Richard Suchenwirth 2006-12-22 - The tk_optionMenu offers a handy alternative to a combobox. But for a larger number of structured choices, it is sometimes better to have cascading menus instead of one. Here's a quick hack for that. It follows the same simple API as tk_optionMenu, but if an item is a list of more than one elements, it is turned into a submenu. (Add an extra layer of braces around labels that contain spaces - see example below.) Oh, and the special item "--" makes a separator.
proc tk_optionCascade {w varName args} {
set dn [image create bitmap -data "#define i_width 7\n\#define i_height 5
static char i_bits[] = {\n0,127,62,28,8\n}"]
set it [lindex $args 0]
while {[llength $it]>1} {set it [lindex $it 0]}
set ::$varName $it
menubutton $w -menu $w.m -text $it -relief raised \
-image $dn -compound right
menu $w.m -tearoff 0
tk_optionCascade_add $w.m $varName $args
trace var ::$varName w "$w config -text $$varName ;\#"
return $w.m
}
proc tk_optionCascade_add {w varName argl} {
set n 0
foreach arg $argl {
if {$arg eq "--"} {
$w add separator
} elseif {[llength $arg] == 1} {
$w add radiobutton -label [join $arg] -variable $varName
} else {
set child [menu $w.[incr n] -tearoff 0]
$w add cascade -label [lindex $arg 0] -menu $child
tk_optionCascade_add $child $varName [lrange $arg 1 end]
}
}
}# Demo and testing:
package require Tk
tk_optionCascade .o myvar \
{color red green blue -- {other yellow magenta cyan}} \
{hue dark medium light} \
-- {"multi word example"} ok
pack .o