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

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.

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 tag 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. Event
bindings for a text widget use the current mark 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 and keyboard events are directed to the current 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 just before 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 mouse button  2.  If  mouse  button  2  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