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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Free Documentation License
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of this
+** file.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \example widgets/lineedits
+ \title Line Edits Example
+
+ The Line Edits example demonstrates the many ways that QLineEdit can be used, and
+ shows the effects of various properties and validators on the input and output
+ supplied by the user.
+
+ \image lineedits-example.png
+
+ The example consists of a single \c Window class, containing a selection of
+ line edits with different input constraints and display properties that can be
+ changed by selecting items from comboboxes. Presenting these together helps
+ developers choose suitable properties to use with line edits, and makes it easy
+ to compare the effects of each validator on user input.
+
+ \section1 Window Class Definition
+
+ The \c Window class inherits QWidget and contains a constructor and several
+ slots:
+
+ \snippet examples/widgets/lineedits/window.h 0
+
+ The slots are used to update the type of validator used for a given line edit when
+ a new validator has been selected in the associated combobox. The line edits
+ are stored in the window for use in these slots.
+
+ \section1 Window Class Implementation
+
+ The \c Window constructor is used to set up the line edits, validators,
+ and comboboxes, connect signals from the comboboxes to slots in the \c Window
+ class, and arrange the child widgets in layouts.
+
+ We begin by constructing a \l{QGroupBox}{group box} to hold a label, combobox,
+ and line edit so that we can demonstrate the QLineEdit::echoMode property:
+
+ \snippet examples/widgets/lineedits/window.cpp 0
+
+ At this point, none of these widgets have been arranged in layouts. Eventually,
+ the \c echoLabel, \c echoComboBox, and \c echoLineEdit will be placed in a
+ vertical layout inside the \c echoGroup group box.
+
+ Similarly, we construct group boxes and collections of widgets to show the
+ effects of QIntValidator and QDoubleValidator on a line edit's contents:
+
+ \snippet examples/widgets/lineedits/window.cpp 1
+
+ Text alignment is demonstrated by another group of widgets:
+
+ \snippet examples/widgets/lineedits/window.cpp 2
+
+ QLineEdit supports the use of \l{QLineEdit::inputMask}{input masks}.
+ These only allow the user to type characters into the line edit that
+ follow a simple specification. We construct a group of widgets to
+ demonstrate a selection of predefined masks:
+
+ \snippet examples/widgets/lineedits/window.cpp 3
+
+ Another useful feature of QLineEdit is its ability to make its contents
+ read-only. This property is used to control access to a line edit in the
+ following group of widgets:
+
+ \snippet examples/widgets/lineedits/window.cpp 4
+
+ Now that all the child widgets have been constructed, we connect signals
+ from the comboboxes to slots in the \c Window object:
+
+ \snippet examples/widgets/lineedits/window.cpp 5
+
+ Each of these connections use the QComboBox::activated() signal that
+ supplies an integer to the slot. This will be used to efficiently
+ make changes to the appropriate line edit in each slot.
+
+ We place each combobox, line edit, and label in a layout for each group
+ box, beginning with the layout for the \c echoGroup group box:
+
+ \snippet examples/widgets/lineedits/window.cpp 6
+
+ The other layouts are constructed in the same way:
+
+ \snippet examples/widgets/lineedits/window.cpp 7
+
+ Finally, we place each group box in a grid layout for the \c Window object
+ and set the window title:
+
+ \snippet examples/widgets/lineedits/window.cpp 8
+
+ The slots respond to signals emitted when the comboboxes are changed by the
+ user.
+
+ When the combobox for the \gui{Echo} group box is changed, the \c echoChanged()
+ slot is called:
+
+ \snippet examples/widgets/lineedits/window.cpp 9
+
+ The slot updates the line edit in the same group box to use an echo mode that
+ corresponds to the entry described in the combobox.
+
+ When the combobox for the \gui{Validator} group box is changed, the
+ \c validatorChanged() slot is called:
+
+ \snippet examples/widgets/lineedits/window.cpp 10
+
+ The slot either creates a new validator for the line edit to use, or it removes
+ the validator in use by calling QLineEdit::setValidator() with a zero pointer.
+ We clear the line edit in this case to ensure that the new validator is
+ initially given valid input to work with.
+
+ When the combobox for the \gui{Alignment} group box is changed, the
+ \c alignmentChanged() slot is called:
+
+ \snippet examples/widgets/lineedits/window.cpp 11
+
+ This changes the way that text is displayed in the line edit to correspond with
+ the description selected in the combobox.
+
+ The \c inputMaskChanged() slot handles changes to the combobox in the
+ \gui{Input Mask} group box:
+
+ \snippet examples/widgets/lineedits/window.cpp 12
+
+ Each entry in the relevant combobox is associated with an input mask. We set
+ a new mask by calling the QLineEdit::setMask() function with a suitable string;
+ the mask is disabled if an empty string is used.
+
+ The \c accessChanged() slot handles changes to the combobox in the
+ \gui{Access} group box:
+
+ \snippet examples/widgets/lineedits/window.cpp 13
+
+ Here, we simply associate the \gui{False} and \gui{True} entries in the combobox
+ with \c false and \c true values to be passed to QLineEdit::setReadOnly(). This
+ allows the user to enable and disable input to the line edit.
+*/