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