## text

Create and manipulate text widgets

### SYNOPSIS

(text widget-name ?options?)

### STANDARD OPTIONS

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

### WIDGET-SPECIFIC OPTIONS

Name: height
Class: Height
Option keyword: :height
STklos slot name: 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.

Name: spacing1
Class: Spacing1
Option keyword: :spacing1
STklos slot name: spacing1
  Requests additional space above each text line in the widget, using any of the standard forms for screen distances. If a line wraps, this option only applies to the first line on the display. This option may be overriden with :spacing1 options in tags.

Name: spacing2
Class: Spacing2
Option keyword: :spacing2
STklos slot name: spacing2
  For lines that wrap (so that they cover more than one line on the display) this option specifies additional space to provide between the display lines that represent a single line of text. The value may have any of the standard forms for screen distances. This option may be overriden with :spacing2 options in tags.

Name: spacing3
Class: Spacing3
Option keyword: :spacing3
STklos slot name: spacing3
  Requests additional space below each text line in the widget, using any of the standard forms for screen distances. If a line wraps, this option only applies to the last line on the display. This option may be overriden with :spacing3 options in tags.

Name: state
Class: State
Option keyword: :state
STklos slot name: 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.

Name: tabs
Class: Tabs
Option keyword: :tabs
STklos slot name: tabs
  Specifies a set of tab stops for the window. The option's value consists of a list of screen distances giving the positions of the tab stops. Each position may optionally be followed in the next list element by one of the keywords left, right, center, or numeric, which specifies how to justify text relative to the tab stop. Left is the default; it causes the text following the tab character to be positioned with its left edge at the tab position. Right means that the right edge of the text following the tab character is positioned at the tab position, and center means that the text is centered at the tab position. Numeric means that the decimal point in the text is positioned at the tab position; if there is no decimal point then the least significant digit of the number is positioned just to the left of the tab position; if there is no number in the text then the text is right-justified at the tab position. For example, :tabs `(2c left 4c 6c center) creates three tab stops at two-centimeter intervals; the first two use left justification and the third uses center justification. If the list of tab stops does not have enough elements to cover all of the tabs in a text line, then Tk extrapolates new tab stops using the spacing and alignment from the last tab stop in the list. The value of the tabs option may be overridden by :tabs options in tags. If no :tabs option is specified, or if it is specified as an empty list, then Tk uses default tabs spaced every eight (average size) characters.

Name: width
Class: Width
Option keyword: :width
STklos slot name: width
  Specifies the desired width for the window in units of characters in the font given by the :font option. If the font doesn't have a uniform width then the width of the character ``0'' is used in translating from character units to screen units.

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

### DESCRIPTION

The text procedure creates a new window (given by the widget-name argument) and makes it into a text widget. Additional options, described above, may be specified on the procedure line or in the option database to configure aspects of the text such as its default background color and relief. The text procedure 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, STk procedures can be associated with tags so that scripts are invoked when particular actions such as keystrokes and mouse button presses occur in particular ranges of the text. See TAGS below for more details.

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

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

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

### INDICES

Many of the widget procedures for texts take one or more indices as arguments. An index is a string used to indicate a particular place within a text, such as a place to insert characters or one endpoint of a range of characters to delete. Indices have the syntax

    base modifier modifier modifier ...

Where base gives a starting point and the modifiers adjust the index from the starting point (e.g. move forward or backward one character). Every index must contain a base, but the modifiers are optional.

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

line.char
(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.

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

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

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

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

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

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

.VS
  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 chars
  Adjust the index forward by count characters, moving to later lines in the text if necessary. If there are fewer than count characters in the text after the current index, then set the index to the last character in the text. Spaces on either side of count are optional.

: count chars
  Adjust the index backward by count characters, moving to earlier lines in the text if necessary. If there are fewer than count characters in the text before the current index, then set the index to the first character in the text. Spaces on either side of count are optional.

+ count lines
  Adjust the index forward by count lines, retaining the same character position within the line. If there are fewer than count lines after the line containing the current index, then set the index to refer to the same character position on the last line of the text. Then, if the line is not long enough to contain a character at the indicated character position, adjust the character position to refer to the last character of the line (the newline). Spaces on either side of count are optional.

- count lines
  Adjust the index backward by count lines, retaining the same character position within the line. If there are fewer than count lines before the line containing the current index, then set the index to refer to the same character position on the first line of the text. Then, if the line is not long enough to contain a character at the indicated character position, adjust the character position to refer to the last character of the line (the newline). Spaces on either side of count are optional.

linestart
  Adjust the index to refer to the first character on the line.

lineend
  Adjust the index to refer to the last character on the line (the newline).

wordstart
  Adjust the index to refer to the first character of the word containing the current index. A word consists of any number of adjacent characters that are letters, digits, or underscores, or a single character that is not one of these.

wordend
  Adjust the index to refer to the character just after the last one of the word containing the current index. If the current index refers to the last character of the text then it is not modified.

If more than one modifier is present then they are applied in left-to-right order. For example, the index ``end - 1 chars'' refers to the next-to-last character in the text and ``insert wordstart - 1 c'' refers to the character just before the first one in the word containing the insertion cursor.

### TAGS

The first form of annotation in text widgets is a tag. A tag is a textual string that is associated with some of the characters in a text. Tags may contain arbitrary characters, but it is probably best to avoid using the the characters `` '' (space), +, or :: these characters have special meaning in indices, so tags containing them can't be used as indices. There may be any number of tags associated with characters in a text. Each tag may refer to a single character, a range of characters, or several ranges of characters. An individual character may have any number of tags associated with it.

A priority order is defined among tags, and this order is used in implementing some of the tag-related functions described below. When a tag is defined (by associating it with characters or setting its display options or binding procedures to it), it is given a priority higher than any existing tag. The priority order of tags may be redefined using the ``widget-name 'tag 'raise'' and ``widget-name 'tag 'lower'' widget procedures.

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 ``widget-name tag configure'' widget procedure. If a character has been tagged, then the display options associated with the tag override the default display style. The following options are currently supported for tags:

:background color
  Color specifies the background color to use for characters associated with the tag. It may have any of the forms accepted by Tk_GetColor.

:bgstipple bitmap
  Bitmap specifies a bitmap that is used as a stipple pattern for the background. It may have any of the forms accepted by Tk_GetBitmap. If bitmap hasn't been specified, or if it is specified as an empty string, then a solid fill will be used for the background.

:borderwidth pixels
  Pixels specifies the width of a 3-D border to draw around the background. It may have any of the forms accepted by Tk_GetPixels. This option is used in conjunction with the :relief option to give a 3-D appearance to the background for characters; it is ignored unless the :background option has been set for the tag.

:fgstipple bitmap
  Bitmap specifies a bitmap that is used as a stipple pattern when drawing text and other foreground information such as underlines. It may have any of the forms accepted by Tk_GetBitmap. If bitmap hasn't been specified, or if it is specified as an empty string, then a solid fill will be used.

:font fontName
  FontName is the name of a font to use for drawing characters. It may have any of the forms accepted by Tk_GetFontStruct.

:foreground color
  Color specifies the color to use when drawing text and other foreground information such as underlines. It may have any of the forms accepted by Tk_GetColor.

:justify justify
  If the first character of a display line has a tag for which this option has been specified, then justify determines how to justify the line. It must be one of left, right, or center. If a line wraps, then the justification for each line on the display is determined by the first character of that display line.

:lmargin1 pixels
  If the first character of a text line has a tag for which this option has been specified, then pixels specifies how much the line should be indented from the left edge of the window. Pixels may have any of the standard forms for screen distances. If a line of text wraps, this option only applies to the first line on the display; the :lmargin2 option controls the indentation for subsequent lines.

:lmargin2 pixels
  If the first character of a display line has a tag for which this option has been specified, and if the display line is not the first for its text line (i.e., the text line has wrapped), then pixels specifies how much the line should be indented from the left edge of the window. Pixels may have any of the standard forms for screen distances. This option is only used when wrapping is enabled, and it only applies to the second and later display lines for a text line.

:offset pixels
  Pixels specifies an amount by which the text's baseline should be offset vertically from the baseline of the overall line, in pixels. For example, a positive offset can be used for superscripts and a negative offset can be used for subscripts. Pixels may have any of the standard forms for screen distances.

:overstrike boolean
  Specifies whether or not to draw a horizontal rule through the middle of characters. Boolean may have any of the forms accepted by Tk_GetBoolean.

:relief relief
  Relief specifies the 3-D relief to use for drawing backgrounds, in any of the forms accepted by Tk_GetRelief. This option is used in conjunction with the :borderwidth option to give a 3-D appearance to the background for characters; it is ignored unless the :background option has been set for the tag.

:rmargin pixels
  If the first character of a display line has a tag for which this option has been specified, then pixels specifies how wide a margin to leave between the end of the line and the right edge of the window. Pixels may have any of the standard forms for screen distances. This option is only used when wrapping is enabled. If a text line wraps, the right margin for each line on the display is determined by the first character of that display line.

:spacing1 pixels
  Pixels specifies how much additional space should be left above each text line, using any of the standard forms for screen distances. If a line wraps, this option only applies to the first line on the display.

:spacing2 pixels
  For lines that wrap, this option specifies how much additional space to leave between the display lines for a single text line. Pixels may have any of the standard forms for screen distances.

:spacing3 pixels
  Pixels specifies how much additional space should be left below each text line, using any of the standard forms for screen distances. If a line wraps, this option only applies to the last line on the display.

:tabs tabList
  TabList specifies a set of tab stops in the same form as for the :tabs option for the text widget. This option only applies to a display line if it applies to the first character on that display line. If this option is specified as an empty string, it cancels the option, leaving it unspecified for the tag (the default). If the option is specified as a non-empty string that is an empty list, such as :tags " ", then it requests default 8-character tabs as described for the tags widget option.

:underline boolean
  Boolean specifies whether or not to draw an underline underneath characters. It may have any of the forms accepted by Tk_GetBoolean.

:wrap mode
  Mode specifies how to handle lines that are wider than the text's window. It has the same legal values as the :wrap option for the text widget: none, char, or word. If this tag option is specified, it overrides the :wrap option for the text widget.

If a character has several tags associated with it, and if their display options conflict, then the options of the highest priority tag are used. If a particular display option hasn't been specified for a particular tag, or if it 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 STk procedure will be executed. Tag bindings can be used to give behaviors to ranges of characters; among other things, this allows hypertext-like features to be implemented. For details, see the description of the tag bind widget procedure below.

The third use for tags is in managing the selection. See THE SELECTION below.

### MARKS

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

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

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

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

### EMBEDDED WINDOWS

The third form of annotation in text widgets is an embedded window. Each embedded window annotation causes a window to be displayed at a particular point in the text. There may be any number of embedded windows in a text widget, and any widget may be used as an embedded window (subject to the usual rules for geometry management, which require the text window to be the parent of the embedded window or a descendant of its parent). The embedded window's position on the screen will be updated as the text is modified or scrolled, and it will be mapped and unmapped as it moves into and out of the visible area of the text widget. Each embedded window occupies one character's worth of index space in the text widget, and it may be referred to either by the name of its embedded window or by its position in the widget's index space. If the range of text containing the embedded window is deleted then the window is destroyed.

When an embedded window is added to a text widget with the window create widget procedure, several configuration options may be associated with it. These options may be modified later with the window configure widget procedure. 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 procedure
  Specifies a STk procedure 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 that window as its result. If the annotation's window should ever be deleted, procedure 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 widget-name
  Specifies the window to display in the annotation.

### EMBEDDED IMAGES

The final form of annotation in text widgets is an embedded image. Each embedded image annotation causes an image to be displayed at a particular point in the text. There may be any number of embedded images in a text widget, and a particular image may be embedded in multiple places in the same text widget. The embedded image's position on the screen will be updated as the text is modified or scrolled. Each embedded image occupies one character's worth of index space in the text widget, and it may be referred to either by its position in the widget's index space, or the name it is assigned when the image is inserted into the text widget widh image create. If the range of text containing the embedded image is deleted then that copy of the image is removed from the screen.

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

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

{ B:align} { Iwhere R}
  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).

{ B:image} { Iimage R}
  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.

{ B:name} { IImageName R}
  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.

{ B:padx} { Ipixels R}
  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.

{ B:pady} { Ipixels R}
  Pixels specifies the amount of extra space to leave on the top and on the bottom of the embedded image. It may have any of the usual forms defined for a screen distance.

### THE SELECTION

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

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

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

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

The sel tag is automatically defined when a text widget is created, and it may not be deleted with the ``widget-name 'tag 'delete'' widget procedure. Furthermore, the selectBackground, selectBorderWidth, and selectForeground options for the text widget are tied to the :background, :borderwidth, and :foreground options for the sel tag: changes in either will automatically be reflected in the other.

### THE INSERTION CURSOR

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

### WIDGET PROCEDURE

The text procedure creates a new STk procedure whose name is the same as the path name of the text's window. This procedure may be used to invoke various operations on the widget. It has the following general form:

    (widget-name option ?arg arg ...?)

PathName is the name of the procedure, which is the same as the text widget's path name. Option and the args determine the exact behavior of the procedure. The following procedures are possible for text widgets:

(widget-name '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.

(widget-name 'cget option)
  Returns the current value of the configuration option given by option. Option may have any of the values accepted by the text procedure.

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

(widget-name '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 widget-name (see Tk_ConfigureInfo for information on the format of this list). If option is specified with no value, then the procedure 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 procedure modifies the given widget option(s) to have the given value(s); in this case the procedure returns an empty string. Option may have any of the values accepted by the text procedure.

(widget-name 'debug )
(widget-name '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 procedure returns an empty string. If boolean is not specified then the procedure 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.

(widget-name 'delete index1 )
(widget-name 'delete index1 index2)
  Delete a range of characters from the text. If both index1 and index2 are specified, then delete all the characters starting with the one given by index1 and stopping just before index2 (i.e. the character at index2 is not deleted). If index2 doesn't specify a position later in the text than index1 then no characters are deleted. If index2 isn't specified then the single character at index1 is deleted. It is not allowable to delete characters in a way that would leave the text without a newline as the last character. The procedure returns an empty string.

(widget-name '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.

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

key1 value1 index1 key2 value2 index2 ...

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

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

:command closure
  Instead of returning the information as the result of the dump operation, invoke the closure on each element of the text widget within the range. The command must have three arguments: key, value, and index.

:mark
  Include information about marks in the dump results.

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

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

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

(widget-name 'get index1 )
(widget-name 'get index1 index2)
  Return a range of characters from the text. The return value will be all the characters in the text starting with the one whose index is index1 and ending just before the one whose index is index2 (the character at index2 will not be returned). If index2 is omitted then the single character at index1 is returned. If there are no characters in the specified range (e.g. index1 is past the end of the file or index2 is less than or equal to index1) then an empty string is returned. If the specified range contains embedded windows, no information about them is included in the returned string.

(widget-name 'image option ?arg arg ...?)
  This command is used to manipulate embedded images. The behavior of the command depends on the option argument that follows the tag argument. The following forms of the command are currently supported:

  (widget-name '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.

  (widget-name '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.

  (Widget-name '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.

  (Widget-name 'image 'names)
    Returns a list whose elements are the names of all image instances currently embedded in window.

(widget-name '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.

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

(widget-name 'mark option ?arg arg ...?)
  This procedure is used to manipulate marks. The exact behavior of the procedure depends on the option argument that follows the mark argument. The following forms of the procedure are currently supported:

  (widget-name 'mark 'gravity markName)
  (widget-name '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.

  (widget-name 'mark 'names)
    Returns a list whose elements are the names of all the marks that are currently set.

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

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

  (widget-name 'mark 'set markName index)
    Sets the mark named markName to a position just before the character at index. If markName already exists, it is moved from its old position; if it doesn't exist, a new mark is created. This procedure returns an empty string.

  (widget-name '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 ``widget-name mark names''. This procedure returns an empty string.

(widget-name 'scan option args)
  This procedure is used to implement scanning on texts. It has two forms, depending on option:

  (widget-name 'scan 'mark x y)
    Records x and y and the current view in the text window, for use in conjunction with later scan dragto procedures. Typically this procedure is associated with a mouse button press in the widget. It returns an empty string.

  (widget-name 'scan 'dragto x y)
    This procedure computes the difference between its x and y arguments and the x and y arguments to the last scan mark procedure for the widget. It then adjusts the view by 10 times the difference in coordinates. This procedure 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.

(widget-name search ?switches? pattern index ?stopIndex?)
  Searches the text in widget-name 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.

  :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 procedure for details).

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

  :count varName
    The argument following :count gives the name of a variable; if a match is found, the number of characters in the matching range will be stored in the variable.

  :environment env
    The argument following :environment gives the definition environment of the variable counting matches (i.e. the one given to the :count option). :- This switch has no effect except to terminate the list of switches: the next argument will be treated as pattern even if it starts with :.

  The matching range must be entirely within a single line of text. For regular expression matching the newlines are removed from the ends of the lines before matching: use the $ feature in regular expressions to match the end of a line. For exact matching the newlines are retained. If stopIndex is specified, the search stops at that index: for forward searches, no match at or after stopIndex will be considered; for backward searches, no match earlier in the text than stopIndex will be considered. If stopIndex is omitted, the entire text will be searched: when the beginning or end of the text is reached, the search continues at the other end until the starting location is reached again; if stopIndex is specified, no wrap-around will occur.

(widget-name '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 procedure does nothing. If index is a short distance out of view, the procedure adjusts the view just enough to make index visible at the edge of the window. If index is far out of view, then the procedure centers index in the window.

(widget-name 'tag option ?arg arg ...?)
  This procedure is used to manipulate tags. The exact behavior of the procedure depends on the option argument that follows the tag argument. The following forms of the procedure are currently supported:

  (widget-name 'tag 'add tagName index1 ?index2 index1 index2 ...?)
    Associate the tag tagName with all of the characters starting with index1 and ending just before index2 (the character at index2 isn't tagged). A single procedure 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 procedure has no effect.

  (widget-name 'tag 'bind tagName)
  (widget-name 'tag 'bind tagName sequence)
  (widget-name 'tag 'bind tagName sequence script)
    This procedure 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 procedure is similar to the bind procedure 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. In this case the return value is an empty string. If script is omitted then the procedure 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 procedure returns a list of all the sequences for which bindings have been defined for tagName.

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

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

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

  (widget-name 'tag 'cget tagName option)
    This procedure returns the current value of the option named option associated with the tag given by tagName. Option may have any of the values accepted by the tag configure widget procedure.

  (widget-name 'tag 'configure tagName ?option? ?value? ?option value ...?)
    This procedure is similar to the configure widget procedure 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 procedure 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 procedure 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 procedure modifies the given option(s) to have the given value(s) in tagName; in this case the procedure returns an empty list. See TAGS above for details on the options available for tags.

  (widget-name 'tag 'delete tagName ?tagName ...?)
    Deletes all tag information for each of the tagName arguments. The procedure 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 procedure returns an empty list.

  (widget-name'tag 'lower tagName )
  (widget-name'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.

  (widget-name 'tag 'names )
  (widget-name '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 ``widget-name tag'' widget procedure but haven't been deleted by a ``widget-name tag delete'' widget procedure, even if no characters are currently marked with the tag). The list will be sorted in order from lowest priority to highest priority.

  (widget-name 'tag 'nextrange tagName index1 )
  (widget-name 'tag 'nextrange tagName index1 index2)
    This procedure 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 procedure'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 list. If index2 is not given then it defaults to the end of the text.

  (widget-name 'tag 'prevrange tagName index1 )
  (widget-name '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.

  (widget-name'tag 'raise tagName )
  (widget-name'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.

  (widget-name '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 list is returned.

  (widget-name 'tag 'remove tagName index1 ?index2 index1 index2 ...?)
    Remove the tag tagName from all of the characters starting at index1 and ending just before index2 (the character at index2 isn't affected). A single procedure 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 procedure has no effect. This procedure returns an empty list.

(widget-name 'window option ?arg arg ...?)
  This procedure is used to manipulate embedded windows. The behavior of the procedure depends on the option argument that follows the tag argument. The following forms of the procedure are currently supported:

  (widget-name '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.

  (widget-name '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 procedure 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 procedure modifies the given option(s) to have the given value(s); in this case the procedure returns an empty list. See EMBEDDED WINDOWS for information on the options that are supported.

  (widget-name 'window 'create index ?option value ...?)
    This procedure 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 list.

  (widget-name 'window 'names)
    Returns a list whose elements are the names of all windows currently embedded in window.

(widget-name 'xview option args)
  This procedure 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:

  (widget-name '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 :xscrollprocedure option.

  (widget-name '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.

  (widget-name 'xview 'scroll number what)
    This procedure shifts the view in the window left or right according to number and what. Number must be an integer. What must be either units or pages or an abbreviation of one of these. If what is units, the view adjusts left or right by number average-width characters on the display; if it is pages then the view adjusts by number screenfuls. If number is negative then characters farther to the left become visible; if it is positive then characters farther to the right become visible.

(widget-name 'yview ?args?)
  This procedure 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:

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

  (widget-name 'yview 'moveto fraction)
    Adjusts the view in the window so that the character given by fraction appears on the top line of the window. Fraction is a fraction between 0 and 1; 0 indicates the first character in the text, 0.33 indicates the character one-third the way through the text, and so on.

  (widget-name 'yview 'scroll number what)
    This procedure adjust the view in the window up or down according to number and what. Number must be an integer. What must be either units or pages. If what is units, the view adjusts up or down by number lines on the display; if it is pages then the view adjusts by number screenfuls. If number is negative then earlier positions in the text become visible; if it is positive then later positions in the text become visible.

  (widget-name yview index)
  (widget-name yview :pickplace index)
    Changes the view in the widget's window to make index visible. If the :pickplace option isn't specified then index will appear at the top of the window. If :pickplace is specified then the widget chooses where index appears in the window:

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

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

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

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

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

  (widget-name 'yview number)
    This procedure 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 procedure 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'' refers to a contiguous group of letters, digits, or ``_'' characters, or any single character other than these.

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

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

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

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

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

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

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

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

{[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 Next and Prior keys move the insertion cursor forward or backwards by one screenful and clear any selection in the text. If the Shift key is held down while Next or Prior is typed, then the selection is extended to include the new character. Control-v moves the view down one screenful without moving the insertion cursor or adjusting the selection.

{[11]}
  Control-Next and Control-Prior scroll the view right or left by one page without moving the insertion cursor or affecting the selection.

{[12]}
  Home and Control-a move the insertion cursor to the beginning of its line and clear any selection in the widget. Shift-Home moves the insertion cursor to the beginning of the line and also extends the selection to that point.

{[13]}
  End and Control-e move the insertion cursor to the end of the line and clear any selection in the widget. Shift-End moves the cursor to the end of the line and extends the selection to that point.

{[14]}
  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.

{[15]}
  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.

{[16]}
  The Select key and Control-Space set the selection anchor to the position of the insertion cursor. They don't affect the current selection. Shift-Select and Control-Shift-Space adjust the selection to the current position of the insertion cursor, selecting from the anchor to the insertion cursor if there was not any selection previously.

{[17]}
  Control-/ selects the entire contents of the widget.

{[18]}
  Control-\ clears any selection in the widget.

{[19]}
  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.

{[20]}
  The F20 key (labelled Cut on many Sun workstations) or Control-w copies the selection in the widget to the clipboard and deletes the selection. If there is no selection in the widget then these keys have no effect.

{[21]}
  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.

{[22]}
  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.

{[23]}
  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.

{[24]}
  Control-d deletes the character to the right of the insertion cursor.

{[25]}
  Meta-d deletes the word to the right of the insertion cursor.

{[26]}
  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.

{[27]}
  Control-o opens a new line by inserting a newline character in front of the insertion cursor without moving the insertion cursor.

{[28]}
  Meta-backspace and Meta-Delete delete the word to the left of the insertion cursor.

{[29]}
  Control-x deletes whatever is selected in the text widget.

{[30]}
  Control-t reverses the order of the two characters to the right of the insertion cursor.

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

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

### PERFORMANCE ISSUES

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

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

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

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

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