text (GCL TK Manual)

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### 2.9 text

text \- Create and manipulate text widgets

#### Synopsis

text pathName ?options?

#### Standard Options

    background      foreground        insertWidth      selectBorderWidth
    borderWidth     insertBackground  padX             selectForeground
    cursor          insertBorderWidth padY             setGrid
    exportSelection insertOffTime     relief           yScrollCommand
    font            insertOnTime      selectBackground

See options, for more information.

#### Arguments for Text

`:height`

  Name=`"height" Class=`"`Height"`

  Specifies the desired height for the window, in units of characters. Must be at least one.

`:state`

  Name=`"state" 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.

`:width`

  Name=`"width" Class=`"`Width"`

  Specifies the desired width for the window in units of characters. 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.

`:wrap`

  Name=`"wrap" Class=`"`Wrap"`

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

#### Description

The text command creates a new window (given by the pathName argument) and makes it into a text widget. Additional options, described above, may be specified on the command line or in the option database to configure aspects of the text such as its default background color and relief. The text command returns the path name of the new window.

A text widget displays one or more lines of text and allows that text to be edited. Text widgets support three different kinds of annotations on the text, called tags, marks, and windows. 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 commands 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 displayed in the text widget. See WINDOWS below for more details.

#### Indices

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

base modifier modifier modifier ...

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

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

line.char

  Indicates char’th character on line line. Lines are numbered from 1 for consistency with other UNIX programs that use this numbering scheme. Within a line, characters are numbered from 0.

@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 last character in the text, which is always a newline character.

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.

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 “\fBend \- 1 chars” refers to the next-to-last character in the text and “\fBinsert 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. 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 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.

:relief relief

  \fIRelief 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.

:underline boolean

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

  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 optionl, then the default style for the widget will be used.

  The second purpose for tags is event bindings. You can associate bindings with a tag in much the same way you can associate bindings with a widget class: whenever particular X events occur on characters with the given tag, a given Tcl command will be executed. Tag bindings can be used to give behaviors to ranges of characters; among other things, this allows hypertext-like features to be implemented. For details, see the description of the tag bind widget command below.

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

#### Marks

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

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 unset.

#### Windows

The third form of annotation in text widgets is a window. Window support isn’t implemented yet, but when it is it will be described here.

#### The Selection

Text widgets support the standard X 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 charaters with the sel tag.
- [3] If the selection is claimed away by another application or by another window within this application, then the sel tag will be removed from all characters in the text.

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

#### The Insertion Cursor

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

#### A Text Widget’s Arguments

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 :compare index1 op index2

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

pathName :configure ?option? ?value option value ...?

  Query or modify the configuration options of the widget. If no option is specified, returns a list describing all of the available options for pathName (see Tk_ConfigureInfo for information on the format of this list). If option is specified with no value, then the command returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified). If one or more option:value pairs are specified, then the command modifies the given widget option(s) to have the given value(s); in this case the command returns an empty string. Option may have any of the values accepted by the text command.

pathName :debug ?boolean?

  If boolean is specified, then it must have one of the true or false values accepted by Tcl_GetBoolean. If the value is a true one then internal consistency checks will be turned on in the B-tree code associated with text widgets. If boolean has a false value then the debugging checks will be turned off. In either case the command returns an empty string. If boolean is not specified then the command returns on or off to indicate whether or not debugging is turned on. There is a single debugging switch shared by all text widgets: turning debugging on or off in any widget turns it on or off for all widgets. For widgets with large amounts of text, the consistency checks may cause a noticeable slow-down.

pathName :delete index1 ?index2?

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

pathName :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.

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 \fIindex chars

  Inserts chars into the text just before the character at index and returns an empty string. It is not possible to insert characters after the last newline of the text.

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 :names

    Returns a list whose elements are the names of all the marks that are currently set.

  pathName :mark :set markName index

    Sets the mark named markName to a position just before the character at index. If markName already exists, it is moved from its old position; if it doesn’t exist, a new mark is created. This command returns an empty string.

  pathName :mark :unset markName ?markName markName ...?

    Remove the mark corresponding to each of the markName arguments. The removed marks will not be usable in indices and will not be returned by future calls to “pathName :mark names”. This command returns an empty string.

pathName :scan option args

  This command is used to implement scanning on texts. It has two forms, depending on option:

  pathName :scan :mark y

    Records y and the current view in the text window; used in conjunction with later scan dragto commands. Typically this command is associated with a mouse button press in the widget. It returns an empty string.

  pathName :scan :dragto y

    This command computes the difference between its y argument and the y argument to the last scan mark command for the widget. It then adjusts the view up or down by 10 times the difference in y-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 :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?

    Associate the tag tagName with all of the characters starting with index1 and ending just before index2 (the character at index2 isn’t tagged). If index2 is omitted then the single character at index1 is tagged. If there are no characters in the specified range (e.g. index1 is past the end of the file or index2 is less than or equal to index1) then the command has no effect. This command returns an empty string.

  pathName :tag :bind tagName ?sequence? ?command?

    This command associates command with the tag given by tagName. Whenever the event sequence given by sequence occurs for a character that has been tagged with tagName, the command 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 command 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 command is “+” then command augments an existing binding rather than replacing it). In this case the return value is an empty string. If command is omitted then the command returns the command associated with tagName and sequence (an error occurs if there is no such binding). If both command 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. Event bindings for a text widget use the current mark described under MARKS above. Enter events trigger for a character when it becomes the current character (i.e. the current mark moves to just in front of that character). Leave events trigger for a character when it ceases to be the current item (i.e. the current mark moves away from that character, or the character is deleted). These events are different than Enter and Leave events for windows. Mouse and keyboard events are directed to the current character.

    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, the binding from the highest priority tag is used. If a particular tag doesn’t have a binding that matches an event, then the tag is ignored and tags with lower priority will be checked.

    If bindings are created for the widget as a whole using the bind command, then those bindings will supplement the tag bindings. This means that a single event can trigger two Tcl scripts, one for a widget-level binding and one for a tag-level binding.

  pathName :tag :configure tagName ?option? ?value? ?option value ...?

    This command is similar to the configure widget command except that it modifies options associated with the tag given by tagName instead of modifying options for the overall text widget. If no option is specified, the 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 haven’t been deleted by a “pathName :tag :delete” widget command, even if no characters are currently marked with the tag). The list will be sorted in order from lowest priority to highest priority.

  pathName :tag :nextrange tagName index1 ?index2?

    This command searches the text for a range of characters tagged with tagName where the first character of the range is no earlier than the character at index1 and no later than the character just before index2 (a range starting at index2 will not be considered). If several matching ranges exist, the first one is chosen. The command’s return value is a list containing two elements, which are the index of the first character of the range and the index of the character just after the last one in the range. 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 :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?

    Remove the tag tagName from all of the characters starting at index1 and ending just before index2 (the character at index2 isn’t affected). If index2 is omitted then the single character at index1 is untagged. 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 :yview ?:pickplace? what

  This command changes the view in the widget’s window so that the line given by what is visible in the window. What may be either an absolute line number, where 0 corresponds to the first line of the file, or an index with any of the forms described under INDICES above. The first form (absolute line number) is used in the commands issued by scrollbars to control the widget’s view. If the :pickplace option isn’t specified then what will appear at the top of the window. If :pickplace is specified then the widget chooses where what appears in the window:

  - [1] If what is already visible somewhere in the window then the command does nothing.
  - [2] If what is only a few lines off-screen above the window then it will be positioned at the top of the window.
  - [3] If what is only a few lines off-screen below the window then it will be positioned at the bottom of the window.
  - [4] Otherwise, what will be centered in the window.

  The :pickplace option is typically used after inserting text to make sure that the insertion cursor is still visible on the screen. This command returns an empty string.

#### Bindings

Tk automatically creates class bindings for texts that give them the following default behavior:

- [1] Pressing mouse button 1 in an text positions the insertion cursor just before the character underneath the mouse cursor and sets the input focus to this widget.
- [2] Dragging with mouse button 1 strokes out a selection between the insertion cursor and the character under the mouse.
- [3] If you double-press mouse button 1 then the word under the mouse cursor will be selected, the insertion cursor will be positioned at the beginning of the word, and dragging the mouse will stroke out a selection whole words at a time.
- [4] If you triple-press mouse button 1 then the line under the mouse cursor will be selected, the insertion cursor will be positioned at the beginning of the line, and dragging the mouse will stroke out a selection whole line at a time.
- [5] 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 selection was made in word or line mode then it will be adjusted in this same mode.
- [6] The view in the text can be adjusted by dragging with mouse button 2.
- [7] If the input focus is in a text widget and characters are typed on the keyboard, the characters are inserted just before the insertion cursor.
- [8] Control+h and the Backspace and Delete keys erase the character just before the insertion cursor.
- [9] Control+v inserts the current selection just before the insertion cursor.
- [10] Control+d deletes the selected characters; an error occurs if the selection is not in this widget.

If the text is disabled using the state option, then the text’s view can still be adjusted and text in the 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. The only known mode of operation where a text widget may not run efficiently is if it has a very large number of different tags. Hundreds of tags should be fine, or even a thousand, but tens of thousands of tags will make texts consume a lot of memory and run slowly.

#### Keywords

text, widget

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