- Qt 6.9
- Qt Graphs
- C++ Classes
- QtGraphs
- QPieSlice
- Qt Graphs | Commercial or GPLv3

# QPieSlice Class

The QPieSlice class represents a single slice in a pie series. More...

Header: | `#include <QPieSlice>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Graphs)` `target_link_libraries(mytarget PRIVATE Qt6::Graphs)`
qmake: | `QT += graphs`
In QML: | PieSlice

- List of all members, including inherited members
- QPieSlice is part of Qt Graphs C++ Classes for 2D.

## Public Types

enum class | LabelPosition { Outside, InsideHorizontal, InsideTangential, InsideNormal }

## Properties

- angleSpan : const qreal
- borderColor : QColor
- borderWidth : qreal
- color : QColor
- explodeDistanceFactor : qreal
- exploded : bool
- label : QString
- labelArmLengthFactor : qreal

- labelColor : QColor
- labelFont : QFont
- labelPosition : LabelPosition
- labelVisible : bool
- percentage : const qreal
- startAngle : const qreal
- value : qreal

## Public Functions

| QPieSlice(QObject *parent = nullptr)
| QPieSlice(const QString &label, qreal value, QObject *parent = nullptr)
virtual | ~QPieSlice() override
qreal | angleSpan() const
QColor | borderColor() const
qreal | borderWidth() const
QColor | color() const
qreal | explodeDistanceFactor() const
bool | isExploded() const
bool | isLabelVisible() const
QString | label() const
qreal | labelArmLengthFactor() const
QColor | labelColor() const
QFont | labelFont() const
QPieSlice::LabelPosition | labelPosition()
qreal | percentage() const
QPieSeries * | series() const
void | setBorderColor(QColor color)
void | setBorderWidth(qreal borderWidth)
void | setColor(QColor color)
void | setExplodeDistanceFactor(qreal factor)
void | setExploded(bool exploded)
void | setLabel(const QString &label)
void | setLabelArmLengthFactor(qreal factor)
void | setLabelColor(QColor color)
void | setLabelFont(const QFont &font)
void | setLabelPosition(QPieSlice::LabelPosition position)
void | setLabelVisible(bool visible = true)
void | setValue(qreal value)
qreal | startAngle() const
qreal | value() const

## Signals

void | angleSpanChanged()
void | borderColorChanged()
void | borderWidthChanged()
void | colorChanged()
void | explodeDistanceFactorChanged()
void | explodedChanged()
void | labelArmLengthFactorChanged()
void | labelChanged()
void | labelColorChanged()
void | labelFontChanged()
void | labelPositionChanged()
void | labelVisibleChanged()
void | percentageChanged()
void | startAngleChanged()
void | valueChanged()

## Detailed Description

A pie slice has a value and a label. When the slice is added to a pie series, the QPieSeries object calculates the percentage of the slice compared with the sum of all slices in the series to determine the actual size of the slice in the graph.

By default, the label is hidden. If it is visible, it can be either located outside the slice and connected to it with an arm or centered inside the slice either horizontally or in parallel with the tangential or normal of the slice's arc.

By default, the visual appearance of the slice is set by a theme, but the theme can be overridden by specifying slice properties. However, if the theme is changed after the slices are customized, all customization will be lost.

To enable user interaction with the pie graph, some basic signals are emitted when users click pie slices or hover the mouse over them.

See also QPieSeries.

## Member Type Documentation

### enum class QPieSlice::LabelPosition

This enum describes the position of the slice label.

Constant | Value | Description
--- | --- | ---
`QPieSlice::LabelPosition::Outside` | `0` | The label is located outside the slice connected to it with an arm. This is the default value.
`QPieSlice::LabelPosition::InsideHorizontal` | `1` | The label is centered within the slice and laid out horizontally.
`QPieSlice::LabelPosition::InsideTangential` | `2` | The label is centered within the slice and rotated to be parallel with the tangential of the slice's arc.
`QPieSlice::LabelPosition::InsideNormal` | `3` | The label is centered within the slice and rotated to be parallel with the normal of the slice's arc.

## Property Documentation

### `[read-only]` angleSpan : const qreal

This property holds the span of the slice in degrees. A full pie is 360 degrees, where 0 degrees is at 12 a'clock. Updated automatically once the slice is added to the series.

Access functions:

qreal | angleSpan() const

Notifier signal:

void | angleSpanChanged()

### borderColor : QColor

This property holds the color used to draw the slice border. This is a convenience property for modifying the slice.

Access functions:

QColor | borderColor() const
void | setBorderColor(QColor color)

Notifier signal:

void | borderColorChanged()

See also borderWidth.

### borderWidth : qreal

This property holds the width of the slice border. This is a convenience property for modifying the slice border width.

Access functions:

qreal | borderWidth() const
void | setBorderWidth(qreal borderWidth)

Notifier signal:

void | borderWidthChanged()

See also borderColor.

### color : QColor

This property holds the fill color of the slice. This is a convenience property for modifying the slice fill color.

Access functions:

QColor | color() const
void | setColor(QColor color)

Notifier signal:

void | colorChanged()

### explodeDistanceFactor : qreal

Determines how far away from the pie the slice is exploded.

- 1.0 means that the distance is the same as the radius.
- 0.5 means that the distance is half of the radius.

By default, the distance is 0.15

Access functions:

qreal | explodeDistanceFactor() const
void | setExplodeDistanceFactor(qreal factor)

Notifier signal:

void | explodeDistanceFactorChanged()

See also exploded.

### exploded : bool

This property holds whether the slice is separated from the pie.

Access functions:

bool | isExploded() const
void | setExploded(bool exploded)

Notifier signal:

void | explodedChanged()

See also explodeDistanceFactor.

### label : QString

This property holds the label of the slice.

Note: The string can be HTML formatted.

Access functions:

QString | label() const
void | setLabel(const QString &label)

Notifier signal:

void | labelChanged()

See also labelVisible, labelFont, and labelArmLengthFactor.

### labelArmLengthFactor : qreal

This property holds the length of the label arm. The factor is relative to the pie radius. For example:

- 1.0 means that the length is the same as the radius.
- 0.5 means that the length is half of the radius.

By default, the arm length is 0.15

Access functions:

qreal | labelArmLengthFactor() const
void | setLabelArmLengthFactor(qreal factor)

Notifier signal:

void | labelArmLengthFactorChanged()

See also label, labelVisible, and labelFont.

### labelColor : QColor

This property holds the color used to draw the slice label.

Access functions:

QColor | labelColor() const
void | setLabelColor(QColor color)

Notifier signal:

void | labelColorChanged()

### labelFont : QFont

This property holds the font used for drawing the label text.

Access functions:

QFont | labelFont() const
void | setLabelFont(const QFont &font)

Notifier signal:

void | labelFontChanged()

See also label, labelVisible, and labelArmLengthFactor.

### labelPosition : LabelPosition

This property holds the position of the slice label.

Access functions:

QPieSlice::LabelPosition | labelPosition()
void | setLabelPosition(QPieSlice::LabelPosition position)

Notifier signal:

void | labelPositionChanged()

See also label and labelVisible.

### labelVisible : bool

This property holds the visibility of the slice label. By default, the label is not visible.

Access functions:

bool | isLabelVisible() const
void | setLabelVisible(bool visible = true)

Notifier signal:

void | labelVisibleChanged()

See also label, labelFont, and labelArmLengthFactor.

### `[read-only]` percentage : const qreal

This property holds the percentage of the slice compared to the sum of all slices in the series. The actual value ranges from 0.0 to 1.0. Updated automatically once the slice is added to the series.

Access functions:

qreal | percentage() const

Notifier signal:

void | percentageChanged()

See also value and QPieSeries::sum.

### `[read-only]` startAngle : const qreal

This property holds the starting angle of this slice in the series it belongs to. A full pie is 360 degrees, where 0 degrees is at 12 a'clock. Updated automatically once the slice is added to the series.

Access functions:

qreal | startAngle() const

Notifier signal:

void | startAngleChanged()

### value : qreal

This property holds the value of the slice.

Note: A negative value is converted to a positive value.

Access functions:

qreal | value() const
void | setValue(qreal value)

Notifier signal:

void | valueChanged()

See also percentage() and QPieSeries::sum().

## Member Function Documentation

### `[explicit]` QPieSlice::QPieSlice(QObject *parent = nullptr)

Constructs an empty slice with the parent parent.

See also QPieSeries::append() and QPieSeries::insert().

### QPieSlice::QPieSlice(const QString &label, qreal value, QObject *parent = nullptr)

Constructs an empty slice with the specified value, label, and parent.

See also QPieSeries::append() and QPieSeries::insert().

### `[override virtual noexcept]` QPieSlice::~QPieSlice()

Removes the slice. The slice should not be removed if it has been added to a series.

### QPieSeries *QPieSlice::series() const

Returns the series that this slice belongs to.

See also QPieSeries::append().