# jtext.tcl

## Introduction

The jtext.tcl library is distributed as part of the jstools package. It provides wrappers around the widget commands that manipulate the contents of a text widget, building additional functionality on top of them or making them more convenient to use.

This document describes jtext.tcl version 4.1/4.4.

## Usage

### Accessing the Library

In order to use the jtext.tcl library, it (and any other libraries it depends on) must be in your Tcl `auto_path`, described in `tclvars`(n). Information about how to arrange that, and other conventions common to the jstools libraries, is in the Usage section of The jstools Libraries.

### Using jtext.tcl as an Interface to the Text Widget

The purpose of the jtext.tcl library is as an interface to the text widget allowing additional functionality to be built on top of its widget command. For instance, `j:text:insert`, along with the jtexttags.tcl library, can support the notion of a set of `current tags' automatically applied to newlyinserted text. My main goal with this library is to use it to build a general undo facility, allowing an arbitrary number of changes to a text widget to be undone and redone by journaling changes to the text widget. (This is not yet supported.) This means that it's very important that if an application uses the jtext.tcl procedures with a particular text widget, all changes to that widget must be made through the jtext.tcl procedures.

The jtext.tcl library also keeps track of the state of the text widget - whether it's `clean' or `dirty'. This will only be accurate if all your accesses to the widget are through the jtext.tcl library.

(Actions that don't affect the contents of the text widget in any way, or that you don't care about being able to undo, don't need to go through the library. For instance, there's no `j:text:get` procedure, because there's no need to journal pathname`get` commands.)

## Credits and Copyright

### Author

Jay Sekora
`js@aq.org`
`http://www.aq.org/~js/`

### Copyright

The library is copyright © 1992-1995 by Jay Sekora, but may be freely redistributed under the conditions at the top of the file.

## Overview

### Procedures

`j:text:insert` - insert text into text widget at insert point
`j:text:insert_string` - deprecated alias for `j:text:insert`
`j:text:move` - move insert mark in text widget to a particular position
`j:text:delete` - delete a range of characters in a text widget
`j:text:replace` - replace a range of characters in a text widget with a string
`j:text:mark_dirty` - specify that a text widget has been modified
`j:text:mark_clean` - specify that a text widget has been saved
`j:text:is_dirty` - true if a text widget has been modified since it was saved
`j:text:has_selection` - true if there is a selection in a text widget
`j:text:insert_touches_selection` - true if insert point touches or is in selection
`j:text:tagged_insert` - insert tagged sequences of text
`j:text:find` - search for patterns in a text widget

### See Also

jtexttags.tcl

## j:text:insert

### Usage

`j:text:insert` w`` text

### Arguments

w is the text widget to insert into
text is the text to insert

### Description

This procedure inserts text into w at w's insert point.

If w has been configured for use with the jtexttags.tcl library (specifically, if a taglist has been set for it with `j:tag:set_tags`, or `j:tag:set_tag`), then the text will be inserted with w's current tag list (and no other tags); see the jtexttags.tcl documentation for more about this.

If `J_PREFS(typeover)`is true - if the user has selected `Typing replaces selection' on the Global Preferences panel - then if (1) there is a selection in w and (2) the insert point is within or adjacent to the selection, the selection will be deleted and replaced by text. (The requirement that the insert point be in or next to the selection is so that the user can't inadvertently delete text distant from the place in the document where sie's working, possibly without realising it.)

## j:text:move

### Usage

`j:text:move` t`` index

### Arguments

t is the text widget whose insert point is being changed
index is the new position of the insert point

### Description

This procedure moved text widget t's insert point to index. index can be in any of the legal forms for a text widget index; see `text`(n) for details.

If w has been configured for use with the jtexttags.tcl library (specifically, if a taglist has been set for it with `j:tag:set_tags`, or `j:tag:set_tag`), then w's current tag list will be set based on the tags of the (new) neighbouring characters; see the jtexttags.tcl documentation for more about this.

## j:text:delete

### Usage

`j:text:delete` t`` from`` to

### Arguments

t is the text widget whose insert point is being changed
from is the index of the first character in t to delete
to is the index of the character after the last character in t to delete

### Description

This procedure deletes all characters in t from from, inclusive, to to, exclusive. (I.e., the character at from and any characters between from and to will be deleted, but the char at to itself won't be.) from and to can be in any of the legal forms for a text widget index; see `text`(n) for details.
``

## j:text:replace

### Usage

`j:text:replace` t`` from`` to`` string

### Arguments

t is the text widget you want to replace text in
from is the index of the first character to replace
to is the index of the character after the last character to replace
string is the string to insert in t in place of the range from from to to

### Description

This procedure replaces a sequence of character in text widget t with string. After being inserted, string will have all (and only) the tags that the character at from had before the replacement. The insertion point is left after string.

## j:text:mark_dirty

### Usage

`j:text:mark_dirty` t

### Argument

t is the text widget which has been changed

### Description

This procedure marks the text widget t as having been changed. It should be used after all actions that modify the contents of the widget. It's intended for applications such as editors, which need to know whether a document has been modified since it was last saved.

All the jtext.tcl procedures that modify text call this properly, so you should never need to set it yourself.

## j:text:mark_clean

### Usage

`j:text:mark_clean` t

### Argument

t is the text widget which no longer has pending changes

### Description

This procedure marks the text widget t as not having pending changes. Typically, this is used after an application has saved the widget's contents into a file, or is done with the widget. It's intended for applications such as editors, which need to know whether a document has been modified since it was last saved.

## j:text:is_dirty

### Usage

`j:text:is_dirty` t

### Argument

t is the text widget whose state you want to query

### Description

This procedure returns true (`1`) if the text widget t has pending changes (i.e., if its contents have been changed since it was created or since it was last marked clean with `j:text:mark_clean`). Otherwise it returns false (0).

## j:text:has_selection

### Usage

`j:text:has_selection` t

### Argument

t is the text widget whose situation you want to query

### Description

This procedure returns true (`1`) if there is currently a selection in text widget t. Otherwise it returns false (0).

## j:text:insert_touches_selection

### Usage

`j:text:insert_touches_selection` t

### Argument

t is the text widget whose situation you want to query

### Description

This procedure returns true (`1`) if there is currently a selection in text widget t and t's insert point is within or next to the selection. Otherwise it returns false (0).

##
j:text:tagged_insert

### Usage

`j:text:tagged_insert` t`` list

### Arguments

t is the text widget the text is to be inserted into
list is a list of text ranges and the tags to apply to them, described below

### Example

`j:text:tagged_insert $info {
{Warning:} {bold red}
{ can't open } {}
{errlog} {typewriter}
{ for writing.} {}
}
`

### Description

This procedure is essentially a wrapper around the (Tk4.0 and above) text widget `insert` command. The list argument contains pairs of strings and corresponding lists of tags. Each string (evennumbered elements of list) is inserted into t, tagged with all the corresponding tags (the following oddnumbered element of list), and no others. In the example above, for instance, the string `Warning:` is inserted into text widget `$info`, and tagged with the `bold` and `red` tags. All text is inserted at the widget's `insert` mark (and after insertion, the `insert` mark is left after the newlyinserted text).

## j:text:find

### Usage

`j:text:find` t`` [options]

### Argument

t is the text widget to search in

### Options

`-pattern` pattern`` (default `{}` - not really optional)
`-tag` tag`` (default `select`)
`-backwards` backwards`` (default `0`)
`-regexp` regexp`` (default `0`)
`-case` case`` (default `1`)
`-wrap` wrap`` (default `1`)

### Example

`j:text:find $t -regexp 1 -pattern "^proc[ \t]"
# The following example shows the use of the return value.
# Note the importance of specifying "-wrap 0" in this case.
$t tag configure blue -background blue -foreground white
$t mark set insert 1.0
while {[j:text:find $t \
-wrap 0 -tag blue -case 0 -pattern blue]} {
;
}
`

### Description

This procedure searches for pattern, which can be either a string or a regular expression, in the contents of text widget t, returning `1` if the pattern is found, and `0` if it is not. The search will start at the current insert point and progress forwards unless backwards is true, in which case (surprise!) it will progress backwards. Unless wrap is false (`0`), the search will wrap around at the end (beginning for a backwards search) of the widget.

If a match is found, the text that matches has the tag tag applied to it, and the insert point is moved to the end (beginning for a backwards search) of the matching text. If tag is `sel` (the default), the text widget's selection (if any) will first be cleared, so you don't end up with multiple ranges in a widget tagged with `sel`. (There's no problem with multiple ranges of other tags.)

If regexp is `1`, then pattern is a regular expression and matching will follow the rules described in Tcl's `regexp`(n) man page. If it is `0` (the default), ordinary literal string matching is performed. In either case, the search will be casesensitive if case is `1` (the default); caseinsensitive if it is specified as `0`.

This procedure uses the Tk text widget's `find` method. Because the text widget performs searches linebyline, search patterns can't span lines. I hope to work around this in future versions. Because versions of Tk earlier than 4.0 don't provide the text widget `find` method, this procedure doesn't work under Tk 3.6 or earlier.

## Bugs and Misfeatures

- The interaction of `j:text:insert` with `J_PREFS(typeover)` is for the benefit of keyboard bindings and other changes based on user actions. It's not appropriate for other uses. There should really be a bindingsspecific version of `j:text:insert` (perhaps `j:text:type`?) and a generic one.
- The `j:text:find` procedure can't search for anything that spans lines. That means you can't (for instance) easily convert multiple contiguous blank lines to a single blank line.

## Future Directions

- As mentioned above in Usage, I hope to implement a generalised undo facility in this library.

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