Entry

Section: User Contributed Perl Documentation (3)
Updated: 2021-01-27
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NAME

Tk::Entry - Create and manipulate Entry widgets

SYNOPSIS

$entry = $parent->Entry(?options?);

STANDARD OPTIONS

-background    -highlightbackground    -insertontime   -selectforeground
-borderwidth    -highlightcolor -insertwidth    -takefocus
-cursor -highlightthickness     -justify        -textvariable
-exportselection        -insertbackground       -relief -xscrollcommand
-font   -insertborderwidth      -selectbackground
-foreground     -insertofftime  -selectborderwidth

WIDGET-SPECIFIC OPTIONS

Command-Line Name: -disabledbackground
Database Name: disabledBackground
Database Class: DisabledBackground: Specifies the background color to use when the entry is disabled. If this option is the empty string, the normal background color is used.
Command-Line Name: -disabledforeground
Database Name: disabledForeground
Database Class: DisabledForeground: Specifies the foreground color to use when the entry is disabled. If this option is the empty string, the normal foreground color is used.
Name: invalidCommand
Class: InvalidCommand
Switch: -invalidcommand
Alias: -invcmd: Specifies a script to eval when validateCommand returns 0. Setting it to <undef> disables this feature (the default). The best use of this option is to set it to bell. See Validation below for more information.
Command-Line Name: -readonlybackground
Database Name: readonlyBackground
Database Class: ReadonlyBackground: Specifies the background color to use when the entry is read-only. If this option is the empty string, the normal background color is used.
Name: show
Class: Show
Switch: -show: If this option is specified, then the true contents of the entry are not displayed in the window. Instead, each character in the entry's value will be displayed as the first character in the value of this option, such as ``*''. This is useful, for example, if the entry is to be used to enter a password. If characters in the entry are selected and copied elsewhere, the information copied will be what is displayed, not the true contents of the entry.
Name: state
Class: State
Switch: -state: Specifies one of three states for the entry: normal, disabled, or readonly. If the entry is readonly, then the value may not be changed using widget commands and no insertion cursor will be displayed, even if the input focus is in the widget; the contents of the widget may still be selected. If the entry is disabled, the value may not be changed, no insertion cursor will be displayed, the contents will not be selectable, and the entry may be displayed in a different color, depending on the values of the -disabledforeground and -disabledbackground options.
Name: validate
Class: Validate
Switch: -validate: Specifies the mode in which validation should operate: none, focus, focusin, focusout, key, or all. It defaults to none. When you want validation, you must explicitly state which mode you wish to use. See Validation below for more.
Name: validateCommand
Class: ValidateCommand
Switch: -validatecommand
Alias: -vcmd: Specifies a script to eval when you want to validate the input into the entry widget. Setting it to "undef" disables this feature (the default). This command must return a valid boolean value. If it returns 0 (or the valid boolean equivalent) then it means you reject the new edition and it will not occur and the invalidCommand will be evaluated if it is set. If it returns 1, then the new edition occurs. See Validation below for more information.
Name: width
Class: Width
Switch: -width: Specifies an integer value indicating the desired width of the entry window, in average-size characters of the widget's font. If the value is less than or equal to zero, the widget picks a size just large enough to hold its current text.

DESCRIPTION

The Entry method creates a new window (given by the $entry argument) and makes it into an entry widget. Additional options, described above, may be specified on the command line or in the option database to configure aspects of the entry such as its colors, font, and relief. The entry command returns its $entry argument. At the time this command is invoked, there must not exist a window named $entry, but $entry's parent must exist.

An entry is a widget that displays a one-line text string and allows that string to be edited using methods described below, which are typically bound to keystrokes and mouse actions. When first created, an entry's string is empty. A portion of the entry may be selected as described below. If an entry is exporting its selection (see the exportSelection option), then it will observe the standard X11 protocols for handling the selection; entry selections are available as type STRING. Entries also observe the standard Tk rules for dealing with the input focus. When an entry has the input focus it displays an insertion cursor to indicate where new characters will be inserted.

Entries are capable of displaying strings that are too long to fit entirely within the widget's window. In this case, only a portion of the string will be displayed; methods described below may be used to change the view in the window. Entries use the standard xScrollCommand mechanism for interacting with scrollbars (see the description of the -xscrollcommand option for details). They also support scanning, as described below.

VALIDATION

Validation of entry widgets is derived from part of the patch written by jhobbs@cs.uoregon.edu. This works by setting the validateCommand option to a callback which will be evaluated according to the validate option as follows:

none: Default. This means no validation will occur.
focus: validateCommand will be called when the entry receives or loses focus.
focusin: validateCommand will be called when the entry receives focus.
focusout: validateCommand will be called when the entry loses focus.
key: validateCommand will be called when the entry is edited.
all: validateCommand will be called for all above conditions.

The validateCommand and invalidCommand are called with the following arguments:

•: The proposed value of the entry. If you are configuring the entry widget to have a new textvariable, this will be the value of that textvariable.
•: The characters to be added (or deleted). This will be "undef" if validation is due to focus, explcit call to validate or if change is due to "-textvariable" changing.
•: The current value of entry i.e. before the proposed change.
•: index of char string to be added/deleted, if any. -1 otherwise
•: type of action. 1 == INSERT, 0 == DELETE, -1 if it's a forced validation or textvariable validation

In general, the textVariable and validateCommand can be dangerous to mix. If you try set the textVariable to something that the validateCommand will not accept it will be set back to the value of the entry widget. Using the textVariable for read-only purposes will never cause problems.

The validateCommand will turn itself off by setting validate to none when an error occurs, for example when the validateCommand or invalidCommand encounters an error in its script while evaluating, or validateCommand does not return a valid boolean value.

With the perl/Tk version validate option is supposed to be ``suspended'' while executing the validateCommand or the invalidCommand. This is experimental but in theory either callback can ``correct'' the value of the widget, and override the proposed change. (validateCommand should still return false to inhibit the change from happening when it returns.)

WIDGET METHODS

The Entry method creates a widget object. This object supports the configure and cget methods described in Tk::options which can be used to enquire and modify the options described above. The widget also inherits all the methods provided by the generic Tk::Widget class.

Many of the additional methods for entries take one or more indices as arguments. An index specifies a particular character in the entry's string, in any of the following ways:

number: Specifies the character as a numerical index, where 0 corresponds to the first character in the string.
anchor: Indicates the anchor point for the selection, which is set with the selectionFrom and selectionAdjust methods.
end: Indicates the character just after the last one in the entry's string. This is equivalent to specifying a numerical index equal to the length of the entry's string.
insert: Indicates the character adjacent to and immediately following the insertion cursor.
sel.first: Indicates the first character in the selection. It is an error to use this form if the selection isn't in the entry window.
sel.last: Indicates the character just after the last one in the selection. It is an error to use this form if the selection isn't in the entry window.
@number: In this form, number is treated as an x-coordinate in the entry's window; the character spanning that x-coordinate is used. For example, ``@0'' indicates the left-most character in the window.

Abbreviations may be used for any of the forms above, e.g. ``e'' or ``sel.f''. In general, out-of-range indices are automatically rounded to the nearest legal value.

The following additional methods are available for entry widgets:

$entry->bbox(index)

Returns a list of four numbers describing the bounding box 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 screen area covered by the character (in pixels relative to the widget) and the last two elements give the width and height of the character, in pixels. The bounding box may refer to a region outside the visible area of the window.

$entry->cget(?option?)

Returns the current value of the configuration option given by option. Option may have any of the values accepted by the entry command.

$entry->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 $entry (see Tk::configure 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 entry command.

$entry->delete(first, ?last?)

Delete one or more elements of the entry. First is the index of the first character to delete, and last is the index of the character just after the last one to delete. If last isn't specified it defaults to first+1, i.e. a single character is deleted. This method returns an empty string.

$entry->get

Returns the entry's string.

$entry->icursor(index)

Arrange for the insertion cursor to be displayed just before the character given by index. Returns an empty string.

$entry->index(index)

Returns the numerical index corresponding to index.

$entry->insert(index, string)

Insert the characters of string just before the character indicated by index. Returns an empty string.

$entry->scan(option, args)

$entry->scanOption(args)

This method is used to implement scanning on entries. It has two forms, depending on Option:

$entry->scanMark(x): Records x and the current view in the entry widget; used in conjunction with later scanDragto methods. Typically this method is associated with a mouse button press in the widget. It returns an empty string.
$entry->scanDragto(x): This method computes the difference between its x argument and the x argument to the last scanMark method for the widget. It then adjusts the view left or right by 10 times the difference in x-coordinates. This method is typically associated with mouse motion events in the widget, to produce the effect of dragging the entry at high speed through the widget. The return value is an empty string.

$entry->selection(option, arg)

$entry->selectionOption(arg)

This method is used to adjust the selection within an entry. It has several forms, depending on Option:

$entry->selectionAdjust(index): Locate the end of the selection nearest to the character given by index, and adjust that end of the selection to be at index (i.e including but not going beyond index). The other end of the selection is made the anchor point for future selectionTo methods. If the selection isn't currently in the entry, then a new selection is created to include the characters between index and the most recent selection anchor point, inclusive. Returns an empty string.
$entry->selectionClear: Clear the selection if it is currently in this widget. If the selection isn't in this widget then the method has no effect. Returns an empty string.
$entry->selectionFrom(index): Set the selection anchor point to just before the character given by index. Doesn't change the selection. Returns an empty string.
$entry->selectionPresent: Returns 1 if there is are characters selected in the entry, 0 if nothing is selected.
$entry->selectionRange(start, end): Sets the selection to include the characters starting with the one indexed by start and ending with the one just before end. If end refers to the same character as start or an earlier one, then the entry's selection is cleared.
$entry->selectionTo(index): If index is before the anchor point, set the selection to the characters from index up to but not including the anchor point. If index is the same as the anchor point, do nothing. If index is after the anchor point, set the selection to the characters from the anchor point up to but not including index. The anchor point is determined by the most recent selectionFrom or selectionAdjust method in this widget. If the selection isn't in this widget then a new selection is created using the most recent anchor point specified for the widget. Returns an empty string.

$entry->validate

This command is used to force an evaluation of the validateCommand independent of the conditions specified by the validate option. It returns 0 or 1.

$entry->xview(args)

This command is used to query and change the horizontal position of the text in the widget's window. It can take any of the following forms:

$entry->xview: Returns a list containing two elements. Each element is a real fraction between 0 and 1; together they describe the horizontal span that is visible in the window. For example, if the first element is .2 and the second element is .7, 20% of the entry's text is off-screen to the left, the middle 50% is visible in the window, and 30% of the text is off-screen to the right. These are the same values passed to scrollbars via the -xscrollcommand option.
$entry->xview(index): Adjusts the view in the window so that the character given by index is displayed at the left edge of the window.
$entry->xviewMoveto(fraction): Adjusts the view in the window so that the character fraction of the way through the text appears at the left edge of the window. Fraction must be a fraction between 0 and 1.
$entry->xviewScroll(number, what): This method 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.

DEFAULT BINDINGS

Tk automatically creates class bindings for entries 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 all of the text in the entry and positions the insertion cursor before the first character.

[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.

[5]

Clicking mouse button 1 with the Control key down will position the insertion cursor in the entry without affecting the selection.

[6]

If any normal printing characters are typed in an entry, they are inserted at the point of the insertion cursor.

[7]

The view in the entry 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 entry at the position of the mouse cursor.

[8]

If the mouse is dragged out of the entry on the left or right sides 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 entry and set the selection anchor. 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 Home key, or Control-a, will move the insertion cursor to the beginning of the entry and clear any selection in the entry. Shift-Home moves the insertion cursor to the beginning of the entry and also extends the selection to that point.

[11]

The End key, or Control-e, will move the insertion cursor to the end of the entry and clear any selection in the entry. Shift-End moves the cursor to the end and extends the selection to that point.

[12]

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.

[13]

Control-/ selects all the text in the entry.

[14]

Control-\ clears any selection in the entry.

[15]

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.

[16]

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.

[17]

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.

[18]

The Delete key deletes the selection, if there is one in the entry. If there is no selection, it deletes the character to the right of the insertion cursor.

[19]

The BackSpace key and Control-h delete the selection, if there is one in the entry. If there is no selection, it deletes the character to the left of the insertion cursor.

[20]

Control-d deletes the character to the right of the insertion cursor.

[21]

Meta-d deletes the word to the right of the insertion cursor.

[22]

Control-k deletes all the characters to the right of the insertion cursor.

[23]

Control-t reverses the order of the two characters to the right of the insertion cursor.

If the entry is disabled using the -state option, then the entry's view can still be adjusted and text in the entry can still be selected, but no insertion cursor will be displayed and no text modifications will take place.

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

KEYWORDS

entry, widget