QLCDNumber Class

The QLCDNumber widget displays a number with LCD-like digits. More...

Header:	#include <QLCDNumber>
qmake:	QT += widgets
Inherits:	QFrame

• List of all members, including inherited members
• Obsolete members

Public Types

enum	Mode { Hex, Dec, Oct, Bin }
enum	SegmentStyle { Outline, Filled, Flat }

Properties

digitCount : int intValue : int mode : Mode

segmentStyle : SegmentStyle smallDecimalPoint : bool value : double

• 6 properties inherited from QFrame
• 59 properties inherited from QWidget
• 1 property inherited from QObject

Public Functions

	QLCDNumber(QWidget *parent = nullptr)
	QLCDNumber(uint numDigits, QWidget *parent = nullptr)
virtual	~QLCDNumber()
bool	checkOverflow(double num) const
bool	checkOverflow(int num) const
int	digitCount() const
int	intValue() const
QLCDNumber::Mode	mode() const
QLCDNumber::SegmentStyle	segmentStyle() const
void	setDigitCount(int numDigits)
void	setMode(QLCDNumber::Mode)
void	setSegmentStyle(QLCDNumber::SegmentStyle)
bool	smallDecimalPoint() const
double	value() const

Reimplemented Public Functions

virtual QSize

sizeHint() const override

• 14 public functions inherited from QFrame
• 214 public functions inherited from QWidget
• 31 public functions inherited from QObject
• 14 public functions inherited from QPaintDevice

Public Slots

void	display(const QString &s)
void	display(int num)
void	display(double num)
void	setBinMode()
void	setDecMode()
void	setHexMode()
void	setOctMode()
void	setSmallDecimalPoint(bool)

• 19 public slots inherited from QWidget
• 1 public slot inherited from QObject

Signals

void	overflow()

• 3 signals inherited from QWidget
• 2 signals inherited from QObject

Static Public Members

const QMetaObject

staticMetaObject

• 5 static public members inherited from QWidget
• 9 static public members inherited from QObject

Reimplemented Protected Functions

virtual bool	event(QEvent *e) override
virtual void	paintEvent(QPaintEvent *) override

• 4 protected functions inherited from QFrame
• 35 protected functions inherited from QWidget
• 9 protected functions inherited from QObject
• 1 protected function inherited from QPaintDevice

Additional Inherited Members

• 4 protected functions inherited from QFrame
• 35 protected functions inherited from QWidget
• 9 protected functions inherited from QObject
• 1 protected function inherited from QPaintDevice
• 1 protected slot inherited from QWidget

Detailed Description

The QLCDNumber widget displays a number with LCD-like digits.

It can display a number in just about any size. It can display decimal, hexadecimal, octal or binary numbers. It is easy to connect to data sources using the display() slot, which is overloaded to take any of five argument types.

There are also slots to change the base with setMode() and the decimal point with setSmallDecimalPoint().

QLCDNumber emits the overflow() signal when it is asked to display something beyond its range. The range is set by setDigitCount(), but setSmallDecimalPoint() also influences it. If the display is set to hexadecimal, octal or binary, the integer equivalent of the value is displayed.

These digits and other symbols can be shown: 0/O, 1, 2, 3, 4, 5/S, 6, 7, 8, 9/g, minus, decimal point, A, B, C, D, E, F, h, H, L, o, P, r, u, U, Y, colon, degree sign (which is specified as single quote in the string) and space. QLCDNumber substitutes spaces for illegal characters.

It is not possible to retrieve the contents of a QLCDNumber object, although you can retrieve the numeric value with value(). If you really need the text, we recommend that you connect the signals that feed the display() slot to another slot as well and store the value there.

Incidentally, QLCDNumber is the very oldest part of Qt, tracing its roots back to a BASIC program on the Sinclair Spectrum.

See also QLabel, QFrame, Digital Clock Example, and Tetrix Example.

Member Type Documentation

enum QLCDNumber::Mode

This type determines how numbers are shown.

Constant	Value	Description
QLCDNumber::Hex	0	Hexadecimal
QLCDNumber::Dec	1	Decimal
QLCDNumber::Oct	2	Octal
QLCDNumber::Bin	3	Binary

If the display is set to hexadecimal, octal or binary, the integer equivalent of the value is displayed.

enum QLCDNumber::SegmentStyle

This type determines the visual appearance of the QLCDNumber widget.

Constant	Value	Description
QLCDNumber::Outline	0	gives raised segments filled with the background color.
QLCDNumber::Filled	1	gives raised segments filled with the windowText color.
QLCDNumber::Flat	2	gives flat segments filled with the windowText color.

Member Function Documentation

QLCDNumber::QLCDNumber(QWidget *parent = nullptr)

Constructs an LCD number, sets the number of digits to 5, the base to decimal, the decimal point mode to 'small' and the frame style to a raised box. The segmentStyle() is set to Outline.

The parent argument is passed to the QFrame constructor.

See also setDigitCount() and setSmallDecimalPoint().

QLCDNumber::QLCDNumber(uint numDigits, QWidget *parent = nullptr)

Constructs an LCD number, sets the number of digits to numDigits, the base to decimal, the decimal point mode to 'small' and the frame style to a raised box. The segmentStyle() is set to Filled.

The parent argument is passed to the QFrame constructor.

See also setDigitCount() and setSmallDecimalPoint().

[virtual] QLCDNumber::~QLCDNumber()

Destroys the LCD number.

bool QLCDNumber::checkOverflow(double num) const

Returns true if num is too big to be displayed in its entirety; otherwise returns false.

See also display(), digitCount(), and smallDecimalPoint().

bool QLCDNumber::checkOverflow(int num) const

This is an overloaded function.

Returns true if num is too big to be displayed in its entirety; otherwise returns false.

See also display(), digitCount(), and smallDecimalPoint().

int QLCDNumber::digitCount() const

Returns the current number of digits.

Note: Getter function for property digitCount.

See also setDigitCount().

[slot] void QLCDNumber::display(const QString &s)

Displays the number represented by the string s.

This version of the function disregards mode() and smallDecimalPoint().

These digits and other symbols can be shown: 0/O, 1, 2, 3, 4, 5/S, 6, 7, 8, 9/g, minus, decimal point, A, B, C, D, E, F, h, H, L, o, P, r, u, U, Y, colon, degree sign (which is specified as single quote in the string) and space. QLCDNumber substitutes spaces for illegal characters.

Note: Setter function for property intValue. Setter function for property value.

[slot] void QLCDNumber::display(int num)

This is an overloaded function.

Displays the number num.

Note: Setter function for property intValue. Setter function for property value.

[slot] void QLCDNumber::display(double num)

This is an overloaded function.

Displays the number num.

Note: Setter function for property intValue. Setter function for property value.

[override virtual protected] bool QLCDNumber::event(QEvent *e)

Reimplemented from QFrame::event().

[signal] void QLCDNumber::overflow()

This signal is emitted whenever the QLCDNumber is asked to display a too-large number or a too-long string.

It is never emitted by setDigitCount().

[override virtual protected] void QLCDNumber::paintEvent(QPaintEvent *)

Reimplemented from QFrame::paintEvent().

[slot] void QLCDNumber::setBinMode()

Calls setMode(Bin). Provided for convenience (e.g. for connecting buttons to it).

See also setMode(), setHexMode(), setDecMode(), setOctMode(), and mode().

[slot] void QLCDNumber::setDecMode()

Calls setMode(Dec). Provided for convenience (e.g. for connecting buttons to it).

See also setMode(), setHexMode(), setOctMode(), setBinMode(), and mode().

void QLCDNumber::setDigitCount(int numDigits)

Sets the current number of digits to numDigits. Must be in the range 0..99.

Note: Setter function for property digitCount.

See also digitCount().

[slot] void QLCDNumber::setHexMode()

Calls setMode(Hex). Provided for convenience (e.g. for connecting buttons to it).

See also setMode(), setDecMode(), setOctMode(), setBinMode(), and mode().

[slot] void QLCDNumber::setOctMode()

Calls setMode(Oct). Provided for convenience (e.g. for connecting buttons to it).

See also setMode(), setHexMode(), setDecMode(), setBinMode(), and mode().

[override virtual] QSize QLCDNumber::sizeHint() const

Reimplemented from QFrame::sizeHint().