QLCDNumber Class
The QLCDNumber widget displays a number with LCD-like digits. More...
| Header: | #include <QLCDNumber> |
| CMake: | find_package(Qt6 COMPONENTS Widgets REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Widgets) |
| qmake: | QT += widgets |
| Inherits: | QFrame |
Public Types
| enum | Mode { Hex, Dec, Oct, Bin } |
| enum | SegmentStyle { Outline, Filled, Flat } |
Properties
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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:
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:
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.