OS/2 Shareware BBS: 10 Tools/10-Tools.zip/tkisrc04.zip/lib/tk/focus.tcl

Text File | 1998-09-09 | 5KB | 181 lines

# focus.tcl --
#
# This file defines several procedures for managing the input
# focus.
#
# SCCS: @(#) focus.tcl 1.17 96/02/16 10:48:21
#
# 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] == $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] == $cur} {
        break
        }
        set parent [winfo parent $parent]
        set children [winfo children $parent]
        set i [lsearch -exact $children $cur]
    }
    if {($cur == $w) || [tkFocusOK $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] == $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] == $cur} {
        continue
        }
        set parent $cur
        set children [winfo children $parent]
        set i [llength $children]
    }
    set cur $parent
    if {($cur == $w) || [tkFocusOK $cur]} {
        return $cur
    }
    }
}

# tkFocusOK --
#
# 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 tkFocusOK w {
    set code [catch {$w cget -takefocus} value]
    if {($code == 0) && ($value != "")} {
    if {$value == 0} {
        return 0
    } elseif {$value == 1} {
        return [winfo viewable $w]
    } else {
        set value [uplevel #0 $value $w]
        if {$value != ""} {
        return $value
        }
    }
    }
    if {![winfo viewable $w]} {
    return 0
    }
    set code [catch {$w cget -state} value]
    if {($code == 0) && ($value == "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" == "NotifyAncestor") || ("%d" == "NotifyNonlinear")
        || ("%d" == "NotifyInferior")} {
        if [tkFocusOK %W] {
        focus %W
        }
    }
    }
    if {$old != ""} {
    bind all <Enter> "$old; $script"
    } else {
    bind all <Enter> $script
    }
}