Updated 2012-12-07 01:44:06 by AMG

if 0 {Richard Suchenwirth 2004-10-23 - BWidget's Tree is a powerful widget, useful for browsing hierarchical structures (e.g. the file system, widget or namespace hierarchies, etc.)

LemonTree is a weekend fun project to explore its possibilities - "very pretty", but some fruits first were sour for me :) One quirk was that each node has to have a unique name, which better not contain "::" - but a simple solution is to just increment an integer uniqueID. }
 package require BWidget
 namespace eval LemonTree {variable uniqueID 0}

if 0 {The Tree widget allows a -data item for each node, which I use for a dict-like list that contains the node's type and "real name" (as opposed to the "display name" - for instance, a dir node would display only its [file tail], but the real name is the full path). This routine adds a node to the LemonTree: }
 proc LemonTree::add {w parent type name {text ""}} {
    variable uniqueID; variable icon
    if {$text eq ""} {set text $name}
    set id n[incr uniqueID]
    set data [list type $type name $name]
    set fill [expr {[string match (* $text]? "blue": "black"}]
    set drawcross [expr {[info proc ::LemonTree::kids($type)] eq ""?
         "never": "allways"}]
    $w insert end $parent $id -text $text -data $data \
        -drawcross $drawcross -fill $fill
    if [info exists icon($type)] {
        $w itemconfigure $id -image $icon($type)

if 0 {For speed, a Tree isn't drawn fully expanded at the beginning. Instead, nodes are opened on demand, when the user clicks on the [+] icon. I use the -drawcross "allways" mode (shudder - should be fixed to "always", but then older code might break) to indicate that the node hasn't been opened before - after the first opening, the mode is set to "auto", meaning to draw a cross only if the node has children. }
 proc LemonTree::open {w node} {
    if {[$w itemcget $node -drawcross] eq "allways"} {
        set data [$w itemcget $node -data]
        set type [dict'get $data type]
        foreach {ktype kids} [kids($type) $w $node] {
            foreach kid $kids {add $w $node $ktype $kid}
        $w itemconfigure $node -drawcross auto

if 0 {So far for the generic LemonTree - the rest is already customization for specific item types. The kids($type) call above looks like an array element - in fact it's a way of dispatching the generic operation of providing the list of children of an entity of given type, which of course depends on the type. For instance, the children of a directory are its subdirectories, and then its files (with special-casing for Windows, so that drive letters are the children of "/"): }
 proc LemonTree::kids(dir) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    if {$::tcl_platform(platform) eq "windows" && $name eq "/"} {
        return [list dir [file volumes]]
    set dirs  [lsort [glob -nocomplain -type d $name/*]]
    set files [lsort [glob -nocomplain -type f $name/*]]
    list dir $dirs file $files

if 0 {Namespaces have a hierarchy, but contain collections of commands and variables as well. So I introduced an intermediate layer (parens around the display name make these "meta-children" come displayed in blue):}
 proc LemonTree::kids(namespace) {w node} {
    list ns-commands (Commands) ns-vars (Variables) ns-children (Children)
 proc LemonTree::kids(ns-children) {w node} {
    set ns [dict'get [$w itemcget [$w parent $node] -data] name]
    list namespace [lsort [namespace children $ns]]
 proc LemonTree::kids(ns-commands) {w node} {
    set ns [dict'get [$w itemcget [$w parent $node] -data] name]
    list command [lsort [info commands ${ns}::*]]
 proc LemonTree::kids(ns-vars) {w node} {
    set ns [dict'get [$w itemcget [$w parent $node] -data] name]
    set res ""
    foreach var [lsort [info vars ${ns}::*]] {
        lappend res [expr {[array exists $var]? "array": "variable"}] $var
    set res

#-- Arrays can also be seen as a one-level subtree:
 proc LemonTree::kids(array) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    list variable [lsort [array names $name]]
 proc LemonTree::kids(widget) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    list widget [winfo children $name]

if 0 {A Tree looks prettier if nodes have icons, so I'm using some of those that BWidget comes with:}
 set path $BWIDGET::LIBRARY/images
 foreach {type name} {dir folder file file array copy} {
    set LemonTree::icon($type) [image create photo -file $path/$name.gif]

# Some more icons come from adavis's Icons package:
 set LemonTree::icon(widget) [image create photo -data {
 set LemonTree::icon(namespace) [image create photo -data {
 set LemonTree::icon(command) [image create photo -data {
 set LemonTree::icon(variable) [image create photo -data {

if 0 {This thing is more useful if you can get more information about an item by clicking on it - for a file, its size and date; for a variable, its value; for a proc, its full specification, etc. As a small first shot, I selected a "balloon" for that purpose. }
 proc LemonTree::Info {w node} {
    set type [dict'get [$w itemcget $node -data] type]
    if {[info proc ::LemonTree::info($type)] ne ""} {
        balloon $w [info($type) $w $node]

#-- type-specific info providers:
 proc LemonTree::info(array) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    return "$name: array, [array size $name] elements"
 proc LemonTree::info(command) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    if {[info procs $name] ne ""} {
        return [procinfo $name]
    } else {return "$name: compiled command"}
 proc LemonTree::info(dir) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    set mtime [clock format [file mtime $name] -format %y-%m-%d,%H:%M:%S]
    set nfiles [llength [glob -nocomplain $name/*]]
    return "$name\n$nfiles files\nModified: $mtime"
 proc LemonTree::info(file) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    set mtime [clock format [file mtime $name] -format %y-%m-%d,%H:%M:%S]
    return "$name\n[file size $name] bytes\nModified: $mtime"
 proc LemonTree::info(namespace) {w node} {
    set ns [dict'get [$w itemcget $node -data] name]
    return "namespace $ns\n[llength [info commands ${ns}::*]] commands,\
        [llength [info vars ${ns}::*]] variables,\
        [llength [namespace children $ns]] child(ren)"
 proc LemonTree::info(variable) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    if [info exists $name] {
        list $name = [set $name]
    } else { #-- array element
        set arr [dict'get [$w itemcget [$w parent $node] -data] name]
        list ${arr}($name) = [set ${arr}($name)]
 proc LemonTree::info(widget) {w node} {
    set name [dict'get [$w itemcget $node -data] name]
    return "[winfo class $name] $name [winfo geometry $name]"

#-- A simple ballon, modified from Bag of Tk algorithms:
  proc balloon {w text} {
    set top .balloon
    catch {destroy $top}
    toplevel $top -bd 1
    pack [message $top.txt -aspect 10000 -bg lightyellow \
        -borderwidth 0 -text $text -font {Helvetica 9}]
    wm overrideredirect $top 1
    wm geometry $top +[winfo pointerx $w]+[winfo pointery $w]
    bind  $top <1> [list destroy $top]
    raise $top

if 0 {From Tcl 8.5, one would use a real dict, but it's easy to make a replacement that works roughly the same in 8.4 (it returns "" for non- existing keys instead of throwing an error), and might be slower, but I won't notice on dicts with two elements ;-}
 proc dict'get {dict key} {
    foreach {k value} $dict {if {$k eq $key} {return $value}}

#-- reconstruct a proc's definition as a string:
 proc procinfo name {
    set args ""
    foreach arg [info args $name] {
        if [info default $name $arg def] {lappend arg $def}
        lappend args $arg
    return "proc $name {$args} {[info body $name]}"

#-- Now to demonstrate and test the whole thing:
 Tree .t -background white -opencmd {LemonTree::open .t} \
    -width 40 -height 30 -yscrollcommand {.y set}
 .t bindText  <1> {LemonTree::Info .t}
 .t bindImage <1> {LemonTree::Info .t}
 LemonTree::add .t root dir       /  "(Files /)"
 LemonTree::add .t root namespace :: "(Namespace ::)"
 LemonTree::add .t root widget    .  "(Widget .)"

 pack [scrollbar .y -command {.t yview}] -side right -fill y
 pack .t -fill both -expand 1 -side left

#-- Little development helpers:
 bind . <Escape> {exec wish $argv0 &; exit}
 bind . <F1> {console show}

if 0 {To summarize, for adding a new item type foo to a LemonTree, there are three optional steps:

  • if the type has children, write a proc LemonTree::kids(foo)
  • if you want an icon, enter its image into the array LemonTree::icon(foo)
  • if you want balloon help, write a proc LemonTree::info(foo)

Also, the type foo must be mentioned in at least one "kid-bearer" proc, or as root child, to be reachable.

See also stardom.

TV (Oct 25 2004) Cool.

RS 2008-11-03 - Years later, on request from a colleague, I added bindings for multiple range or additive selection:
 .t bindText <1>         {+ set last}
 .t bindText <Shift-1>   {.t selection range $last}
 .t bindText <Control-1> {.t selection add}

Examples how to retrieve the selection (maybe bound to a keypress):
 % .t selection get
 n77 n78 n79 n80 n81 n83
 % .t itemcget n77 -data
 type file name D:/Tcl/BulgingSquare.tcl

see also