# 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 $w]]" } # ::tk_focusFollowsMouse -- # # If this procedure is invoked, Tk will enter "focus-follows-mouse" # mode, where the focus is always on whatever window contains the # mouse. If this procedure isn't invoked, then the user typically # has to click on a window to give it the focus. # # Arguments: # None. proc ::tk_focusFollowsMouse {} { set old [bind all ] set script { if {"%d" eq "NotifyAncestor" || "%d" eq "NotifyNonlinear" \ || "%d" eq "NotifyInferior"} { if {[tk::FocusOK %W]} { focus %W } } } if {$old ne ""} { bind all "$old; $script" } else { bind all $script } }