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ntextIndent(n) 0.81 tklib "ntext Indentation for the Text Widget"


ntextIndent - ntext Indentation for the Text Widget

Table Of Contents


  • package require Tcl 8.5
  • package require Tk 8.5
  • package require ntext ?0.81?


The ntext package provides a binding tag named Ntext for use by text widgets in place of the default Text binding tag.

Tk's text widget may be configured to wrap lines of text that are longer than the width of the text area, a feature that is familiar from text editors and word processors. A complete line of text (delimited by newlines, or by the beginning or end of the document) is called a "logical line". When a logical line is wrapped onto more than one line of the display area, these fragments of the logical line are called "display lines".

If a logical line begins with whitespace, then wrapped display lines begin further to the left than the first display line, which can make the text layout untidy and difficult to read. The Ntext binding tag provides facilities so that a text widget in -wrap word mode will automatically indent display lines (other than the first) to match the initial whitespace of the first display line.

This indentation is available to text widgets only in -wrap word mode.


The behavior of Ntext may be configured application-wide by setting the values of a number of namespace variables:


Advanced Use



To use Ntext 's display line indentation:

  1. Set the variable ::ntext::classicWrap to 0 (default value is 1). This enables bindings that will preserve indentation whenever the user modifies the widget contents using the keyboard and mouse. If the widget already holds text, call ::ntext::wrapIndent to initialise indentation.

    Further instructions apply if the program changes the widget's contents, wrap configuration, or indent configuration.

  2. The program can change the text contents, e.g. by the .text insert command. Such a change does not trigger a window binding, so the program should explicitly call function ::ntext::wrapIndent after inserting text.

  3. Auto-indentation occurs only if the widget is in -wrap word mode. If the program changes to or from -wrap word when the widget is not empty, it should call ::ntext::wrapIndent to format the widget's text.

  4. If indentation is used, and then switched off by setting ::ntext::classicWrap to 1, call ::ntext::wrapIndent to remove indentation.


::ntext::wrapIndent textWidget ?index1? ?index2?

::ntext::wrapIndent textWidget

::ntext::wrapIndent textWidget index1

::ntext::wrapIndent textWidget index1 index2



To switch on Ntext 's indentation and use it in widget .t:

package require ntext
set ::ntext::classicWrap 0
text .t -wrap word
bindtags .t {.t Ntext . all}

To decide later to switch off Ntext 's indentation:

set ::ntext::classicWrap 1
::ntext::wrapIndent .t

To decide later to switch Ntext 's indentation back on:

set ::ntext::classicWrap 0
::ntext::wrapIndent .t 1.0 end

To inject some text into the widget:

set foo [.t index end]
.t insert end {This line was added by the script, not the keyboard!}
::ntext::wrapIndent .t $foo end

To switch to -wrap char mode:

.t configure -wrap char
::ntext::wrapIndent .t

Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category ntext of the Tklib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

See Also

bindtags, ntext, re_syntax, regexp, text


bindtags, re_syntax, regexp, text