path: root/library/accessibility.tcl

# accessibility.tcl --

# This file defines the 'tk accessible' command for screen reader support
# on X11, Windows, and macOS. It implements an abstraction layer that
# presents a consistent API across the three platforms.

# Copyright © 2009 Allen B. Taylor.
# Copyright © 2024-2025 Kevin Walzer.
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#

if {[info commands ::tk::accessible::check_screenreader] eq "" || [::tk::accessible::check_screenreader] eq 0 || [::tk::accessible::check_screenreader] eq ""} {
    # Do not load if screen reader is not running or command is unavailable
    proc ::tk::accessible args {
	return 0
    }
} else {
    if {[tk windowingsystem] eq "x11" && [::tk::accessible::check_screenreader] eq 1} {

	# Add border to all X11 widgets with accessible focus. A highlight rectangle
	# is drawn over focused widgets by the screen reader app on
	# macOS and Windows (VoiceOver, NVDA), but not on X11. Configuring
	# "-relief groove" and binding to FocusIn/Out events is the cleanest
	# way to accomplish this.

	namespace eval ::tk::accessible {
	    variable origConfig
	    array set origConfig {}

	    # Apply to classic Tk widgets
	    proc ClassicFocusIn {w} {
		variable origConfig
		if {![info exists origConfig($w)]} {
		    set origConfig($w) [list [$w cget -relief] [$w cget -borderwidth]]
		}
		$w configure -relief groove -borderwidth 2
	    }

	    proc ClassicFocusOut {w} {
		variable origConfig
		if {[info exists origConfig($w)]} {
		    lassign $origConfig($w) relief border
		    $w configure -relief $relief -borderwidth $border
		}
	    }

	    # Apply focus bindings to a widget
	    proc AddClassic {w} {
		bindtags $w [linsert [bindtags $w] 0 FocusBorder]
	    }

	    # Setup global ttk styles
	    proc InitTtk {} {
		foreach class {TButton TEntry TCombobox TCheckbutton TRadiobutton \
				   Treeview TScrollbar TScale TSpinbox TLabel} {
		    ttk::style map $class \
			-relief {focus groove !focus flat} \
			-borderwidth {focus 2 !focus 1}
		}
	    }

	    # Install focusborder bindtag for classic widgets
	    bind FocusBorder <FocusIn>  {+::tk::accessible::ClassicFocusIn %W}
	    bind FocusBorder <FocusOut> {+::tk::accessible::ClassicFocusOut %W}

	    # Install ttk mappings
	    ::tk::accessible::InitTtk

	    # Save the original widget commands and replace with wrappers
	    foreach wtype {button entry text listbox scale spinbox scrollbar label radiobutton checkbutton} {
		if {[llength [info commands ::tk::accessible::orig_$wtype]] == 0} {
		    rename ::$wtype ::tk::accessible::orig_$wtype
		    proc ::$wtype {args} [string map [list %TYPE% $wtype] {
			# Create the widget with the original command
			set w [::tk::accessible::orig_%TYPE% {*}$args]
			# Add focus bindings
			::tk::accessible::AddClassic $w
			return $w
		    }]
		}
	    }
	}
    }

    namespace eval ::tk::accessible {

	if {[tk windowingsystem] eq "x11" } {
	    # ATK/Orca has trouble with some data, especially with fine-grained
	    # text operations. In those cases when Orca is not picking up on
	    # text/selection updates from Tk, try shelling out to the
	    # command-line voice that comes with Orca.
	    proc speak {text} {
		if {[::tk::accessible::check_screenreader] eq "1"} {
		    # Escape quotes in the text.
		    set safe_text [string map {"\"" "\\\""} $text]

		    # Try spd-say first.
		    if {[catch {exec spd-say $safe_text} result]} {
			# fallback to espeak if spd-say fails
			catch {exec espeak $safe_text} result
		    }
		}
	    }
	}

	# Attach a variable trace to run _updateselection when a button changes.
	proc _attach_trace {w} {
	    # Radiobuttons/Checkbuttons always have a -variable.
	    set var [$w cget -variable]
	    if {$var ne ""} {
		# Avoid multiple traces on the same variable.
		catch {trace remove variable $var write [list ::tk::accessible::_vartrace $w]}
		trace add variable ::$var write [list ::tk::accessible::_vartrace $w]
	    }
	}

	# Trace handler.
	proc _vartrace {w args} {
	    if {[winfo exists $w]} {
		::tk::accessible::_updateselection $w
	    }
	}

	# Get button text
	proc _getbuttontext {w} {
	    set txt [$w cget -text]
	    ::tk::accessible::speak $txt
	}

	# Check message text on dialog.
	proc _getdialogtext {w} {
	    if {[winfo exists $w.msg]} {
		return [$w.msg cget -text]
	    }
	}

	# Get text in text widget.
	proc _gettext {w} {
	    if {[winfo class $w] ne "Text"} {
		return ""
	    }
	    if {[$w tag ranges sel] eq ""} {
		set data [$w get 1.0 end]
	    }  else {
		set data [$w get sel.first sel.last]
	    }
	    return $data
	}

	# Get text in entry widget.
	proc _getentrytext {w} {
	    set data [$w get]
	    return $data
	}

	# Create keypress/word bindings once for all supported widgets.
	proc install_keycapture {w} {
	    # Ensure we don’t double-bind
	    if {[lsearch -exact [bindtags $w] KeyCaptureTag] == -1} {
		bindtags $w [linsert [bindtags $w] 1 KeyCaptureTag]
	    }
	}

	# Core binding tag (shared by text, entry, ttk::entry).
	bind KeyCaptureTag <KeyPress> {+::tk::accessible::_handle_keypress %W %K}
	bind KeyCaptureTag <KeyRelease-space> {+ after 10 [list ::tk::accessible::_get_prev_word %W]}

	# Handle each keypress event.
	proc _handle_keypress {w key} {
	    # Ignore modifier keys and non-printables
	    if {$key eq "" || [string length $key] > 1} {
		return
	    }

	    # If user pressed space, do nothing here — handled on KeyRelease.
	    if {$key eq "space"} {
		return
	    }

	    # Otherwise emit single-character updates.
	    ::tk::accessible::set_acc_value $w $key
	    if {[tk windowingsystem] eq "x11"} {
		::tk::accessible::speak $key
		# Windows speaks the individual keypress by default
	    } elseif {[tk windowingsystem] eq "aqua"}  {
		::tk::accessible::emit_selection_change $w
	    }
	}

	# Retrieve the previous word before the cursor (called after space release).
	proc _get_prev_word {w} {
	    update idletasks   ;# ensure buffer is current
	    set class [winfo class $w]
	    set before ""

	    if {$class eq "Text"} {
		# For text widgets.
		set start [$w index "insert linestart"]
		if {[$w compare insert == $start]} {
		    # nothing before cursor at start of line.
		    return
		}
		set before [$w get $start "insert -1c"]
	    } elseif {$class eq "Entry" || $class eq "TEntry"} {
		# For entry/ttk::entry widgets.
		set full [$w get]
		set pos [$w index insert]
		if {$pos > 0} {
		    set before [string range $full 0 [expr {$pos - 2}]]
		}
	    } else {
		return
	    }

	    # Extract last word before the space.
	    if {[regexp -nocase -- {\S+$} $before match]} {
		::tk::accessible::set_acc_value $w $match
		if {[tk windowingsystem] eq "x11"} {
		    ::tk::accessible::speak $match
		} else {
		    ::tk::accessible::emit_selection_change $w
		}
	    }
	}

	# Attempt to verify if treeview is tree or table. This works
	# for simple cases but may not be perfect.
	proc _checktree {w} {
	    if {[expr {"tree" in [$w cget -show]}] eq 1} {
		return "Tree"
	    } else {
		return "Table"
	    }
	}

	# Get data from ttk::treeview.
	proc _gettreeviewdata {w} {
	    set values [$w item [lindex [$w selection] 0] -values]
	    return $values
	}

	# Get treeview column names.
	proc _getcolumnnames {w} {
	    set columns [$w cget -columns]
	    foreach col $columns {
		set text [$w heading $col -text]
		lappend headerlist $text
	    }
	    return $headerlist
	}

	# Get selection status from radiobuttons.
	proc _getradiodata {w} {
	    set var [$w cget -variable]
	    if {$var ne "" && [uplevel #0 info exists $var]} {
		set value [uplevel #0 set $var]
		set result [expr {$value eq [$w cget -value]}]
		if {$result eq 1} {
		    return "selected"
		} else {
		    return "not selected"
		}
		return 0
	    }
	}

	# Get selection status from checkbuttons.
	proc _getcheckdata {w} {
	    set var [$w cget -variable]
	    if {$var ne "" && [uplevel #0 info exists $var]} {
		set value [uplevel #0 set $var]
		set result [expr {$value eq [$w cget -onvalue]}]
		if {$result eq 1} {
		    return "selected"
		} else {
		    return "not selected"
		}
		return 0
	    }
	}

	# Update data selection for various widgets.
	proc _updateselection {w} {
	    if {[winfo class $w] eq "Radiobutton" || [winfo class $w] eq "TRadiobutton"} {
		set data [::tk::accessible::_getradiodata $w]
		set role [::tk::accessible::get_acc_role $w]
		set description [::tk::accessible::get_acc_description $w]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
		if {[tk windowingsystem] eq "x11"} {
		    ::tk::accessible::speak "$role $description $data"
		}
	    }
	    if {[winfo class $w] eq "Checkbutton" || [winfo class $w] eq "TCheckbutton" || [winfo class $w] eq "Toggleswitch"} {
		set data [::tk::accessible::_getcheckdata $w]
		set role [::tk::accessible::get_acc_role $w]
		set description [::tk::accessible::get_acc_description $w]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
		if {[tk windowingsystem] eq "x11"} {
		    ::tk::accessible::speak "$role $description $data"
		}
	    }

	    if {[winfo class $w] eq "Listbox"} {
		set data [$w get [$w curselection]]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    if {[winfo class $w] eq "Treeview"} {
		set data [::tk::accessible::_gettreeviewdata $w]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    if {[winfo class $w] eq "Entry" || [winfo class $w] eq "TEntry"}  {
		set data [::tk::accessible::_getentrytext $w]
		::tk::accessible::set_acc_value $w $data
		if {[tk windowingsystem] eq "x11"} {
		    ::tk::accessible::speak $data
		} else {
		    ::tk::accessible::emit_selection_change $w
		}
	    }
	    if {[winfo class $w] eq "TCombobox"} {
		set data [$w get]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    if {[winfo class $w] eq "TNotebook"}  {
		set data  [$w tab current -text]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    if {[winfo class $w] eq "Text"}  {
		set data [::tk::accessible::_gettext $w]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    if {[winfo class $w] eq "TProgressbar"}  {
		set data [::tk::accessible::_getpbvalue $w]
		::tk::accessible::set_acc_value $w $data
		::tk::accessible::emit_selection_change $w
	    }
	    # Menu only needs to be tracked on X11 - native on Aqua and Windows.
	    if {[tk windowingsystem] eq "x11"} {
		if {[winfo class $w] eq "Menu"} {
		    set data [$w entrycget active -label]
		    ::tk::accessible::set_acc_value $w $data
		    ::tk::accessible::emit_selection_change $w
		    ::tk::accessible::emit_focus_change $w
		}
	    }
	}

	# Increment values in various widgets in response to keypress events.
	proc _updatescale {w key} {
	    if {[winfo class $w] eq "Scale"} {
		switch -- $key {
		    Right {
			tk::ScaleIncrement $w down little noRepeat
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		    Left {
			tk::ScaleIncrement $w up little noRepeat
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }
	    if {[winfo class $w] eq "TScale"} {
		switch -- $key {
		    Right {
			ttk::scale::Increment $w 1
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		    Left {
			ttk::scale::Increment $w -1
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }

	    if {[winfo class $w] eq "Spinbox"} {
		switch -- $key {
		    Up {
			$w invoke buttonup
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		    Down {
			$w invoke buttondown
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }
	    if {[winfo class $w] eq "TSpinbox"} {
		switch -- $key {
		    Up {
			ttk::spinbox::Spin $w +1
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		    Down {
			ttk::spinbox::Spin $w -1
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }
	    if {[winfo class $w] eq "TCombobox"} {
		switch -- $key {
		    Down {
			ttk::combobox::Post $w
			set data [$w get]
		    }
		    Escape {
			ttk::combobox::Unpost $w
			$w selection range 0 end
			if {[tk windowingsystem] eq "aqua"} {
			    event generate <Command-a>
			} else {
			    event generate <Control-a>
			}
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }
	    if {[winfo class $w] eq "TNotebook"} {
		switch -- $key {
		    Right {
			{ ttk::notebook::CycleTab %W  1; break }
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		    Left {
			ttk::scale::Increment $w -1
			set data [$w get]
			::tk::accessible::set_acc_value $w $data
			::tk::accessible::emit_selection_change $w
		    }
		}
	    }
	}

	# Get value of progress bar.
	proc _getpbvalue  {pb} {
	    # Make sure widget exists
	    if {![winfo exists $pb]} { return "" }

	    set mode [$pb cget -mode]

	    if {$mode eq "indeterminate"} {
		# Any indeterminate bar is considered busy
		return "busy"
	    } else {
		# Determinate: busy if value < maximum
		if {[$pb cget -value] < [$pb cget -maximum]} {
		    return "busy"
		} else {
		    return ""
		}
	    }
	}


	# Some widgets will not respond to keypress events unless
	# they have focus. Force Tk focus on the widget that currently has
	# accessibility focus if needed.

	proc _forceTkFocus {w} {
	    # Check to make sure window is not destroyed.
	    if {[winfo exists $w]} {
		if {[tk windowingsystem] eq "aqua"} {
		    if {[winfo class $w] in {Scale TScale Spinbox TSpinbox Listbox Treeview TProgressbar}} {
			if {[focus] ne $w} {
			    focus -force $w
			}
		    }
		} elseif {[tk windowingsystem] eq "win32"} {
		    ::tk::accessible::emit_focus_change $w
		}
	    }
	}

	# Set initial accessible attributes and add binding to <Map> event.
	# If the accessibility role is already set, return because
	# we only want these to fire once.
	proc _init {w role name description value state action} {
	    if {[catch {::tk::accessible::get_acc_role $w} msg]} {
		if {$msg == $role} {
		    return
		}
	    }
	    if {[tk windowingsystem] ne "aqua"} {
		# This is necessary to ensure correct accessible keyboard navigation
		if [winfo exists $w] {
		    $w configure -takefocus 1
		}
	    }

	    ::tk::accessible::set_acc_role $w $role
	    ::tk::accessible::set_acc_name $w $name
	    ::tk::accessible::set_acc_description $w $description
	    ::tk::accessible::set_acc_value $w $value
	    ::tk::accessible::set_acc_state $w $state
	    ::tk::accessible::set_acc_action $w $action

	}

	# Toplevel bindings.
	bind Toplevel <Map> {+::tk::accessible::_init \
				 %W \
				 Toplevel \
				 [wm title %W] \
				 {}  \
				 {} \
				 {} \
				 {} \
			     }

	# Button/TButton bindings.
	bind Button <Map> {+::tk::accessible::_init \
			       %W \
			       Button \
			       Button \
			       [%W cget -text] \
			       {} \
			       [%W cget -state] \
			       {%W invoke}\
			   }
	bind TButton <Map> {+::tk::accessible::_init \
				%W \
				Button \
				Button \
				[%W cget -text] \
				{}\
				[%W cget -state] \
				{%W invoke}\
			    }

	# Menubutton/TMButton bindings.
	bind Menubutton <Map> {+::tk::accessible::_init \
				   %W \
				   Button \
				   Button \
				   [%W cget -text] \
				   {} \
				   [%W cget -state] \
				   {%W invoke}\
			       }
	bind TMenubutton <Map> {+::tk::accessible::_init \
				    %W \
				    Button \
				    Button \
				    [%W cget -text] \
				    {} \
				    [%W cget -state] \
				    {%W invoke}\
				}

	# Canvas bindings.
	bind Canvas <Map> {+::tk::accessible::_init \
			       %W \
			       Canvas \
			       Canvas \
			       Canvas \
			       {} \
			       {} \
			       {}\
			   }

	# Checkbutton/TCheckbutton/Toggleswitch bindings.
	bind Checkbutton <Map> {+::tk::accessible::_init \
				    %W \
				    Checkbutton \
				    Checkbutton \
				    [%W cget -text] \
				    [set [%W cget -variable]] \
				    [%W cget -state] \
				    {%W invoke}\
				}
	bind TCheckbutton <Map> {+::tk::accessible::_init \
				     %W \
				     Checkbutton \
				     Checkbutton \
				     [%W cget -text] \
				     [set [%W cget -variable]] \
				     [%W cget -state] \
				     {%W invoke}\
				 }
	bind Toggleswitch <Map> {+::tk::accessible::_init \
				     %W \
				     Toggleswitch \
				     Toggleswitch \
				     Toggleswitch \
				     [%W switchstate] \
				     {} \
				     {%W toggle}\
				 }

	# Combobox bindings.
	bind TCombobox <Map> {+::tk::accessible::_init \
				  %W \
				  Combobox \
				  Combobox \
				  Combobox \
				  [%W get] \
				  [%W cget -state] \
				  {} \
			      }

	# Dialog bindings.
	bind Dialog <Map> {+::tk::accessible::_init\
			       %W \
			       Dialog \
			       [wm title %W] \
			       [::tk::accessible::_getdialogtext %W] \
			       {} \
			       {} \
			       {}\
			   }

	# Entry/TEntry bindings.
	bind Entry <Map> {+::tk::accessible::_init \
			      %W \
			      Entry \
			      Entry \
			      Entry \
			      [%W get] \
			      [%W cget -state] \
			      {} \
			      ; ::tk::accessible::install_keycapture %W}


	bind TEntry <Map> {+::tk::accessible::_init \
			       %W \
			       Entry \
			       Entry \
			       Entry \
			       [%W get] \
			       [%W state]\
			       {} \
			       ; ::tk::accessible::install_keycapture %W}


	# Listbox bindings.
	bind Listbox <Map> {+::tk::accessible::_init \
				%W \
				Listbox \
				Listbox \
				Listbox \
				[%W get [%W curselection]] \
				[%W cget -state]\
				{%W invoke}\
			    }

	# Progressbar bindings.
	bind TProgressbar <Map> {+::tk::accessible::_init \
				     %W \
				     Progressbar \
				     Progressbar \
				     Progressbar \
				     [::tk::accessible::_getpbvalue %W] \
				     [%W state] \
				     {}\
				 }

	# Radiobutton/TRadiobutton bindings.
	bind Radiobutton <Map> {+::tk::accessible::_init \
				    %W \
				    Radiobutton \
				    Radiobutton \
				    [%W cget -text] \
				    [%W cget -variable] \
				    [%W cget -state] \
				    {%W invoke}\
				}
	bind TRadiobutton <Map> {+::tk::accessible::_init \
				     %W \
				     Radiobutton \
				     Radiobutton \
				     [%W cget -text] \
				     [%W cget -variable] \
				     [%W cget -state] \
				     {%W invoke}\
				 }

	# Scale/TScale bindings.
	bind Scale <Map> {+::tk::accessible::_init \
			      %W \
			      Scale \
			      Scale \
			      Scale \
			      [%W get] \
			      [%W cget -state]\
			      {%W set}\
			  }
	bind TScale <Map> {+::tk::accessible::_init \
			       %W \
			       Scale \
			       Scale \
			       Scale \
			       [%W get] \
			       [%W cget -state] \
			       {%W set} \
			   }

	# Menu accessibility bindings for X11 only. Menus are native
	# on macOS/Windows, so we don’t expose them here.

	if {[tk windowingsystem] eq "x11"} {
	    variable prevActiveIndex
	    set prevActiveIndex ""

	    # Update the accessible notifications after idle.
	    proc _update_active_entry {menuWidget} {
		variable prevActiveIndex

		# Determine if this is a menubar or submenu.
		set isMenubar [expr {[winfo manager $menuWidget] eq "menubar"}]

		# Get current active index.
		set idx [$menuWidget index active]
		if {$idx eq "none" || $idx eq ""} {
		    return
		}

		# Build a safer unique key (include parent to avoid collisions).
		set currentKey "[winfo parent $menuWidget]-$menuWidget-$idx"

		# Prevent duplicate processing of the same index.
		if {[info exists prevActiveIndex] && $prevActiveIndex eq $currentKey} {
		    return
		}
		set prevActiveIndex $currentKey

		# Get the label of the active entry safely.
		if {[catch {set label [$menuWidget entrycget $idx -label]} err]} {
		    set label ""
		}

		# Announce menubar immediately.
		if $isMenubar {
		    ::tk::accessible::speak $label

		    # Clear dedupe cache so submenu index 1 is NOT skipped.
		    unset -nocomplain prevActiveIndex
		} else {
		    # Submenu - add gentle pause before announcing.
		    if {$label ne "" && [$menuWidget type $idx] ne "separator"} {
			after 100 [list ::tk::accessible::speak $label]
		    }
		}

		# Update accessible object.
		::tk::accessible::set_acc_name   $menuWidget $label
		::tk::accessible::set_acc_action $menuWidget [list $menuWidget invoke $idx]
		::tk::accessible::emit_selection_change $menuWidget
		::tk::accessible::emit_focus_change     $menuWidget
	    }


	    # Bind <<MenuSelect>> for mouse/keyboard navigation.
	    bind Menu <<MenuSelect>> {
		after idle [list ::tk::accessible::_update_active_entry %W]
	    }

	    # Key bindings - handle navigation AND announcement together
	    bind Menu <Up> {+
		# Only process if this is a submenu (not menubar)
		if {[winfo manager %W] ne "menubar"} {
		    set current [%W index active]
		    if {$current eq ""} {
			set idx [%W index last]
		    } else {
			set idx [expr {$current - 1}]
		    }
		    set lastIndex [%W index last]
		    while {$idx >= 0} {
			if {[%W type $idx] ne "separator" && [%W entrycget $idx -state] ne "disabled"} {
			    %W activate $idx
			    after idle [list ::tk::accessible::_update_active_entry %W]
			    break
			}
			incr idx -1
		    }
		}
	    }

	    bind Menu <Down> {+
		# Only process if this is a submenu (not menubar)
		if {[winfo manager %W] ne "menubar"} {
		    set current [%W index active]
		    if {$current eq ""} {
			set idx 0
		    } else {
			set idx [expr {$current + 1}]
		    }
		    set lastIndex [%W index last]
		    while {$idx <= $lastIndex} {
			if {[%W type $idx] ne "separator" && [%W entrycget $idx -state] ne "disabled"} {
			    %W activate $idx
			    after idle [list ::tk::accessible::_update_active_entry %W]
			    break
			}
			incr idx
		    }
		}
	    }

	    bind Menu <Return> {+
		set idx [%W index active]
		if {$idx ne "" && [%W type $idx] ne "separator" && [%W entrycget $idx -state] ne "disabled"} {
		    %W invoke $idx
		}
	    }

	    # Add bindings to catch when menus are posted/unposted.
	    bind Menu <Map> {+
		# Determine role based on whether this is a menubar.
		if {[winfo manager %W] eq "menubar"} {
		    set role Menubar ;# ATK_ROLE_MENU_BAR
		} else {
		    set role Menu ;# ATK_ROLE_MENU
		}

		::tk::accessible::_init \
				 %W \
				 $role \
				 $role \
				 {} \
				 {} \
				 {} \
				 {}

		# Handle initial vocalization based on menu type.
		if {$role eq "Menubar"} {
		    focus %W
		    after idle {
			set idx [%W index active]
			if {$idx eq "none" || $idx eq ""} {
			    %W activate 0
			}
			::tk::accessible::_update_active_entry %W
		    }
		} else {
		    # For submenus, announce the active entry when mapped.
		    after idle [list ::tk::accessible::_update_active_entry %W]
		}
	    }

	    # Handle initial menubar focus.
	    bind Menu <FocusIn> {+
		if {[winfo manager %W] eq "menubar"} {
		    set idx [%W index active]
		    if {$idx eq "none" || $idx eq ""} {
			%W activate 0
		    }
		    after idle [list ::tk::accessible::_update_active_entry %W]
		}
	    }
	}

	# Scrollbar/TScrollbar bindings.
	bind Scrollbar <Map> {+::tk::accessible::_init \
				  %W \
				  Scrollbar \
				  Scrollbar \
				  Scrollbar \
				  {} \
				  {} \
				  {}\
			      }
	bind TScrollbar <Map> {+::tk::accessible::_init \
				   %W \
				   Scrollbar \
				   Scrollbar \
				   Scrollbar \
				   {} \
				   {} \
				   {}\
			       }

	# Spinbox/TSpinbox bindings.
	bind Spinbox <Map> {+::tk::accessible::_init \
				%W \
				Spinbox \
				Spinbox \
				Spinbox \
				[%W get] \
				[%W cget -state] \
				{%W cget -command}\
			    }
	bind TSpinbox <Map> {+::tk::accessible::_init \
				 %W \
				 Spinbox \
				 Spinbox \
				 Spinbox \
				 [%W get] \
				 [%W state] \
				 {%W cget -command}\
			     }


	# Treeview bindings.
	bind Treeview <Map> {+::tk::accessible::_init \
				 %W \
				 [::tk::accessible::_checktree %W] \
				 [::tk::accessible::_checktree %W] \
				 [::tk::accessible::_getcolumnnames %W] \
				 [::tk::accessible::_gettreeviewdata %W] \
				 [%W state] \
				 {ttk::treeview::Press %W %x %y }\
			     }

	# Text bindings.
	bind Text <Map> {+::tk::accessible::_init \
			     %W \
			     Text \
			     Text \
			     Text \
			     [::tk::accessible::_gettext %W] \
			     [%W cget -state] \
			     {}\
			     ; ::tk::accessible::install_keycapture %W}

	# Label/TLabel bindings.
	bind Label <Map>  {+::tk::accessible::_init \
			       %W \
			       Label \
			       Label \
			       {} \
			       [%W cget -text] \
			       {}\
			       {}\
			   }

	bind TLabel <Map>    {+::tk::accessible::_init \
				  %W \
				  Label \
				  Label \
				  {} \
				  [%W cget -text] \
				  {}\
				  {}\
			      }

	# Notebook bindings - bind to the <<NotebookTabChanged>> event rather
	# than <Map> because this event is generated before the <Map> event,
	# which returns an error because the accessibility data has not been
	# initialized yet.
	bind TNotebook <<NotebookTabChanged>> {+::tk::accessible::_init \
						   %W \
						   Notebook \
						   Notebook \
						   Notebook \
						   [%W tab current -text] \
						   {} \
						   {}\
					       }

	bind all <Map> {+::tk::accessible::add_acc_object %W}

	# Various bindings to capture data/selection changes for
	# widgets that support returning a value.

	# Selection changes.
	bind Listbox <<ListboxSelect>> {+::tk::accessible::_updateselection %W}
	bind Treeview <<TreeviewSelect>> {+::tk::accessible::_updateselection %W}
	bind TCombobox <<ComboboxSelected>> {+::tk::accessible::_updateselection %W}
	bind Text <<Selection>> {+::tk::accessible::_updateselection %W}

	if {[tk windowingsystem] eq "x11"} {
	    # Automatically hook up new checkbuttons/radiobuttons
	    # to notify the accessibility system when their selection
	    #state changes.
	    bind Radiobutton   <Map> {+::tk::accessible::_attach_trace %W}
	    bind TRadiobutton  <Map> {+::tk::accessible::_attach_trace %W}
	    bind Checkbutton   <Map> {+::tk::accessible::_attach_trace %W}
	    bind TCheckbutton  <Map> {+::tk::accessible::_attach_trace %W}
	    bind Toggleswitch  <Map> {+::tk::accessible::_attach_trace %W}
	}

	# Capture value changes from scale widgets.
	bind Scale <Right> {+::tk::accessible::_updatescale %W Right}
	bind Scale <Left> {+::tk::accessible::_updatescale %W Left}
	bind TScale <Right> {+::tk::accessible::_updatescale %W Right}
	bind TScale <Left> {+::tk::accessible::_updatescale %W Left}

	# In some contexts, the accessibility API is confused about widget
	# roles because of the way the widget is constructed. For instance,
	# VoiceOver and Orca misread the ttk::spinbox as an entry because
	# of how it is constructed. In such cases, let's re-use an old trick
	# that we used with the Aqua scrollbar when the ttk widgets were first
	# developed - map the ttk widget to its classic equivalent. There may
	# be a visual conflict but it is more important that the AT be able
	# to correctly identify widget and its value.

	if {[tk windowingsystem] eq "aqua" || [tk windowingsystem] eq "x11"} {
	    set result [::tk::accessible::check_screenreader]
	    if {$result > 0} {
		interp alias {} ::ttk::spinbox {} ::tk::spinbox
	    }
	}
	if {[tk windowingsystem] eq "x11"} {
	    set result [::tk::accessible::check_screenreader]
	    if {$result > 0} {
		interp alias {} ::ttk::radiobutton {} ::tk::radiobutton
		interp alias {} ::ttk::checkbutton {} ::tk::checkbutton
		interp alias {} ::ttk::scale {} ::tk::scale

	    }
	}

	if {[tk windowingsystem] eq "win32"} {
	    set result [::tk::accessible::check_screenreader]
	    if {$result > 0} {
		interp alias {} ::ttk::radiobutton {} ::tk::radiobutton
		interp alias {} ::ttk::checkbutton {} ::tk::checkbutton
		interp alias {} ::ttk::spinbox {} ::tk::spinbox
	    }
	}

	# Capture value changes from spinbox widgets.
	bind Spinbox <Up> {+::tk::accessible::_updatescale %W Up}
	bind Spinbox <Down> {+::tk::accessible::_updatescale %W Down}
	bind TSpinbox <Up> {+::tk::accessible::_updatescale %W Up}
	bind TSpinbox <Down> {+::tk::accessible::_updatescale %W Down}

	# Capture notebook selection.
	bind TNotebook <Map> {+::ttk::notebook::enableTraversal %W}
	bind TNotebook <<NotebookTabChanged>> {+::tk::accessible::_updateselection %W}

	# Capture text selection in entry widgets.
	bind Entry <KeyPress> {+::tk::accessible::_updateselection %W}
	bind TEntry <KeyPress> {+::tk::accessible::_updateselection %W}
	bind Entry <Left> {+::tk::accessible::_updateselection %W}
	bind TEntry <Left> {+::tk::accessible::_updateselection %W}
	bind Entry <Right> {+::tk::accessible::_updateselection %W}
	bind TEntry <Right> {+::tk::accessible::_updateselection %W}
	bind Entry <<Selection>> {+::tk::accessible::_updateselection %W}
	bind TEntry <<Selection>> {+::tk::accessible::_updateselection %W}

	# Progressbar updates.
	bind TProgressbar <FocusIn> {+::tk::accessible::_updateselection %W}

	bind Scrollbar <Up> {+%W set [expr {[%W get] - 0.1}]; ::tk::accessible::emit_selection_change %W}
	bind Scrollbar <Down> {+%W set [expr {[%W get] + 0.1}]; ::tk::accessible::emit_selection_change %W}
	bind TScrollbar <Up> {+%W set [expr {[%W get] - 0.1}]; ::tk::accessible::emit_selection_change %W}
	bind TScrollbar <Down> {+%W set [expr {[%W get] + 0.1}]; ::tk::accessible::emit_selection_change %W}

	bind Dialog <Return> {+::tk::dialog::OK %W; ::tk::accessible::emit_selection_change %W}
	bind Dialog <Escape> {+::tk::dialog::Cancel %W; ::tk::accessible::emit_selection_change %W}

	# Help text for widgets that require additional direction
	# on keyboard navigation - these widgets will use standard keyboard
	# navigation when they obtain focus rather than the accessibility
	# keyboard shortcuts. We are mostly limiting the accessibility tree to one
	# level - toplevel window and child windows - to reduce the complexity of
	# the implementation, which is tied tighly to Tk windows. Component
	# elements of many widgets such listbox or treeview rows are not exposed as
	# Tk windows, and there is no simple way to expose them to the platforms'
	# accessibility API's directly, but they can be navigated via the keyboard
	# and their data (obtained via selection events) can be piped to the
	# screen reader for vocalization. The help text here assists the user
	# in switching to the standard keys for navigation as needed.

	bind Listbox <Map> {+::tk::accessible::set_acc_help %W "To navigate, click the mouse or trackpad and then use the standard Up-Arrow and Down-Arrow keys."}
	bind Treeview <Map> {+::tk::accessible::set_acc_help %W "To navigate, click the mouse or trackpad and then use the standard Up-Arrow and Down-Arrow keys. To open or close a tree node, click the Space key."}
	bind Entry <Map> {+::tk::accessible::set_acc_help %W "To navigate, click the mouse or trackpad and then use standard keyboard navigation. To hear the contents of the entry field, select all."}
	bind TEntry <Map> {+::tk::accessible::set_acc_help %W "To navigate, click the mouse or trackpad and then use standard keyboard navigation. To hear the contents of the entry field, select all."}
	bind Scale <Map> {+::tk::accessible::set_acc_help %W "Click the right or left arrows to move the scale."}
	bind TScale <Map> {+::tk::accessible::set_acc_help %W "Click the right or left arrows to move the scale."}
	bind Spinbox <Map> {+::tk::accessible::set_acc_help %W "Click the up or down arrows to change the value."}
	bind TSpinbox <Map> {+::tk::accessible::set_acc_help %W "Click the up or down arrows to change the value."}
	bind Canvas <Map> {+::tk::accessible::set_acc_help %W "The canvas widget is not accessible."}
	bind Scrollbar <Map> {+::tk::accessible::set_acc_help %W "Use the touchpad or mouse wheel to move the scrollbar."}
	bind TScrollbar <Map> {+::tk::accessible::set_acc_help %W "Use the touchpad or mouse wheel to move the scrollbar."}
	bind Menubutton <Map> {+::tk::accessible::set_acc_help %W "Use the touchpad or mouse wheel to pop up the menu."}
	bind TMenubutton <Map> {+::tk::accessible::set_acc_help %W "Use the touchpad or mouse wheel to pop up the menu."}
	bind TNotebook <Map> {+::tk::accessible::set_acc_help %W "Use the Tab and Right/Left arrow keys to navigate between notebook tabs."}
	bind Text <Map> {+::tk::accessible::set_acc_help %W "Use normal keyboard shortcuts to navigate the text widget."}

	if {[tk windowingsystem] eq "win32"} {
	    bind all <FocusIn> {+::tk::accessible::_forceTkFocus %W}
	}

	if {[tk windowingsystem] eq "x11"} {
	    bind Button <FocusIn> {+::tk::accessible::_getbuttontext %W}
	    bind TButton <FocusIn> {+::tk::accessible::_getbuttontext %W}
	}

	# Finally, export the main commands.
	namespace export set_acc_role set_acc_name set_acc_description set_acc_value set_acc_state set_acc_action set_acc_help get_acc_role get_acc_name get_acc_description get_acc_value get_acc_state get_acc_action get_acc_help add_acc_object emit_selection_change check_screenreader emit_focus_change
	namespace ensemble create
    }

}
# Add these commands to the tk command ensemble: tk accessible.
namespace ensemble configure tk -map \
    [dict merge [namespace ensemble configure tk -map] \
	 {accessible ::tk::accessible}]