14 May 2003 - [Eric Boudaillier]

[Arjen Markus] asked ''Support for quick positioning by typing first letter'' in Tk features request. After playing with this feature in Windows Explorer, I have written a little command which do this to place in binding.


 # ----------------------------------------------------------------------
 #  ListboxQuickSelect --
 #
 #	This command implements quick positioning inside a listbox
 #	with key press. Each key pressed are buffered for the search.
 #
 #	Typical usage is through binding:
 #	   bind $listbox <KeyPress> "ListboxQuickSelect %W %A"
 #
 # ----------------------------------------------------------------------
 proc ListboxQuickSelect {listbox key} {
    upvar 0 ::ListboxQuickSelect:$listbox data

    if {[string equal $key ""]} {
	# %A substitute non unicode character by empty string
	return
    }
    set sel [$listbox curselection]
    if {[llength $sel] > 1} {
	# Listbox has more than one selected item
	return
    }

    # Initialize index where search begin
    if {[llength $sel] == 1} {
	set startIndex [lindex $sel 0]
    } else {
	set startIndex 0
    }

    if {[info exists data(searchPrefix)]} {
	set searchPrefix $data(searchPrefix)
    } else {
	set searchPrefix ""
    }

    if {[string equal -nocase $searchPrefix $key]} {	
	# User presses twice the same key for the first char.
	# Search the next item which begin with that char (handled below).
    } else {
	append searchPrefix $key
    }

    # Skip current selected item if searchPrefix is one char
    # and selected item starts with this char.
    if {[llength $sel] == 1 &&
	[string length $searchPrefix] == 1 &&
	[string match -nocase "$searchPrefix*" \
	     [$listbox get $startIndex]]} {
	incr startIndex
    }

    # Now search for searchPrefix after current item,
    # and wrap if not found.
    foreach {start end} [list $startIndex end 0 $startIndex] {
	set index $start
	foreach item [$listbox get $start $end] {
	    if {[string match -nocase "$searchPrefix*" $item]} {
		set newSelectedIndex $index
		break
	    }
	    incr index
	}

	if {[info exists newSelectedIndex]} {
	    # We have found a new item, select it and stop search
	    $listbox selection clear 0 end
	    $listbox selection set $newSelectedIndex
	    $listbox see $newSelectedIndex
	    break
	}
    }

    # Bufferize searchPrefix. Discard it in a small delay
    if {[info exists data(afterId)]} {
	after cancel $data(afterId)
    }
    set data(searchPrefix) $searchPrefix
    set data(afterId)      [after 1000 "unset ::ListboxQuickSelect:$listbox"]
 }


 # --- Test code ---

 package require Tk

 set listbox [listbox .listbox]
 eval $listbox insert end [lsort [glob -nocomplain -directory / -tail *]]
 bind $listbox <KeyPress> {
    ListboxQuickSelect %W %A
 }

 focus $listbox
 pack $listbox

----

ulis, 2003-05-21: Hugecombo has this fonctionality implemented. And has also a search-by-pattern implemented.

Hugecombo: http://perso.wanadoo.fr/maurice.ulis/tcl/Hugecombo

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