ntextIndent - ntext Indentation for the Text Widget
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:
::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.
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.
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?
- •
- 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.
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]
::ntext::wrapIndent .t $foo end
To switch to -wrap char mode:
::ntext::wrapIndent .t
bindtags, ntext, re_syntax, regexp, text
bindtags, re_syntax, regexp, text