422NAME is an image file name sans extension.
423Return the image found, or nil if not found."
424  (when (tree-widget-use-image-p)
425    ;; Ensure there is an active theme.
426    (tree-widget-set-theme (tree-widget-theme-name))
427    (let ((image (assoc name (aref tree-widget--theme 3))))
428      ;; The image NAME is found in the cache.
429      (if image
430          (cdr image)
431        ;; Search the image in current, and default themes.
432        (prog1
433            (setq image (tree-widget-lookup-image name))
434          ;; Store image reference in the cache for later use.
435          (push (cons name image) (aref tree-widget--theme 3))))
436      )))
437
438;;; Widgets
439;;
440(defun tree-widget-button-click (event)
441  "Move to the position clicked on, and if it is a button, invoke it.
442EVENT is the mouse event received."
443  (interactive "e")
444  (mouse-set-point event)
445  (let ((pos (widget-event-point event)))
446    (if (get-char-property pos 'button)
447        (widget-button-click event))))
448
449(defvar tree-widget-button-keymap
450  (let ((km (make-sparse-keymap)))
451    (if (boundp 'widget-button-keymap)
452        ;; XEmacs
453        (progn
454          (set-keymap-parent km widget-button-keymap)
455          (define-key km [button1] 'tree-widget-button-click))
456      ;; Emacs
457      (set-keymap-parent km widget-keymap)
458      (define-key km [down-mouse-1] 'tree-widget-button-click))
459    km)
460  "Keymap used inside node buttons.
461Handle mouse button 1 click on buttons.")
462
463(define-widget 'tree-widget-icon 'push-button
464  "Basic widget other tree-widget icons are derived from."
465  :format        "%[%t%]"
466  :button-keymap tree-widget-button-keymap ; XEmacs
467  :keymap        tree-widget-button-keymap ; Emacs
468  :create        'tree-widget-icon-create
469  :action        'tree-widget-icon-action
470  :help-echo     'tree-widget-icon-help-echo
471  )
472
473(define-widget 'tree-widget-open-icon 'tree-widget-icon
474  "Icon for an expanded tree-widget node."
475  :tag        "[-]"
476  :glyph-name "open"
477  )
478
479(define-widget 'tree-widget-empty-icon 'tree-widget-icon
480  "Icon for an expanded tree-widget node with no child."
481  :tag        "[X]"
482  :glyph-name "empty"
483  )
484
485(define-widget 'tree-widget-close-icon 'tree-widget-icon
486  "Icon for a collapsed tree-widget node."
487  :tag        "[+]"
488  :glyph-name "close"
489  )
490
491(define-widget 'tree-widget-leaf-icon 'tree-widget-icon
492  "Icon for a tree-widget leaf node."
493  :tag        ""
494  :glyph-name "leaf"
495  :button-face 'default
496  )
497
498(define-widget 'tree-widget-guide 'item
499  "Vertical guide line."
500  :tag       " |"
501  ;;:tag-glyph (tree-widget-find-image "guide")
502  :format    "%t"
503  )
504
505(define-widget 'tree-widget-end-guide 'item
506  "End of a vertical guide line."
507  :tag       " `"
508  ;;:tag-glyph (tree-widget-find-image "end-guide")
509  :format    "%t"
510  )
511
512(define-widget 'tree-widget-no-guide 'item
513  "Invisible vertical guide line."
514  :tag       "  "
515  ;;:tag-glyph (tree-widget-find-image "no-guide")
516  :format    "%t"
517  )
518
519(define-widget 'tree-widget-handle 'item
520  "Horizontal guide line that joins a vertical guide line to a node."
521  :tag       "-"
522  ;;:tag-glyph (tree-widget-find-image "handle")
523  :format    "%t"
524  )
525
526(define-widget 'tree-widget-no-handle 'item
527  "Invisible handle."
528  :tag       " "
529  ;;:tag-glyph (tree-widget-find-image "no-handle")
530  :format    "%t"
531  )
532
533(define-widget 'tree-widget 'default
534  "Tree widget."
535  :format         "%v"
536  :convert-widget 'tree-widget-convert-widget
537  :value-get      'widget-value-value-get
538  :value-delete   'widget-children-value-delete
539  :value-create   'tree-widget-value-create
540  :action         'tree-widget-action
541  :help-echo      'tree-widget-help-echo
542  :expander-p     'tree-widget-expander-p
543  :open-icon      'tree-widget-open-icon
544  :close-icon     'tree-widget-close-icon
545  :empty-icon     'tree-widget-empty-icon
546  :leaf-icon      'tree-widget-leaf-icon
547  :guide          'tree-widget-guide
548  :end-guide      'tree-widget-end-guide
549  :no-guide       'tree-widget-no-guide
550  :handle         'tree-widget-handle
551  :no-handle      'tree-widget-no-handle
552  )
553
554;;; Widget support functions
555;;
556(defun tree-widget-p (widget)
557  "Return non-nil if WIDGET is a tree-widget."
558  (let ((type (widget-type widget)))
559    (while (and type (not (eq type 'tree-widget)))
560      (setq type (widget-type (get type 'widget-type))))
561    (eq type 'tree-widget)))
562
563(defun tree-widget-node (widget)
564  "Return WIDGET's :node child widget.
565If not found, setup an `item' widget as default.
566Signal an error if the :node widget is a tree-widget.
567WIDGET is, or derives from, a tree-widget."
568  (let ((node (widget-get widget :node)))
569    (if node
570        ;; Check that the :node widget is not a tree-widget.
571        (and (tree-widget-p node)
572             (error "Invalid tree-widget :node %S" node))
573      ;; Setup an item widget as default :node.
574      (setq node `(item :tag ,(or (widget-get widget :tag)
575                                  (widget-princ-to-string
576                                   (widget-value widget)))))
577      (widget-put widget :node node))
578    node))
579
580(defun tree-widget-keep (arg widget)
581  "Save in ARG the WIDGET's properties specified by :keep."
582  (dolist (prop (widget-get widget :keep))
583    (widget-put arg prop (widget-get widget prop))))
584
585(defun tree-widget-children-value-save (widget &optional args node)
586  "Save WIDGET children values.
587WIDGET is, or derives from, a tree-widget.
588Children properties and values are saved in ARGS if non-nil, else in
589WIDGET's :args property value.  Properties and values of the
590WIDGET's :node sub-widget are saved in NODE if non-nil, else in
591WIDGET's :node sub-widget."
592  (let ((args (cons (or node (widget-get widget :node))
593                    (or args (widget-get widget :args))))
594        (children (widget-get widget :children))
595        arg child)
596    (while (and args children)
597      (setq arg      (car args)
598            args     (cdr args)
599            child    (car children)
600            children (cdr children))
601       (if (tree-widget-p child)
602;;;; The child is a tree node.
603           (progn
604             ;; Backtrack :args and :node properties.
605             (widget-put arg :args (widget-get child :args))
606             (widget-put arg :node (widget-get child :node))
607             ;; Save :open property.
608             (widget-put arg :open (widget-get child :open))
609             ;; The node is open.
610             (when (widget-get child :open)
611               ;; Save the widget value.
612               (widget-put arg :value (widget-value child))
613               ;; Save properties specified in :keep.
614               (tree-widget-keep arg child)
615               ;; Save children.
616               (tree-widget-children-value-save
617                child (widget-get arg :args) (widget-get arg :node))))
618;;;; Another non tree node.
619         ;; Save the widget value.
620         (widget-put arg :value (widget-value child))
621         ;; Save properties specified in :keep.
622         (tree-widget-keep arg child)))))
623
624;;; Widget creation
625;;
626(defvar tree-widget-before-create-icon-functions nil
627  "Hooks run before to create a tree-widget icon.
628Each function is passed the icon widget not yet created.
629The value of the icon widget :node property is a tree :node widget or
630a leaf node widget, not yet created.
631This hook can be used to dynamically change properties of the icon and
632associated node widgets.  For example, to dynamically change the look
633and feel of the tree-widget by changing the values of the :tag
634and :glyph-name properties of the icon widget.
635This hook should be local in the buffer setup to display widgets.")
636
637(defun tree-widget-icon-create (icon)
638  "Create the ICON widget."
639  (run-hook-with-args 'tree-widget-before-create-icon-functions icon)
640  (widget-put icon :tag-glyph
641              (tree-widget-find-image (widget-get icon :glyph-name)))
642  ;; Ensure there is at least one char to display the image.
643  (and (widget-get icon :tag-glyph)
644       (equal "" (or (widget-get icon :tag) ""))
645       (widget-put icon :tag " "))
646  (widget-default-create icon)
647  ;; Insert space between the icon and the node widget.
648  (insert-char ?  1)
649  (put-text-property
650   (1- (point)) (point)
651   'display (list 'space :width tree-widget-space-width)))
652
653(defun tree-widget-convert-widget (widget)
654  "Convert :args as widget types in WIDGET."
655  (let ((tree (widget-types-convert-widget widget)))
656    ;; Compatibility
657    (widget-put tree :expander (or (widget-get tree :expander)
658                                   (widget-get tree :dynargs)))
659    tree))
660
661(defun tree-widget-value-create (tree)
662  "Create the TREE tree-widget."
663  (let* ((node   (tree-widget-node tree))
664         (flags  (widget-get tree :tree-widget--guide-flags))
665         (indent (widget-get tree :indent))
666         ;; Setup widget's image support.  Looking up for images, and
667         ;; setting widgets' :tag-glyph is done here, to allow to
668         ;; dynamically change the image theme.
669         (widget-image-enable (tree-widget-use-image-p))     ; Emacs
670         (widget-glyph-enable widget-image-enable)           ; XEmacs
671         children buttons)
672    (and indent (not (widget-get tree :parent))
673         (insert-char ?\  indent))
674    (if (widget-get tree :open)
675;;;; Expanded node.
676        (let ((args     (widget-get tree :args))
677              (guide    (widget-get tree :guide))
678              (noguide  (widget-get tree :no-guide))
679              (endguide (widget-get tree :end-guide))
680              (handle   (widget-get tree :handle))
681              (nohandle (widget-get tree :no-handle))
682              (guidi    (tree-widget-find-image "guide"))
683              (noguidi  (tree-widget-find-image "no-guide"))
684              (endguidi (tree-widget-find-image "end-guide"))
685              (handli   (tree-widget-find-image "handle"))
686              (nohandli (tree-widget-find-image "no-handle")))
687          ;; Request children at run time, when requested.
688          (when (and (widget-get tree :expander)
689                     (widget-apply tree :expander-p))
690            (setq args (mapcar 'widget-convert
691                               (widget-apply tree :expander)))
692            (widget-put tree :args args))
693          ;; Defer the node widget creation after icon creation.
694          (widget-put tree :node (widget-convert node))
695          ;; Create the icon widget for the expanded tree.
696          (push (widget-create-child-and-convert
697                 tree (widget-get tree (if args :open-icon :empty-icon))
698                 ;; Pass the node widget to child.
699                 :node (widget-get tree :node))
700                buttons)
701          ;; Create the tree node widget.
702          (push (widget-create-child tree (widget-get tree :node))
703                children)
704          ;; Update the icon :node with the created node widget.
705          (widget-put (car buttons) :node (car children))
706          ;; Create the tree children.
707          (while args
708            (setq node (car args)
709                  args (cdr args))
710            (and indent (insert-char ?\  indent))
711            ;; Insert guide lines elements from previous levels.
712            (dolist (f (reverse flags))
713              (widget-create-child-and-convert
714               tree (if f guide noguide)
715               :tag-glyph (if f guidi noguidi))
716              (widget-create-child-and-convert
717               tree nohandle :tag-glyph nohandli))
718            ;; Insert guide line element for this level.
719            (widget-create-child-and-convert
720             tree (if args guide endguide)
721             :tag-glyph (if args guidi endguidi))
722            ;; Insert the node handle line
723            (widget-create-child-and-convert
724             tree handle :tag-glyph handli)
725            (if (tree-widget-p node)
726                ;; Create a sub-tree node.
727                (push (widget-create-child-and-convert
728                       tree node :tree-widget--guide-flags
729                       (cons (if args t) flags))
730                      children)
731              ;; Create the icon widget for a leaf node.
732              (push (widget-create-child-and-convert
733                     tree (widget-get tree :leaf-icon)
734                     ;; At this point the node widget isn't yet created.
735                     :node (setq node (widget-convert
736                                       node :tree-widget--guide-flags
737                                       (cons (if args t) flags)))
738                     :tree-widget--leaf-flag t)
739                    buttons)
740              ;; Create the leaf node widget.
741              (push (widget-create-child tree node) children)
742              ;; Update the icon :node with the created node widget.
743              (widget-put (car buttons) :node (car children)))))
744;;;; Collapsed node.
745      ;; Defer the node widget creation after icon creation.
746      (widget-put tree :node (widget-convert node))
747      ;; Create the icon widget for the collapsed tree.
748      (push (widget-create-child-and-convert
749             tree (widget-get tree :close-icon)
750             ;; Pass the node widget to child.
751             :node (widget-get tree :node))
752            buttons)
753      ;; Create the tree node widget.
754      (push (widget-create-child tree (widget-get tree :node))
755            children)
756      ;; Update the icon :node with the created node widget.
757      (widget-put (car buttons) :node (car children)))
758    ;; Save widget children and buttons.  The tree-widget :node child
759    ;; is the first element in :children.
760    (widget-put tree :children (nreverse children))
761    (widget-put tree :buttons  buttons)))
762
763;;; Widget callbacks
764;;
765(defsubst tree-widget-leaf-node-icon-p (icon)
766  "Return non-nil if ICON is a leaf node icon.
767That is, if its :node property value is a leaf node widget."
768  (widget-get icon :tree-widget--leaf-flag))
769
770(defun tree-widget-icon-action (icon &optional event)
771  "Handle the ICON widget :action.
772If ICON :node is a leaf node it handles the :action.  The tree-widget
773parent of ICON handles the :action otherwise.
774Pass the received EVENT to :action."
775  (let ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
776                                   :node :parent))))
777    (widget-apply node :action event)))
778
779(defun tree-widget-icon-help-echo (icon)
780  "Return the help-echo string of ICON.
781If ICON :node is a leaf node it handles the :help-echo.  The tree-widget
782parent of ICON handles the :help-echo otherwise."
783  (let* ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
784                                    :node :parent)))
785         (help-echo (widget-get node :help-echo)))
786    (if (functionp help-echo)
787        (funcall help-echo node)
788      help-echo)))
789
790(defvar tree-widget-after-toggle-functions nil
791  "Hooks run after toggling a tree-widget expansion.
792Each function is passed a tree-widget.  If the value of the :open
793property is non-nil the tree has been expanded, else collapsed.
794This hook should be local in the buffer setup to display widgets.")
795
796(defun tree-widget-action (tree &optional event)
797  "Handle the :action of the TREE tree-widget.
798That is, toggle expansion of the TREE tree-widget.
799Ignore the EVENT argument."
800  (let ((open (not (widget-get tree :open))))
801    (or open
802        ;; Before to collapse the node, save children values so next
803        ;; open can recover them.
804        (tree-widget-children-value-save tree))
805    (widget-put tree :open open)
806    (widget-value-set tree open)
807    (run-hook-with-args 'tree-widget-after-toggle-functions tree)))
808
809(defun tree-widget-help-echo (tree)
810  "Return the help-echo string of the TREE tree-widget."
811  (if (widget-get tree :open)
812      "Collapse node"
813    "Expand node"))
814
815(defun tree-widget-expander-p (tree)
816  "Return non-nil if the TREE tree-widget :expander has to be called.
817That is, if TREE :args is nil."
818  (null (widget-get tree :args)))
819
820(provide 'tree-widget)
821
822;; arch-tag: c3a1ada2-1663-41dc-9d16-2479ed8320e8
823;;; tree-widget.el ends here
824