text(n) Tk Built-In Commands text(n) ______________________________________________________________________________
NAME
text, tk_textCopy, tk_textCut, tk_textPaste - Create and manipulate
'text' hypertext editing widgets
SYNOPSIS
text pathName ?options?
tk_textCopy pathName
tk_textCut pathName
tk_textPaste pathName
STANDARD OPTIONS
-background -highlightthickness -relief
-borderwidth -insertbackground -selectbackground
-cursor -insertborderwidth -selectborderwidth
-exportselection -insertofftime -selectforeground
-font -insertontime -setgrid
-foreground -insertwidth -takefocus
-highlightbackground -padx -xscrollcommand
-highlightcolor -pady -yscrollcommand
See the options manual entry for details on the standard options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-autoseparators
Database Name: autoSeparators
Database Class: AutoSeparators
Specifies a boolean that says whether separators are
automatically inserted in the undo stack. Only meaningful when
the -undo option is true.
Command-Line Name:-blockcursor
Database Name: blockCursor
Database Class: BlockCursor
Specifies a boolean that says whether the blinking insertion
cursor should be drawn as a character-sized rectangular block.
If false (the default) a thin vertical line is used for the
insertion cursor.
Command-Line Name:-endline
Database Name: endLine
Database Class: EndLine
Specifies an integer line index representing the line of the
underlying textual data store that should be just after the last
line contained in the widget. This allows a text widget to
reflect only a portion of a larger piece of text. Instead of an
integer, the empty string can be provided to this configuration
option, which will configure the widget to end at the very last
line in the textual data store.
Command-Line Name:-height
Database Name: height
Database Class: Height
Specifies the desired height for the window, in units of
characters in the font given by the -font option. Must be at
least one.
Command-Line Name:-inactiveselectbackground
Database Name: inactiveSelectBackground
Database Class: Foreground
Specifies the colour to use for the selection (the sel tag) when
the window does not have the input focus. If empty, {}, then no
selection is shown when the window does not have the focus.
Command-Line Name:-insertunfocussed
Database Name: insertUnfocussed
Database Class: InsertUnfocussed
Specifies how to display the insertion cursor when the widget |
does not have the focus. Must be none (the default) which means |
to not display the cursor, hollow which means to display a |
hollow box, or solid which means to display a solid box. Note |
that hollow and solid will appear very similar when the |
-blockcursor option is false.
Command-Line Name:-maxundo
Database Name: maxUndo
Database Class: MaxUndo
Specifies the maximum number of compound undo actions on the
undo stack. A zero or a negative value imply an unlimited undo
stack.
Command-Line Name:-spacing1
Database Name: spacing1
Database Class: Spacing1
Requests additional space above each text line in the widget,
using any of the standard forms for screen distances. If a line
wraps, this option only applies to the first line on the
display. This option may be overridden with -spacing1 options in
tags.
Command-Line Name:-spacing2
Database Name: spacing2
Database Class: Spacing2
For lines that wrap (so that they cover more than one line on
the display) this option specifies additional space to provide
between the display lines that represent a single line of text.
The value may have any of the standard forms for screen
distances. This option may be overridden with -spacing2 options
in tags.
Command-Line Name:-spacing3
Database Name: spacing3
Database Class: Spacing3
Requests additional space below each text line in the widget,
using any of the standard forms for screen distances. If a line
wraps, this option only applies to the last line on the display.
This option may be overridden with -spacing3 options in tags.
Command-Line Name:-startline
Database Name: startLine
Database Class: StartLine
Specifies an integer line index representing the first line of
the underlying textual data store that should be contained in
the widget. This allows a text widget to reflect only a portion
of a larger piece of text. Instead of an integer, the empty
string can be provided to this configuration option, which will
configure the widget to start at the very first line in the
textual data store.
Command-Line Name:-state
Database Name: state
Database Class: State
Specifies one of two states for the text: normal or disabled. If
the text is disabled then characters may not be inserted or
deleted and no insertion cursor will be displayed, even if the
input focus is in the widget.
Command-Line Name:-tabs
Database Name: tabs
Database Class: Tabs
Specifies a set of tab stops for the window. The option's value
consists of a list of screen distances giving the positions of
the tab stops, each of which is a distance relative to the left
edge of the widget (excluding borders, padding, etc). Each
position may optionally be followed in the next list element by
one of the keywords left, right, center, or numeric, which
specifies how to justify text relative to the tab stop. Left is
the default; it causes the text following the tab character to
be positioned with its left edge at the tab position. Right
means that the right edge of the text following the tab
character is positioned at the tab position, and center means
that the text is centered at the tab position. Numeric means
that the decimal point in the text is positioned at the tab
position; if there is no decimal point then the least
significant digit of the number is positioned just to the left
of the tab position; if there is no number in the text then the
text is right-justified at the tab position. For example, "-tabs
{2c left 4c 6c center}" creates three tab stops at two-
centimeter intervals; the first two use left justification and
the third uses center justification.
If the list of tab stops does not have enough elements to cover
all of the tabs in a text line, then Tk extrapolates new tab
stops using the spacing and alignment from the last tab stop in
the list. Tab distances must be strictly positive, and must
always increase from one tab stop to the next (if not, an error
is thrown). The value of the -tabs option may be overridden by
-tabs options in tags.
If no -tabs option is specified, or if it is specified as an
empty list, then Tk uses default tabs spaced every eight
(average size) characters. To achieve a different standard
spacing, for example every 4 characters, simply configure the
widget with "-tabs "[expr {4 * [font measure $font 0]}] left"
-tabstyle wordprocessor".
Command-Line Name:-tabstyle
Database Name: tabStyle
Database Class: TabStyle
Specifies how to interpret the relationship between tab stops on
a line and tabs in the text of that line. The value must be
tabular (the default) or wordprocessor. Note that tabs are
interpreted as they are encountered in the text. If the tab
style is tabular then the n'th tab character in the line's text
will be associated with the n'th tab stop defined for that line.
If the tab character's x coordinate falls to the right of the
n'th tab stop, then a gap of a single space will be inserted as
a fallback. If the tab style is wordprocessor then any tab
character being laid out will use (and be defined by) the first
tab stop to the right of the preceding characters already laid
out on that line. The value of the -tabstyle option may be
overridden by -tabstyle options in tags.
Command-Line Name:-undo
Database Name: undo
Database Class: Undo
Specifies a boolean that says whether the undo mechanism is
active or not.
Command-Line Name:-width
Database Name: width
Database Class: Width
Specifies the desired width for the window in units of
characters in the font given by the -font option. If the font
does not have a uniform width then the width of the character
"0" is used in translating from character units to screen units.
Command-Line Name:-wrap
Database Name: wrap
Database Class: Wrap
Specifies how to handle lines in the text that are too long to
be displayed in a single line of the text's window. The value
must be none or char or word. A wrap mode of none means that
each line of text appears as exactly one line on the screen;
extra characters that do not fit on the screen are not
displayed. In the other modes each line of text will be broken
up into several screen lines if necessary to keep all the
characters visible. In char mode a screen line break may occur
after any character; in word mode a line break will only be made
at word boundaries.
______________________________________________________________________________
DESCRIPTION
The text command creates a new window (given by the pathName argument)
and makes it into a text widget. Additional options, described above,
may be specified on the command line or in the option database to
configure aspects of the text such as its default background color and
relief. The text command returns the path name of the new window.
A text widget displays one or more lines of text and allows that text
to be edited. Text widgets support four different kinds of annotations
on the text, called tags, marks, embedded windows or embedded images.
Tags allow different portions of the text to be displayed with
different fonts and colors. In addition, Tcl commands can be associated
with tags so that scripts are invoked when particular actions such as
keystrokes and mouse button presses occur in particular ranges of the
text. See TAGS below for more details.
The second form of annotation consists of floating markers in the text
called "marks". Marks are used to keep track of various interesting
positions in the text as it is edited. See MARKS below for more
details.
The third form of annotation allows arbitrary windows to be embedded in
a text widget. See EMBEDDED WINDOWS below for more details.
The fourth form of annotation allows Tk images to be embedded in a text
widget. See EMBEDDED IMAGES below for more details.
The text widget also has a built-in undo/redo mechanism. See THE UNDO
MECHANISM below for more details.
The text widget allows for the creation of peer widgets. These are
other text widgets which share the same underlying data (text, marks,
tags, images, etc). See PEER WIDGETS below for more details.
INDICES
Many of the widget commands for texts take one or more indices as
arguments. An index is a string used to indicate a particular place
within a text, such as a place to insert characters or one endpoint of
a range of characters to delete. Indices have the syntax
base modifier modifier modifier ...
Where base gives a starting point and the modifiers adjust the index
from the starting point (e.g. move forward or backward one character).
Every index must contain a base, but the modifiers are optional. Most
modifiers (as documented below) allow an optional submodifier. Valid
submodifiers are any and display. If the submodifier is abbreviated,
then it must be followed by whitespace, but otherwise there need be no
space between the submodifier and the following modifier. Typically
the display submodifier adjusts the meaning of the following modifier
to make it refer to visual or non-elided units rather than logical
units, but this is explained for each relevant case below. Lastly,
where count is used as part of a modifier, it can be positive or
negative, so "base - -3 lines" is perfectly valid (and equivalent to
"base +3lines").
The base for an index must have one of the following forms:
line.char Indicates char'th character on line line. Lines are
numbered from 1 for consistency with other UNIX programs
that use this numbering scheme. Within a line, characters
are numbered from 0. If char is end then it refers to the
newline character that ends the line.
@x,y Indicates the character that covers the pixel whose x and y
coordinates within the text's window are x and y.
end Indicates the end of the text (the character just after the
last newline).
mark Indicates the character just after the mark whose name is
mark (see MARKS for details).
tag.first Indicates the first character in the text that has been
tagged with tag. This form generates an error if no
characters are currently tagged with tag.
tag.last Indicates the character just after the last one in the text
that has been tagged with tag. This form generates an error
if no characters are currently tagged with tag.
pathName Indicates the position of the embedded window whose name is
pathName. This form generates an error if there is no
embedded window by the given name.
imageName Indicates the position of the embedded image whose name is
imageName. This form generates an error if there is no
embedded image by the given name.
If the base could match more than one of the above forms, such as a
mark and imageName both having the same value, then the form earlier in
the above list takes precedence. If modifiers follow the base index,
each one of them must have one of the forms listed below. Keywords such
as chars and wordend may be abbreviated as long as the abbreviation is
unambiguous.
+ count ?submodifier? chars
Adjust the index forward by count characters, moving to later
lines in the text if necessary. If there are fewer than count
characters in the text after the current index, then set the
index to the last index in the text. Spaces on either side of
count are optional. If the display submodifier is given, elided
characters are skipped over without being counted. If any is
given, then all characters are counted. For historical reasons,
if neither modifier is given then the count actually takes place
in units of index positions (see INDICES for details). This
behaviour may be changed in a future major release, so if you
need an index count, you are encouraged to use indices instead
wherever possible.
- count ?submodifier? chars
Adjust the index backward by count characters, moving to earlier
lines in the text if necessary. If there are fewer than count
characters in the text before the current index, then set the
index to the first index in the text (1.0). Spaces on either
side of count are optional. If the display submodifier is given,
elided characters are skipped over without being counted. If any
is given, then all characters are counted. For historical
reasons, if neither modifier is given then the count actually
takes place in units of index positions (see INDICES for
details). This behavior may be changed in a future major
release, so if you need an index count, you are encouraged to
use indices instead wherever possible.
+ count ?submodifier? indices
Adjust the index forward by count index positions, moving to
later lines in the text if necessary. If there are fewer than
count index positions in the text after the current index, then
set the index to the last index position in the text. Spaces on
either side of count are optional. Note that an index position
is either a single character or a single embedded image or
embedded window. If the display submodifier is given, elided
indices are skipped over without being counted. If any is given,
then all indices are counted; this is also the default behaviour
if no modifier is given.
- count ?submodifier? indices
Adjust the index backward by count index positions, moving to
earlier lines in the text if necessary. If there are fewer than
count index positions in the text before the current index, then
set the index to the first index position (1.0) in the text.
Spaces on either side of count are optional. If the display
submodifier is given, elided indices are skipped over without
being counted. If any is given, then all indices are counted;
this is also the default behaviour if no modifier is given.
+ count ?submodifier? lines
Adjust the index forward by count lines, retaining the same
character position within the line. If there are fewer than
count lines after the line containing the current index, then
set the index to refer to the same character position on the
last line of the text. Then, if the line is not long enough to
contain a character at the indicated character position, adjust
the character position to refer to the last character of the
line (the newline). Spaces on either side of count are
optional. If the display submodifier is given, then each visual
display line is counted separately. Otherwise, if any (or no
modifier) is given, then each logical line (no matter how many
times it is visually wrapped) counts just once. If the relevant
lines are not wrapped, then these two methods of counting are
equivalent.
- count ?submodifier? lines
Adjust the index backward by count logical lines, retaining the
same character position within the line. If there are fewer than
count lines before the line containing the current index, then
set the index to refer to the same character position on the
first line of the text. Then, if the line is not long enough to
contain a character at the indicated character position, adjust
the character position to refer to the last character of the
line (the newline). Spaces on either side of count are optional.
If the display submodifier is given, then each visual display
line is counted separately. Otherwise, if any (or no modifier)
is given, then each logical line (no matter how many times it is
visually wrapped) counts just once. If the relevant lines are
not wrapped, then these two methods of counting are equivalent.
?submodifier? linestart
Adjust the index to refer to the first index on the line. If the
display submodifier is given, this is the first index on the
display line, otherwise on the logical line.
?submodifier? lineend
Adjust the index to refer to the last index on the line (the
newline). If the display submodifier is given, this is the last
index on the display line, otherwise on the logical line.
?submodifier? wordstart
Adjust the index to refer to the first character of the word
containing the current index. A word consists of any number of
adjacent characters that are letters, digits, or underscores, or
a single character that is not one of these. If the display
submodifier is given, this only examines non-elided characters,
otherwise all characters (elided or not) are examined.
?submodifier? wordend
Adjust the index to refer to the character just after the last
one of the word containing the current index. If the current
index refers to the last character of the text then it is not
modified. If the display submodifier is given, this only
examines non-elided characters, otherwise all characters (elided
or not) are examined.
If more than one modifier is present then they are applied in left-to-
right order. For example, the index "end - 1 chars" refers to the next-
to-last character in the text and "insert wordstart - 1 c" refers to
the character just before the first one in the word containing the
insertion cursor. Modifiers are applied one by one in this left to
right order, and after each step the resulting index is constrained to
be a valid index in the text widget. So, for example, the index "1.0
-1c +1c" refers to the index "2.0".
Where modifiers result in index changes by display lines, display chars
or display indices, and the base refers to an index inside an elided
tag, that base index is considered to be equivalent to the first
following non-elided index.
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 characters " " (space), +, or -: these characters have
special meaning in indices, so tags containing them cannot 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 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 has not 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 border to draw around the tag
using any of the forms accepted by Tk_GetPixels. This option
should be used in conjunction with the -relief option to provide
the desired border.
-elide boolean
Elide specifies whether the data should be elided. Elided data
(characters, images, embedded windows, etc.) 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
underlines. It may have any of the forms accepted by
Tk_GetBitmap. If bitmap has not 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 non-elided 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 display is determined by the first non-elided
character of that display line.
-lmargin1 pixels
If the first non-elided 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 non-elided 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.
-lmargincolor color
Color specifies the background color to use in regions that do
not contain characters because they are indented by -lmargin1 or
-lmargin2. It may have any of the forms accepted by Tk_GetColor.
If color has not been specified, or if it is specified as an
empty string, then the color used is specified by the
-background tag option (or, if this is also unspecified, by the
-background widget option).
-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 Tcl_GetBoolean.
-overstrikefg color
Color specifies the color to use when displaying the overstrike.
It may have any of the forms accepted by Tk_GetColor. If color
has not been specified, or if it is specified as an empty
string, then the color specified by the -foreground tag option
is used.
-relief relief
Relief specifies the relief style to use for drawing the border,
in any of the forms accepted by Tk_GetRelief. This option is
used in conjunction with the -borderwidth option to enable to
the desired border appearance.
-rmargin pixels
If the first non-elided 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 non-elided
character of that display line.
-rmargincolor color
Color specifies the background color to use in regions that do
not contain characters because they are indented by -rmargin. It
may have any of the forms accepted by Tk_GetColor. If color has
not been specified, or if it is specified as an empty string,
then the color used is specified by the -background tag option
(or, if this is also unspecified, by the -background widget
option).
-selectbackground color
Color specifies the background color to use when displaying
selected items. It may have any of the forms accepted by
Tk_GetColor. If color has not been specified, or if it is
specified as an empty string, then the color specified by the
-background tag option is used.
-selectforeground color
Color specifies the foreground color to use when displaying
selected items. It may have any of the forms accepted by
Tk_GetColor. If color has not been specified, or if it is
specified as an empty string, then the color specified by the
-foreground tag option is used.
-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 non-elided 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.
-tabstyle style
Style specifies either the tabular or wordprocessor style of
tabbing to use for the text widget. This option only applies to
a display line if it applies to the first non-elided 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).
-underline boolean
Boolean specifies whether or not to draw an underline underneath
characters. It may have any of the forms accepted by
Tcl_GetBoolean.
-underlinefg color
Color specifies the color to use when displaying the underline.
It may have any of the forms accepted by Tk_GetColor. If color
has not been specified, or if it is specified as an empty
string, then the color specified by the -foreground tag option
is used.
-wrap mode
Mode specifies how to handle lines that are wider than the
text's window. This option only applies to a display line if it
applies to the first non-elided character on that display line.
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 has not been specified for a
particular 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
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 "pathName tag bind" widget command
below. Tag bindings are shared between all peer widgets (including any
bindings for the special sel tag).
The third use for tags is in managing the selection. See THE SELECTION
below. With the exception of the special sel tag, all tags are shared
between peer text widgets, and may be manipulated on an equal basis
from any such widget. The sel tag exists separately and independently
in each peer text widget (but any tag bindings to sel are shared).
MARKS
The second form of annotation in text widgets is a mark. Marks are used
for remembering particular places in a text. They are something like
tags, in that they have names and they refer to places in the file, but
a mark is not associated with particular characters. Instead, a mark is
associated with the gap between two characters. Only a single position
may be associated with a mark at any given time. If the characters
around a mark are deleted the mark will still remain; it will just have
new neighbor characters. In contrast, if the characters containing a
tag are deleted then the tag will no longer have an association with
characters in the file. Marks may be manipulated with the "pathName
mark" widget command, and their current locations may be determined by
using the mark name as an index in widget commands.
Each mark also has a "gravity", which is either left or right. The
gravity for a mark specifies what happens to the mark when text is
inserted at the point of the mark. If a mark has left gravity, then the
mark is treated as if it were attached to the character on its left, so
the mark will remain to the left of any text inserted at the mark
position. If the mark has right gravity, new text inserted at the mark
position will appear to the left of the mark (so that the mark remains
rightmost). The gravity for a mark defaults to right.
The name space for marks is different from that for tags: the same name
may be used for both a mark and a tag, but they will refer to different
things.
Two marks have special significance. First, the mark insert is
associated with the insertion cursor, as described under THE INSERTION
CURSOR below. Second, the mark current is associated with the character
closest to the mouse and is adjusted automatically to track the mouse
position and any changes to the text in the widget (one exception:
current is not updated in response to mouse motions if a mouse button
is down; the update will be deferred until all mouse buttons have been
released). Neither of these special marks may be deleted. With the
exception of these two special marks, all marks are shared between peer
text widgets, and may be manipulated on an equal basis from any peer.
EMBEDDED WINDOWS
The third form of annotation in text widgets is an embedded window.
Each embedded window annotation causes a window to be displayed at a
particular point in the text. There may be any number of embedded
windows in a text widget, and any widget may be used as an embedded
window (subject to the usual rules for geometry management, which
require the text window to be the parent of the embedded window or a
descendant of its parent).
The embedded window's position on the screen will be updated as the
text is modified or scrolled, and it will be mapped and unmapped as it
moves into and out of the visible area of the text widget. Each
embedded window occupies one unit's worth of index space in the text
widget, and it may be referred to either by the name of its embedded
window or by its position in the widget's index space. If the range of
text containing the embedded window is deleted then the window is
destroyed. Similarly if the text widget as a whole is deleted, then the
window is destroyed.
Eliding an embedded window immediately after scheduling it for creation
via pathName window create index -create will prevent it from being
effectively created. Uneliding an elided embedded window scheduled for
creation via pathName window create index -create will automatically
trigger the associated creation script. After destroying an elided
embedded window, the latter won't get automatically recreated.
When an embedded window is added to a text widget with the pathName
window create widget command, several configuration options may be
associated with it. These options may be modified later with the
pathName window configure widget command. The following options are
currently supported:
-align where
If the window is not as tall as the line in which it is
displayed, this option determines where the window is displayed
in the line. Where must have one of the values top (align the
top of the window with the top of the line), center (center the
window within the range of the line), bottom (align the bottom
of the window with the bottom of the line's area), or baseline
(align the bottom of the window with the baseline of the line).
-create script
Specifies a Tcl script that may be evaluated to create the
window for the annotation. If no -window option has been
specified for the annotation this script will be evaluated when
the annotation is about to be displayed on the screen. Script
must create a window for the annotation and return the name of
that window as its result. Two substitutions will be performed
in script before evaluation. %W will be substituted by the name
of the parent text widget, and %% will be substituted by a
single %. If the annotation's window should ever be deleted,
script will be evaluated again the next time the annotation is
displayed.
-padx pixels
Pixels specifies the amount of extra space to leave on each side
of the embedded window. It may have any of the usual forms
defined for a screen distance.
-pady pixels
Pixels specifies the amount of extra space to leave on the top
and on the bottom of the embedded window. It may have any of the
usual forms defined for a screen distance.
-stretch boolean
If the requested height of the embedded window is less than the
height of the line in which it is displayed, this option can be
used to specify whether the window should be stretched
vertically to fill its line. If the -pady option has been
specified as well, then the requested padding will be retained
even if the window is stretched.
-window pathName
Specifies the name of a window to display in the annotation.
Note that if a pathName has been set, then later configuring a
window to the empty string will not delete the widget
corresponding to the old pathName. Rather it will remove the
association between the old pathName and the text widget. If
multiple peer widgets are in use, it is usually simpler to use
the -create option if embedded windows are desired in each peer.
EMBEDDED IMAGES
The final form of annotation in text widgets is an embedded image. Each
embedded image annotation causes an image to be displayed at a
particular point in the text. There may be any number of embedded
images in a text widget, and a particular image may be embedded in
multiple places in the same text widget.
The embedded image's position on the screen will be updated as the text
is modified or scrolled. Each embedded image occupies one unit's worth
of index space in the text widget, and it may be referred to either by
its position in the widget's index space, or the name it is assigned
when the image is inserted into the text widget with pathName image
create. If the range of text containing the embedded image is deleted
then that copy of the image is removed from the screen.
Eliding an embedded image immediately after scheduling it for creation
via pathName image create index -create will prevent it from being
effectively created. Uneliding an elided embedded image scheduled for
creation via pathName image create index -create will automatically
trigger the associated creation script. After destroying an elided
embedded image, the latter won't get automatically recreated.
When an embedded image is added to a text widget with the pathName
image create widget command, a name unique to this instance of the
image is returned. This name may then be used to refer to this image
instance. The name is taken to be the value of the -name option
(described below). If the -name option is not provided, the -image name
is used instead. If the imageName is already in use in the text
widget, then #nn is added to the end of the imageName, where nn is an
arbitrary integer. This insures the imageName is unique. Once this name
is assigned to this instance of the image, it does not change, even
though the -image or -name values can be changed with pathName image
configure.
When an embedded image is added to a text widget with the pathName
image create widget command, several configuration options may be
associated with it. These options may be modified later with the
pathName image configure widget command. The following options are
currently supported:
-align where
If the image is not as tall as the line in which it is
displayed, this option determines where the image is displayed
in the line. Where must have one of the values top (align the
top of the image with the top of the line), center (center the
image within the range of the line), bottom (align the bottom of
the image with the bottom of the line's area), or baseline
(align the bottom of the image with the baseline of the line).
-image image
Specifies the name of the Tk image to display in the annotation.
If image is not a valid Tk image, then an error is returned.
-name ImageName
Specifies the name by which this image instance may be
referenced in the text widget. If ImageName is not supplied,
then the name of the Tk image is used instead. If the imageName
is already in use, #nn is appended to the end of the name as
described above.
-padx pixels
Pixels specifies the amount of extra space to leave on each side
of the embedded image. It may have any of the usual forms
defined for a screen distance.
-pady pixels
Pixels specifies the amount of extra space to leave on the top
and on the bottom of the embedded image. It may have any of the
usual forms defined for a screen distance.
THE SELECTION
Selection support is implemented via tags. If the -exportselection
option for the text widget is true then the sel tag will be associated
with the selection:
[1] Whenever characters are tagged with sel the text widget will
claim ownership of the selection.
[2] Attempts to retrieve the selection will be serviced by the text
widget, returning all the characters with the sel tag.
[3] If the selection is claimed away by another application or by
another window within this application, then the sel tag will be
removed from all characters in the text.
[4] Whenever the sel tag range changes a virtual event <<Selection>>
is generated. It might also be generated when selection is
affected but not actually changed. Further, multiple selection
changes could happen before events can be processed leading to
multiple events with the same visible selection.
The sel tag is automatically defined when a text widget is created, and
it may not be deleted with the "pathName tag delete" widget command.
Furthermore, the -selectbackground, -selectborderwidth, and
-selectforeground options for the text widget are tied to the
-background, -borderwidth, and -foreground options for the sel tag:
changes in either will automatically be reflected in the other. Also
the -inactiveselectbackground option for the text widget is used
instead of -selectbackground when the text widget does not have the
focus. This allows programmatic control over the visualization of the
sel tag for foreground and background windows, or to have sel not shown
at all (when -inactiveselectbackground is empty) for background
windows. Each peer text widget has its own sel tag which can be
separately configured and set.
THE INSERTION CURSOR
The mark named insert has special significance in text widgets. It is
defined automatically when a text widget is created and it may not be
unset with the "pathName mark unset" widget command. The insert mark
represents the position of the insertion cursor, and the insertion
cursor will automatically be drawn at this point whenever the text
widget has the input focus.
THE MODIFIED FLAG
The text widget can keep track of changes to the content of the widget
by means of the modified flag. Inserting or deleting text will set this
flag. The flag can be queried, set and cleared programmatically as
well. Whenever the flag changes state a <<Modified>> virtual event is
generated. See the pathName edit modified widget command for more
details.
THE UNDO MECHANISM
The text widget has an unlimited undo and redo mechanism (when the
-undo widget option is true) which records every insert and delete
action on a stack.
Boundaries (called "separators") are inserted between edit actions. The
purpose of these separators is to group inserts, deletes and replaces
into one compound edit action. When undoing a change everything between
two separators will be undone. The undone changes are then moved to the
redo stack, so that an undone edit can be redone again. The redo stack
is cleared whenever new edit actions are recorded on the undo stack.
The undo and redo stacks can be cleared to keep their depth under
control.
Separators are inserted automatically when the -autoseparators widget
option is true. You can insert separators programmatically as well. If
a separator is already present at the top of the undo stack no other
will be inserted. That means that two separators on the undo stack are
always separated by at least one insert or delete action.
The <<UndoStack>> virtual event is generated every time the undo stack
or the redo stack becomes empty or unempty.
The undo mechanism is also linked to the modified flag. This means that
undoing or redoing changes can take a modified text widget back to the
unmodified state or vice versa. The modified flag will be set
automatically to the appropriate state. This automatic coupling does
not work when the modified flag has been set by the user, until the
flag has been reset again.
See below for the pathName edit widget command that controls the undo
mechanism.
PEER WIDGETS
The text widget has a separate store of all its data concerning each
line's textual contents, marks, tags, images and windows, and the undo
stack.
While this data store cannot be accessed directly (i.e. without a text
widget as an intermediary), multiple text widgets can be created, each
of which present different views on the same underlying data. Such text
widgets are known as peer text widgets.
As text is added, deleted, edited and coloured in any one widget, and
as images, marks, tags are adjusted, all such changes will be reflected
in all peers.
All data and markup is shared, except for a few small details. First,
the sel tag may be set and configured (in its display style)
differently for each peer. Second, each peer has its own insert and
current mark positions (but all other marks are shared). Third,
embedded windows, which are arbitrary other widgets, cannot be shared
between peers. This means the -window option of embedded windows is
independently set for each peer (it is advisable to use the -create
script capabilities to allow each peer to create its own embedded
windows as needed). Fourth, all of the configuration options of each
peer (e.g. -font, etc) can be set independently, with the exception of
-undo, -maxundo, -autoseparators (i.e. all undo, redo and modified
state issues are shared).
Finally any single peer need not contain all lines from the underlying
data store. When creating a peer, a contiguous range of lines (e.g.
only lines 52 through 125) may be specified. This allows a peer to
contain just a small portion of the overall text. The range of lines
will expand and contract as text is inserted or deleted. The peer will
only ever display complete lines of text (one cannot share just part of
a line). If the peer's contents contracts to nothing (i.e. all complete
lines in the peer widget have been deleted from another widget), then
it is impossible for new lines to be inserted. The peer will simply
become an empty shell on which the background can be configured, but
which will never show any content (without manual reconfiguration of
the start and end lines). Note that a peer which does not contain all
of the underlying data store still has indices numbered from "1.0" to
"end". It is simply that those indices reflect a subset of the total
data, and data outside the contained range is not accessible to the
peer. This means that the command peerName index end may return quite
different values in different peers. Similarly, commands like peerName
tag ranges will not return index ranges outside that which is
meaningful to the peer. The configuration options -startline and
-endline may be used to control how much of the underlying data is
contained in any given text widget.
Note that peers are really peers. Deleting the "original" text widget
will not cause any other peers to be deleted, or otherwise affected.
See below for the pathName peer widget command that controls the
creation of peer widgets.
ASYNCHRONOUS UPDATE OF LINE HEIGHTS
In order to maintain a responsive user-experience, the text widget
calculates lines metrics (line heights in pixels) asynchronously.
Because of this, some commands of the text widget may return wrong
results if the asynchronous calculations are not finished at the time
of calling. This applies to pathName count -ypixels and pathName yview.
Again for performance reasons, it would not be appropriate to let these
commands always wait for the end of the update calculation each time
they are called. In most use cases of these commands a more or less
inaccurate result does not really matter compared to execution speed.
In case accurate result is needed (and if the text widget is managed by
a geometry manager), one can resort to pathName sync and pathName
pendingsync to control the synchronization of the view of text widgets.
The <<WidgetViewSync>> virtual event fires when the line heights of the
text widget become obsolete (due to some editing command or
configuration change), and again when the internal data of the text
widget are back in sync with the widget view. The detail field (%d
substitution) is either true (when the widget is in sync) or false
(when it is not).
pathName sync, pathName pendingsync and <<WidgetViewSync>> apply to
each text widget independently of its peers.
Examples of use:
## Example 1:
# immediately complete line metrics at any cost (GUI unresponsive)
$w sync
$w yview moveto $fraction
## Example 2:
# synchronously wait for up-to-date line metrics (GUI responsive)
# before executing the scheduled command, but don't block execution flow
$w sync -command [list $w yview moveto $fraction]
## Example 3:
# init
set yud($w) 0
proc updateaction w {
set ::yud($w) 1
# any other update action here...
}
# runtime, synchronously wait for up-to-date line metrics (GUI responsive)
$w sync -command [list updateaction $w]
vwait yud($w)
$w yview moveto $fraction
## Example 4:
# init
set todo($w) {}
proc updateaction w {
foreach cmd $::todo($w) {uplevel #0 $cmd}
set todo($w) {}
}
# runtime
lappend todo($w) [list $w yview moveto $fraction]
$w sync -command [list updateaction $w]
## Example 5:
# init
set todo($w) {}
bind $w <<WidgetViewSync>> {
if {%d} {
foreach cmd $todo(%W) {eval $cmd}
set todo(%W) {}
}
}
# runtime
if {![$w pendingsync]} {
$w yview moveto $fraction
} else {
lappend todo($w) [list $w yview moveto $fraction]
}
WIDGET COMMAND
The text command creates a new Tcl command whose name is the same as
the path name of the text's window. This command may be used to invoke
various operations on the widget. It has the following general form:
pathName option ?arg arg ...?
PathName is the name of the command, which is the same as the text
widget's path name. Option and the args determine the exact behavior of
the command. The following commands are possible for text widgets:
pathName bbox index
Returns a list of four elements describing the screen area of
the character given by index. The first two elements of the list
give the x and y coordinates of the upper-left corner of the
area occupied by the character, and the last two elements give
the width and height of the area. If the character is only
partially visible on the screen, then the return value reflects
just the visible part. If the character is not visible on the
screen then the return value is an empty list.
pathName cget option
Returns the current value of the configuration option given by
option. Option may have any of the values accepted by the text
command.
pathName compare index1 op index2
Compares the indices given by index1 and index2 according to the
relational operator given by op, and returns 1 if the
relationship is satisfied and 0 if it is not. Op must be one of
the operators <, <=, ==, >=, >, or !=. If op is == then 1 is
returned if the two indices refer to the same character, if op
is < then 1 is returned if index1 refers to an earlier character
in the text than index2, and so on.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the widget. If no
option is specified, returns a list describing all of the
available options for pathName (see Tk_ConfigureInfo for
information on the format of this list). If option is specified
with no value, then the command returns a list describing the
one named option (this list will be identical to the
corresponding sublist of the value returned if no option is
specified). If one or more option-value pairs are specified,
then the command modifies the given widget option(s) to have the
given value(s); in this case the command returns an empty
string. Option may have any of the values accepted by the text
command.
pathName count ?options? index1 index2
Counts the number of relevant things between the two indices. If
index1 is after index2, the result will be a negative number
(and this holds for each of the possible options). The actual
items which are counted depend on the options given. The result
is a list of integers, one for the result of each counting
option given. Valid counting options are -chars, -displaychars,
-displayindices, -displaylines, -indices, -lines, -xpixels and
-ypixels. The default value, if no option is specified, is
-indices. There is an additional possible option -update which
is a modifier. If given (and if the text widget is managed by a
geometry manager), then all subsequent options ensure that any
possible out of date information is recalculated. This
currently only has any effect for the -ypixels count (which, if
-update is not given, will use the text widget's current cached
value for each line). This -update option is obsoleted by
pathName sync, pathName pendingsync and <<WidgetViewSync>>. The
count options are interpreted as follows:
-chars count all characters, whether elided or not. Do not count
embedded windows or images.
-displaychars
count all non-elided characters.
-displayindices
count all non-elided characters, windows and images.
-displaylines
count all display lines (i.e. counting one for each time
a line wraps) from the line of the first index up to, but
not including the display line of the second index.
Therefore if they are both on the same display line, zero
will be returned. By definition displaylines are visible
and therefore this only counts portions of actual visible
lines.
-indices
count all characters and embedded windows or images (i.e.
everything which counts in text-widget index space),
whether they are elided or not.
-lines count all logical lines (irrespective of wrapping) from
the line of the first index up to, but not including the
line of the second index. Therefore if they are both on
the same line, zero will be returned. Logical lines are
counted whether they are currently visible (non-elided)
or not.
-xpixels
count the number of horizontal pixels from the first
pixel of the first index to (but not including) the first
pixel of the second index. To count the total desired
width of the text widget (assuming wrapping is not
enabled), first find the longest line and then use ".text
count -xpixels "${line}.0" "${line}.0 lineend"".
-ypixels
count the number of vertical pixels from the first pixel
of the first index to (but not including) the first pixel
of the second index. If both indices are on the same
display line, zero will be returned. To count the total
number of vertical pixels in the text widget, use ".text
count -ypixels 1.0 end", and to ensure this is up to
date, use ".text count -update -ypixels 1.0 end".
The command returns a positive or negative integer corresponding
to the number of items counted between the two indices. One such
integer is returned for each counting option given, so a list is
returned if more than one option was supplied. For example
".text count -xpixels -ypixels 1.3 4.5" is perfectly valid and
will return a list of two elements.
pathName debug ?boolean?
If boolean is specified, then it must have one of the true or
false values accepted by Tcl_GetBoolean. If the value is a true
one then internal consistency checks will be turned on in the B-
tree code associated with text widgets. If boolean has a false
value then the debugging checks will be turned off. In either
case the command returns an empty string. If boolean is not
specified then the command returns on or off to indicate whether
or not debugging is turned on. There is a single debugging
switch shared by all text widgets: turning debugging on or off
in any widget turns it on or off for all widgets. For widgets
with large amounts of text, the consistency checks may cause a
noticeable slow-down.
When debugging is turned on, the drawing routines of the text
widget set the global variables tk_textRedraw and
tk_textRelayout to the lists of indices that are redrawn. The
values of these variables are tested by Tk's test suite.
pathName delete index1 ?index2 ...?
Delete a range of characters from the text. If both index1 and
index2 are specified, then delete all the characters starting
with the one given by index1 and stopping just before index2
(i.e. the character at index2 is not deleted). If index2 does
not specify a position later in the text than index1 then no
characters are deleted. If index2 is not specified then the
single character at index1 is deleted. Attempts to delete
characters in a way that would leave the text without a newline
as the last character will be tweaked by the text widget to
avoid this. In particular, deletion of complete lines of text up
to the end of the text will also delete the newline character
just before the deleted block so that it is replaced by the new
final newline of the text widget. The command returns an empty
string. If more indices are given, multiple ranges of text will
be deleted. All indices are first checked for validity before
any deletions are made. They are sorted and the text is removed
from the last range to the first range so deleted text does not
cause an undesired index shifting side-effects. If multiple
ranges with the same start index are given, then the longest
range is used. If overlapping ranges are given, then they will
be merged into spans that do not cause deletion of text outside
the given ranges due to text shifted during deletion.
pathName dlineinfo index
Returns a list with five elements describing the area occupied
by the display line containing index. The first two elements of
the list give the x and y coordinates of the upper-left corner
of the area occupied by the line, the third and fourth elements
give the width and height of the area, and the fifth element
gives the position of the baseline for the line, measured down
from the top of the area. All of this information is measured in
pixels. If the current wrap mode is none and the line extends
beyond the boundaries of the window, the area returned reflects
the entire area of the line, including the portions that are out
of the window. If the line is shorter than the full width of the
window then the area returned reflects just the portion of the
line that is occupied by characters and embedded windows. If the
display line containing index is not visible on the screen then
the return value is an empty list.
pathName dump ?switches? index1 ?index2?
Return the contents of the text widget from index1 up to, but
not including index2, including the text and information about
marks, tags, and embedded windows. If index2 is not specified,
then it defaults to one character past index1. The information
is returned in the following format:
key1 value1 index1 key2 value2 index2 ...
The possible key values are text, mark, tagon, tagoff, image,
and window. The corresponding value is the text, mark name, tag
name, image name, or window name. The index information is the
index of the start of the text, mark, tag transition, image or
window. One or more of the following switches (or abbreviations
thereof) may be specified to control the dump:
-all Return information about all elements: text, marks, tags,
images and windows. This is the default.
-command command
Instead of returning the information as the result of the
dump operation, invoke the command on each element of the
text widget within the range. The command has three
arguments appended to it before it is evaluated: the key,
value, and index.
-image Include information about images in the dump results.
-mark Include information about marks in the dump results.
-tag Include information about tag transitions in the dump
results. Tag information is returned as tagon and tagoff
elements that indicate the begin and end of each range of
each tag, respectively.
-text Include information about text in the dump results. The
value is the text up to the next element or the end of
range indicated by index2. A text element does not span
newlines. A multi-line block of text that contains no
marks or tag transitions will still be dumped as a set of
text segments that each end with a newline. The newline
is part of the value.
-window
Include information about embedded windows in the dump
results. The value of a window is its Tk pathname, unless
the window has not been created yet. (It must have a
create script.) In this case an empty string is returned,
and you must query the window by its index position to
get more information.
pathName edit option ?arg arg ...?
This command controls the undo mechanism and the modified flag.
The exact behavior of the command depends on the option argument
that follows the edit argument. The following forms of the
command are currently supported:
pathName edit canredo
Returns a boolean true if redo is possible, i.e. when the
redo stack is not empty. Otherwise returns false.
pathName edit canundo
Returns a boolean true if undo is possible, i.e. when the
undo stack is not empty. Otherwise returns false.
pathName edit modified ?boolean?
If boolean is not specified, returns the modified flag of
the widget. The insert, delete, edit undo and edit redo
commands or the user can set or clear the modified flag.
If boolean is specified, sets the modified flag of the
widget to boolean.
pathName edit redo
When the -undo option is true, reapplies the last undone
edits provided no other edits were done since then.
Generates an error when the redo stack is empty. Does
nothing when the -undo option is false.
pathName edit reset
Clears the undo and redo stacks.
pathName edit separator
Inserts a separator (boundary) on the undo stack. Does
nothing when the -undo option is false.
pathName edit undo
Undoes the last edit action when the -undo option is
true. An edit action is defined as all the insert and
delete commands that are recorded on the undo stack in
between two separators. Generates an error when the undo
stack is empty. Does nothing when the -undo option is
false.
pathName get ?-displaychars? ?--? index1 ?index2 ...?
Return a range of characters from the text. The return value
will be all the characters in the text starting with the one
whose index is index1 and ending just before the one whose index
is index2 (the character at index2 will not be returned). If
index2 is omitted then the single character at index1 is
returned. If there are no characters in the specified range
(e.g. index1 is past the end of the file or index2 is less than
or equal to index1) then an empty string is returned. If the
specified range contains embedded windows, no information about
them is included in the returned string. If multiple index pairs
are given, multiple ranges of text will be returned in a list.
Invalid ranges will not be represented with empty strings in the
list. The ranges are returned in the order passed to pathName
get. If the -displaychars option is given, then, within each
range, only those characters which are not elided will be
returned. This may have the effect that some of the returned
ranges are empty strings.
pathName image option ?arg arg ...?
This command is used to manipulate embedded images. The behavior
of the command depends on the option argument that follows the
image argument. The following forms of the command are currently
supported:
pathName image cget index option
Returns the value of a configuration option for an
embedded image. Index identifies the embedded image, and
option specifies a particular configuration option, which
must be one of the ones listed in the section EMBEDDED
IMAGES.
pathName image configure index ?option value ...?
Query or modify the configuration options for an embedded
image. If no option is specified, returns a list
describing all of the available options for the embedded
image at index (see Tk_ConfigureInfo for information on
the format of this list). If option is specified with no
value, then the command returns a list describing the one
named option (this list will be identical to the
corresponding sublist of the value returned if no option
is specified). If one or more option-value pairs are
specified, then the command modifies the given option(s)
to have the given value(s); in this case the command
returns an empty string. See EMBEDDED IMAGES for
information on the options that are supported.
pathName image create index ?option value ...?
This command creates a new image annotation, which will
appear in the text at the position given by index. Any
number of option-value pairs may be specified to
configure the annotation. Returns a unique identifier
that may be used as an index to refer to this image. See
EMBEDDED IMAGES for information on the options that are
supported, and a description of the identifier returned.
pathName image names
Returns a list whose elements are the names of all image
instances currently embedded in window.
pathName index index
Returns the position corresponding to index in the form
line.char where line is the line number and char is the
character number. Index may have any of the forms described
under INDICES above.
pathName insert index chars ?tagList chars tagList ...?
Inserts all of the chars arguments just before the character at
index. If index refers to the end of the text (the character
after the last newline) then the new text is inserted just
before the last newline instead. If there is a single chars
argument and no tagList, then the new text will receive any tags
that are present on both the character before and the character
after the insertion point; if a tag is present on only one of
these characters then it will not be applied to the new text. If
tagList is specified then it consists of a list of tag names;
the new characters will receive all of the tags in this list and
no others, regardless of the tags present around the insertion
point. If multiple chars-tagList argument pairs are present,
they produce the same effect as if a separate pathName insert
widget command had been issued for each pair, in order. The last
tagList argument may be omitted.
pathName mark option ?arg arg ...?
This command is used to manipulate marks. The exact behavior of
the command depends on the option argument that follows the mark
argument. The following forms of the command are currently
supported:
pathName mark gravity markName ?direction?
If direction is not specified, returns left or right to
indicate which of its adjacent characters markName is
attached to. If direction is specified, it must be left
or right; the gravity of markName is set to the given
value.
pathName mark names
Returns a list whose elements are the names of all the
marks that are currently set.
pathName mark next index
Returns the name of the next mark at or after index. If
index is specified in numerical form, then the search for
the next mark begins at that index. If index is the name
of a mark, then the search for the next mark begins
immediately after that mark. This can still return a mark
at the same position if there are multiple marks at the
same index. These semantics mean that the mark next
operation can be used to step through all the marks in a
text widget in the same order as the mark information
returned by the pathName dump operation. If a mark has
been set to the special end index, then it appears to be
after end with respect to the pathName mark next
operation. An empty string is returned if there are no
marks after index.
pathName mark previous index
Returns the name of the mark at or before index. If index
is specified in numerical form, then the search for the
previous mark begins with the character just before that
index. If index is the name of a mark, then the search
for the next mark begins immediately before that mark.
This can still return a mark at the same position if
there are multiple marks at the same index. These
semantics mean that the pathName mark previous operation
can be used to step through all the marks in a text
widget in the reverse order as the mark information
returned by the pathName dump operation. An empty string
is returned if there are no marks before index.
pathName mark set markName index
Sets the mark named markName to a position just before
the character at index. If markName already exists, it is
moved from its old position; if it does not exist, a new
mark is created. This command returns an empty string.
pathName mark unset markName ?markName markName ...?
Remove the mark corresponding to each of the markName
arguments. The removed marks will not be usable in
indices and will not be returned by future calls to
"pathName mark names". This command returns an empty
string.
pathName peer option args
This command is used to create and query widget peers. It has
two forms, depending on option:
pathName peer create newPathName ?options?
Creates a peer text widget with the given newPathName,
and any optional standard configuration options (as for
the text command). By default the peer will have the same
start and end line as the parent widget, but these can be
overridden with the standard configuration options.
pathName peer names
Returns a list of peers of this widget (this does not
include the widget itself). The order within this list is
undefined.
pathName pendingsync
Returns 1 if the line heights calculations are not up-to-date, 0
otherwise.
pathName replace index1 index2 chars ?tagList chars tagList ...?
Replaces the range of characters between index1 and index2 with
the given characters and tags. See the section on pathName
insert for an explanation of the handling of the tagList...
arguments, and the section on pathName delete for an explanation
of the handling of the indices. If index2 corresponds to an
index earlier in the text than index1, an error will be
generated.
The deletion and insertion are arranged so that no unnecessary
scrolling of the window or movement of insertion cursor occurs.
In addition the undo/redo stack are correctly modified, if undo
operations are active in the text widget. The command returns an
empty string.
pathName scan option args
This command is used to implement scanning on texts. It has two
forms, depending on option:
pathName scan mark x y
Records x and y and the current view in the text window,
for use in conjunction with later pathName scan dragto
commands. Typically this command is associated with a
mouse button press in the widget. It returns an empty
string.
pathName scan dragto x y
This command computes the difference between its x and y
arguments and the x and y arguments to the last pathName
scan mark command for the widget. It then adjusts the
view by 10 times the difference in coordinates. This
command is typically associated with mouse motion events
in the widget, to produce the effect of dragging the text
at high speed through the window. The return value is an
empty string.
pathName search ?switches? pattern index ?stopIndex?
Searches the text in pathName starting at index for a range of
characters that matches pattern. If a match is found, the index
of the first character in the match is returned as result;
otherwise an empty string is returned. One or more of the
following switches (or abbreviations thereof) may be specified
to control the search:
-forwards
The search will proceed forward through the text, finding
the first matching range starting at or after the
position given by index. This is the default.
-backwards
The search will proceed backward through the text,
finding the matching range closest to index whose first
character is before index (it is not allowed to be at
index). Note that, for a variety of reasons, backwards
searches can be substantially slower than forwards
searches (particularly when using -regexp), so it is
recommended that performance-critical code use forward
searches.
-exact Use exact matching: the characters in the matching range
must be identical to those in pattern. This is the
default.
-regexp
Treat pattern as a regular expression and match it
against the text using the rules for regular expressions
(see the regexp command and the re_syntax page for
details). The default matching automatically passes both
the -lineanchor and -linestop options to the regexp
engine (unless -nolinestop is used), so that ^$ match
beginning and end of line, and ., [^ sequences will never
match the newline character \n.
-nolinestop
This allows . and [^ sequences to match the newline
character \n, which they will otherwise not do (see the
regexp command for details). This option is only
meaningful if -regexp is also given, and an error will be
thrown otherwise. For example, to match the entire text,
use "pathName search -nolinestop -regexp ".*" 1.0".
-nocase
Ignore case differences between the pattern and the text.
-count varName
The argument following -count gives the name of a
variable; if a match is found, the number of index
positions between beginning and end of the matching range
will be stored in the variable. If there are no embedded
images or windows in the matching range (and there are no
elided characters if -elide is not given), this is
equivalent to the number of characters matched. In either
case, the range matchIdx to matchIdx + $count chars will
return the entire matched text.
-all Find all matches in the given range and return a list of
the indices of the first character of each match. If a
-count varName switch is given, then varName is also set
to a list containing one element for each successful
match. Note that, even for exact searches, the elements
of this list may be different, if there are embedded
images, windows or hidden text. Searches with -all
behave very similarly to the Tcl command regexp -all, in
that overlapping matches are not normally returned. For
example, applying an -all search of the pattern "\w+"
against "hello there" will just match twice, once for
each word, and matching "Z[a-z]+Z" against "ZooZooZoo"
will just match once.
-overlap
When performing -all searches, the normal behaviour is
that matches which overlap an already-found match will
not be returned. This switch changes that behaviour so
that all matches which are not totally enclosed within
another match are returned. For example, applying an
-overlap search of the pattern "\w+" against "hello
there" will just match twice (i.e. no different to just
-all), but matching "Z[a-z]+Z" against "ZooZooZoo" will
now match twice. An error will be thrown if this switch
is used without -all.
-strictlimits
When performing any search, the normal behaviour is that
the start and stop limits are checked with respect to the
start of the matching text. With the -strictlimits flag,
the entire matching range must lie inside the start and
stop limits specified for the match to be valid.
-elide Find elided (hidden) text as well. By default only
displayed text is searched.
-- This switch has no effect except to terminate the list of
switches: the next argument will be treated as pattern
even if it starts with -.
The matching range may be within a single line of text, or run
across multiple lines (if parts of the pattern can match a new-
line). For regular expression matching one can use the various
newline-matching features such as $ to match the end of a line,
^ to match the beginning of a line, and to control whether . is
allowed to match a new-line. If stopIndex is specified, the
search stops at that index: for forward searches, no match at or
after stopIndex will be considered; for backward searches, no
match earlier in the text than stopIndex will be considered. If
stopIndex is omitted, the entire text will be searched: when the
beginning or end of the text is reached, the search continues at
the other end until the starting location is reached again; if
stopIndex is specified, no wrap-around will occur. This means
that, for example, if the search is -forwards but stopIndex is
earlier in the text than startIndex, nothing will ever be found.
See KNOWN BUGS below for a number of minor limitations of the
pathName search command.
pathName see index
Adjusts the view in the window so that the character given by
index is completely visible. If index is already visible then
the command does nothing. If index is a short distance out of
view, the command adjusts the view just enough to make index
visible at the edge of the window. If index is far out of view,
then the command centers index in the window.
pathName sync ?-command command?
Controls the synchronization of the view of the text widget.
pathName sync
Immediately brings the line metrics up-to-date by forcing
computation of any outdated line heights. The command
returns immediately if there is no such outdated line
heights, otherwise it returns only at the end of the
computation. The command returns an empty string.
pathName sync -command command
Schedules command to be executed (by the event loop)
exactly once as soon as all line heights are up-to-date.
If there are no pending line metrics calculations, the
scheduling is immediate. The command returns the empty
string. bgerror is called on command failure.
pathName tag option ?arg arg ...?
This command is used to manipulate tags. The exact behavior of
the command depends on the option argument that follows the tag
argument. The following forms of the command are currently
supported:
pathName tag add tagName index1 ?index2 index1 index2 ...?
Associate the tag tagName with all of the characters
starting with index1 and ending just before index2 (the
character at index2 is not tagged). A single command may
contain any number of index1-index2 pairs. If the last
index2 is omitted then the single character at index1 is
tagged. If there are no characters in the specified range
(e.g. index1 is past the end of the file or index2 is
less than or equal to index1) then the command has no
effect.
pathName tag bind tagName ?sequence? ?script?
This command associates script with the tag given by
tagName. Whenever the event sequence given by sequence
occurs for a character that has been tagged with tagName,
the script will be invoked. This widget command is
similar to the bind command except that it operates on
characters in a text rather than entire widgets. See the
bind manual entry for complete details on the syntax of
sequence and the substitutions performed on script before
invoking it. If all arguments are specified then a new
binding is created, replacing any existing binding for
the same sequence and tagName (if the first character of
script is "+" then script augments an existing binding
rather than replacing it). In this case the return value
is an empty string. If script is omitted then the command
returns the script associated with tagName and sequence
(an error occurs if there is no such binding). If both
script and sequence are omitted then the command returns
a list of all the sequences for which bindings have been
defined for tagName.
The only events for which bindings may be specified are
those related to the mouse and keyboard (such as Enter,
Leave, ButtonPress, Motion, and KeyPress) or virtual
events. Mouse and keyboard event bindings for a text
widget respectively use the current and insert marks
described under MARKS above. An Enter event triggers for
a tag when the tag first becomes present on the current
character, and a Leave event triggers for a tag when it
ceases to be present on the current character. Enter and
Leave events can happen either because the current mark
moved or because the character at that position changed.
Note that these events are different than Enter and Leave
events for windows. Mouse events are directed to the
current character, while keyboard events are directed to
the insert character. If a virtual event is used in a
binding, that binding can trigger only if the virtual
event is defined by an underlying mouse-related or
keyboard-related event.
It is possible for the current character to have multiple
tags, and for each of them to have a binding for a
particular event sequence. When this occurs, one binding
is invoked for each tag, in order from lowest-priority to
highest priority. If there are multiple matching bindings
for a single tag, then the most specific binding is
chosen (see the manual entry for the bind command for
details). continue and break commands within binding
scripts are processed in the same way as for bindings
created with the bind command.
If bindings are created for the widget as a whole using
the bind command, then those bindings will supplement the
tag bindings. The tag bindings will be invoked first,
followed by bindings for the window as a whole.
pathName tag cget tagName option
This command returns the current value of the option
named option associated with the tag given by tagName.
Option may have any of the values accepted by the
pathName tag configure widget command.
pathName tag configure tagName ?option? ?value? ?option value
...? This command is similar to the pathName configure widget
command except that it modifies options associated with
the tag given by tagName instead of modifying options for
the overall text widget. If no option is specified, the
command returns a list describing all of the available
options for tagName (see Tk_ConfigureInfo for information
on the format of this list). If option is specified with
no value, then the command returns a list describing the
one named option (this list will be identical to the
corresponding sublist of the value returned if no option
is specified). If one or more option-value pairs are
specified, then the command modifies the given option(s)
to have the given value(s) in tagName; in this case the
command returns an empty string. See TAGS above for
details on the options available for tags.
pathName tag delete tagName ?tagName ...?
Deletes all tag information for each of the tagName
arguments. The command removes the tags from all
characters in the file and also deletes any other
information associated with the tags, such as bindings
and display information. The command returns an empty
string.
pathName tag lower tagName ?belowThis?
Changes the priority of tag tagName so that it is just
lower in priority than the tag whose name is belowThis.
If belowThis is omitted, then tagName's priority is
changed to make it lowest priority of all tags.
pathName tag names ?index?
Returns a list whose elements are the names of all the
tags that are active at the character position given by
index. If index is omitted, then the return value will
describe all of the tags that exist for the text (this
includes all tags that have been named in a "pathName
tag" widget command but have not been deleted by a
"pathName tag delete" widget command, even if no
characters are currently marked with the tag). The list
will be sorted in order from lowest priority to highest
priority.
pathName tag nextrange tagName index1 ?index2?
This command searches the text for a range of characters
tagged with tagName where the first character of the
range is no earlier than the character at index1 and no
later than the character just before index2 (a range
starting at index2 will not be considered). If several
matching ranges exist, the first one is chosen. The
command's return value is a list containing two elements,
which are the index of the first character of the range
and the index of the character just after the last one in
the range. If no matching range is found then the return
value is an empty string. If index2 is not given then it
defaults to the end of the text.
pathName tag prevrange tagName index1 ?index2?
This command searches the text for a range of characters
tagged with tagName where the first character of the
range is before the character at index1 and no earlier
than the character at index2 (a range starting at index2
will be considered). If several matching ranges exist,
the one closest to index1 is chosen. The command's return
value is a list containing two elements, which are the
index of the first character of the range and the index
of the character just after the last one in the range. If
no matching range is found then the return value is an
empty string. If index2 is not given then it defaults to
the beginning of the text.
pathName tag raise tagName ?aboveThis?
Changes the priority of tag tagName so that it is just
higher in priority than the tag whose name is aboveThis.
If aboveThis is omitted, then tagName's priority is
changed to make it highest priority of all tags.
pathName tag ranges tagName
Returns a list describing all of the ranges of text that
have been tagged with tagName. The first two elements of
the list describe the first tagged range in the text, the
next two elements describe the second range, and so on.
The first element of each pair contains the index of the
first character of the range, and the second element of
the pair contains the index of the character just after
the last one in the range. If there are no characters
tagged with tag then an empty string is returned.
pathName tag remove tagName index1 ?index2 index1 index2 ...?
Remove the tag tagName from all of the characters
starting at index1 and ending just before index2 (the
character at index2 is not affected). A single command
may contain any number of index1-index2 pairs. If the
last index2 is omitted then the tag is removed from the
single character at index1. If there are no characters in
the specified range (e.g. index1 is past the end of the
file or index2 is less than or equal to index1) then the
command has no effect. This command returns an empty
string.
pathName window option ?arg arg ...?
This command is used to manipulate embedded windows. The
behavior of the command depends on the option argument that
follows the window argument. The following forms of the command
are currently supported:
pathName window cget index option
Returns the value of a configuration option for an
embedded window. Index identifies the embedded window,
and option specifies a particular configuration option,
which must be one of the ones listed in the section
EMBEDDED WINDOWS.
pathName window configure index ?option value ...?
Query or modify the configuration options for an embedded
window. If no option is specified, returns a list
describing all of the available options for the embedded
window at index (see Tk_ConfigureInfo for information on
the format of this list). If option is specified with no
value, then the command returns a list describing the one
named option (this list will be identical to the
corresponding sublist of the value returned if no option
is specified). If one or more option-value pairs are
specified, then the command modifies the given option(s)
to have the given value(s); in this case the command
returns an empty string. See EMBEDDED WINDOWS for
information on the options that are supported.
pathName window create index ?option value ...?
This command creates a new window annotation, which will
appear in the text at the position given by index. Any
number of option-value pairs may be specified to
configure the annotation. See EMBEDDED WINDOWS for
information on the options that are supported. Returns an
empty string.
pathName window names
Returns a list whose elements are the names of all
windows currently embedded in window.
pathName xview option args
This command is used to query and change the horizontal position
of the text in the widget's window. It can take any of the
following forms:
pathName xview
Returns a list containing two elements. Each element is a
real fraction between 0 and 1; together they describe the
portion of the document's horizontal span that is visible
in the window. For example, if the first element is .2
and the second element is .6, 20% of the text is off-
screen to the left, the middle 40% is visible in the
window, and 40% of the text is off-screen to the right.
The fractions refer only to the lines that are actually
visible in the window: if the lines in the window are all
very short, so that they are entirely visible, the
returned fractions will be 0 and 1, even if there are
other lines in the text that are much wider than the
window. These are the same values passed to scrollbars
via the -xscrollcommand option.
pathName xview moveto fraction
Adjusts the view in the window so that fraction of the
horizontal span of the text is off-screen to the left.
Fraction is a fraction between 0 and 1.
pathName xview scroll number what
This command shifts the view in the window left or right
according to number and what. What must be units, pages
or pixels. If what is units or pages then number must be
an integer, otherwise number may be specified in any of
the forms acceptable to Tk_GetPixels, such as "2.0c" or
"1i" (the result is rounded to the nearest integer value.
If no units are given, pixels are assumed). If what is
units, the view adjusts left or right by number average-
width characters on the display; if it is pages then the
view adjusts by number screenfuls; if it is pixels then
the view adjusts by number pixels. If number is negative
then characters farther to the left become visible; if it
is positive then characters farther to the right become
visible.
pathName yview ?args?
This command is used to query and change the vertical position
of the text in the widget's window. It can take any of the
following forms:
pathName yview
Returns a list containing two elements, both of which are
real fractions between 0 and 1. The first element gives
the position of the first visible pixel of the first
character (or image, etc) in the top line in the window,
relative to the text as a whole (0.5 means it is halfway
through the text, for example). The second element gives
the position of the first pixel just after the last
visible one in the bottom line of the window, relative to
the text as a whole. These are the same values passed to
scrollbars via the -yscrollcommand option.
pathName yview moveto fraction
Adjusts the view in the window so that the pixel given by
fraction appears at the top of the top line of the
window. Fraction is a fraction between 0 and 1; 0
indicates the first pixel of the first character in the
text, 0.33 indicates the pixel that is one-third the way
through the text; and so on. Values close to 1 will
indicate values close to the last pixel in the text (1
actually refers to one pixel beyond the last pixel), but
in such cases the widget will never scroll beyond the
last pixel, and so a value of 1 will effectively be
rounded back to whatever fraction ensures the last pixel
is at the bottom of the window, and some other pixel is
at the top.
pathName yview scroll number what
This command adjust the view in the window up or down
according to number and what. What must be units, pages
or pixels. If what is units or pages then number must be
an integer, otherwise number may be specified in any of
the forms acceptable to Tk_GetPixels, such as "2.0c" or
"1i" (the result is rounded to the nearest integer value.
If no units are given, pixels are assumed). If what is
units, the view adjusts up or down by number lines on the
display; if it is pages then the view adjusts by number
screenfuls; if it is pixels then the view adjusts by
number pixels. If number is negative then earlier
positions in the text become visible; if it is positive
then later positions in the text become visible.
pathName yview ?-pickplace? index
Changes the view in the widget's window to make index
visible. If the -pickplace option is not specified then
index will appear at the top of the window. If -pickplace
is specified then the widget chooses where index appears
in the window:
[1] If index is already visible somewhere in the
window then the command does nothing.
[2] If index is only a few lines off-screen above the
window then it will be positioned at the top of
the window.
[3] If index is only a few lines off-screen below the
window then it will be positioned at the bottom of
the window.
[4] Otherwise, index will be centered in the window.
The -pickplace option has been obsoleted by the pathName
see widget command (pathName see handles both x- and y-
motion to make a location visible, whereas the -pickplace
mode only handles motion in y).
pathName yview number
This command makes the first character on the line after
the one given by number visible at the top of the window.
Number must be an integer. This command used to be used
for scrolling, but now it is obsolete.
BINDINGS
Tk automatically creates class bindings for texts that give them the
following default behavior. In the descriptions below, "word" is
dependent on the value of the tcl_wordchars variable. See tclvars(n).
[1] Clicking mouse button 1 positions the insertion cursor at the
closest edge of the character underneath the mouse cursor, sets
the input focus to this widget, and clears any selection in the
widget. Dragging with mouse button 1 strokes out a selection
between the insertion cursor and the character under the mouse.
[2] Double-clicking with mouse button 1 selects the word under the
mouse and positions the insertion cursor at the start of the
word. Dragging after a double click will stroke out a selection
consisting of whole words.
[3] Triple-clicking with mouse button 1 selects the line under the
mouse and positions the insertion cursor at the start of the
line. Dragging after a triple click will stroke out a selection
consisting of whole lines.
[4] The ends of the selection can be adjusted by dragging with mouse
button 1 while the Shift key is down; this will adjust the end
of the selection that was nearest to the mouse cursor when
button 1 was pressed. If the button is double-clicked before
dragging then the selection will be adjusted in units of whole
words; if it is triple-clicked then the selection will be
adjusted in units of whole lines.
[5] Clicking mouse button 1 with the Control key down will
reposition the insertion cursor without affecting the selection.
[6] If any normal printing characters are typed, they are inserted
at the point of the insertion cursor.
[7] The view in the widget can be adjusted by dragging with the
middle mouse button (button 2, or button 3 in TkAqua). If the
middle mouse button is clicked without moving the mouse, the
selection is copied into the text at the position of the mouse
cursor. The Insert key also inserts the selection, but at the
position of the insertion cursor.
[8] If the mouse is dragged out of the widget while button 1 is
pressed, the entry will automatically scroll to make more text
visible (if there is more text off-screen on the side where the
mouse left the window).
[9] The Left and Right keys move the insertion cursor one character
to the left or right; they also clear any selection in the text.
If Left or Right is typed with the Shift key down, then the
insertion cursor moves and the selection is extended to include
the new character. Control-Left and Control-Right move the
insertion cursor by words, and Control-Shift-Left and Control-
Shift-Right move the insertion cursor by words and also extend
the selection. Control-b and Control-f behave the same as Left
and Right, respectively. Meta-b and Meta-f behave the same as
Control-Left and Control-Right, respectively.
[10] The Up and Down keys move the insertion cursor one line up or
down and clear any selection in the text. If Up or Right is
typed with the Shift key down, then the insertion cursor moves
and the selection is extended to include the new character.
Control-Up and Control-Down move the insertion cursor by
paragraphs (groups of lines separated by blank lines), and
Control-Shift-Up and Control-Shift-Down move the insertion
cursor by paragraphs and also extend the selection. Control-p
and Control-n behave the same as Up and Down, respectively.
[11] The Next and Prior keys move the insertion cursor forward or
backwards by one screenful and clear any selection in the text.
If the Shift key is held down while Next or Prior is typed, then
the selection is extended to include the new character.
[12] Control-Next and Control-Prior scroll the view right or left by
one page without moving the insertion cursor or affecting the
selection.
[13] Home and Control-a move the insertion cursor to the beginning of
its display line and clear any selection in the widget. Shift-
Home moves the insertion cursor to the beginning of the display
line and also extends the selection to that point.
[14] End and Control-e move the insertion cursor to the end of the
display line and clear any selection in the widget. Shift-End
moves the cursor to the end of the display line and extends the
selection to that point.
[15] Control-Home and Meta-< move the insertion cursor to the
beginning of the text and clear any selection in the widget.
Control-Shift-Home moves the insertion cursor to the beginning
of the text and also extends the selection to that point.
[16] Control-End and Meta-> move the insertion cursor to the end of
the text and clear any selection in the widget. Control-Shift-
End moves the cursor to the end of the text and extends the
selection to that point.
[17] The Select key and Control-Space set the selection anchor to the
position of the insertion cursor. They do not affect the current
selection. Shift-Select and Control-Shift-Space adjust the
selection to the current position of the insertion cursor,
selecting from the anchor to the insertion cursor if there was
not any selection previously.
[18] Control-/ selects the entire contents of the widget.
[19] Control-\ clears any selection in the widget.
[20] The F16 key (labelled Copy on many Sun workstations) or Meta-w
copies the selection in the widget to the clipboard, if there is
a selection. This action is carried out by the command
tk_textCopy.
[21] The F20 key (labelled Cut on many Sun workstations) or Control-w
copies the selection in the widget to the clipboard and deletes
the selection. This action is carried out by the command
tk_textCut. If there is no selection in the widget then these
keys have no effect.
[22] The F18 key (labelled Paste on many Sun workstations) or
Control-y inserts the contents of the clipboard at the position
of the insertion cursor. This action is carried out by the
command tk_textPaste.
[23] The Delete key deletes the selection, if there is one in the
widget. If there is no selection, it deletes the character to
the right of the insertion cursor.
[24] Backspace and Control-h delete the selection, if there is one in
the widget. If there is no selection, they delete the character
to the left of the insertion cursor.
[25] Control-d deletes the character to the right of the insertion
cursor.
[26] Meta-d deletes the word to the right of the insertion cursor.
[27] Control-k deletes from the insertion cursor to the end of its
line; if the insertion cursor is already at the end of a line,
then Control-k deletes the newline character.
[28] Control-o opens a new line by inserting a newline character in
front of the insertion cursor without moving the insertion
cursor.
[29] Meta-backspace and Meta-Delete delete the word to the left of
the insertion cursor.
[30] Control-x deletes whatever is selected in the text widget after
copying it to the clipboard.
[31] Control-t reverses the order of the two characters to the right
of the insertion cursor.
[32] Control-z undoes the last edit action if the -undo option is
true. Does nothing otherwise.
[33] Control-Z (or Control-y on Windows) reapplies the last undone
edit action if the -undo option is true. Does nothing otherwise.
If the widget is disabled using the -state option, then its view can
still be adjusted and text can still be selected, but no insertion
cursor will be displayed and no text modifications will take place.
The behavior of texts can be changed by defining new bindings for
individual widgets or by redefining the class bindings.
KNOWN ISSUES
ISSUES CONCERNING CHARS AND INDICES
Before Tk 8.5, the widget used the string "chars" to refer to index
positions (which included characters, embedded windows and embedded
images). As of Tk 8.5 the text widget deals separately and correctly
with "chars" and "indices". For backwards compatibility, however, the
index modifiers "+N chars" and "-N chars" continue to refer to indices.
One must use any of the full forms "+N any chars" or "-N any chars"
etc. to refer to actual character indices. This confusion may be fixed
in a future release by making the widget correctly interpret "+N chars"
as a synonym for "+N any chars".
PERFORMANCE ISSUES
Text widgets should run efficiently under a variety of conditions. The
text widget uses about 2-3 bytes of main memory for each byte of text,
so texts containing a megabyte or more should be practical on most
workstations. Text is represented internally with a modified B-tree
structure that makes operations relatively efficient even with large
texts. Tags are included in the B-tree structure in a way that allows
tags to span large ranges or have many disjoint smaller ranges without
loss of efficiency. Marks are also implemented in a way that allows
large numbers of marks. In most cases it is fine to have large numbers
of unique tags, or a tag that has many distinct ranges.
One performance problem can arise if you have hundreds or thousands of
different tags that all have the following characteristics: the first
and last ranges of each tag are near the beginning and end of the text,
respectively, or a single tag range covers most of the text widget. The
cost of adding and deleting tags like this is proportional to the
number of other tags with the same properties. In contrast, there is no
problem with having thousands of distinct tags if their overall ranges
are localized and spread uniformly throughout the text.
Very long text lines can be expensive, especially if they have many
marks and tags within them.
The display line with the insert cursor is redrawn each time the cursor
blinks, which causes a steady stream of graphics traffic. Set the
-insertofftime attribute to 0 avoid this.
KNOWN BUGS
The pathName search -regexp sub-command attempts to perform
sophisticated regexp matching across multiple lines in an efficient
fashion (since Tk 8.5), examining each line individually, and then in
small groups of lines, whether searching forwards or backwards. Under
certain conditions the search result might differ from that obtained by
applying the same regexp to the entire text from the widget in one go.
For example, when searching with a greedy regexp, the widget will
continue to attempt to add extra lines to the match as long as one of
two conditions are true: either Tcl's regexp library returns a code to
indicate a longer match is possible (but there are known bugs in Tcl
which mean this code is not always correctly returned); or if each
extra line added results in at least a partial match with the pattern.
This means in the case where the first extra line added results in no
match and Tcl's regexp system returns the incorrect code and adding a
second extra line would actually match, the text widget will return the
wrong result. In practice this is a rare problem, but it can occur, for
example:
pack [text .t]
.t insert 1.0 "aaaa\nbbbb\ncccc\nbbbb\naaaa\n"
.t search -regexp -- {(a+|b+\nc+\nb+)+\na+} 1.0
will not find a match when one exists of 19 characters starting from
the first "b".
Whenever one possible match is fully enclosed in another, the search
command will attempt to ensure only the larger match is returned. When
performing backwards regexp searches it is possible that Tcl will not
always achieve this, in the case where a match is preceded by one or
more short, non-overlapping matches, all of which are preceded by a
large match which actually encompasses all of them. The search
algorithm used by the widget does not look back arbitrarily far for a
possible match which might cover large portions of the widget. For
example:
pack [text .t]
.t insert 1.0 "aaaa\nbbbb\nbbbb\nbbbb\nbbbb\n"
.t search -regexp -backward -- {b+\n|a+\n(b+\n)+} end
matches at "5.0" when a true greedy match would match at "1.0".
Similarly if we add -all to this case, it matches at all of "5.0",
"4.0", "3.0" and "1.0", when really it should only match at "1.0" since
that match encloses all the others.
SEE ALSO
entry(n), scrollbar(n)
KEYWORDS
text, widget, tkvars
Tk 8.5 text(n)
tk 8.6.14 - Generated Mon Mar 4 15:54:49 CST 2024