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QLineEdit Class Reference

The QLineEdit widget is a one-line text editor. More...

#include <qlineedit.h>

Inherits QFrame.

List of all member functions.

Public Members

Public Slots

Signals

Properties

Protected Members

Detailed Description

The QLineEdit widget is a one-line text editor.

A line edit allows the user to enter and edit a single line of plain text with a useful collection of editing functions, including undo and redo, cut and paste, and drag and drop.

By changing the echoMode() of a line edit, it can also be used as a "write-only" field, for inputs such as passwords.

The length of the field can be constrained to maxLength(), or the value can be arbitrarily constrained using a validator().

A related class is QTextEdit which allows multi-line, rich-text editing.

You can change the text with setText() or insert(). The text is retrieved with text(); the displayed text (which may be different, see EchoMode) is retrieved with displayText(). Text can be selected with setSelection() or selectAll(), and the selection can be cut(), copy()ied and paste()d. The text can be aligned with setAlignment().

When the text changes the textChanged() signal is emitted; when the Return or Enter key is pressed the returnPressed() signal is emitted. Note that if there is a validator set on the line edit, the returnPressed() signal will only be emitted if the validator returns Acceptable.

By default, QLineEdits have a frame as specified by the Windows and Motif style guides; you can turn it off by calling setFrame(FALSE).

The default key bindings are described below. A right mouse button menu presents some of the editing commands to the user.

Keypress Action
Left Arrow moves the cursor one character to the left.
Right Arrow moves the cursor one character to the right.
Backspace deletes the character to the left of the cursor.
Ctrl+Backspace Delete the word to the left of the cursor
Delete Delete the character to the right of the cursor
Ctrl+Delete Delete the word to the right of the cursor
Home moves the cursor to the beginning of the line.
End moves the cursor to the end of the line.
Delete deletes the character to the right of the cursor.
Shift+Left Arrow moves and selects text one character to the left.
Shift+Right Arrow moves and selects text one character to the right.
Ctrl+A moves the cursor to the beginning of the line.
Ctrl+B moves the cursor one character to the left.
Ctrl+C copies the selected text to the clipboard. (Windows also supports Ctrl+Insert for this operation.)
Ctrl+D deletes the character to the right of the cursor.
Ctrl+E moves the cursor to the end of the line.
Ctrl+F moves the cursor one character to the right.
Ctrl+H deletes the character to the left of the cursor.
Ctrl+K deletes to the end of the line.
Ctrl+V pastes the clipboard text into line edit. (Windows also supports Shift+Insert for this operation.)
Ctrl+X deletes the selected text and copies it to the clipboard. (Windows also supports Shift+Delete for this operation.)
Ctrl+Z undoes the last operation.
Ctrl+Y redoes the last undone operation.

Any other key sequence, that represents a valid character, will cause the character to be inserted into the line.

See also QTextEdit, QLabel, QComboBox, GUI Design Handbook: Field, Entry, and Basic Widgets.

Member Type Documentation

QLineEdit::EchoMode

This enum type describes how a line edit should display its contents.

See also echoMode and echoMode.

Member Function Documentation

QLineEdit::QLineEdit ( QWidget * parent, const char * name = 0 )

Constructs a line edit with no text.

The maximum text length is set to 32767 characters.

The parent and name arguments are sent to the QWidget constructor.

See also text and maxLength.

QLineEdit::QLineEdit ( const QString & contents, QWidget * parent, const char * name = 0 )

Constructs a line edit containing the text contents.

The cursor position is set to the end of the line and the maximum text length to 32767 characters.

The parent and name arguments are sent to the QWidget constructor.

See also text and maxLength.

QLineEdit::QLineEdit ( const QString & contents, const QString & inputMask, QWidget * parent, const char * name = 0 )

Constructs a line edit with an input inputMask and the text contents.

The cursor position is set to the end of the line and the maximum text length is set to the length of the mask (the number of mask characters and separators).

The parent and name arguments are sent to the QWidget constructor.

See also setMask() and text.

QLineEdit::~QLineEdit ()

Destroys the line edit.

int QLineEdit::alignment () const

Returns the alignment of the line edit. See the "alignment" property for details.

void QLineEdit::backspace ()

Deletes the character to the left of the text cursor and moves the cursor one position to the left. If any text has been selected by the user (e.g. by clicking and dragging), the cursor will be put at the beginning of the selected text and the selected text will be removed.

See also del().

int QLineEdit::characterAt ( int xpos, QChar * chr ) const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

void QLineEdit::clear () [virtual slot]

Clears the contents of the editor.

void QLineEdit::clearModified ()

Resets the modified flag to FALSE.

See also modified.

void QLineEdit::clearValidator () [virtual slot]

This slot is equivalent to setValidator( 0 ).

void QLineEdit::copy () const [virtual slot]

Copies the selected text to the clipboard, if there is any, and if echoMode() is Normal.

See also cut() and paste().

QPopupMenu * QLineEdit::createPopupMenu () [virtual protected]

This function is called to create the popup menu which is shown when the user clicks on the line edit with the right mouse button. If you want to create a custom popup menu, reimplement this function and return the popup menu you create. The popup menu's ownership is transferred to the caller.

void QLineEdit::cursorBackward ( bool mark, int steps = 1 )

Moves the cursor back steps characters. If mark is TRUE each character moved over is added to the selection; if mark is FALSE the selection is cleared.

See also cursorForward().

void QLineEdit::cursorForward ( bool mark, int steps = 1 )

Moves the cursor forward steps characters. If mark is TRUE each character moved over is added to the selection; if mark is FALSE the selection is cleared.

See also cursorBackward().

void QLineEdit::cursorLeft ( bool mark, int steps = 1 )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

For compatibilty with older applications only. Use cursorBackward() instead.

See also cursorBackward().

int QLineEdit::cursorPosition () const

Returns the current cursor position for this line edit. See the "cursorPosition" property for details.

void QLineEdit::cursorRight ( bool mark, int steps = 1 )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use cursorForward() instead.

See also cursorForward().

void QLineEdit::cursorWordBackward ( bool mark )

Moves the cursor one word backward. If mark is TRUE, the word is also selected.

See also cursorWordForward().

void QLineEdit::cursorWordForward ( bool mark )

Moves the cursor one word forward. If mark is TRUE, the word is also selected.

See also cursorWordBackward().

void QLineEdit::cut () [virtual slot]

Copies the selected text to the clipboard and deletes it, if there is any, and if echoMode() is Normal.

If the current validator disallows deleting the selected text, cut() will copy it but not delete it.

See also copy() and paste().

void QLineEdit::del ()

Deletes the character to the right of the text cursor. If any text has been selected by the user (e.g. by clicking and dragging), the cursor will be put at the beginning of the selected text and the selected text will be removed.

See also backspace().

void QLineEdit::deselect () [virtual slot]

De-selects all text (i.e. removes highlighting) and leaves the cursor at the current position.

See also setSelection() and selectAll().

QString QLineEdit::displayText () const

Returns the displayed text. See the "displayText" property for details.

bool QLineEdit::dragEnabled () const

Returns TRUE if the lineedit starts a drag if the user presses and moves the mouse on some selected text; otherwise returns FALSE. See the "dragEnabled" property for details.

EchoMode QLineEdit::echoMode () const

Returns the line edit's echo mode. See the "echoMode" property for details.

bool QLineEdit::edited () const

Returns TRUE if the line edit has been edited. Use modified instead; otherwise returns FALSE. See the "edited" property for details.

void QLineEdit::end ( bool mark )

Moves the text cursor to the end of the line. If mark is TRUE, text is selected towards the last position; otherwise, any selected text is unselected if the cursor is moved.

See also home().

bool QLineEdit::frame () const

Returns TRUE if the line edit draws itself with a frame; otherwise returns FALSE. See the "frame" property for details.

bool QLineEdit::getSelection ( int * start, int * end )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. use selectedText(), selectionStart()

bool QLineEdit::hasAcceptableInput () const

Returns holds whether the input satisfies the inputMask and the validator. See the "acceptableInput" property for details.

bool QLineEdit::hasMarkedText () const

Returns TRUE if part of the text has been selected by the user. Use hasSelectedText instead; otherwise returns FALSE. See the "hasMarkedText" property for details.

bool QLineEdit::hasSelectedText () const

Returns TRUE if there is any text selected; otherwise returns FALSE. See the "hasSelectedText" property for details.

void QLineEdit::home ( bool mark )

Moves the text cursor to the beginning of the line. If mark is TRUE, text is selected towards the first position; otherwise, any selected text is unselected if the cursor is moved.

See also end().

QString QLineEdit::inputMask () const

Returns the validation input mask. See the "inputMask" property for details.

void QLineEdit::insert ( const QString & newText ) [virtual slot]

Removes any selected text, inserts newText, and validates the result. If it is valid, it sets it as the new contents of the line edit.

bool QLineEdit::isModified () const

Returns TRUE if the line edit's content has been modified by the user; otherwise returns FALSE. See the "modified" property for details.

bool QLineEdit::isReadOnly () const

Returns TRUE if the line edit is read only; otherwise returns FALSE. See the "readOnly" property for details.

bool QLineEdit::isRedoAvailable () const

Returns TRUE if redo is available; otherwise returns FALSE. See the "redoAvailable" property for details.

bool QLineEdit::isUndoAvailable () const

Returns TRUE if undo is available; otherwise returns FALSE. See the "undoAvailable" property for details.

void QLineEdit::keyPressEvent ( QKeyEvent * e ) [virtual protected]

Converts key press event e into a line edit action.

If Return or Enter is pressed and the current text is valid (or can be made valid by the validator), the signal returnPressed() is emitted.

The default key bindings are listed in the detailed description.

Reimplemented from QWidget.

void QLineEdit::lostFocus () [signal]

This signal is emitted when the line edit has lost focus.

See also focus, QWidget::focusInEvent(), and QWidget::focusOutEvent().

QString QLineEdit::markedText () const

Returns the text selected by the user. Use selectedText instead. See the "markedText" property for details.

int QLineEdit::maxLength () const

Returns the maximum permitted length of the text. See the "maxLength" property for details.

QSize QLineEdit::minimumSizeHint () const [virtual]

Returns a minimum size for the line edit.

The width returned is enough for at least one character.

Reimplemented from QWidget.

void QLineEdit::paste () [virtual slot]

Inserts the clipboard's text at the cursor position, deleting any selected text.

If the end result is not acceptable for the current validator, nothing happens.

See also copy() and cut().

void QLineEdit::redo () [virtual slot]

Redoes the last operation.

void QLineEdit::repaintArea ( int from, int to ) [protected]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Repaints all characters from from to to. If cursorPos is between from and to, ensures that cursorPos is visible.

void QLineEdit::returnPressed () [signal]

This signal is emitted when the Return or Enter key is pressed. Note that if there is a validator or inputMask set on the line edit, the returnPressed() signal will only be emitted if the input follows the inputMask and/or the validator returns Acceptable.

Example: popup/popup.cpp.

void QLineEdit::selectAll () [virtual slot]

Selects all the text (i.e. highlights it) and moves the cursor to the end. This is useful when a default value has been inserted because if the user types before clicking on the widget, the selected text will be erased.

See also setSelection() and deselect().

QString QLineEdit::selectedText () const

Returns the selected text. See the "selectedText" property for details.

void QLineEdit::selectionChanged () [signal]

This signal is emitted whenever the selection changes.

See also hasSelectedText and selectedText.

int QLineEdit::selectionStart () const

selectionStart() returns the index of the first selected character in the line edit or -1 if no text is selected.

See also selectedText.

void QLineEdit::setAlignment ( int flag ) [virtual slot]

Sets the alignment of the line edit to flag. See the "alignment" property for details.

void QLineEdit::setCursorPosition ( int ) [virtual slot]

Sets the current cursor position for this line edit. See the "cursorPosition" property for details.

void QLineEdit::setDragEnabled ( bool b ) [virtual slot]

Sets whether the lineedit starts a drag if the user presses and moves the mouse on some selected text to b. See the "dragEnabled" property for details.

void QLineEdit::setEchoMode ( EchoMode ) [virtual slot]

Sets the line edit's echo mode. See the "echoMode" property for details.

void QLineEdit::setEdited ( bool )

Sets whether the line edit has been edited. Use modified instead. See the "edited" property for details.

void QLineEdit::setFrame ( bool ) [virtual slot]

Sets whether the line edit draws itself with a frame. See the "frame" property for details.

void QLineEdit::setInputMask ( const QString & inputMask )

Sets the validation input mask to inputMask. See the "inputMask" property for details.

void QLineEdit::setMaxLength ( int ) [virtual slot]

Sets the maximum permitted length of the text. See the "maxLength" property for details.

void QLineEdit::setReadOnly ( bool ) [virtual slot]

Sets whether the line edit is read only. See the "readOnly" property for details.

void QLineEdit::setSelection ( int start, int length ) [virtual slot]

Sets the selected area of this line edit to start at position start and be length characters long.

See also deselect(), selectAll(), and getSelection().

void QLineEdit::setText ( const QString & ) [virtual slot]

Sets the line edit's text. See the "text" property for details.

void QLineEdit::setValidator ( const QValidator * v ) [virtual slot]

Sets this line edit to only accept input that the validator, v, will accept. This allows you to place any arbitrary constraints on the text which may be entered.

If v == 0, setValidator() removes the current input validator. The initial setting is to have no input validator (i.e. any input is accepted up to maxLength()).

See also validator() and QValidator.

Examples: lineedits/lineedits.cpp and wizard/wizard.cpp.

QSize QLineEdit::sizeHint () const [virtual]

Returns a recommended size for the widget.

The width returned, in pixels, is usually enough for about 15 to 20 characters.

Example: addressbook/centralwidget.cpp.

QString QLineEdit::text () const

Returns the line edit's text. See the "text" property for details.

void QLineEdit::textChanged ( const QString & ) [signal]

This signal is emitted whenever the text changes. The argument is the new text.

Examples: wizard/wizard.cpp and xform/xform.cpp.

void QLineEdit::undo () [virtual slot]

Undoes the last operation. Deselects any current selection, and updates the selection start to the current cursor position.

bool QLineEdit::validateAndSet ( const QString & newText, int newPos, int newMarkAnchor, int newMarkDrag )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. Use setText(), setCursorPosition() and setSelection() instead.

const QValidator * QLineEdit::validator () const

Returns a pointer to the current input validator, or 0 if no validator has been set.

See also setValidator().

Example: wizard/wizard.cpp.

Property Documentation

bool acceptableInput

This property holds holds whether the input satisfies the inputMask and the validator.

Get this property's value with hasAcceptableInput().

See also inputMask and setValidator().

Alignment alignment

This property holds the alignment of the line edit.

Possible Values are Qt::AlignAuto, Qt::AlignLeft, Qt::AlignRight and Qt::AlignHCenter.

Attempting to set the alignment to an illegal flag combination does nothing.

See also Qt::AlignmentFlags.

Set this property's value with setAlignment() and get this property's value with alignment().

int cursorPosition

This property holds the current cursor position for this line edit.

Setting the cursor position causes a repaint when appropriate.

Set this property's value with setCursorPosition() and get this property's value with cursorPosition().

QString displayText

This property holds the displayed text.

If EchoMode is Normal this returns the same as text(); if EchoMode is Password it returns a string of asterisks the text().length() characters long, e.g. "******"; if EchoMode is NoEcho returns an empty string, "".

See also echoMode, text, and EchoMode.

Get this property's value with displayText().

bool dragEnabled

This property holds whether the lineedit starts a drag if the user presses and moves the mouse on some selected text.

Set this property's value with setDragEnabled() and get this property's value with dragEnabled().

EchoMode echoMode

This property holds the line edit's echo mode.

The initial setting is Normal, but QLineEdit also supports NoEcho and Password modes.

The widget's display and the ability to copy or drag the text is affected by this setting.

See also EchoMode and displayText.

Set this property's value with setEchoMode() and get this property's value with echoMode().

bool edited

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

This property holds whether the line edit has been edited. Use modified instead.

Set this property's value with setEdited() and get this property's value with edited().

bool frame

This property holds whether the line edit draws itself with a frame.

If enabled (the default) the line edit draws itself inside a two-pixel frame, otherwise the line edit draws itself without any frame.

Set this property's value with setFrame() and get this property's value with frame().

bool hasMarkedText

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

This property holds whether part of the text has been selected by the user. Use hasSelectedText instead.

Get this property's value with hasMarkedText().

bool hasSelectedText

This property holds whether there is any text selected.

hasSelectedText() returns TRUE if some or all of the text has been selected by the user (e.g. by clicking and dragging); otherwise returns FALSE.

See also selectedText.

Get this property's value with hasSelectedText().

QString inputMask

This property holds the validation input mask.

If no mask is set, mask() returns QString::null.

Sets the QLineEdit's validation mask. Validators can be used instead of, or in conjunction with masks; see setValidator().

Unset the mask and return to normal QLineEdit operation by passing an empty string ("") or just calling it with no arguments.

The mask format takes these mask characters:

Character Meaning
A ASCII alphabetic character required. A-Z, a-z.
a ASCII alphabetic character permitted but not required.
N ASCII alphanumeric character required. A-Z, a-z, 0-9.
n ASCII alphanumeric character permitted but not required.
X Any character required.
x Any character permitted but not required.
9 Numeric character required. 0-9.
0 Numeric character permitted but not required.
D Numeric character required. 1-9.
d Numeric character permitted but not required.
# Numeric character or plus/minus sign permitted but not required.
> All following alphabetic characters are uppercased.
< All following alphabetic characters are lowercased.
! No case conversion.
\ Use \ to escape the special characters listed above to use them as separators.

The mask consists of a string of mask characters and separators, optionally followed by a semi-colon and the character used for blanks - the blank characters are always removed from the end text. The default blank character is space, and regardless

Examples:

Mask Notes
000.000.000.000;_ IP address; blanks are _
0000-00-00 ISO Date; blanks are space
>AAAAA-AAAAA-AAAAA-AAAAA-AAAAA;# License number; blanks are - and all (alphabetic) characters are converted to uppercase.

To get range control (e.g. for an IP address) use masks together with validators.

See also maxLength.

Set this property's value with setInputMask() and get this property's value with inputMask().

QString markedText

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

This property holds the text selected by the user. Use selectedText instead.

Get this property's value with markedText().

int maxLength

This property holds the maximum permitted length of the text.

If the text is too long, it is truncated at the limit.

If truncation occurs any selected text will be unselected, the cursor position is set to 0 and the first part of the string is shown.

If the line edit has an input mask, this mask defines the maximum string length.

See also inputMask.

Set this property's value with setMaxLength() and get this property's value with maxLength().

bool modified

This property holds whether the line edit's content has been modified by the user.

The modified flag is never read by QLineEdit; it has a default value of FALSE and is changed to TRUE whenever the user changes the line edit's contents.

This is useful for things that need to provide a default value but cannot find the default at once. Just start the line edit without the best default; when the default is known, check the modified() return value and set the line edit's contents if the user has not started editing the line edit.

Calling clearModified() or setText() resets the modified flag to FALSE.

Get this property's value with isModified().

bool readOnly

This property holds whether the line edit is read only.

In read-only mode, the user can still copy the text to the clipboard or drag-and-drop the text, but cannot edit it.

QLineEdit does not show a cursor in read-only mode.

See also enabled.

Set this property's value with setReadOnly() and get this property's value with isReadOnly().

bool redoAvailable

This property holds whether redo is available.

Get this property's value with isRedoAvailable().

QString selectedText

This property holds the selected text.

If there is no selected text this property's value is QString::null.

See also hasSelectedText.

Get this property's value with selectedText().

QString text

This property holds the line edit's text.

Setting this property clears the selection, clears the undo/redo history, moves the cursor to the end of the line and resets the modified property to FALSE. The text is not validated when inserted with setText().

setText() ignores any validator.

The text is truncated to maxLength() length.

See also insert().

Set this property's value with setText() and get this property's value with text().

bool undoAvailable

This property holds whether undo is available.

Get this property's value with isUndoAvailable().

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Qt version 3.2.0b2