ntextIndent - ntext Indentation for the Text Widget

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# ntextIndent(n) 1.0 tklib "ntext Indentation for the Text Widget"

## Name

ntextIndent - ntext Indentation for the Text Widget

## Synopsis

- package require Tcl 8.5
- package require Tk 8.5
- package require ntext ?1.0?

- ::ntext::new_textCopy pathName
- ::ntext::new_textCut pathName
- ::ntext::new_textPaste pathName
- ::ntext::syncIndentColor pathName

## Description

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.

## COMMANDS

::ntext::new_textCopy pathName

  Replacement for ::tk_textCopy.

::ntext::new_textCut pathName

  Replacement for ::tk_textCut that also maintains Ntext indentation.

::ntext::new_textPaste pathName

  Replacement for ::tk_textPaste that also maintains Ntext indentation.

::ntext::syncIndentColor pathName

  Command to apply the current value of the variable ::ntext::indentColor to existing lines in a text widget. This command is useful if a text widget has been created, text has been inserted in the widget, and then the value of ::ntext::indentColor is changed.

## CONFIGURATION OPTIONS

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

::ntext::classicWrap

- 0 - selects Ntext behaviour, i.e. display lines are indented to match the initial whitespace of the first display line of a logical line.

  No other action is required if this option, and the text widget's -wrap option, are set before any text is entered in the widget, and if text is entered and edited only by the mouse and keyboard. If, instead, text is manipulated by the script, or if the text widget's -wrap option or the value of ::ntext::classicWrap are changed while the widget holds text, then calls to ntext functions are needed to alter the indentation. See the section INDENTING DISPLAY LINES for detailed instructions.

- 1 - (default value) selects classic Text behaviour, i.e. no indentation.

::ntext::indentColor

- {} - if the value is the empty string, then the indent of wrapped display lines has the same color as the widget background.

- color - a valid Tk color to use for the indent of wrapped display lines (default value #d9d9d9).

  Coloring is implemented with the text widget tag option -lmargincolor, which is available from Tk 8.6.6 onwards. Ntext indent coloring has no effect in earlier versions of Tk.

  The value of ::ntext::indentColor will often be set at startup. If the value is changed when text widgets already exist and contain text, those widgets can be updated by calling command ::ntext::syncIndentColor.

Advanced Use

::ntext::newWrapRegexp

- the value is a regexp pattern that determines the character of a logical line to which display lines other than the first will be aligned. The default value, [^[:space:]], ensures alignment with the first non-whitespace character.

## INDENTING DISPLAY LINES

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.

## FUNCTIONS

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

- Adjust the indentation of a text widget. Different cases are discussed below.

::ntext::wrapIndent textWidget

- Adjust the indentation of all the text in text widget textWidget.

::ntext::wrapIndent textWidget index1

- Adjust the indentation of a single logical line of a text widget - the line of textWidget that contains the index index1.

::ntext::wrapIndent textWidget index1 index2

- Adjust the indentation of a range of logical lines of a text widget - the lines of textWidget that contain indices index1 to index2.

Usage

- ::ntext::wrapIndent should be called only if the script changes the widget's contents or display properties. If the contents of the widget have been modified by the keyboard or mouse, it is not necessary for the script to call ::ntext::wrapIndent because the appropriate calls are made automatically by the Ntext bindings.

- The script should normally call ::ntext::wrapIndent if, for example, the script changes one of the following when the widget is not empty: the value of ::ntext::classicWrap, or the widget's -wrap status, or the widget's tab spacing, or the font size, or the widget's contents.

- A call of the form ::ntext::wrapIndent textWidget will always suffice, but if changes are needed only to certain lines, it is more efficient to specify those lines with the optional arguments ?index1?, ?index2?.

- If the widget is in -word wrap mode, and if ::ntext::classicWrap is set to 0, ::ntext::wrapIndent will apply indentation to the logical lines within the range specified by the function's arguments.

- In other cases, i.e. if the widget is in -word char or -word none mode, or if ::ntext::classicWrap is set to 1, ::ntext::wrapIndent will remove the indentation of the logical lines within the range specified by the function's arguments.

## BUGS

This version of ntext is intended to be compatible with all releases of Tk 8.5 and 8.6, and with the branches core-8-5-branch, core-8-6-branch, and trunk in the source code repository for Tk. Any incompatibility with any of these versions, for any Tk windowing system, should be reported as a bug. Please report such in the category ntext of the Tklib Trackers.

## EXAMPLES

To switch on Ntext 's indentation and use it in widget .t, using the default indent color #d9d9d9:

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

To switch on Ntext 's indentation and use it in widget .t, without colored indents:

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

To switch on Ntext 's indentation and use it in widget .t, coloring the indents black:

    package require ntext
    set ::ntext::classicWrap 0
    set ::ntext::indentColor black
    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 change the indentation color when a widget .t already holds text:

    set ::ntext::indentColor black
    ::ntext::syncIndentColor .t

To switch to -wrap char mode:

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

## See Also

bindtags, ntext, re_syntax, regexp, text

## Keywords

bindtags, re_syntax, regexp, text