QLCDNumber Class

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

Header:	#include <QLCDNumber>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Widgets) target_link_libraries(mytarget PRIVATE Qt6::Widgets)
qmake:	QT += widgets
Inherits:	QFrame

List of all members, including inherited 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

Public Functions

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

Public Slots

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

Signals

void	overflow()

Reimplemented Protected Functions

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

Detailed Description

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.

Property Documentation

digitCount : int

This property holds the current number of digits displayed

Corresponds to the current number of digits. If QLCDNumber::smallDecimalPoint is false, the decimal point occupies one digit position.

By default, this property contains a value of 5.

Access functions:

int	digitCount() const
void	setDigitCount(int numDigits)

See also smallDecimalPoint.

intValue : int

This property holds the displayed value rounded to the nearest integer

This property corresponds to the nearest integer to the current value displayed by the LCDNumber. This is the value used for hexadecimal, octal and binary modes.

If the displayed value is not a number, the property has a value of 0.

By default, this property contains a value of 0.

Access functions:

int	intValue() const
void	display(const QString &s)
void	display(int num)
void	display(double num)

mode : Mode

This property holds the current display mode (number base)

Corresponds to the current display mode, which is one of Bin, Oct, Dec (the default) and Hex. Dec mode can display floating point values, the other modes display the integer equivalent.

Access functions:

QLCDNumber::Mode	mode() const
void	setMode(QLCDNumber::Mode)

See also smallDecimalPoint(), setHexMode(), setDecMode(), setOctMode(), and setBinMode().

segmentStyle : SegmentStyle

This property holds the style of the LCDNumber

Style	Result
`Outline`	Produces raised segments filled with the background color
`Filled` (this is the default).	Produces raised segments filled with the foreground color.
`Flat`	Produces flat segments filled with the foreground color.

Outline and Filled will additionally use QPalette::light() and QPalette::dark() for shadow effects.

Access functions:

QLCDNumber::SegmentStyle	segmentStyle() const
void	setSegmentStyle(QLCDNumber::SegmentStyle)

smallDecimalPoint : bool

This property holds the style of the decimal point

If true the decimal point is drawn between two digit positions. Otherwise it occupies a digit position of its own, i.e. is drawn in a digit position. The default is false.

The inter-digit space is made slightly wider when the decimal point is drawn between the digits.

Access functions:

bool	smallDecimalPoint() const
void	setSmallDecimalPoint(bool)

See also mode.

value : double

This property holds the displayed value

This property corresponds to the current value displayed by the LCDNumber.

If the displayed value is not a number, the property has a value of 0.

By default, this property contains a value of 0.

Access functions:

double	value() const
void	display(const QString &s)
void	display(int num)
void	display(double num)

Member Function Documentation

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().

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().

`[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.

`[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(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.

`[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().

`[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().

`[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().

`[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().

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

Reimplements: QFrame::event(QEvent *e).

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

Reimplements: QFrame::paintEvent(QPaintEvent *).

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().

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

Reimplements: QFrame::sizeHint() const.

Contents

QLCDNumber Class

Public Types

Properties

Public Functions

Reimplemented Public Functions

Public Slots

Signals

Reimplemented Protected Functions

Detailed Description

Member Type Documentation

enum QLCDNumber::Mode

enum QLCDNumber::SegmentStyle

Property Documentation

digitCount : int

intValue : int

mode : Mode

segmentStyle : SegmentStyle

smallDecimalPoint : bool

value : double

Member Function Documentation

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

QLCDNumber::QLCDNumber(QWidget *parent = nullptr)

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

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

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

[signal] void QLCDNumber::overflow()

[slot] void QLCDNumber::setBinMode()

[slot] void QLCDNumber::setDecMode()

[slot] void QLCDNumber::setHexMode()

[slot] void QLCDNumber::setOctMode()

[virtual] QLCDNumber::~QLCDNumber()

bool QLCDNumber::checkOverflow(double num) const

bool QLCDNumber::checkOverflow(int num) const

int QLCDNumber::digitCount() const

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

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

void QLCDNumber::setDigitCount(int numDigits)

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

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

QLCDNumber::QLCDNumber(QWidget **parent* = nullptr)

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

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

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

`[signal]` void QLCDNumber::overflow()

`[slot]` void QLCDNumber::setBinMode()

`[slot]` void QLCDNumber::setDecMode()

`[slot]` void QLCDNumber::setHexMode()

`[slot]` void QLCDNumber::setOctMode()

`[virtual]` QLCDNumber::~QLCDNumber()

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

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

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