/**************************************************************************** ** ** Copyright (C) 2012 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. ** ** $QT_BEGIN_LICENSE:FDL$ ** 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. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \example widgets/spinboxes \title Spin Boxes Example The Spin Boxes example shows how to use the many different types of spin boxes available in Qt, from a simple QSpinBox widget to more complex editors like the QDateTimeEdit widget. \image spinboxes-example.png The example consists of a single \c Window class that is used to display the different spin box-based widgets available with Qt. \section1 Window Class Definition The \c Window class inherits QWidget and contains two slots that are used to provide interactive features: \snippet examples/widgets/spinboxes/window.h 0 The private functions are used to set up each type of spin box in the window. We use member variables to keep track of various widgets so that they can be reconfigured when required. \section1 Window Class Implementation The constructor simply calls private functions to set up the different types of spin box used in the example, and places each group in a layout: \snippet examples/widgets/spinboxes/window.cpp 0 We use the layout to manage the arrangement of the window's child widgets, and change the window title. The \c createSpinBoxes() function constructs a QGroupBox and places three QSpinBox widgets inside it with descriptive labels to indicate the types of input they expect. \snippet examples/widgets/spinboxes/window.cpp 1 The first spin box shows the simplest way to use QSpinBox. It accepts values from -20 to 20, the current value can be increased or decreased by 1 with either the arrow buttons or \key{Up} and \key{Down} keys, and the default value is 0. The second spin box uses a larger step size and displays a suffix to provide more information about the type of data the number represents: \snippet examples/widgets/spinboxes/window.cpp 2 This spin box also displays a \l{QAbstractSpinBox::specialValueText}{special value} instead of the minimum value defined for it. This means that it will never show \gui{0%}, but will display \gui{Automatic} when the minimum value is selected. The third spin box shows how a prefix can be used: \snippet examples/widgets/spinboxes/window.cpp 4 For simplicity, we show a spin box with a prefix and no suffix. It is also possible to use both at the same time. \snippet examples/widgets/spinboxes/window.cpp 5 The rest of the function sets up a layout for the group box and places each of the widgets inside it. The \c createDateTimeEdits() function constructs another group box with a selection of spin boxes used for editing dates and times. \snippet examples/widgets/spinboxes/window.cpp 6 The first spin box is a QDateEdit widget that is able to accept dates within a given range specified using QDate values. The arrow buttons and \key{Up} and \key{Down} keys can be used to increase and decrease the values for year, month, and day when the cursor is in the relevant section. The second spin box is a QTimeEdit widget: \snippet examples/widgets/spinboxes/window.cpp 7 Acceptable values for the time are defined using QTime values. The third spin box is a QDateTimeEdit widget that can display both date and time values, and we place a label above it to indicate the range of allowed times for a meeting. These widgets will be updated when the user changes a format string. \snippet examples/widgets/spinboxes/window.cpp 8 The format string used for the date time editor, which is also shown in the string displayed by the label, is chosen from a set of strings in a combobox: \snippet examples/widgets/spinboxes/window.cpp 9 \codeline \snippet examples/widgets/spinboxes/window.cpp 10 A signal from this combobox is connected to a slot in the \c Window class (shown later). \snippet examples/widgets/spinboxes/window.cpp 11 Each child widget of the group box in placed in a layout. The \c setFormatString() slot is called whenever the user selects a new format string in the combobox. The display format for the QDateTimeEdit widget is set using the raw string passed by the signal: \snippet examples/widgets/spinboxes/window.cpp 12 Depending on the visible sections in the widget, we set a new date or time range, and update the associated label to provide relevant information for the user: \snippet examples/widgets/spinboxes/window.cpp 13 When the format string is changed, there will be an appropriate label and entry widget for dates, times, or both types of input. The \c createDoubleSpinBoxes() function constructs three spin boxes that are used to input double-precision floating point numbers: \snippet examples/widgets/spinboxes/window.cpp 14 Before the QDoubleSpinBox widgets are constructed, we create a spin box to control how many decimal places they show. By default, only two decimal places are shown in the following spin boxes, each of which is the equivalent of a spin box in the group created by the \c createSpinBoxes() function. The first double spin box shows a basic double-precision spin box with the same range, step size, and default value as the first spin box in the \c createSpinBoxes() function: \snippet examples/widgets/spinboxes/window.cpp 15 However, this spin box also allows non-integer values to be entered. The second spin box displays a suffix and shows a special value instead of the minimum value: \snippet examples/widgets/spinboxes/window.cpp 16 The third spin box displays a prefix instead of a suffix: \snippet examples/widgets/spinboxes/window.cpp 17 We connect the QSpinBox widget that specifies the precision to a slot in the \c Window class. \snippet examples/widgets/spinboxes/window.cpp 18 The rest of the function places each of the widgets into a layout for the group box. The \c changePrecision() slot is called when the user changes the value in the precision spin box: \snippet examples/widgets/spinboxes/window.cpp 19 This function simply uses the integer supplied by the signal to specify the number of decimal places in each of the QDoubleSpinBox widgets. Each one of these will be updated automatically when their \l{QDoubleSpinBox::decimals}{decimals} property is changed. */