text(n) Tk (4.0) text(n)
_________________________________________________________________
NAME
text - Create and manipulate text widgets
SYNOPSIS
text pathName ?options?
STANDARD OPTIONS
-background-highlightbackground-insertontime-selectborderwidth
-borderwidth-highlightcolor-insertwidth-selectforeground
-cursor-highlightthickness-padx-setgrid
-exportselection-insertbackground-pady-takefocus
-font-insertborderwidth-relief-xscrollcommand
-foreground-insertofftime -selectbackground-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 characters 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 display. 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 distances. This
option may be overriden with -spacing2 options in tags.
Command-Line Name:-spacing3
Database Name: spacing3
Database Class: Spacing3
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text(n) Tk (4.0) text(n)
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 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. 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
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text(n) Tk (4.0) text(n)
Specifies the desired width for the window in units of
characters 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
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 marks, which are
floating markers in the text. 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.
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text(n) Tk (4.0) text(n)
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 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.
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 ||
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text(n) Tk (4.0) text(n)
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 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.
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text(n) Tk (4.0) text(n)
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 containing the insertion
cursor.
TAGS
The first form of annotation in text widgets is a tag. A
tag is a textual 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 characters, 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 display 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 commands.
Tags serve three purposes in text widgets. First, they
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text(n) Tk (4.0) text(n)
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 associated 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_GetPixels. 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.
-fgstipple bitmap
Bitmap specifies a bitmap that is used as a stipple
pattern when drawing text and other foreground
information such as underlines. 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_GetFontStruct.
-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
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text(n) Tk (4.0) text(n)
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 display 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. Pixels 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 standard 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 superscripts and a negative
offset can be used for subscripts. Pixels 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
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text(n) Tk (4.0) text(n)
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 display line.
-spacing1 pixels
Pixels specifies how much additional space should be
left above each text line, using any of the standard
forms for screen distances. 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 distances. 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 display 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_GetBoolean.
-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 display options conflict, then the options of the
highest priority tag are used. If a particular display
option hasn't been specified for a particular tag, or if it
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text(n) Tk (4.0) text(n)
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 bindings 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
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 right of the mark.
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
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text(n) Tk (4.0) text(n)
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.
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 create widget command, several configuration options
may be associated with it. These options may be modified
later with the 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
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as its result. 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.
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 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 |
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text(n) Tk (4.0) text(n)
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 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
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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 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.
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.
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.
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text(n) Tk (4.0) text(n)
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
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 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 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
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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 single 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 window. 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, 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
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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.
-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 behavior of the command depends on the option
argument that follows the tag argument. The following
forms of the command are currently supported:
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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
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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 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 dump operation.
If a mark has been set to the special 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
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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 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
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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.
-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
variable; if a match is found, the number of
characters in the matching range will be stored in
the variable.
-- 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
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text(n) Tk (4.0) text(n)
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 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 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 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.
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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 tag configure widget command.
value ...?
pathName tag configure tagName ?option? ?value? ?option
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 command returns a list
describing all of the available options for
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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 haven't 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.
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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 isn't affected). 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. This
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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 tag 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;
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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. 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 screenfuls.
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
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
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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 display; 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 -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
see widget 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
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text(n) Tk (4.0) text(n)
Tk automatically creates class bindings for texts that give
them the following default behavior. In the descriptions
below, ``word'' refers to a contiguous group of letters,
digits, or ``_'' characters, or any single character other
than these.
[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 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).
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text(n) Tk (4.0) text(n)
[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. Control-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 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
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text(n) Tk (4.0) text(n)
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 Control-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.
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[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.
[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 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.
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
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text(n) Tk (4.0) text(n)
the cursor blinks, which causes a steady stream of graphics
traffic. Set the insertOffTime attribute to 0 avoid this.
KEYWORDS
text, widget
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