WJG (25/11/08) What use is text widget without an undo/redo? For some reasons known only to the Gtk core development team, there's not direct support for undo/redo (as yet at least) but the signals to implement the feature are already in place. The Gnome sourceView widget has support for undo/redo plus a whole host of code editing functionality, but gnocl::sourceView will be shipped with layer with the release of Gnocl 0.9.93. So, here's the script for undo/redo. One of the nice
#---------------
# gnoclTextUndoRedo.tcl
#---------------
# Created by WIlliam J Giddings
# 03/08/2008
#---------------
# Description:
# Provide undo/redo functionality for the gnocl text widget.
#---------------
# Notes:
#
#---------------
# use arrays to create stacks to contain details of the events
# this is more effecient than using lists
# see Welch, Jones & Hobbs(2003, pp101)
proc push {stack value} {
upvar $stack S
if { ! [info exists S(top)] } {
set S(top) 0
}
set S($S(top)) $value
incr S(top)
}
proc pop { stack } {
upvar $stack S
if { ![info exists S(top)] } {
return {}
}
if {$S(top) == 0 } {
return {}
} else {
incr S(top) -1
set x $S($S(top))
unset S($S(top))
return $x
}
}
#
# UNDO / REDO proceedures
#
# Notes:
# -----
# Create undo/redo buffers unique to the widget.
proc on_undo { w } {
global ${w}.UNDO
global ${w}.REDO
if { [array size ${w}.UNDO] == 0 } {
return
}
set action [pop ${w}.UNDO]
switch [lindex $action 0 ] {
"insert-text"
{
# determine the end of range to delete from length of text inserted
set col [expr [lindex [lindex $action 1] 1] +[lindex $action 3] ]
set row [lindex [lindex $action 1] 0]
$w erase [lindex $action 1] [list $row $col]
# resposition the cursor
$w setCursor [list $row $col]
}
"delete-range"
{
# strip leading and trailing braces from the string
$w insert [lindex $action 1] [string trim [lindex $action 3] \{\}]
# resposition the cursor to the end of the inserted text
$w setCursor [lindex $action 1]
$w setCursor cursor+[string length [lindex $action 2]]
}
}
# display the changes
$w scrollToPosition cursor
$w configure -hasFocus 1
push ${w}.REDO $action
}
proc on_redo { w } {
global ${w}.UNDO
global ${w}.REDO
if { [array size ${w}.REDO] == 0 } {
return
}
set action [pop ${w}.REDO]
switch [lindex $action 0 ] {
"insert-text"
{
# determine the end of range to delete from length of text inserted
# The text is returned as a list, so if there is purely whitespace this
# will re mis-read as a sub-list by the interpreter.
# So, get the text as the first item to prevent this.
$w insert [lindex $action 1] [lindex [lindex $action 2] 0]
# resposition the cursor to the end of the inserted text
$w setCursor [lindex $action 1]
$w setCursor cursor+[string length [lindex $action 2]]
}
"delete-range"
{
# determine the end of range to delete from length of text inserted
set col [expr [lindex [lindex $action 1] 1] +[lindex $action 3] ]
set row [lindex [lindex $action 1] 0]
$w erase [lindex $action 1] [list $row $col]
# resposition the cursor
$w setCursor [list $row $col]
}
}
# display the changes
$w scrollToPosition cursor
$w configure -hasFocus 1
push ${w}.UNDO $action
}Note, to run the demo, it'll be necessary to load a further module, gnocBind.tcl. Get it here:
So, at last, here's the demo script:
#---------------
# UndoRedoDemo.tcl
#---------------
# Created by WIlliam J Giddings
# March, 2008
#---------------
# Description:
# Demonstrates simple textBuffer undo/redo functionality.
#---------------
# Notes:
# cd /Desktop/GnoclEdit_2/undoer/wjgstuff
#
# This version has a single buffer to show edit history
#
#---------------
# basic Tcl/Gnocl Script
#! /bin/sh/
#\
exec tclsh "$0" "$@"
package require Gnocl
source gnoclTextUndoRedo.tcl
source gnoclBind.tcl
set text [gnocl::text]
set box1 [gnocl::box -orientation vertical]
set box2 [gnocl::box -orientation horizontal ]
set undo [gnocl::button -text "%#Undo" -onClicked { on_undo $text } ]
set redo [gnocl::button -text "%#Redo" -onClicked { on_redo $text } ]
$box2 add [list $undo $redo]
$box1 add $box2
$box1 add $text -fill {1 1} -expand 1
gnocl::window -title "Text" -child $box1
set userAction 1
#----------------
# UNDO/REDO STUFF
#----------------
# respond to text insert signals
$text configure -onInsertText {
if { $userAction } {
# add the event details to the undo stack
push ${text}.UNDO "insert-text \{%r %c\} \{%t\} \{%l\}"
# clear the redo stack
catch { unset ${text}.REDO }
}
}
# respond to text insert signals
$text configure -onDeleteRange {
if { $userAction } {
push ${text}.UNDO "delete-range \{%r %c\} \{%l %o\} \{%t\}"
}
}
# respond to text action signals
$text configure -onBeginUserAction {
set userAction 1
}
$text configure -onEndUserAction {
set userAction 0
}
# there are no default Undo/Redo bindings, so set your own
# (GtkSourceView widget defaults to Ctrl-z & Ctrl-Z
gnocl::bind $text <Ctrl-Key-z> "on_undo $text"
gnocl::bind $text <Ctrl-Key-y> "on_redo $text"
$text insert end "Ctrl-z undo\nCtrl-y redo"
#-----------------
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