- Qt 6.8
- Qt Charts
- C++ Classes
- QPieSlice
- Qt Charts | Commercial or GPLv3

# QPieSlice Class

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

Header: | #include <QPieSlice>
Instantiated By: | PieSlice
Inherits: | QObject

- List of all members, including inherited members

## Public Types

enum | LabelPosition { LabelOutside, LabelInsideHorizontal, LabelInsideTangential, LabelInsideNormal }

## Properties

angleSpan : const qreal borderColor : QColor borderWidth : int brush : QBrush color : QColor explodeDistanceFactor : qreal exploded : bool label : QString labelArmLengthFactor : qreal | labelBrush : QBrush labelColor : QColor labelFont : QFont labelPosition : LabelPosition labelVisible : bool pen : QPen percentage : const qreal startAngle : const qreal value : qreal

## Public Functions

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

## Signals

void | angleSpanChanged()
void | borderColorChanged()
void | borderWidthChanged()
void | brushChanged()
void | clicked()
void | colorChanged()
void | doubleClicked()
void | hovered(bool state)
void | labelBrushChanged()
void | labelChanged()
void | labelColorChanged()
void | labelFontChanged()
void | labelVisibleChanged()
void | penChanged()
void | percentageChanged()
void | pressed()
void | released()
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 chart.

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 chart, some basic signals are emitted when users click pie slices or hover the mouse over them.

See also QPieSeries.

## Member Type Documentation

### enum QPieSlice::LabelPosition

This enum describes the position of the slice label.

Constant | Value | Description
--- | --- | ---
`QPieSlice::LabelOutside` | `0` | The label is located outside the slice connected to it with an arm. This is the default value.
`QPieSlice::LabelInsideHorizontal` | `1` | The label is centered within the slice and laid out horizontally.
`QPieSlice::LabelInsideTangential` | `2` | The label is centered within the slice and rotated to be parallel with the tangential of the slice's arc.
`QPieSlice::LabelInsideNormal` | `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 pen.

Access functions:

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

Notifier signal:

void | borderColorChanged()

See also pen and borderWidth.

### borderWidth : int

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

Access functions:

int | borderWidth()
void | setBorderWidth(int width)

Notifier signal:

void | borderWidthChanged()

See also pen and borderColor.

### brush : QBrush

This property holds the brush used to fill the slice.

Access functions:

QBrush | brush() const
void | setBrush(const QBrush &brush)

Notifier signal:

void | brushChanged()

### color : QColor

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

Access functions:

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

Notifier signal:

void | colorChanged()

See also brush.

### 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)

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 = true)

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(QString label)

Notifier signal:

void | labelChanged()

See also labelVisible, labelBrush, 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)

See also label, labelVisible, labelBrush, and labelFont.

### labelBrush : QBrush

This property holds the brush used to draw the label and label arm of the slice.

Access functions:

QBrush | labelBrush() const
void | setLabelBrush(const QBrush &brush)

Notifier signal:

void | labelBrushChanged()

See also label, labelVisible, labelFont, and labelArmLengthFactor.

### labelColor : QColor

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

Access functions:

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

Notifier signal:

void | labelColorChanged()

See also labelBrush.

### 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)

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, labelBrush, labelFont, and labelArmLengthFactor.

### pen : QPen

This property holds the pen used to draw the slice border.

Access functions:

QPen | pen() const
void | setPen(const QPen &pen)

Notifier signal:

void | penChanged()

### `[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(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().

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

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

### `[signal]` void QPieSlice::angleSpanChanged()

This signal is emitted when the angle span of the slice changes.

Note: Notifier signal for property angleSpan.

See also angleSpan.

### `[signal]` void QPieSlice::borderColorChanged()

This signal is emitted when the slice border color changes.

Note: Notifier signal for property borderColor.

See also pen and borderColor.

### `[signal]` void QPieSlice::borderWidthChanged()

This signal is emitted when the slice border width changes.

Note: Notifier signal for property borderWidth.

See also pen and borderWidth.

### `[signal]` void QPieSlice::brushChanged()

This signal is emitted when the brush used to fill the slice changes.

Note: Notifier signal for property brush.

See also brush.

### `[signal]` void QPieSlice::clicked()

This signal is emitted when the slice is clicked.

See also QPieSeries::clicked().

### `[signal]` void QPieSlice::colorChanged()

This signal is emitted when the slice color changes.

Note: Notifier signal for property color.

See also brush.

### `[signal]` void QPieSlice::doubleClicked()

This signal is emitted when user double-clicks the slice.

See also QPieSeries::doubleClicked().

### `[signal]` void QPieSlice::hovered(bool state)

This signal is emitted when a mouse is hovered over the slice. When the mouse moves over the slice, state turns `true`, and when the mouse moves away again, it turns `false`.

See also QPieSeries::hovered().

### `[signal]` void QPieSlice::labelBrushChanged()

This signal is emitted when the label brush of the slice changes.

Note: Notifier signal for property labelBrush.

See also labelBrush.

### `[signal]` void QPieSlice::labelChanged()

This signal is emitted when the slice label changes.

Note: Notifier signal for property label.

See also label.

### `[signal]` void QPieSlice::labelColorChanged()

This signal is emitted when the slice label color changes.

Note: Notifier signal for property labelColor.

See also labelColor.

### `[signal]` void QPieSlice::labelFontChanged()

This signal is emitted when the label font of the slice changes.

Note: Notifier signal for property labelFont.

See also labelFont.

### `[signal]` void QPieSlice::labelVisibleChanged()

This signal is emitted when the visibility of the slice label changes.

Note: Notifier signal for property labelVisible.

See also labelVisible.

### `[signal]` void QPieSlice::penChanged()

This signal is emitted when the pen used to draw the slice border changes.

Note: Notifier signal for property pen.

See also pen.

### `[signal]` void QPieSlice::percentageChanged()

This signal is emitted when the percentage of the slice changes.

Note: Notifier signal for property percentage.

See also percentage.

### `[signal]` void QPieSlice::pressed()

This signal is emitted when the user clicks the slice and holds down the mouse button.

See also QPieSeries::pressed().

### `[signal]` void QPieSlice::released()

This signal is emitted when the user releases the mouse press on the slice.

See also QPieSeries::released().

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

Returns the series that this slice belongs to.

See also QPieSeries::append().

### `[signal]` void QPieSlice::startAngleChanged()

This signal is emitted when the starting angle of the slice changes.

Note: Notifier signal for property startAngle.

See also startAngle.

### `[signal]` void QPieSlice::valueChanged()

This signal is emitted when the slice value changes.

Note: Notifier signal for property value.

See also value.