QwtColorCycle Class Reference

Provides cyclic color selection from predefined palettes. More...

#include <qwt_color_cycle.h>

Public Types
enum	Palette {   Default10 , Tab10 , Tab20 , Set1 ,   Set2 , Set3 , OkabeIto }
	Built-in color palettes. More...

Public Member Functions
	QwtColorCycle ()
	Construct with the Default10 palette (matplotlib classic)
	QwtColorCycle (Palette palette)
	Construct with a built-in palette.
	QwtColorCycle (const QVector< QColor > &colors)
	Construct with custom colors.
QColor	color (int index) const
	Get a color by index (wraps around)
int	count () const
	Get the number of colors in the cycle.
void	setPalette (Palette)
	Set the palette from a built-in preset.
void	setColors (const QVector< QColor > &)
	Set custom colors.
QVector< QColor >	colors () const
	Get the current color list.

Static Public Member Functions
static QVector< QColor >	paletteColors (Palette)
	Get the colors for a built-in palette.

Detailed Description

Provides cyclic color selection from predefined palettes.

QwtColorCycle manages an ordered list of colors and returns them in a cyclic manner using the color() method. This is used by QwtPlot to automatically assign distinct colors to plot items (curves, bar charts, etc.) when they are attached without a user-specified pen or brush.

Several built-in palettes are available, inspired by matplotlib, Tableau, ColorBrewer, and the Okabe-Ito colorblind-safe palette.

Example

QwtPlot plot;
plot.setColorCycle(QwtColorCycle(QwtColorCycle::OkabeIto));
 
auto* curve1 = new QwtPlotCurve("Series 1"); // gets color[0]
curve1->attach(&plot);
auto* curve2 = new QwtPlotCurve("Series 2"); // gets color[1]
curve2->attach(&plot);

See also

QwtPlot::setColorCycle(), QwtPlot::colorCycle()

Member Enumeration Documentation

Palette

enum QwtColorCycle::Palette

Built-in color palettes.

Enumerator
Default10	matplotlib classic 10 colors
Tab10	Tableau Tab10 — high-contrast categorical colors.
Tab20	Tableau Tab20 — 20 colors with light/dark pairs.
Set1	ColorBrewer Set1 — 9 colors for qualitative data.
Set2	ColorBrewer Set2 — 8 colors for qualitative data.
Set3	ColorBrewer Set3 — 12 colors for qualitative data.
OkabeIto	Okabe-Ito — 8 colorblind-safe colors.

Constructor & Destructor Documentation

QwtColorCycle() [1/2]

QwtColorCycle::QwtColorCycle ( Palette  palette )

explicit

Construct with a built-in palette.

Parameters

palette

Built-in palette selector

QwtColorCycle() [2/2]

QwtColorCycle::QwtColorCycle ( const QVector< QColor > &  colors )

explicit

Construct with custom colors.

Parameters

colors

Custom color list

Member Function Documentation

color()

QColor QwtColorCycle::color

(

int

index

)

const

Get a color by index (wraps around)

Get a color by index with cyclic wrap-around.

Parameters

index

Zero-based index (negative values are handled)

Returns

Color at position (index % count)

colors()

QVector< QColor > QwtColorCycle::colors

(

)

const

Get the current color list.

Returns

Copy of the internal color list

count()

int QwtColorCycle::count

(

)

const

Get the number of colors in the cycle.

Returns

Number of colors

paletteColors()

QVector< QColor > QwtColorCycle::paletteColors ( Palette  palette )

static

Get the colors for a built-in palette.

Get the color list for a built-in palette.

Parameters

palette

Built-in palette selector

Returns

Color list for the specified palette

setColors()

void QwtColorCycle::setColors

(

const QVector< QColor > &

colors

)

Set custom colors.

Replace current colors with a custom list.

Parameters

colors

Custom color list

setPalette()

void QwtColorCycle::setPalette

(

Palette

palette

)

Set the palette from a built-in preset.

Replace current colors with a built-in palette.

Parameters

palette

Built-in palette selector

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The documentation for this class was generated from the following files:

• /home/runner/work/QWT/QWT/src/core/qwt_color_cycle.h
• /home/runner/work/QWT/QWT/src/core/qwt_color_cycle.cpp