QLCDNumber Class Reference
^{[QtGui module]}

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 setNumDigits(), 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.

LCD number widgets shown in various widget styles (from left to right): Motif, CDE, Windows, Windows XP, Macintosh, Plastique.

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

Member Type Documentation

enum QLCDNumber::Mode

This type determines how numbers are shown.

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.

Property Documentation

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.

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:

• Mode mode () const
• void setMode ( Mode )

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

numDigits : 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.

Access functions:

• int numDigits () const
• void setNumDigits ( int nDigits )

See also smallDecimalPoint.

segmentStyle : SegmentStyle

This property holds the style of the LCDNumber.

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

Access functions:

• SegmentStyle segmentStyle () const
• void setSegmentStyle ( 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.

Access functions:

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

Member Function Documentation

QLCDNumber::QLCDNumber ( QWidget * parent = 0 )

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 setNumDigits() and setSmallDecimalPoint().

QLCDNumber::QLCDNumber ( uint numDigits, QWidget * parent = 0 )

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 Outline.

The parent argument is passed to the QFrame constructor.

See also setNumDigits() and setSmallDecimalPoint().

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(), numDigits(), and smallDecimalPoint().

bool QLCDNumber::checkOverflow ( int num ) const

This is an overloaded member function, provided for convenience.

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

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

void QLCDNumber::overflow ()   [signal]

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 setNumDigits().

void QLCDNumber::setBinMode ()   [slot]

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

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

void QLCDNumber::setDecMode ()   [slot]

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

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

void QLCDNumber::setHexMode ()   [slot]

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

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

void QLCDNumber::setOctMode ()   [slot]

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

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