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| Current File : //usr/share/tk8.5/focus.tcl |
# focus.tcl --
#
# This file defines several procedures for managing the input
# focus.
#
# Copyright (c) 1994-1995 Sun Microsystems, Inc.
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# ::tk_focusNext --
# This procedure returns the name of the next window after "w" in
# "focus order" (the window that should receive the focus next if
# Tab is typed in w). "Next" is defined by a pre-order search
# of a top-level and its non-top-level descendants, with the stacking
# order determining the order of siblings. The "-takefocus" options
# on windows determine whether or not they should be skipped.
#
# Arguments:
# w - Name of a window.
proc ::tk_focusNext w {
set cur $w
while {1} {
# Descend to just before the first child of the current widget.
set parent $cur
set children [winfo children $cur]
set i -1
# Look for the next sibling that isn't a top-level.
while {1} {
incr i
if {$i < [llength $children]} {
set cur [lindex $children $i]
if {[winfo toplevel $cur] eq $cur} {
continue
} else {
break
}
}
# No more siblings, so go to the current widget's parent.
# If it's a top-level, break out of the loop, otherwise
# look for its next sibling.
set cur $parent
if {[winfo toplevel $cur] eq $cur} {
break
}
set parent [winfo parent $parent]
set children [winfo children $parent]
set i [lsearch -exact $children $cur]
}
if {$w eq $cur || [tk::FocusOK $cur]} {
return $cur
}
}
}
# ::tk_focusPrev --
# This procedure returns the name of the previous window before "w" in
# "focus order" (the window that should receive the focus next if
# Shift-Tab is typed in w). "Next" is defined by a pre-order search
# of a top-level and its non-top-level descendants, with the stacking
# order determining the order of siblings. The "-takefocus" options
# on windows determine whether or not they should be skipped.
#
# Arguments:
# w - Name of a window.
proc ::tk_focusPrev w {
set cur $w
while {1} {
# Collect information about the current window's position
# among its siblings. Also, if the window is a top-level,
# then reposition to just after the last child of the window.
if {[winfo toplevel $cur] eq $cur} {
set parent $cur
set children [winfo children $cur]
set i [llength $children]
} else {
set parent [winfo parent $cur]
set children [winfo children $parent]
set i [lsearch -exact $children $cur]
}
# Go to the previous sibling, then descend to its last descendant
# (highest in stacking order. While doing this, ignore top-levels
# and their descendants. When we run out of descendants, go up
# one level to the parent.
while {$i > 0} {
incr i -1
set cur [lindex $children $i]
if {[winfo toplevel $cur] eq $cur} {
continue
}
set parent $cur
set children [winfo children $parent]
set i [llength $children]
}
set cur $parent
if {$w eq $cur || [tk::FocusOK $cur]} {
return $cur
}
}
}
# ::tk::FocusOK --
#
# This procedure is invoked to decide whether or not to focus on
# a given window. It returns 1 if it's OK to focus on the window,
# 0 if it's not OK. The code first checks whether the window is
# viewable. If not, then it never focuses on the window. Then it
# checks the -takefocus option for the window and uses it if it's
# set. If there's no -takefocus option, the procedure checks to
# see if (a) the widget isn't disabled, and (b) it has some key
# bindings. If all of these are true, then 1 is returned.
#
# Arguments:
# w - Name of a window.
proc ::tk::FocusOK w {
set code [catch {$w cget -takefocus} value]
if {($code == 0) && ($value ne "")} {
if {$value == 0} {
return 0
} elseif {$value == 1} {
return [winfo viewable $w]
} else {
set value [uplevel #0 $value [list $w]]
if {$value ne ""} {
return $value
}
}
}
if {![winfo viewable $w]} {
return 0
}
set code [catch {$w cget -state} value]
if {($code == 0) && $value eq "disabled"} {
return 0
}
regexp Key|Focus "[bind $w] [bind [winfo class $w]]"
}
# ::tk_focusFollowsMouse --
#
# If this procedure is invoked, Tk will enter "focus-follows-mouse"
# mode, where the focus is always on whatever window contains the
# mouse. If this procedure isn't invoked, then the user typically
# has to click on a window to give it the focus.
#
# Arguments:
# None.
proc ::tk_focusFollowsMouse {} {
set old [bind all <Enter>]
set script {
if {"%d" eq "NotifyAncestor" || "%d" eq "NotifyNonlinear" \
|| "%d" eq "NotifyInferior"} {
if {[tk::FocusOK %W]} {
focus %W
}
}
}
if {$old ne ""} {
bind all <Enter> "$old; $script"
} else {
bind all <Enter> $script
}
}