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++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
++
++ /*!
++ \example widgets/lineedits
++ \title Line Edits Example
++ \examplecategory {User Interface Components}
++ \ingroup examples-widgets
++ \brief 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
++ {Application with various types and uses of line edits}
++
++ 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 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 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 widgets/lineedits/window.cpp 1
++
++ Text alignment is demonstrated by another group of widgets:
++
++ \snippet 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 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 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 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 widgets/lineedits/window.cpp 6
++
++ The other layouts are constructed in the same way:
++
++ \snippet 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 widgets/lineedits/window.cpp 8
++
++ The slots respond to signals emitted when the comboboxes are changed by the
++ user.
++
++ When the combobox for the \uicontrol{Echo} group box is changed, the \c echoChanged()
++ slot is called:
++
++ \snippet 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 \uicontrol{Validator} group box is changed, the
++ \c validatorChanged() slot is called:
++
++ \snippet 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 \uicontrol{Alignment} group box is changed, the
++ \c alignmentChanged() slot is called:
++
++ \snippet 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
++ \uicontrol{Input Mask} group box:
++
++ \snippet 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::setInputMask() 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
++ \uicontrol{Access} group box:
++
++ \snippet widgets/lineedits/window.cpp 13
++
++ Here, we simply associate the \uicontrol{False} and \uicontrol{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.
++ */