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# QSpinBox Class Reference

The QSpinBox class provides a spin box widget. More...

    #include <QSpinBox>

Inherits QAbstractSpinBox.

- List of all members, including inherited members
- Compatibility members

### Writable Properties

- maximum : int
- minimum : int
- prefix : QString
- singleStep : int

- specialValueText : QString
- suffix : QString
- value : int

- 6 writable properties inherited from QAbstractSpinBox
- 33 writable properties inherited from QWidget
- 1 writable property inherited from QObject

### Read-Only Properties

- 2 read-only properties inherited from QAbstractSpinBox
- 20 read-only properties inherited from QWidget

### Public Functions

- QSpinBox ( QWidget * parent = 0 )
- void setRange ( int min, int max )

- 2 public functions inherited from QAbstractSpinBox
- 92 public functions inherited from QWidget
- 26 public functions inherited from QObject
- 10 public functions inherited from QPaintDevice

### Public Slots

- void setValue ( int val )

- 16 public slots inherited from QWidget
- 1 public slot inherited from QObject

### Signals

- void valueChanged ( int i )
- void valueChanged ( QString text )

- 1 signal inherited from QObject

### Static Public Members

- 4 static public members inherited from QWidget
- 4 static public members inherited from QObject

### Protected Functions

- virtual int mapTextToValue ( QString * txt, QValidator::State * state ) const
- virtual QString mapValueToText ( int v ) const

- 3 protected functions inherited from QAbstractSpinBox
- 42 protected functions inherited from QWidget
- 7 protected functions inherited from QObject

## Detailed Description

The QSpinBox class provides a spin box widget.

QSpinBox is designed to handle integers and discrete sets of values (such as month names); use QDoubleSpinBox for floating point values.

QSpinBox allows the user to choose a value by clicking the up/down buttons or pressing up/down on the keyboard to increase/decrease the value currently displayed. The user can also type the value in manually. If the value is entered directly into the spin box, the value will be changed and valueChanged() will be emitted with the new value when Enter/Return is pressed, when the spin box looses focus or when the spin box is deactivated (see QWidget::windowActivationChanged()) If tracking() is true the value will be changed each time the value is changed in the editor. The spin box supports integer values but can be extended to use different strings with mapValueToText() and mapTextToValue().

Every time the value changes QSpinBox emits the valueChanged() signals. The current value can be fetched with value() and set with setValue().

Clicking the up/down buttons or using the keyboard accelerator's up and down arrows will increase or decrease the current value in steps of size lineStep(). If you want to change this behaviour you can reimplement the virtual function stepBy(). The minimum and maximum value and the step size can be set using one of the constructors, and can be changed later with setMinimum(), setMaximum() and setLineStep().

Most spin boxes are directional, but QSpinBox can also operate as a circular spin box, i.e. if the range is 0-99 and the current value is 99, clicking "up" will give 0 if wrapping() is set to true. Use setWrapping() if you want circular behavior.

The displayed value can be prepended and appended with arbitrary strings indicating, for example, currency or the unit of measurement. See setPrefix() and setSuffix(). The text in the spin box is retrieved with text() (which includes any prefix() and suffix()), or with cleanText() (which has no prefix(), no suffix() and no leading or trailing whitespace).

It is often desirable to give the user a special (often default) choice in addition to the range of numeric values. See setSpecialValueText() for how to do this with QSpinBox.

If using prefix(), suffix() and specialValueText() don't provide enough control, you can ignore them and subclass QSpinBox instead.

Here's an example QSpinBox subclass that provides a month picker.

        class monthSpin : public QSpinBox
        {
            Q_OBJECT
        public:
            monthSpin(QWidget *parent = 0)
                : QSpinBox(0, 12, 1, parent)
            {
                setSpecialValueText("None");
                setValue(0);
            }

            QString mapValueToText(int v) const
            {
                return QDate::longMonthName(v);
            }

            int mapTextToValue(const QString &text, QValidator::State *state) const
            {
                for (int i = 1; i <= 12; ++i) {
                    if (text == QDate::longMonthName(i) || text == QDate::shortMonthName(i)) {
                        if (state)
                            *state = QValidator::Acceptable;
                        return i;
                    }
                }
                if (state)
                    *state = QValidator::Invalid;
                return 0;
            }

            void keyPressEvent(QKeyEvent *e)
            {
                if (e->key() == Qt::Key_P) {
                    stepBy(1);
                    e->accept();
                } else if (e->key() == Qt::Key_N) {
                    stepBy(-1);
                    e->accept();
                } else {
                    QSpinBox::keyPressEvent(e);
                }
            }

## Property Documentation

### maximum : int

This property holds the maximum value of the spin box.

When setting this property the minimum is adjusted if necessary, to ensure that the range remains valid.

The default maximum value is 99.

Access functions:

- int maximum () const
- void setMaximum ( int max )

See also setRange() and specialValueText.

### minimum : int

This property holds the minimum value of the spin box.

When setting this property the maximum is adjusted if necessary to ensure that the range remains valid.

The default minimum value is 0.

Access functions:

- int minimum () const
- void setMinimum ( int min )

See also setRange() and specialValueText.

### prefix : QString

This property holds the spin box's prefix.

The prefix is prepended to the start of the displayed value. Typical use is to display a unit of measurement or a currency symbol. For example:

        sb->setPrefix("$");

To turn off the prefix display, set this property to an empty string. The default is no prefix. The prefix is not displayed when value() == minimum() and specialValueText() is set.

If no prefix is set, prefix() returns an empty string.

Access functions:

- QString prefix () const
- void setPrefix ( const QString & p )

See also suffix(), setSuffix(), specialValueText(), and setSpecialValueText().

### singleStep : int

This property holds the step value.

When the user uses the arrows to change the spin box's value the value will be incremented/decremented by the amount of the singleStep. The default value is 1. Setting a singleStep value of less than 0 does nothing.

Access functions:

- int singleStep () const
- void setSingleStep ( int val )

See also setSingleStep().

### specialValueText : QString

This property holds the special-value text.

If set, the spin box will display this text instead of a numeric value whenever the current value is equal to minimum(). Typical use is to indicate that this choice has a special (default) meaning.

For example, if your spin box allows the user to choose the margin width in a print dialog and your application is able to automatically choose a good margin width, you can set up the spin box like this:

        QSpinBox marginBox(-1, 20, 1, parent);
        marginBox.setSuffix(" mm");
        marginBox.setSpecialValueText("Auto");

The user will then be able to choose a margin width from 0-20 millimeters or select "Auto" to leave it to the application to choose. Your code must then interpret the spin box value of -1 as the user requesting automatic margin width.

All values are displayed with the prefix() and suffix() (if set), except for the special value, which only shows the special value text.

To turn off the special-value text display, call this function with an empty string. The default is no special-value text, i.e. the numeric value is shown as usual.

If no special-value text is set, specialValueText() returns an empty string.

Access functions:

- QString specialValueText () const
- void setSpecialValueText ( const QString & s )

### suffix : QString

This property holds the suffix of the spin box.

The suffix is appended to the end of the displayed value. Typical use is to display a unit of measurement or a currency symbol. For example:

        sb->setSuffix(" km");

To turn off the suffix display, set this property to an empty string. The default is no suffix. The suffix is not displayed for the minValue() if specialValueText() is set.

If no suffix is set, suffix() returns an empty string.

Access functions:

- QString suffix () const
- void setSuffix ( const QString & s )

See also prefix(), setPrefix(), specialValueText(), and setSpecialValueText().

### value : int

This property holds the value of the spin box.

setValue() will emit valueChanged() if the new value is different from the old one.

Access functions:

- int value () const
- void setValue ( int val )

See also setValue().

## Member Function Documentation

### QSpinBox::QSpinBox ( QWidget * parent = 0 )

Constructs a spin box with no minimum and maximum values, a step value of 1. The value is initially set to 0. It is parented to parent.

See also minimum(), setMinimum(), maximum(), setMaximum(), lineStep(), and setLineStep().

### int QSpinBox::mapTextToValue ( QString * txt, QValidator::State * state ) const `[virtual protected]`

This virtual function is used by the spin box whenever it needs to interpret text entered by the user as a value. Note that neither prefix() nor suffix() are included when this function is called by Qt. If state is not 0 it is set accordingly.

Subclasses that need to display spin box values in a non-numeric way need to reimplement this function.

Note that Qt handles specialValueText() separately; this function is only concerned with the other values.

The default implementation tries to interpret txt as an integer using QString::toInt() and returns the value. For an empty string or "-" (if negative values are allowed in the spinbox) it returns 0.

Warning: This function must not be called with txt == 0.

See also mapValueToText().

### QString QSpinBox::mapValueToText ( int v ) const `[virtual protected]`

This virtual function is used by the spin box whenever it needs to display value v. The default implementation returns a string containing v printed in the standard way. Reimplementations may return anything. (See the example in the detailed description.)

Note that Qt does not call this function for specialValueText() and that neither prefix() nor suffix() should be included in the return value.

If you reimplement this, you may also need to reimplement mapTextToValue().

See also mapTextToValue().

### void QSpinBox::setRange ( int min, int max )

Convenience function to set the minimum, min, and maximum, max, values with a single function call.

        setRange(min, max);

is equivalent to:

        setMinimum(min);
        setMaximum(max);

See also minimum and maximum.

### void QSpinBox::valueChanged ( int i ) `[signal]`

This signal is emitted whenever the spin box's value is changed. The new value's integer value is passed in i.

### void QSpinBox::valueChanged ( QString text ) `[signal]`

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

The new value is passed literally in text with no prefix() or suffix().