text
text(n) Tk Built-In Commands text(n)
______________________________________________________________________________
NAME
text - Create and manipulate text widgets
SYNOPSIS
text pathName ?options?
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:-height
Database Name: height
Database Class: Height
Specifies the desired height for the window, in units of charac-
ters in the font given by the -font option. Must be at least
one.
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 dis-
play. This option may be overriden 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 dis-
tances. This option may be overriden 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 overriden with -spacing3 options in tags.
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 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 posi-
tion. 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 sig-
nificant 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 align-
ment from the last tab stop in the list. 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.
Command-Line Name:-width
Database Name: width
Database Class: Width
Specifies the desired width for the window in units of charac-
ters in the font given by the -font option. If the font doesn't
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 don't fit on the screen are not displayed.
In the other modes each line of text will be broken up into sev-
eral screen lines if necessary to keep all the characters visi-
ble. In char mode a screen line break may occur after any char-
acter; 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 differ-
ent 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 marks, which are floating
markers in the text. Marks are used to keep track of various interest-
ing 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.
INDICES
Many of the widget commands for texts take one or more indices as argu-
ments. 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.
The base for an index must have one of the following forms:
line.char Indicates char'th character on line line. Lines are num-
bered 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 new-
line 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 char-
acters 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.
image- |
Name | |
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 abbrevia-
tion is unambiguous.
+ count 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 character in the text. Spaces on either side
of count are optional.
- count 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 character in the text. Spaces on either side
of count are optional.
+ count 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.
- count lines
Adjust the index backward by count 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.
linestart
Adjust the index to refer to the first character on the line.
lineend
Adjust the index to refer to the last character on the line (the
newline).
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.
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 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 contain-
ing the insertion cursor.
TAGS
The first form of annotation in text widgets is a tag. A tag is a tex-
tual string that is associated with some of the characters in a text.
Tags may contain arbitrary characters, but it is probably best to avoid
using the the characters `` '' (space), +, or -: these characters have
special meaning in indices, so tags containing them can't be used as
indices. There may be any number of tags associated with characters in
a text. Each tag may refer to a single character, a range of charac-
ters, or several ranges of characters. An individual character may
have any number of tags associated with it.
A priority order is defined among tags, and this order is used in
implementing some of the tag-related functions described below. When a
tag is defined (by associating it with characters or setting its dis-
play options or binding commands to it), it is given a priority higher
than any existing tag. The priority order of tags may be redefined
using the ``pathName tag raise'' and ``pathName tag lower'' widget com-
mands.
Tags serve three purposes in text widgets. First, they control the way
information is displayed on the screen. By default, characters are
displayed as determined by the background, font, and foreground options
for the text widget. However, display options may be associated with
individual tags using the ``pathName tag configure'' widget command.
If a character has been tagged, then the display options associated
with the tag override the default display style. The following options
are currently supported for tags:
-background color
Color specifies the background color to use for characters asso-
ciated with the tag. It may have any of the forms accepted by
Tk_GetColor.
-bgstipple bitmap
Bitmap specifies a bitmap that is used as a stipple pattern for
the background. It may have any of the forms accepted by
Tk_GetBitmap. If bitmap hasn't been specified, or if it is
specified as an empty string, then a solid fill will be used for
the background.
-borderwidth pixels
Pixels specifies the width of a 3-D border to draw around the
background. It may have any of the forms accepted by Tk_GetPix-
els. This option is used in conjunction with the -relief option
to give a 3-D appearance to the background for characters; it is
ignored unless the -background option has been set for the tag.
-elide boolean
Elide specifies whether the data should be elided. Elided data
is not displayed and takes no space on screen, but further on
behaves just as normal data.
-fgstipple bitmap
Bitmap specifies a bitmap that is used as a stipple pattern when
drawing text and other foreground information such as under-
lines. It may have any of the forms accepted by Tk_GetBitmap.
If bitmap hasn't been specified, or if it is specified as an
empty string, then a solid fill will be used.
-font fontName
FontName is the name of a font to use for drawing characters.
It may have any of the forms accepted by Tk_GetFont.
-foreground color
Color specifies the color to use when drawing text and other
foreground information such as underlines. It may have any of
the forms accepted by Tk_GetColor.
-justify justify
If the first character of a display line has a tag for which
this option has been specified, then justify determines how to
justify the line. It must be one of left, right, or center. If
a line wraps, then the justification for each line on the dis-
play is determined by the first character of that display line.
-lmargin1 pixels
If the first character of a text line has a tag for which this
option has been specified, then pixels specifies how much the
line should be indented from the left edge of the window. Pix-
els may have any of the standard forms for screen distances. If
a line of text wraps, this option only applies to the first line
on the display; the -lmargin2 option controls the indentation
for subsequent lines.
-lmargin2 pixels
If the first character of a display line has a tag for which
this option has been specified, and if the display line is not
the first for its text line (i.e., the text line has wrapped),
then pixels specifies how much the line should be indented from
the left edge of the window. Pixels may have any of the stan-
dard forms for screen distances. This option is only used when
wrapping is enabled, and it only applies to the second and later
display lines for a text line.
-offset pixels
Pixels specifies an amount by which the text's baseline should
be offset vertically from the baseline of the overall line, in
pixels. For example, a positive offset can be used for super-
scripts and a negative offset can be used for subscripts. Pix-
els may have any of the standard forms for screen distances.
-overstrike boolean
Specifies whether or not to draw a horizontal rule through the
middle of characters. Boolean may have any of the forms
accepted by Tk_GetBoolean.
-relief relief
Relief specifies the 3-D relief to use for drawing backgrounds,
in any of the forms accepted by Tk_GetRelief. This option is
used in conjunction with the -borderwidth option to give a 3-D
appearance to the background for characters; it is ignored
unless the -background option has been set for the tag.
-rmargin pixels
If the first character of a display line has a tag for which
this option has been specified, then pixels specifies how wide a
margin to leave between the end of the line and the right edge
of the window. Pixels may have any of the standard forms for
screen distances. This option is only used when wrapping is
enabled. If a text line wraps, the right margin for each line
on the display is determined by the first character of that dis-
play line.
-spacing1 pixels
Pixels specifies how much additional space should be left above
each text line, using any of the standard forms for screen dis-
tances. If a line wraps, this option only applies to the first
line on the display.
-spacing2 pixels
For lines that wrap, this option specifies how much additional
space to leave between the display lines for a single text line.
Pixels may have any of the standard forms for screen distances.
-spacing3 pixels
Pixels specifies how much additional space should be left below
each text line, using any of the standard forms for screen dis-
tances. If a line wraps, this option only applies to the last
line on the display.
-tabs tabList
TabList specifies a set of tab stops in the same form as for the
-tabs option for the text widget. This option only applies to a
display line if it applies to the first character on that dis-
play line. If this option is specified as an empty string, it
cancels the option, leaving it unspecified for the tag (the
default). If the option is specified as a non-empty string that
is an empty list, such as -tags { }, then it requests default
8-character tabs as described for the tags widget option.
-underline boolean
Boolean specifies whether or not to draw an underline underneath
characters. It may have any of the forms accepted by Tk_Get-
Boolean.
-wrap mode
Mode specifies how to handle lines that are wider than the
text's window. It has the same legal values as the -wrap option
for the text widget: none, char, or word. If this tag option
is specified, it overrides the -wrap option for the text widget.
If a character has several tags associated with it, and if their dis-
play options conflict, then the options of the highest priority tag are
used. If a particular display option hasn't been specified for a par-
ticular tag, or if it is specified as an empty string, then that option
will never be used; the next-highest-priority tag's option will used
instead. If no tag specifies a particular display option, then the
default style for the widget will be used.
The second purpose for tags is event bindings. You can associate bind-
ings with a tag in much the same way you can associate bindings with a
widget class: whenever particular X events occur on characters with
the given tag, a given Tcl command will be executed. Tag bindings can
be used to give behaviors to ranges of characters; among other things,
this allows hypertext-like features to be implemented. For details,
see the description of the tag bind widget command below.
The third use for tags is in managing the selection. See THE SELECTION
below.
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 isn't associated with particular characters. Instead,
a mark is associated with the gap between two characters. Only a sin-
gle 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 asso-
ciation 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 grav-
ity 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 dif-
ferent things.
Two marks have special significance. First, the mark insert is associ-
ated with the insertion cursor, as described under THE INSERTION CURSOR
below. Second, the mark current is associated with the character clos-
est to the mouse and is adjusted automatically to track the mouse posi-
tion 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.
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 character'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.
When an embedded window is added to a text widget with the window cre-
ate widget command, several configuration options may be associated
with it. These options may be modified later with the window config-
ure widget command. The following options are currently supported:
-align where
If the window is not as tall as the line in which it is dis-
played, 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 win-
dow 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 win-
dow for the annotation. If no -window option has been specified
for the annotation this script will be evaluated when the anno-
tation is about to be displayed on the screen. Script must cre-
ate a window for the annotation and return the name of that win-
dow as its result. If the annotation's window should ever be
deleted, script will be evaluated again the next time the anno-
tation 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 spec-
ified 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.
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 mul- |
tiple 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 character'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 widh image create. If the range of text |
containing the embedded image is deleted then that copy of the image is |
removed from the screen. |
When an embedded image is added to a text widget with the 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 image configure. |
When an embedded image is added to a text widget with the image create |
widget command, several configuration options may be associated with |
it. These options may be modified later with the image configure wid- |
get command. The following options are currently supported: |
-align |
where | |
If the image is not as tall as the line in which it is dis- |
played, 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 Image- |
Name | |
Specifies the name by which this image instance may be refer- |
enced 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 pix- |
els | |
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 pix- |
els | |
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.
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 selectFore-
ground options for the text widget are tied to the -background, -bor-
derwidth, and -foreground options for the sel tag: changes in either
will automatically be reflected in the other.
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 cur-
sor will automatically be drawn at this point whenever the text widget
has the input focus.
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 wid-
get'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 relation-
ship is satisfied and 0 if it isn't. 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 infor-
mation 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 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.
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
doesn't specify a position later in the text than index1 then no
characters are deleted. If index2 isn't specified then the sin-
gle character at index1 is deleted. It is not allowable to
delete characters in a way that would leave the text without a
newline as the last character. The command returns an empty
string.
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, and win-
dow. The corresponding value is the text, mark name, tag name,
or window name. The index information is the index of the start
of the text, the mark, the tag transition, or the 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 seqments 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 get 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.
pathName image option ?arg arg ...?
This command is used to manipulate embedded images. The behav-
ior of the command depends on the option argument that follows
the tag argument. The following forms of the command are cur-
rently supported:
pathName image cget index option
Returns the value of a configuration option for an embed-
ded 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 corre-
sponding sublist of the value returned if no option is
specified). If one or more option-value pairs are speci-
fied, 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 infor-
mation 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 config-
ure 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 charac-
ter 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 insert widget com-
mand 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 sup-
ported:
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 imme-
diately 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 wid-
get in the same order as the mark information returned by
the dump operation. If a mark has been set to the spe-
cial end index, then it appears to be after end with
respect to the 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 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
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 doesn't 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 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 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 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 wid-
get, 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; oth-
erwise an empty string is returned. One or more of the follow-
ing switches (or abbreviations thereof) may be specified to con-
trol the search:
-forwards
The search will proceed forward through the text, finding
the first matching range starting at or after the posi-
tion given by index. This is the default.
-backwards
The search will proceed backward through the text, find-
ing the matching range closest to index whose first char-
acter is before index.
-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 for details).
-nocase
Ignore case differences between the pattern and the text.
-count varName
The argument following -count gives the name of a vari-
able; 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, 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.
-elide Find elidden (hidden) text as well. By default only dis-
played 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 must be entirely within a single line of
text. For regular expression matching the newlines are removed
from the ends of the lines before matching: use the $ feature
in regular expressions to match the end of a line. For exact
matching the newlines are retained. 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.
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 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 sup-
ported:
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 isn't 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 tag-
Name. 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 simi-
lar to the bind command except that it operates on char-
acters 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 com-
mand 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 trig- |
gers 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 cur- |
rent 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 par-
ticular 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 bind-
ings 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 tag
configure widget command.
pathName tag configure tagName ?option? ?value? ?option value
...?
This command is similar to the 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 com-
mand 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 cor-
responding sublist of the value returned if no option is
specified). If one or more option-value pairs are speci-
fied, then the command modifies the given option(s) to
have the given value(s) in tagName; in this case the com-
mand 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 argu-
ments. The command removes the tags from all characters
in the file and also deletes any other information asso-
ciated with the tags, such as bindings and display infor-
mation. 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 haven't been deleted by a
``pathName tag delete'' widget command, even if no char-
acters are currently marked with the tag). The list will
be sorted in order from lowest priority to highest prior-
ity.
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 com-
mand'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 start-
ing at index1 and ending just before index2 (the charac-
ter at index2 isn't affected). A single command may con-
tain 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. This command returns an empty string.
pathName window option ?arg arg ...?
This command is used to manipulate embedded windows. The behav-
ior of the command depends on the option argument that follows
the tag argument. The following forms of the command are cur-
rently supported:
pathName window cget index option
Returns the value of a configuration option for an embed-
ded 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 corre-
sponding sublist of the value returned if no option is
specified). If one or more option-value pairs are speci-
fied, 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 infor-
mation 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 config-
ure 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 win-
dows 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 fol-
lowing 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 win-
dow. 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. Number must be an integer.
What must be either units or pages or an abbreviation of
one of these. 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 screen-
fuls. If number is negative then characters farther to
the left become visible; if it is positive then charac-
ters 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 fol-
lowing 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 character 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 character just after
the last 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 character
given by fraction appears on the top line of the window.
Fraction is a fraction between 0 and 1; 0 indicates the
first character in the text, 0.33 indicates the character
one-third the way through the text, and so on.
pathName yview scroll number what
This command adjust the view in the window up or down
according to number and what. Number must be an integer.
What must be either units or pages. If what is units,
the view adjusts up or down by number lines on the dis-
play; if it is pages then the view adjusts by number
screenfuls. 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 isn't specified then
index will appear at the top of the window. If -pick-
place is specified then the widget chooses where index
appears in the window:
[1] If index is already visible somewhere in the win-
dow 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 see wid-
get command (see handles both x- and y-motion to make a
location visible, whereas -pickplace 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(n).
[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 beginning 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 beginning 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 but-
ton 1 was pressed. If the button is double-clicked before drag-
ging 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 reposi-
tion 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 Con-
trol-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 para-
graphs (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 Con-
trol-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. Con-
trol-v moves the view down one screenful without moving the
insertion cursor or adjusting the selection.
[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 line and clear any selection in the widget. Shift-Home
moves the insertion cursor to the beginning of the line and also
extends the selection to that point.
[14] End and Control-e move the insertion cursor to the end of the
line and clear any selection in the widget. Shift-End moves the
cursor to the end of the line and extends the selection to that
point.
[15] Control-Home and Meta-< move the insertion cursor to the begin-
ning of the text and clear any selection in the widget. Con-
trol-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 don't 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.
[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. 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 Con-
trol-y inserts the contents of the clipboard at the position of
the insertion cursor.
[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 cur-
sor.
[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.
[31] Control-t reverses the order of the two characters to the right
of the insertion cursor.
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 cur-
sor will be displayed and no text modifications will take place.
The behavior of texts can be changed by defining new bindings for indi-
vidual widgets or by redefining the class bindings.
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.
KEYWORDS
text, widget
Tk 4.0 text(n)
