Ubuntu Manpage: text, tk_textCopy, tk_textCut, tk_textPaste - Create and manipulate 'text' hypertext

NAME

       text,  tk_textCopy,  tk_textCut,  tk_textPaste  -  Create  and manipulate 'text' hypertext
       editing widgets

SYNOPSIS

       text pathName ?options?
       tk_textCopy pathName
       tk_textCut pathName
       tk_textPaste pathName

STANDARD OPTIONS

       -background           -highlightthickness  -relief
       -borderwidth          -insertbackground    -selectbackground
       -cursor               -insertborderwidth   -selectborderwidth
       -exportselection      -insertofftime       -selectforeground
       -font                 -insertontime        -setgrid
       -foreground           -insertwidth         -takefocus
       -highlightbackground  -padx                -xscrollcommand
       -highlightcolor       -pady                -yscrollcommand

       See the options manual entry for details on the standard options.

WIDGET-SPECIFIC OPTIONS

Command-Line Name:-autoseparators
Database Name: autoSeparators
Database Class: AutoSeparators

Specifies a boolean that says whether separators are automatically inserted in the
undo stack. Only meaningful when the -undo option is true.

Command-Line Name:-blockcursor
Database Name: blockCursor
Database Class: BlockCursor

Specifies a boolean that says whether the blinking insertion cursor should be drawn
as a character-sized rectangular block. If false (the default) a thin vertical line
is used for the insertion cursor.

Command-Line Name:-endline
Database Name: endLine
Database Class: EndLine

Specifies an integer line index representing the line of the underlying textual
data store that should be just after the last line contained in the widget. This
allows a text widget to reflect only a portion of a larger piece of text. Instead
of an integer, the empty string can be provided to this configuration option, which
will configure the widget to end at the very last line in the textual data store.

Command-Line Name:-height
Database Name: height
Database Class: Height

Specifies the desired height for the window, in units of characters in the font
given by the -font option. Must be at least one.

Command-Line Name:-inactiveselectbackground
Database Name: inactiveSelectBackground
Database Class: Foreground

Specifies the colour to use for the selection (the sel tag) when the window does
not have the input focus. If empty, {}, then no selection is shown when the window
does not have the focus.

Command-Line Name:-insertunfocussed
Database Name: insertUnfocussed
Database Class: InsertUnfocussed

Specifies how to display the insertion cursor when the widget does not have the │
focus. Must be none (the default) which means to not display the cursor, hollow │
which means to display a hollow box, or solid which means to display a solid box. │
Note that hollow and solid will appear very similar when the -blockcursor option is │
false.

Command-Line Name:-maxundo
Database Name: maxUndo
Database Class: MaxUndo

Specifies the maximum number of compound undo actions on the undo stack. A zero or
a negative value imply an unlimited undo stack.

Command-Line Name:-spacing1
Database Name: spacing1
Database Class: Spacing1

Requests additional space above each text line in the widget, using any of the
standard forms for screen distances. If a line wraps, this option only applies to
the first line on the display. This option may be overridden with -spacing1 options
in tags.

Command-Line Name:-spacing2
Database Name: spacing2
Database Class: Spacing2

For lines that wrap (so that they cover more than one line on the display) this
option specifies additional space to provide between the display lines that
represent a single line of text. The value may have any of the standard forms for
screen distances. This option may be overridden with -spacing2 options in tags.

Command-Line Name:-spacing3
Database Name: spacing3
Database Class: Spacing3

Requests additional space below each text line in the widget, using any of the
standard forms for screen distances. If a line wraps, this option only applies to
the last line on the display. This option may be overridden with -spacing3 options
in tags.

Command-Line Name:-startline
Database Name: startLine
Database Class: StartLine

Specifies an integer line index representing the first line of the underlying
textual data store that should be contained in the widget. This allows a text
widget to reflect only a portion of a larger piece of text. Instead of an integer,
the empty string can be provided to this configuration option, which will configure
the widget to start at the very first line in the textual data store.

Command-Line Name:-state
Database Name: state
Database Class: State

Specifies one of two states for the text: normal or disabled. If the text is
disabled then characters may not be inserted or deleted and no insertion cursor
will be displayed, even if the input focus is in the widget.

Command-Line Name:-tabs
Database Name: tabs
Database Class: Tabs

Specifies a set of tab stops for the window. The option's value consists of a list
of screen distances giving the positions of the tab stops, each of which is a
distance relative to the left edge of the widget (excluding borders, padding, etc).
Each position may optionally be followed in the next list element by one of the
keywords left, right, center, or numeric, which specifies how to justify text
relative to the tab stop. Left is the default; it causes the text following the
tab character to be positioned with its left edge at the tab position. Right means
that the right edge of the text following the tab character is positioned at the
tab position, and center means that the text is centered at the tab position.
Numeric means that the decimal point in the text is positioned at the tab position;
if there is no decimal point then the least significant digit of the number is
positioned just to the left of the tab position; if there is no number in the text
then the text is right-justified at the tab position. For example, “-tabs {2c left
4c 6c center}” creates three tab stops at two-centimeter intervals; the first two
use left justification and the third uses center justification.

If the list of tab stops does not have enough elements to cover all of the tabs in
a text line, then Tk extrapolates new tab stops using the spacing and alignment
from the last tab stop in the list. Tab distances must be strictly positive, and
must always increase from one tab stop to the next (if not, an error is thrown).
The value of the -tabs option may be overridden by -tabs options in tags.

If no -tabs option is specified, or if it is specified as an empty list, then Tk
uses default tabs spaced every eight (average size) characters. To achieve a
different standard spacing, for example every 4 characters, simply configure the
widget with “-tabs "[expr {4 * [font measure $font 0]}] left" -tabstyle
wordprocessor”.

Command-Line Name:-tabstyle
Database Name: tabStyle
Database Class: TabStyle

Specifies how to interpret the relationship between tab stops on a line and tabs in
the text of that line. The value must be tabular (the default) or wordprocessor.
Note that tabs are interpreted as they are encountered in the text. If the tab
style is tabular then the n'th tab character in the line's text will be associated
with the n'th tab stop defined for that line. If the tab character's x coordinate
falls to the right of the n'th tab stop, then a gap of a single space will be
inserted as a fallback. If the tab style is wordprocessor then any tab character
being laid out will use (and be defined by) the first tab stop to the right of the
preceding characters already laid out on that line. The value of the -tabstyle
option may be overridden by -tabstyle options in tags.

Command-Line Name:-undo
Database Name: undo
Database Class: Undo

Specifies a boolean that says whether the undo mechanism is active or not.

Command-Line Name:-width
Database Name: width
Database Class: Width

Specifies the desired width for the window in units of characters in the font given
by the -font option. If the font does not have a uniform width then the width of
the character “0” is used in translating from character units to screen units.

Command-Line Name:-wrap
Database Name: wrap
Database Class: Wrap

Specifies how to handle lines in the text that are too long to be displayed in a
single line of the text's window. The value must be none or char or word. A wrap
mode of none means that each line of text appears as exactly one line on the
screen; extra characters that do not fit on the screen are not displayed. In the
other modes each line of text will be broken up into several screen lines if
necessary to keep all the characters visible. In char mode a screen line break may
occur after any character; in word mode a line break will only be made at word
boundaries.
_________________________________________________________________________________________________

DESCRIPTION

The text command creates a new window (given by the pathName argument) and makes it into a
text widget. Additional options, described above, may be specified on the command line or
in the option database to configure aspects of the text such as its default background
color and relief. The text command returns the path name of the new window.

A text widget displays one or more lines of text and allows that text to be edited. Text
widgets support four different kinds of annotations on the text, called tags, marks,
embedded windows or embedded images. Tags allow different portions of the text to be
displayed with different fonts and colors. In addition, Tcl commands can be associated
with tags so that scripts are invoked when particular actions such as keystrokes and mouse
button presses occur in particular ranges of the text. See TAGS below for more details.

The second form of annotation consists of floating markers in the text called “marks”.
Marks are used to keep track of various interesting positions in the text as it is edited.
See MARKS below for more details.

The third form of annotation allows arbitrary windows to be embedded in a text widget. See
EMBEDDED WINDOWS below for more details.

The fourth form of annotation allows Tk images to be embedded in a text widget. See
EMBEDDED IMAGES below for more details.

The text widget also has a built-in undo/redo mechanism. See THE UNDO MECHANISM below for
more details.

The text widget allows for the creation of peer widgets. These are other text widgets
which share the same underlying data (text, marks, tags, images, etc). See PEER WIDGETS
below for more details.

INDICES

Many of the widget commands for texts take one or more indices as arguments. An index is
a string used to indicate a particular place within a text, such as a place to insert
characters or one endpoint of a range of characters to delete. Indices have the syntax
base modifier modifier modifier ...
Where base gives a starting point and the modifiers adjust the index from the starting
point (e.g. move forward or backward one character). Every index must contain a base, but
the modifiers are optional. Most modifiers (as documented below) allow an optional
submodifier. Valid submodifiers are any and display. If the submodifier is abbreviated,
then it must be followed by whitespace, but otherwise there need be no space between the
submodifier and the following modifier. Typically the display submodifier adjusts the
meaning of the following modifier to make it refer to visual or non-elided units rather
than logical units, but this is explained for each relevant case below. Lastly, where
count is used as part of a modifier, it can be positive or negative, so “base - -3 lines”
is perfectly valid (and equivalent to “base +3lines”).

The base for an index must have one of the following forms:

line.char Indicates char'th character on line line. Lines are numbered from 1 for
consistency with other UNIX programs that use this numbering scheme. Within a
line, characters are numbered from 0. If char is end then it refers to the
newline character that ends the line.

@x,y Indicates the character that covers the pixel whose x and y coordinates within
the text's window are x and y.

end Indicates the end of the text (the character just after the last newline).

mark Indicates the character just after the mark whose name is mark.

tag.first Indicates the first character in the text that has been tagged with tag. This
form generates an error if no characters are currently tagged with tag.

tag.last Indicates the character just after the last one in the text that has been
tagged with tag. This form generates an error if no characters are currently
tagged with tag.

pathName Indicates the position of the embedded window whose name is pathName. This
form generates an error if there is no embedded window by the given name.

imageName Indicates the position of the embedded image whose name is imageName. This
form generates an error if there is no embedded image by the given name.

If the base could match more than one of the above forms, such as a mark and imageName
both having the same value, then the form earlier in the above list takes precedence. If
modifiers follow the base index, each one of them must have one of the forms listed below.
Keywords such as chars and wordend may be abbreviated as long as the abbreviation is
unambiguous.

+ count ?submodifier? chars
Adjust the index forward by count characters, moving to later lines in the text if
necessary. If there are fewer than count characters in the text after the current
index, then set the index to the last index in the text. Spaces on either side of
count are optional. If the display submodifier is given, elided characters are
skipped over without being counted. If any is given, then all characters are
counted. For historical reasons, if neither modifier is given then the count
actually takes place in units of index positions (see INDICES for details). This
behaviour may be changed in a future major release, so if you need an index count,
you are encouraged to use indices instead wherever possible.

- count ?submodifier? chars
Adjust the index backward by count characters, moving to earlier lines in the text
if necessary. If there are fewer than count characters in the text before the
current index, then set the index to the first index in the text (1.0). Spaces on
either side of count are optional. If the display submodifier is given, elided
characters are skipped over without being counted. If any is given, then all
characters are counted. For historical reasons, if neither modifier is given then
the count actually takes place in units of index positions (see INDICES for
details). This behavior may be changed in a future major release, so if you need an
index count, you are encouraged to use indices instead wherever possible.

+ count ?submodifier? indices
Adjust the index forward by count index positions, moving to later lines in the
text if necessary. If there are fewer than count index positions in the text after
the current index, then set the index to the last index position in the text.
Spaces on either side of count are optional. Note that an index position is either
a single character or a single embedded image or embedded window. If the display
submodifier is given, elided indices are skipped over without being counted. If any
is given, then all indices are counted; this is also the default behaviour if no
modifier is given.

- count ?submodifier? indices
Adjust the index backward by count index positions, moving to earlier lines in the
text if necessary. If there are fewer than count index positions in the text before
the current index, then set the index to the first index position (1.0) in the
text. Spaces on either side of count are optional. If the display submodifier is
given, elided indices are skipped over without being counted. If any is given, then
all indices are counted; this is also the default behaviour if no modifier is
given.

+ count ?submodifier? lines
Adjust the index forward by count lines, retaining the same character position
within the line. If there are fewer than count lines after the line containing the
current index, then set the index to refer to the same character position on the
last line of the text. Then, if the line is not long enough to contain a character
at the indicated character position, adjust the character position to refer to the
last character of the line (the newline). Spaces on either side of count are
optional. If the display submodifier is given, then each visual display line is
counted separately. Otherwise, if any (or no modifier) is given, then each logical
line (no matter how many times it is visually wrapped) counts just once. If the
relevant lines are not wrapped, then these two methods of counting are equivalent.

- count ?submodifier? lines
Adjust the index backward by count logical lines, retaining the same character
position within the line. If there are fewer than count lines before the line
containing the current index, then set the index to refer to the same character
position on the first line of the text. Then, if the line is not long enough to
contain a character at the indicated character position, adjust the character
position to refer to the last character of the line (the newline). Spaces on either
side of count are optional. If the display submodifier is given, then each visual
display line is counted separately. Otherwise, if any (or no modifier) is given,
then each logical line (no matter how many times it is visually wrapped) counts
just once. If the relevant lines are not wrapped, then these two methods of
counting are equivalent.

?submodifier? linestart
Adjust the index to refer to the first index on the line. If the display
submodifier is given, this is the first index on the display line, otherwise on the
logical line.

?submodifier? lineend
Adjust the index to refer to the last index on the line (the newline). If the
display submodifier is given, this is the last index on the display line, otherwise
on the logical line.

?submodifier? wordstart
Adjust the index to refer to the first character of the word containing the current
index. A word consists of any number of adjacent characters that are letters,
digits, or underscores, or a single character that is not one of these. If the
display submodifier is given, this only examines non-elided characters, otherwise
all characters (elided or not) are examined.

?submodifier? wordend
Adjust the index to refer to the character just after the last one of the word
containing the current index. If the current index refers to the last character of
the text then it is not modified. If the display submodifier is given, this only
examines non-elided characters, otherwise all characters (elided or not) are
examined.

If more than one modifier is present then they are applied in left-to-right order. For
example, the index “end - 1 chars” refers to the next-to-last character in the text and
“insert wordstart - 1 c” refers to the character just before the first one in the word
containing the insertion cursor. Modifiers are applied one by one in this left to right
order, and after each step the resulting index is constrained to be a valid index in the
text widget. So, for example, the index “1.0 -1c +1c” refers to the index “2.0”.

Where modifiers result in index changes by display lines, display chars or display
indices, and the base refers to an index inside an elided tag, that base index is
considered to be equivalent to the first following non-elided index.

MARKS

The second form of annotation in text widgets is a mark. Marks are used for remembering
particular places in a text. They are something like tags, in that they have names and
they refer to places in the file, but a mark is not associated with particular characters.
Instead, a mark is associated with the gap between two characters. Only a single position
may be associated with a mark at any given time. If the characters around a mark are
deleted the mark will still remain; it will just have new neighbor characters. In
contrast, if the characters containing a tag are deleted then the tag will no longer have
an association with characters in the file. Marks may be manipulated with the “pathName
mark” widget command, and their current locations may be determined by using the mark name
as an index in widget commands.

Each mark also has a “gravity”, which is either left or right. The gravity for a mark
specifies what happens to the mark when text is inserted at the point of the mark. If a
mark has left gravity, then the mark is treated as if it were attached to the character on
its left, so the mark will remain to the left of any text inserted at the mark position.
If the mark has right gravity, new text inserted at the mark position will appear to the
left of the mark (so that the mark remains rightmost). The gravity for a mark defaults to
right.

The name space for marks is different from that for tags: the same name may be used for
both a mark and a tag, but they will refer to different things.

Two marks have special significance. First, the mark insert is associated with the
insertion cursor, as described under THE INSERTION CURSOR below. Second, the mark current
is associated with the character closest to the mouse and is adjusted automatically to
track the mouse position and any changes to the text in the widget (one exception: current
is not updated in response to mouse motions if a mouse button is down; the update will be
deferred until all mouse buttons have been released). Neither of these special marks may
be deleted. With the exception of these two special marks, all marks are shared between
peer text widgets, and may be manipulated on an equal basis from any peer.

EMBEDDED WINDOWS

The third form of annotation in text widgets is an embedded window. Each embedded window
annotation causes a window to be displayed at a particular point in the text. There may be
any number of embedded windows in a text widget, and any widget may be used as an embedded
window (subject to the usual rules for geometry management, which require the text window
to be the parent of the embedded window or a descendant of its parent).

The embedded window's position on the screen will be updated as the text is modified or
scrolled, and it will be mapped and unmapped as it moves into and out of the visible area
of the text widget. Each embedded window occupies one unit's worth of index space in the
text widget, and it may be referred to either by the name of its embedded window or by its
position in the widget's index space. If the range of text containing the embedded window
is deleted then the window is destroyed. Similarly if the text widget as a whole is
deleted, then the window is destroyed.

Eliding an embedded window immediately after scheduling it for creation via pathName
window create index -create will prevent it from being effectively created. Uneliding an
elided embedded window scheduled for creation via pathName window create index -create
will automatically trigger the associated creation script. After destroying an elided
embedded window, the latter won't get automatically recreated.

When an embedded window is added to a text widget with the pathName window create widget
command, several configuration options may be associated with it. These options may be
modified later with the pathName window configure widget command. The following options
are currently supported:

-align where
If the window is not as tall as the line in which it is displayed, this option
determines where the window is displayed in the line. Where must have one of the
values top (align the top of the window with the top of the line), center (center
the window within the range of the line), bottom (align the bottom of the window
with the bottom of the line's area), or baseline (align the bottom of the window
with the baseline of the line).

-create script
Specifies a Tcl script that may be evaluated to create the window for the
annotation. If no -window option has been specified for the annotation this script
will be evaluated when the annotation is about to be displayed on the screen.
Script must create a window for the annotation and return the name of that window
as its result. Two substitutions will be performed in script before evaluation. %W
will be substituted by the name of the parent text widget, and %% will be
substituted by a single %. If the annotation's window should ever be deleted,
script will be evaluated again the next time the annotation is displayed.

-padx pixels
Pixels specifies the amount of extra space to leave on each side of the embedded
window. It may have any of the usual forms defined for a screen distance.

-pady pixels
Pixels specifies the amount of extra space to leave on the top and on the bottom of
the embedded window. It may have any of the usual forms defined for a screen
distance.

-stretch boolean
If the requested height of the embedded window is less than the height of the line
in which it is displayed, this option can be used to specify whether the window
should be stretched vertically to fill its line. If the -pady option has been
specified as well, then the requested padding will be retained even if the window
is stretched.

-window pathName
Specifies the name of a window to display in the annotation. Note that if a
pathName has been set, then later configuring a window to the empty string will not
delete the widget corresponding to the old pathName. Rather it will remove the
association between the old pathName and the text widget. If multiple peer widgets
are in use, it is usually simpler to use the -create option if embedded windows are
desired in each peer.

EMBEDDED IMAGES

The final form of annotation in text widgets is an embedded image. Each embedded image
annotation causes an image to be displayed at a particular point in the text. There may be
any number of embedded images in a text widget, and a particular image may be embedded in
multiple places in the same text widget.

The embedded image's position on the screen will be updated as the text is modified or
scrolled. Each embedded image occupies one unit's worth of index space in the text widget,
and it may be referred to either by its position in the widget's index space, or the name
it is assigned when the image is inserted into the text widget with pathName image create.
If the range of text containing the embedded image is deleted then that copy of the image
is removed from the screen.

Eliding an embedded image immediately after scheduling it for creation via pathName image
create index -create will prevent it from being effectively created. Uneliding an elided
embedded image scheduled for creation via pathName image create index -create will
automatically trigger the associated creation script. After destroying an elided embedded
image, the latter won't get automatically recreated.

When an embedded image is added to a text widget with the pathName image create widget
command, a name unique to this instance of the image is returned. This name may then be
used to refer to this image instance. The name is taken to be the value of the -name
option (described below). If the -name option is not provided, the -image name is used
instead. If the imageName is already in use in the text widget, then #nn is added to the
end of the imageName, where nn is an arbitrary integer. This insures the imageName is
unique. Once this name is assigned to this instance of the image, it does not change, even
though the -image or -name values can be changed with pathName image configure.

When an embedded image is added to a text widget with the pathName image create widget
command, several configuration options may be associated with it. These options may be
modified later with the pathName image configure widget command. The following options are
currently supported:

-align where
If the image is not as tall as the line in which it is displayed, this option
determines where the image is displayed in the line. Where must have one of the
values top (align the top of the image with the top of the line), center (center
the image within the range of the line), bottom (align the bottom of the image with
the bottom of the line's area), or baseline (align the bottom of the image with the
baseline of the line).

-image image
Specifies the name of the Tk image to display in the annotation. If image is not a
valid Tk image, then an error is returned.

-name ImageName
Specifies the name by which this image instance may be referenced in the text
widget. If ImageName is not supplied, then the name of the Tk image is used
instead. If the imageName is already in use, #nn is appended to the end of the name
as described above.

-padx pixels
Pixels specifies the amount of extra space to leave on each side of the embedded
image. It may have any of the usual forms defined for a screen distance.

-pady pixels
Pixels specifies the amount of extra space to leave on the top and on the bottom of
the embedded image. It may have any of the usual forms defined for a screen
distance.

THE SELECTION

Selection support is implemented via tags. If the -exportselection option for the text
widget is true then the sel tag will be associated with the selection:

[1] Whenever characters are tagged with sel the text widget will claim ownership of the
selection.

[2] Attempts to retrieve the selection will be serviced by the text widget, returning
all the characters with the sel tag.

[3] If the selection is claimed away by another application or by another window within
this application, then the sel tag will be removed from all characters in the text.

[4] Whenever the sel tag range changes a virtual event <<Selection>> is generated. It
might also be generated when selection is affected but not actually changed.
Further, multiple selection changes could happen before events can be processed
leading to multiple events with the same visible selection.

The sel tag is automatically defined when a text widget is created, and it may not be
deleted with the “pathName tag delete” widget command. Furthermore, the -selectbackground,
-selectborderwidth, and -selectforeground options for the text widget are tied to the
-background, -borderwidth, and -foreground options for the sel tag: changes in either will
automatically be reflected in the other. Also the -inactiveselectbackground option for the
text widget is used instead of -selectbackground when the text widget does not have the
focus. This allows programmatic control over the visualization of the sel tag for
foreground and background windows, or to have sel not shown at all (when
-inactiveselectbackground is empty) for background windows. Each peer text widget has its
own sel tag which can be separately configured and set.

THE INSERTION CURSOR

       The   mark  named  insert  has  special  significance  in  text  widgets.  It  is  defined
       automatically when a text widget is created and it may not be  unset  with  the  “pathName
       mark  unset”  widget  command.  The  insert  mark represents the position of the insertion
       cursor, and the insertion cursor will automatically be drawn at this  point  whenever  the
       text widget has the input focus.

THE MODIFIED FLAG

       The  text  widget  can  keep track of changes to the content of the widget by means of the
       modified flag. Inserting or deleting text will set this flag. The flag can be queried, set
       and  cleared  programmatically  as  well.  Whenever  the flag changes state a <<Modified>>
       virtual event is generated. See  the  pathName  edit  modified  widget  command  for  more
       details.

THE UNDO MECHANISM

The text widget has an unlimited undo and redo mechanism (when the -undo widget option is
true) which records every insert and delete action on a stack.

Boundaries (called “separators”) are inserted between edit actions. The purpose of these
separators is to group inserts, deletes and replaces into one compound edit action. When
undoing a change everything between two separators will be undone. The undone changes are
then moved to the redo stack, so that an undone edit can be redone again. The redo stack
is cleared whenever new edit actions are recorded on the undo stack. The undo and redo
stacks can be cleared to keep their depth under control.

Separators are inserted automatically when the -autoseparators widget option is true. You
can insert separators programmatically as well. If a separator is already present at the
top of the undo stack no other will be inserted. That means that two separators on the
undo stack are always separated by at least one insert or delete action.

The <<UndoStack>> virtual event is generated every time the undo stack or the redo stack
becomes empty or unempty.

The undo mechanism is also linked to the modified flag. This means that undoing or redoing
changes can take a modified text widget back to the unmodified state or vice versa. The
modified flag will be set automatically to the appropriate state. This automatic coupling
does not work when the modified flag has been set by the user, until the flag has been
reset again.

See below for the pathName edit widget command that controls the undo mechanism.

PEER WIDGETS

       The  text  widget  has  a  separate  store  of all its data concerning each line's textual
       contents, marks, tags, images and windows, and the undo stack.

       While this data store cannot be accessed directly  (i.e.  without  a  text  widget  as  an
       intermediary), multiple text widgets can be created, each of which present different views
       on the same underlying data. Such text widgets are known as peer text widgets.

       As text is added, deleted, edited and coloured in any one widget, and  as  images,  marks,
       tags are adjusted, all such changes will be reflected in all peers.

       All  data  and markup is shared, except for a few small details. First, the sel tag may be
       set and configured (in its display style) differently for each peer. Second, each peer has
       its  own  insert  and  current  mark  positions  (but  all other marks are shared). Third,
       embedded windows, which are arbitrary other widgets, cannot be shared between peers.  This
       means  the  -window  option  of embedded windows is independently set for each peer (it is
       advisable to use the -create script capabilities to allow each  peer  to  create  its  own
       embedded  windows  as needed). Fourth, all of the configuration options of each peer (e.g.
       -font,  etc)  can  be  set  independently,  with  the  exception   of   -undo,   -maxundo,
       -autoseparators (i.e. all undo, redo and modified state issues are shared).

       Finally  any  single  peer need not contain all lines from the underlying data store. When
       creating a peer, a contiguous range of lines (e.g. only  lines  52  through  125)  may  be
       specified.  This  allows  a  peer to contain just a small portion of the overall text. The
       range of lines will expand and contract as text is inserted or deleted. The peer will only
       ever  display complete lines of text (one cannot share just part of a line). If the peer's
       contents contracts to nothing (i.e. all complete  lines  in  the  peer  widget  have  been
       deleted from another widget), then it is impossible for new lines to be inserted. The peer
       will simply become an empty shell on which the background can  be  configured,  but  which
       will  never  show any content (without manual reconfiguration of the start and end lines).
       Note that a peer which does not contain all of the underlying data store still has indices
       numbered  from  “1.0”  to  “end”.  It is simply that those indices reflect a subset of the
       total data, and data outside the contained range is not accessible to the peer. This means
       that  the command peerName index end may return quite different values in different peers.
       Similarly, commands like peerName tag ranges will not return  index  ranges  outside  that
       which  is meaningful to the peer. The configuration options -startline and -endline may be
       used to control how much of the underlying data is contained in any given text widget.

       Note that peers are really peers. Deleting the “original” text widget will not  cause  any
       other peers to be deleted, or otherwise affected.

       See below for the pathName peer widget command that controls the creation of peer widgets.

ASYNCHRONOUS UPDATE OF LINE HEIGHTS

       In  order  to  maintain  a  responsive  user-experience,  the text widget calculates lines
       metrics (line heights in pixels) asynchronously. Because of this,  some  commands  of  the
       text  widget may return wrong results if the asynchronous calculations are not finished at
       the time of calling. This applies to pathName count -ypixels and pathName yview.

       Again for performance reasons, it would not be appropriate to let  these  commands  always
       wait for the end of the update calculation each time they are called. In most use cases of
       these commands a more or less  inaccurate  result  does  not  really  matter  compared  to
       execution speed.

       In  case  accurate  result  is  needed  (and  if  the text widget is managed by a geometry
       manager), one can resort  to  pathName  sync  and  pathName  pendingsync  to  control  the
       synchronization of the view of text widgets.

       The <<WidgetViewSync>> virtual event fires when the line heights of the text widget become
       obsolete (due to some editing  command  or  configuration  change),  and  again  when  the
       internal  data  of the text widget are back in sync with the widget view. The detail field
       (%d substitution) is either true (when the widget is in sync) or false (when it is not).

       pathName sync, pathName pendingsync and  <<WidgetViewSync>>  apply  to  each  text  widget
       independently of its peers.

       Examples of use:
              ## Example 1:
              # immediately complete line metrics at any cost (GUI unresponsive)
              $w sync
              $w yview moveto $fraction

              ## Example 2:
              # synchronously wait for up-to-date line metrics (GUI responsive)
              # before executing the scheduled command, but don't block execution flow
              $w sync -command [list $w yview moveto $fraction]

              ## Example 3:
              # init
              set yud($w) 0
              proc updateaction w {
              set ::yud($w) 1
              # any other update action here...
              }
              # runtime, synchronously wait for up-to-date line metrics (GUI responsive)
              $w sync -command [list updateaction $w]
              vwait yud($w)
              $w yview moveto $fraction

              ## Example 4:
              # init
              set todo($w) {}
              proc updateaction w {
              foreach cmd $::todo($w) {uplevel #0 $cmd}
              set todo($w) {}
              }
              # runtime
              lappend todo($w) [list $w yview moveto $fraction]
              $w sync -command [list updateaction $w]

              ## Example 5:
              # init
              set todo($w) {}
              bind $w <<WidgetViewSync>> {
              if {%d} {
              foreach cmd $todo(%W) {eval $cmd}
              set todo(%W) {}
              }
              }
              # runtime
              if {![$w pendingsync]} {
              $w yview moveto $fraction
              } else {
              lappend todo($w) [list $w yview moveto $fraction]
              }

WIDGET COMMAND

The text command creates a new Tcl command whose name is the same as the path name of the
text's window. This command may be used to invoke various operations on the widget. It has
the following general form:
pathName option ?arg arg ...?
PathName is the name of the command, which is the same as the text widget's path name.
Option and the args determine the exact behavior of the command. The following commands
are possible for text widgets:

pathName bbox index
Returns a list of four elements describing the screen area of the character given
by index. The first two elements of the list give the x and y coordinates of the
upper-left corner of the area occupied by the character, and the last two elements
give the width and height of the area. If the character is only partially visible
on the screen, then the return value reflects just the visible part. If the
character is not visible on the screen then the return value is an empty list.

pathName cget option
Returns the current value of the configuration option given by option. Option may
have any of the values accepted by the text command.

pathName compare index1 op index2
Compares the indices given by index1 and index2 according to the relational
operator given by op, and returns 1 if the relationship is satisfied and 0 if it is
not. Op must be one of the operators <, <=, ==, >=, >, or !=. If op is == then 1 is
returned if the two indices refer to the same character, if op is < then 1 is
returned if index1 refers to an earlier character in the text than index2, and so
on.

pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the widget. If no option is specified,
returns a list describing all of the available options for pathName (see
Tk_ConfigureInfo for information on the format of this list). If option is
specified with no value, then the command returns a list describing the one named
option (this list will be identical to the corresponding sublist of the value
returned if no option is specified). If one or more option-value pairs are
specified, then the command modifies the given widget option(s) to have the given
value(s); in this case the command returns an empty string. Option may have any of
the values accepted by the text command.

pathName count ?options? index1 index2
Counts the number of relevant things between the two indices. If index1 is after
index2, the result will be a negative number (and this holds for each of the
possible options). The actual items which are counted depend on the options given.
The result is a list of integers, one for the result of each counting option given.
Valid counting options are -chars, -displaychars, -displayindices, -displaylines,
-indices, -lines, -xpixels and -ypixels. The default value, if no option is
specified, is -indices. There is an additional possible option -update which is a
modifier. If given (and if the text widget is managed by a geometry manager), then
all subsequent options ensure that any possible out of date information is
recalculated. This currently only has any effect for the -ypixels count (which, if
-update is not given, will use the text widget's current cached value for each
line). This -update option is obsoleted by pathName sync, pathName pendingsync and
<<WidgetViewSync>>. The count options are interpreted as follows:

-chars count all characters, whether elided or not. Do not count embedded windows
or images.

-displaychars
count all non-elided characters.

-displayindices
count all non-elided characters, windows and images.

-displaylines
count all display lines (i.e. counting one for each time a line wraps) from
the line of the first index up to, but not including the display line of the
second index. Therefore if they are both on the same display line, zero will
be returned. By definition displaylines are visible and therefore this only
counts portions of actual visible lines.

-indices
count all characters and embedded windows or images (i.e. everything which
counts in text-widget index space), whether they are elided or not.

-lines count all logical lines (irrespective of wrapping) from the line of the
first index up to, but not including the line of the second index. Therefore
if they are both on the same line, zero will be returned. Logical lines are
counted whether they are currently visible (non-elided) or not.

-xpixels
count the number of horizontal pixels from the first pixel of the first
index to (but not including) the first pixel of the second index. To count
the total desired width of the text widget (assuming wrapping is not
enabled), first find the longest line and then use “.text count -xpixels
"${line}.0" "${line}.0 lineend"”.

-ypixels
count the number of vertical pixels from the first pixel of the first index
to (but not including) the first pixel of the second index. If both indices
are on the same display line, zero will be returned. To count the total
number of vertical pixels in the text widget, use “.text count -ypixels 1.0
end”, and to ensure this is up to date, use “.text count -update -ypixels
1.0 end”.

The command returns a positive or negative integer corresponding to the number of
items counted between the two indices. One such integer is returned for each
counting option given, so a list is returned if more than one option was supplied.
For example “.text count -xpixels -ypixels 1.3 4.5” is perfectly valid and will
return a list of two elements.

pathName debug ?boolean?
If boolean is specified, then it must have one of the true or false values accepted
by Tcl_GetBoolean. If the value is a true one then internal consistency checks will
be turned on in the B-tree code associated with text widgets. If boolean has a
false value then the debugging checks will be turned off. In either case the
command returns an empty string. If boolean is not specified then the command
returns on or off to indicate whether or not debugging is turned on. There is a
single debugging switch shared by all text widgets: turning debugging on or off in
any widget turns it on or off for all widgets. For widgets with large amounts of
text, the consistency checks may cause a noticeable slow-down.

When debugging is turned on, the drawing routines of the text widget set the global
variables tk_textRedraw and tk_textRelayout to the lists of indices that are
redrawn. The values of these variables are tested by Tk's test suite.

pathName delete index1 ?index2 ...?
Delete a range of characters from the text. If both index1 and index2 are
specified, then delete all the characters starting with the one given by index1 and
stopping just before index2 (i.e. the character at index2 is not deleted). If
index2 does not specify a position later in the text than index1 then no characters
are deleted. If index2 is not specified then the single character at index1 is
deleted. Attempts to delete characters in a way that would leave the text without
a newline as the last character will be tweaked by the text widget to avoid this.
In particular, deletion of complete lines of text up to the end of the text will
also delete the newline character just before the deleted block so that it is
replaced by the new final newline of the text widget. The command returns an empty
string. If more indices are given, multiple ranges of text will be deleted. All
indices are first checked for validity before any deletions are made. They are
sorted and the text is removed from the last range to the first range so deleted
text does not cause an undesired index shifting side-effects. If multiple ranges
with the same start index are given, then the longest range is used. If
overlapping ranges are given, then they will be merged into spans that do not cause
deletion of text outside the given ranges due to text shifted during deletion.

pathName dlineinfo index
Returns a list with five elements describing the area occupied by the display line
containing index. The first two elements of the list give the x and y coordinates
of the upper-left corner of the area occupied by the line, the third and fourth
elements give the width and height of the area, and the fifth element gives the
position of the baseline for the line, measured down from the top of the area. All
of this information is measured in pixels. If the current wrap mode is none and the
line extends beyond the boundaries of the window, the area returned reflects the
entire area of the line, including the portions that are out of the window. If the
line is shorter than the full width of the window then the area returned reflects
just the portion of the line that is occupied by characters and embedded windows.
If the display line containing index is not visible on the screen then the return
value is an empty list.

pathName dump ?switches? index1 ?index2?
Return the contents of the text widget from index1 up to, but not including index2,
including the text and information about marks, tags, and embedded windows. If
index2 is not specified, then it defaults to one character past index1. The
information is returned in the following format:

key1 value1 index1 key2 value2 index2 ...

The possible key values are text, mark, tagon, tagoff, image, and window. The
corresponding value is the text, mark name, tag name, image name, or window name.
The index information is the index of the start of the text, mark, tag transition,
image or window. One or more of the following switches (or abbreviations thereof)
may be specified to control the dump:

-all Return information about all elements: text, marks, tags, images and
windows. This is the default.

-command command
Instead of returning the information as the result of the dump operation,
invoke the command on each element of the text widget within the range. The
command has three arguments appended to it before it is evaluated: the key,
value, and index.

-image Include information about images in the dump results.

-mark Include information about marks in the dump results.

-tag Include information about tag transitions in the dump results. Tag
information is returned as tagon and tagoff elements that indicate the begin
and end of each range of each tag, respectively.

-text Include information about text in the dump results. The value is the text up
to the next element or the end of range indicated by index2. A text element
does not span newlines. A multi-line block of text that contains no marks or
tag transitions will still be dumped as a set of text segments that each end
with a newline. The newline is part of the value.

-window
Include information about embedded windows in the dump results. The value of
a window is its Tk pathname, unless the window has not been created yet. (It
must have a create script.) In this case an empty string is returned, and
you must query the window by its index position to get more information.

pathName edit option ?arg arg ...?
This command controls the undo mechanism and the modified flag. The exact behavior
of the command depends on the option argument that follows the edit argument. The
following forms of the command are currently supported:

pathName edit canredo
Returns a boolean true if redo is possible, i.e. when the redo stack is not
empty. Otherwise returns false.

pathName edit canundo
Returns a boolean true if undo is possible, i.e. when the undo stack is not
empty. Otherwise returns false.

pathName edit modified ?boolean?
If boolean is not specified, returns the modified flag of the widget. The
insert, delete, edit undo and edit redo commands or the user can set or
clear the modified flag. If boolean is specified, sets the modified flag of
the widget to boolean.

pathName edit redo
When the -undo option is true, reapplies the last undone edits provided no
other edits were done since then. Generates an error when the redo stack is
empty. Does nothing when the -undo option is false.

pathName edit reset
Clears the undo and redo stacks.

pathName edit separator
Inserts a separator (boundary) on the undo stack. Does nothing when the
-undo option is false.

pathName edit undo
Undoes the last edit action when the -undo option is true. An edit action is
defined as all the insert and delete commands that are recorded on the undo
stack in between two separators. Generates an error when the undo stack is
empty. Does nothing when the -undo option is false.

pathName get ?-displaychars? ?--? index1 ?index2 ...?
Return a range of characters from the text. The return value will be all the
characters in the text starting with the one whose index is index1 and ending just
before the one whose index is index2 (the character at index2 will not be
returned). If index2 is omitted then the single character at index1 is returned. If
there are no characters in the specified range (e.g. index1 is past the end of the
file or index2 is less than or equal to index1) then an empty string is returned.
If the specified range contains embedded windows, no information about them is
included in the returned string. If multiple index pairs are given, multiple ranges
of text will be returned in a list. Invalid ranges will not be represented with
empty strings in the list. The ranges are returned in the order passed to pathName
get. If the -displaychars option is given, then, within each range, only those
characters which are not elided will be returned. This may have the effect that
some of the returned ranges are empty strings.

pathName image option ?arg arg ...?
This command is used to manipulate embedded images. The behavior of the command
depends on the option argument that follows the image argument. The following forms
of the command are currently supported:

pathName image cget index option
Returns the value of a configuration option for an embedded image. Index
identifies the embedded image, and option specifies a particular
configuration option, which must be one of the ones listed in the section
EMBEDDED IMAGES.

pathName image configure index ?option value ...?
Query or modify the configuration options for an embedded image. If no
option is specified, returns a list describing all of the available options
for the embedded image at index (see Tk_ConfigureInfo for information on the
format of this list). If option is specified with no value, then the command
returns a list describing the one named option (this list will be identical
to the corresponding sublist of the value returned if no option is
specified). If one or more option-value pairs are specified, then the
command modifies the given option(s) to have the given value(s); in this
case the command returns an empty string. See EMBEDDED IMAGES for
information on the options that are supported.

pathName image create index ?option value ...?
This command creates a new image annotation, which will appear in the text
at the position given by index. Any number of option-value pairs may be
specified to configure the annotation. Returns a unique identifier that may
be used as an index to refer to this image. See EMBEDDED IMAGES for
information on the options that are supported, and a description of the
identifier returned.

pathName image names
Returns a list whose elements are the names of all image instances currently
embedded in window.

pathName index index
Returns the position corresponding to index in the form line.char where line is the
line number and char is the character number. Index may have any of the forms
described under INDICES above.

pathName insert index chars ?tagList chars tagList ...?
Inserts all of the chars arguments just before the character at index. If index
refers to the end of the text (the character after the last newline) then the new
text is inserted just before the last newline instead. If there is a single chars
argument and no tagList, then the new text will receive any tags that are present
on both the character before and the character after the insertion point; if a tag
is present on only one of these characters then it will not be applied to the new
text. If tagList is specified then it consists of a list of tag names; the new
characters will receive all of the tags in this list and no others, regardless of
the tags present around the insertion point. If multiple chars-tagList argument
pairs are present, they produce the same effect as if a separate pathName insert
widget command had been issued for each pair, in order. The last tagList argument
may be omitted.

pathName mark option ?arg arg ...?
This command is used to manipulate marks. The exact behavior of the command depends
on the option argument that follows the mark argument. The following forms of the
command are currently supported:

pathName mark gravity markName ?direction?
If direction is not specified, returns left or right to indicate which of
its adjacent characters markName is attached to. If direction is specified,
it must be left or right; the gravity of markName is set to the given value.

pathName mark names
Returns a list whose elements are the names of all the marks that are
currently set.

pathName mark next index
Returns the name of the next mark at or after index. If index is specified
in numerical form, then the search for the next mark begins at that index.
If index is the name of a mark, then the search for the next mark begins
immediately after that mark. This can still return a mark at the same
position if there are multiple marks at the same index. These semantics mean
that the mark next operation can be used to step through all the marks in a
text widget in the same order as the mark information returned by the
pathName dump operation. If a mark has been set to the special end index,
then it appears to be after end with respect to the pathName mark next
operation. An empty string is returned if there are no marks after index.

pathName mark previous index
Returns the name of the mark at or before index. If index is specified in
numerical form, then the search for the previous mark begins with the
character just before that index. If index is the name of a mark, then the
search for the next mark begins immediately before that mark. This can still
return a mark at the same position if there are multiple marks at the same
index. These semantics mean that the pathName mark previous operation can be
used to step through all the marks in a text widget in the reverse order as
the mark information returned by the pathName dump operation. An empty
string is returned if there are no marks before index.

pathName mark set markName index
Sets the mark named markName to a position just before the character at
index. If markName already exists, it is moved from its old position; if it
does not exist, a new mark is created. This command returns an empty string.

pathName mark unset markName ?markName markName ...?
Remove the mark corresponding to each of the markName arguments. The removed
marks will not be usable in indices and will not be returned by future calls
to “pathName mark names”. This command returns an empty string.

pathName peer option args
This command is used to create and query widget peers. It has two forms, depending
on option:

pathName peer create newPathName ?options?
Creates a peer text widget with the given newPathName, and any optional
standard configuration options (as for the text command). By default the
peer will have the same start and end line as the parent widget, but these
can be overridden with the standard configuration options.

pathName peer names
Returns a list of peers of this widget (this does not include the widget
itself). The order within this list is undefined.

pathName pendingsync
Returns 1 if the line heights calculations are not up-to-date, 0 otherwise.

pathName replace index1 index2 chars ?tagList chars tagList ...?
Replaces the range of characters between index1 and index2 with the given
characters and tags. See the section on pathName insert for an explanation of the
handling of the tagList... arguments, and the section on pathName delete for an
explanation of the handling of the indices. If index2 corresponds to an index
earlier in the text than index1, an error will be generated.

The deletion and insertion are arranged so that no unnecessary scrolling of the
window or movement of insertion cursor occurs. In addition the undo/redo stack are
correctly modified, if undo operations are active in the text widget. The command
returns an empty string.

pathName scan option args
This command is used to implement scanning on texts. It has two forms, depending on
option:

pathName scan mark x y
Records x and y and the current view in the text window, for use in
conjunction with later pathName scan dragto commands. Typically this command
is associated with a mouse button press in the widget. It returns an empty
string.

pathName scan dragto x y
This command computes the difference between its x and y arguments and the x
and y arguments to the last pathName scan mark command for the widget. It
then adjusts the view by 10 times the difference in coordinates. This
command is typically associated with mouse motion events in the widget, to
produce the effect of dragging the text at high speed through the window.
The return value is an empty string.

pathName search ?switches? pattern index ?stopIndex?
Searches the text in pathName starting at index for a range of characters that
matches pattern. If a match is found, the index of the first character in the match
is returned as result; otherwise an empty string is returned. One or more of the
following switches (or abbreviations thereof) may be specified to control the
search:

-forwards
The search will proceed forward through the text, finding the first matching
range starting at or after the position given by index. This is the default.

-backwards
The search will proceed backward through the text, finding the matching
range closest to index whose first character is before index (it is not
allowed to be at index). Note that, for a variety of reasons, backwards
searches can be substantially slower than forwards searches (particularly
when using -regexp), so it is recommended that performance-critical code use
forward searches.

-exact Use exact matching: the characters in the matching range must be identical
to those in pattern. This is the default.

-regexp
Treat pattern as a regular expression and match it against the text using
the rules for regular expressions (see the regexp command and the re_syntax
page for details). The default matching automatically passes both the
-lineanchor and -linestop options to the regexp engine (unless -nolinestop
is used), so that ^$ match beginning and end of line, and ., [^ sequences
will never match the newline character \n.

-nolinestop
This allows . and [^ sequences to match the newline character \n, which they
will otherwise not do (see the regexp command for details). This option is
only meaningful if -regexp is also given, and an error will be thrown
otherwise. For example, to match the entire text, use “pathName search
-nolinestop -regexp ".*" 1.0”.

-nocase
Ignore case differences between the pattern and the text.

-count varName
The argument following -count gives the name of a variable; if a match is
found, the number of index positions between beginning and end of the
matching range will be stored in the variable. If there are no embedded
images or windows in the matching range (and there are no elided characters
if -elide is not given), this is equivalent to the number of characters
matched. In either case, the range matchIdx to matchIdx + $count chars will
return the entire matched text.

-all Find all matches in the given range and return a list of the indices of the
first character of each match. If a -count varName switch is given, then
varName is also set to a list containing one element for each successful
match. Note that, even for exact searches, the elements of this list may be
different, if there are embedded images, windows or hidden text. Searches
with -all behave very similarly to the Tcl command regexp -all, in that
overlapping matches are not normally returned. For example, applying an -all
search of the pattern “\w+” against “hello there” will just match twice,
once for each word, and matching “Z[a-z]+Z” against “ZooZooZoo” will just
match once.

-overlap
When performing -all searches, the normal behaviour is that matches which
overlap an already-found match will not be returned. This switch changes
that behaviour so that all matches which are not totally enclosed within
another match are returned. For example, applying an -overlap search of the
pattern “\w+” against “hello there” will just match twice (i.e. no different
to just -all), but matching “Z[a-z]+Z” against “ZooZooZoo” will now match
twice. An error will be thrown if this switch is used without -all.

-strictlimits
When performing any search, the normal behaviour is that the start and stop
limits are checked with respect to the start of the matching text. With the
-strictlimits flag, the entire matching range must lie inside the start and
stop limits specified for the match to be valid.

-elide Find elided (hidden) text as well. By default only displayed text is
searched.

-- This switch has no effect except to terminate the list of switches: the next
argument will be treated as pattern even if it starts with -.

The matching range may be within a single line of text, or run across multiple
lines (if parts of the pattern can match a new-line). For regular expression
matching one can use the various newline-matching features such as $ to match the
end of a line, ^ to match the beginning of a line, and to control whether . is
allowed to match a new-line. If stopIndex is specified, the search stops at that
index: for forward searches, no match at or after stopIndex will be considered; for
backward searches, no match earlier in the text than stopIndex will be considered.
If stopIndex is omitted, the entire text will be searched: when the beginning or
end of the text is reached, the search continues at the other end until the
starting location is reached again; if stopIndex is specified, no wrap-around will
occur. This means that, for example, if the search is -forwards but stopIndex is
earlier in the text than startIndex, nothing will ever be found. See KNOWN BUGS
below for a number of minor limitations of the pathName search command.

pathName see index
Adjusts the view in the window so that the character given by index is completely
visible. If index is already visible then the command does nothing. If index is a
short distance out of view, the command adjusts the view just enough to make index
visible at the edge of the window. If index is far out of view, then the command
centers index in the window.

pathName sync ?-command command?
Controls the synchronization of the view of the text widget.

pathName sync
Immediately brings the line metrics up-to-date by forcing computation of any
outdated line heights. The command returns immediately if there is no such
outdated line heights, otherwise it returns only at the end of the
computation. The command returns an empty string.

pathName sync -command command
Schedules command to be executed (by the event loop) exactly once as soon as
all line heights are up-to-date. If there are no pending line metrics
calculations, the scheduling is immediate. The command returns the empty
string. bgerror is called on command failure.

pathName tag option ?arg arg ...?
This command is used to manipulate tags. The exact behavior of the command depends
on the option argument that follows the tag argument. The following forms of the
command are currently supported:

pathName tag add tagName index1 ?index2 index1 index2 ...?
Associate the tag tagName with all of the characters starting with index1
and ending just before index2 (the character at index2 is not tagged). A
single command may contain any number of index1-index2 pairs. If the last
index2 is omitted then the single character at index1 is tagged. If there
are no characters in the specified range (e.g. index1 is past the end of the
file or index2 is less than or equal to index1) then the command has no
effect.

pathName tag bind tagName ?sequence? ?script?
This command associates script with the tag given by tagName. Whenever the
event sequence given by sequence occurs for a character that has been tagged
with tagName, the script will be invoked. This widget command is similar to
the bind command except that it operates on characters in a text rather than
entire widgets. See the bind manual entry for complete details on the syntax
of sequence and the substitutions performed on script before invoking it. If
all arguments are specified then a new binding is created, replacing any
existing binding for the same sequence and tagName (if the first character
of script is “+” then script augments an existing binding rather than
replacing it). In this case the return value is an empty string. If script
is omitted then the command returns the script associated with tagName and
sequence (an error occurs if there is no such binding). If both script and
sequence are omitted then the command returns a list of all the sequences
for which bindings have been defined for tagName.

The only events for which bindings may be specified are those related to the
mouse and keyboard (such as Enter, Leave, ButtonPress, Motion, and KeyPress)
or virtual events. Mouse and keyboard event bindings for a text widget
respectively use the current and insert marks described under MARKS above.
An Enter event triggers for a tag when the tag first becomes present on the
current character, and a Leave event triggers for a tag when it ceases to be
present on the current character. Enter and Leave events can happen either
because the current mark moved or because the character at that position
changed. Note that these events are different than Enter and Leave events
for windows. Mouse events are directed to the current character, while
keyboard events are directed to the insert character. If a virtual event is
used in a binding, that binding can trigger only if the virtual event is
defined by an underlying mouse-related or keyboard-related event.

It is possible for the current character to have multiple tags, and for each
of them to have a binding for a particular event sequence. When this occurs,
one binding is invoked for each tag, in order from lowest-priority to
highest priority. If there are multiple matching bindings for a single tag,
then the most specific binding is chosen (see the manual entry for the bind
command for details). continue and break commands within binding scripts are
processed in the same way as for bindings created with the bind command.

If bindings are created for the widget as a whole using the bind command,
then those bindings will supplement the tag bindings. The tag bindings will
be invoked first, followed by bindings for the window as a whole.

pathName tag cget tagName option
This command returns the current value of the option named option associated
with the tag given by tagName. Option may have any of the values accepted by
the pathName tag configure widget command.

pathName tag configure tagName ?option? ?value? ?option value ...?
This command is similar to the pathName configure widget command except that
it modifies options associated with the tag given by tagName instead of
modifying options for the overall text widget. If no option is specified,
the command returns a list describing all of the available options for
tagName (see Tk_ConfigureInfo for information on the format of this list).
If option is specified with no value, then the command returns a list
describing the one named option (this list will be identical to the
corresponding sublist of the value returned if no option is specified). If
one or more option-value pairs are specified, then the command modifies the
given option(s) to have the given value(s) in tagName; in this case the
command returns an empty string. See TAGS above for details on the options
available for tags.

pathName tag delete tagName ?tagName ...?
Deletes all tag information for each of the tagName arguments. The command
removes the tags from all characters in the file and also deletes any other
information associated with the tags, such as bindings and display
information. The command returns an empty string.

pathName tag lower tagName ?belowThis?
Changes the priority of tag tagName so that it is just lower in priority
than the tag whose name is belowThis. If belowThis is omitted, then
tagName's priority is changed to make it lowest priority of all tags.

pathName tag names ?index?
Returns a list whose elements are the names of all the tags that are active
at the character position given by index. If index is omitted, then the
return value will describe all of the tags that exist for the text (this
includes all tags that have been named in a “pathName tag” widget command
but have not been deleted by a “pathName tag delete” widget command, even if
no characters are currently marked with the tag). The list will be sorted in
order from lowest priority to highest priority.

pathName tag nextrange tagName index1 ?index2?
This command searches the text for a range of characters tagged with tagName
where the first character of the range is no earlier than the character at
index1 and no later than the character just before index2 (a range starting
at index2 will not be considered). If several matching ranges exist, the
first one is chosen. The command's return value is a list containing two
elements, which are the index of the first character of the range and the
index of the character just after the last one in the range. If no matching
range is found then the return value is an empty string. If index2 is not
given then it defaults to the end of the text.

pathName tag prevrange tagName index1 ?index2?
This command searches the text for a range of characters tagged with tagName
where the first character of the range is before the character at index1 and
no earlier than the character at index2 (a range starting at index2 will be
considered). If several matching ranges exist, the one closest to index1 is
chosen. The command's return value is a list containing two elements, which
are the index of the first character of the range and the index of the
character just after the last one in the range. If no matching range is
found then the return value is an empty string. If index2 is not given then
it defaults to the beginning of the text.

pathName tag raise tagName ?aboveThis?
Changes the priority of tag tagName so that it is just higher in priority
than the tag whose name is aboveThis. If aboveThis is omitted, then
tagName's priority is changed to make it highest priority of all tags.

pathName tag ranges tagName
Returns a list describing all of the ranges of text that have been tagged
with tagName. The first two elements of the list describe the first tagged
range in the text, the next two elements describe the second range, and so
on. The first element of each pair contains the index of the first
character of the range, and the second element of the pair contains the
index of the character just after the last one in the range. If there are no
characters tagged with tag then an empty string is returned.

pathName tag remove tagName index1 ?index2 index1 index2 ...?
Remove the tag tagName from all of the characters starting at index1 and
ending just before index2 (the character at index2 is not affected). A
single command may contain any number of index1-index2 pairs. If the last
index2 is omitted then the tag is removed from the single character at
index1. If there are no characters in the specified range (e.g. index1 is
past the end of the file or index2 is less than or equal to index1) then the
command has no effect. This command returns an empty string.

pathName window option ?arg arg ...?
This command is used to manipulate embedded windows. The behavior of the command
depends on the option argument that follows the window argument. The following
forms of the command are currently supported:

pathName window cget index option
Returns the value of a configuration option for an embedded window. Index
identifies the embedded window, and option specifies a particular
configuration option, which must be one of the ones listed in the section
EMBEDDED WINDOWS.

pathName window configure index ?option value ...?
Query or modify the configuration options for an embedded window. If no
option is specified, returns a list describing all of the available options
for the embedded window at index (see Tk_ConfigureInfo for information on
the format of this list). If option is specified with no value, then the
command returns a list describing the one named option (this list will be
identical to the corresponding sublist of the value returned if no option is
specified). If one or more option-value pairs are specified, then the
command modifies the given option(s) to have the given value(s); in this
case the command returns an empty string. See EMBEDDED WINDOWS for
information on the options that are supported.

pathName window create index ?option value ...?
This command creates a new window annotation, which will appear in the text
at the position given by index. Any number of option-value pairs may be
specified to configure the annotation. See EMBEDDED WINDOWS for information
on the options that are supported. Returns an empty string.

pathName window names
Returns a list whose elements are the names of all windows currently
embedded in window.

pathName xview option args
This command is used to query and change the horizontal position of the text in the
widget's window. It can take any of the following forms:

pathName xview
Returns a list containing two elements. Each element is a real fraction
between 0 and 1; together they describe the portion of the document's
horizontal span that is visible in the window. For example, if the first
element is .2 and the second element is .6, 20% of the text is off-screen to
the left, the middle 40% is visible in the window, and 40% of the text is
off-screen to the right. The fractions refer only to the lines that are
actually visible in the window: if the lines in the window are all very
short, so that they are entirely visible, the returned fractions will be 0
and 1, even if there are other lines in the text that are much wider than
the window. These are the same values passed to scrollbars via the
-xscrollcommand option.

pathName xview moveto fraction
Adjusts the view in the window so that fraction of the horizontal span of
the text is off-screen to the left. Fraction is a fraction between 0 and 1.

pathName xview scroll number what
This command shifts the view in the window left or right according to number
and what. What must be units, pages or pixels. If what is units or pages
then number must be an integer, otherwise number may be specified in any of
the forms acceptable to Tk_GetPixels, such as “2.0c” or “1i” (the result is
rounded to the nearest integer value. If no units are given, pixels are
assumed). If what is units, the view adjusts left or right by number
average-width characters on the display; if it is pages then the view
adjusts by number screenfuls; if it is pixels then the view adjusts by
number pixels. If number is negative then characters farther to the left
become visible; if it is positive then characters farther to the right
become visible.

pathName yview ?args?
This command is used to query and change the vertical position of the text in the
widget's window. It can take any of the following forms:

pathName yview
Returns a list containing two elements, both of which are real fractions
between 0 and 1. The first element gives the position of the first visible
pixel of the first character (or image, etc) in the top line in the window,
relative to the text as a whole (0.5 means it is halfway through the text,
for example). The second element gives the position of the first pixel just
after the last visible one in the bottom line of the window, relative to the
text as a whole. These are the same values passed to scrollbars via the
-yscrollcommand option.

pathName yview moveto fraction
Adjusts the view in the window so that the pixel given by fraction appears
at the top of the top line of the window. Fraction is a fraction between 0
and 1; 0 indicates the first pixel of the first character in the text, 0.33
indicates the pixel that is one-third the way through the text; and so on.
Values close to 1 will indicate values close to the last pixel in the text
(1 actually refers to one pixel beyond the last pixel), but in such cases
the widget will never scroll beyond the last pixel, and so a value of 1 will
effectively be rounded back to whatever fraction ensures the last pixel is
at the bottom of the window, and some other pixel is at the top.

pathName yview scroll number what
This command adjust the view in the window up or down according to number
and what. What must be units, pages or pixels. If what is units or pages
then number must be an integer, otherwise number may be specified in any of
the forms acceptable to Tk_GetPixels, such as “2.0c” or “1i” (the result is
rounded to the nearest integer value. If no units are given, pixels are
assumed). If what is units, the view adjusts up or down by number lines on
the display; if it is pages then the view adjusts by number screenfuls; if
it is pixels then the view adjusts by number pixels. If number is negative
then earlier positions in the text become visible; if it is positive then
later positions in the text become visible.

pathName yview ?-pickplace? index
Changes the view in the widget's window to make index visible. If the
-pickplace option is not specified then index will appear at the top of the
window. If -pickplace is specified then the widget chooses where index
appears in the window:

[1] If index is already visible somewhere in the window then the command
does nothing.

[2] If index is only a few lines off-screen above the window then it will
be positioned at the top of the window.

[3] If index is only a few lines off-screen below the window then it will
be positioned at the bottom of the window.

[4] Otherwise, index will be centered in the window.

The -pickplace option has been obsoleted by the pathName see widget command
(pathName see handles both x- and y-motion to make a location visible,
whereas the -pickplace mode only handles motion in y).

pathName yview number
This command makes the first character on the line after the one given by
number visible at the top of the window. Number must be an integer. This
command used to be used for scrolling, but now it is obsolete.

BINDINGS

       Tk automatically creates class bindings for texts that give  them  the  following  default
       behavior.    In  the  descriptions  below,  “word”  is  dependent  on  the  value  of  the
       tcl_wordchars variable.  See tclvars(3tcl).

       [1]    Clicking mouse button 1 positions the insertion cursor at the closest edge  of  the
              character  underneath  the  mouse  cursor, sets the input focus to this widget, and
              clears any selection in the widget. Dragging with mouse  button  1  strokes  out  a
              selection between the insertion cursor and the character under the mouse.

       [2]    Double-clicking  with mouse button 1 selects the word under the mouse and positions
              the insertion cursor at the start of the word. Dragging after a double  click  will
              stroke out a selection consisting of whole words.

       [3]    Triple-clicking  with mouse button 1 selects the line under the mouse and positions
              the insertion cursor at the start of the line. Dragging after a triple  click  will
              stroke out a selection consisting of whole lines.

       [4]    The ends of the selection can be adjusted by dragging with mouse button 1 while the
              Shift key is down; this will adjust the end of the selection that  was  nearest  to
              the  mouse cursor when button 1 was pressed. If the button is double-clicked before
              dragging then the selection will be adjusted in units of  whole  words;  if  it  is
              triple-clicked then the selection will be adjusted in units of whole lines.

       [5]    Clicking  mouse  button  1  with the Control key down will reposition the insertion
              cursor without affecting the selection.

       [6]    If any normal printing characters are typed, they are inserted at the point of  the
              insertion cursor.

       [7]    The  view  in  the  widget can be adjusted by dragging with the middle mouse button
              (button 2, or button 3 in TkAqua). If the middle mouse button  is  clicked  without
              moving  the  mouse,  the  selection  is copied into the text at the position of the
              mouse cursor. The Insert key also inserts the selection, but at the position of the
              insertion cursor.

       [8]    If the mouse is dragged out of the widget while button 1 is pressed, the entry will
              automatically scroll to make more text visible (if there is more text off-screen on
              the side where the mouse left the window).

       [9]    The  Left  and  Right  keys  move the insertion cursor one character to the left or
              right; they also clear any selection in the text. If Left or Right  is  typed  with
              the  Shift  key down, then the insertion cursor moves and the selection is extended
              to include the new character. Control-Left and  Control-Right  move  the  insertion
              cursor  by words, and Control-Shift-Left and Control-Shift-Right move the insertion
              cursor by words and also extend the selection. Control-b and Control-f  behave  the
              same as Left and Right, respectively. Meta-b and Meta-f behave the same as Control-
              Left and Control-Right, respectively.

       [10]   The Up and Down keys move the insertion cursor one line up or down  and  clear  any
              selection  in  the  text. If Up or Right is typed with the Shift key down, then the
              insertion cursor moves and the selection is extended to include the new  character.
              Control-Up  and  Control-Down  move  the  insertion cursor by paragraphs (groups of
              lines separated by blank lines), and Control-Shift-Up and  Control-Shift-Down  move
              the  insertion  cursor  by  paragraphs and also extend the selection. Control-p and
              Control-n behave the same as Up and Down, respectively.

       [11]   The Next and Prior keys move the insertion  cursor  forward  or  backwards  by  one
              screenful  and clear any selection in the text. If the Shift key is held down while
              Next or Prior is  typed,  then  the  selection  is  extended  to  include  the  new
              character.

       [12]   Control-Next  and  Control-Prior  scroll the view right or left by one page without
              moving the insertion cursor or affecting the selection.

       [13]   Home and Control-a move the insertion cursor to the beginning of its  display  line
              and clear any selection in the widget. Shift-Home moves the insertion cursor to the
              beginning of the display line and also extends the selection to that point.

       [14]   End and Control-e move the insertion cursor to the end  of  the  display  line  and
              clear  any  selection  in  the widget. Shift-End moves the cursor to the end of the
              display line and extends the selection to that point.

       [15]   Control-Home and Meta-< move the insertion cursor to the beginning of the text  and
              clear any selection in the widget. Control-Shift-Home moves the insertion cursor to
              the beginning of the text and also extends the selection to that point.

       [16]   Control-End and Meta-> move the insertion cursor to the end of the text  and  clear
              any  selection  in the widget. Control-Shift-End moves the cursor to the end of the
              text and extends the selection to that point.

       [17]   The Select key and Control-Space set the selection anchor to the  position  of  the
              insertion  cursor.  They  do  not  affect  the  current selection. Shift-Select and
              Control-Shift-Space adjust the selection to the current position of  the  insertion
              cursor,  selecting  from  the  anchor  to the insertion cursor if there was not any
              selection previously.

       [18]   Control-/ selects the entire contents of the widget.

       [19]   Control-\ clears any selection in the widget.

       [20]   The F16 key (labelled Copy on many Sun workstations) or Meta-w copies the selection
              in the widget to the clipboard, if there is a selection. This action is carried out
              by the command tk_textCopy.

       [21]   The F20 key (labelled Cut  on  many  Sun  workstations)  or  Control-w  copies  the
              selection  in the widget to the clipboard and deletes the selection. This action is
              carried out by the command tk_textCut. If there is no selection in the widget  then
              these keys have no effect.

       [22]   The  F18  key  (labelled  Paste  on many Sun workstations) or Control-y inserts the
              contents of the clipboard at the position of the insertion cursor. This  action  is
              carried out by the command tk_textPaste.

       [23]   The Delete key deletes the selection, if there is one in the widget. If there is no
              selection, it deletes the character to the right of the insertion cursor.

       [24]   Backspace and Control-h delete the selection, if there is one in  the  widget.   If
              there  is  no  selection,  they  delete  the character to the left of the insertion
              cursor.

       [25]   Control-d deletes the character to the right of the insertion cursor.

       [26]   Meta-d deletes the word to the right of the insertion cursor.

       [27]   Control-k deletes from the insertion  cursor  to  the  end  of  its  line;  if  the
              insertion  cursor  is  already  at  the  end  of a line, then Control-k deletes the
              newline character.

       [28]   Control-o opens a new line by  inserting  a  newline  character  in  front  of  the
              insertion cursor without moving the insertion cursor.

       [29]   Meta-backspace and Meta-Delete delete the word to the left of the insertion cursor.

       [30]   Control-x  deletes  whatever is selected in the text widget after copying it to the
              clipboard.

       [31]   Control-t reverses the order of the two characters to the right  of  the  insertion
              cursor.

       [32]   Control-z  undoes  the  last edit action if the -undo option is true.  Does nothing
              otherwise.

       [33]   Control-Z (or Control-y on Windows) reapplies the last undone edit  action  if  the
              -undo option is true. Does nothing otherwise.

       If the widget is disabled using the -state option, then its view can still be adjusted and
       text can still be selected, but  no  insertion  cursor  will  be  displayed  and  no  text
       modifications will take place.

       The behavior of texts can be changed by defining new bindings for individual widgets or by
       redefining the class bindings.

KNOWN ISSUES

ISSUES CONCERNING CHARS AND INDICES
Before Tk 8.5, the widget used the string “chars” to refer to index positions (which
included characters, embedded windows and embedded images). As of Tk 8.5 the text widget
deals separately and correctly with “chars” and “indices”. For backwards compatibility,
however, the index modifiers “+N chars” and “-N chars” continue to refer to indices. One
must use any of the full forms “+N any chars” or “-N any chars” etc. to refer to actual
character indices. This confusion may be fixed in a future release by making the widget
correctly interpret “+N chars” as a synonym for “+N any chars”.

PERFORMANCE ISSUES
Text widgets should run efficiently under a variety of conditions. The text widget uses
about 2-3 bytes of main memory for each byte of text, so texts containing a megabyte or
more should be practical on most workstations. Text is represented internally with a
modified B-tree structure that makes operations relatively efficient even with large
texts. Tags are included in the B-tree structure in a way that allows tags to span large
ranges or have many disjoint smaller ranges without loss of efficiency. Marks are also
implemented in a way that allows large numbers of marks. In most cases it is fine to have
large numbers of unique tags, or a tag that has many distinct ranges.

One performance problem can arise if you have hundreds or thousands of different tags that
all have the following characteristics: the first and last ranges of each tag are near the
beginning and end of the text, respectively, or a single tag range covers most of the text
widget. The cost of adding and deleting tags like this is proportional to the number of
other tags with the same properties. In contrast, there is no problem with having
thousands of distinct tags if their overall ranges are localized and spread uniformly
throughout the text.

Very long text lines can be expensive, especially if they have many marks and tags within
them.

The display line with the insert cursor is redrawn each time the cursor blinks, which
causes a steady stream of graphics traffic. Set the -insertofftime attribute to 0 avoid
this.

KNOWN BUGS
The pathName search -regexp sub-command attempts to perform sophisticated regexp matching
across multiple lines in an efficient fashion (since Tk 8.5), examining each line
individually, and then in small groups of lines, whether searching forwards or backwards.
Under certain conditions the search result might differ from that obtained by applying the
same regexp to the entire text from the widget in one go. For example, when searching with
a greedy regexp, the widget will continue to attempt to add extra lines to the match as
long as one of two conditions are true: either Tcl's regexp library returns a code to
indicate a longer match is possible (but there are known bugs in Tcl which mean this code
is not always correctly returned); or if each extra line added results in at least a
partial match with the pattern. This means in the case where the first extra line added
results in no match and Tcl's regexp system returns the incorrect code and adding a second
extra line would actually match, the text widget will return the wrong result. In practice
this is a rare problem, but it can occur, for example:
pack [text .t]
.t insert 1.0 "aaaa\nbbbb\ncccc\nbbbb\naaaa\n"
.t search -regexp -- {(a+|b+\nc+\nb+)+\na+} 1.0
will not find a match when one exists of 19 characters starting from the first “b”.

Whenever one possible match is fully enclosed in another, the search command will attempt
to ensure only the larger match is returned. When performing backwards regexp searches it
is possible that Tcl will not always achieve this, in the case where a match is preceded
by one or more short, non-overlapping matches, all of which are preceded by a large match
which actually encompasses all of them. The search algorithm used by the widget does not
look back arbitrarily far for a possible match which might cover large portions of the
widget. For example:
pack [text .t]
.t insert 1.0 "aaaa\nbbbb\nbbbb\nbbbb\nbbbb\n"
.t search -regexp -backward -- {b+\n|a+\n(b+\n)+} end
matches at “5.0” when a true greedy match would match at “1.0”. Similarly if we add -all
to this case, it matches at all of “5.0”, “4.0”, “3.0” and “1.0”, when really it should
only match at “1.0” since that match encloses all the others.

KEYWORDS

       text, widget, tkvars