Color with alpha channel in RGB space. More...

#include <color.h>

Public Member Functions
	Color (const double &=0.0)
	Creates a greyscale color.

	Color (unsigned long)
	Creates a color given a compact color representation.

	Color (const double &, const double &, const double &, const double &=1.0)
	Creates a color given each of these components.

	Color (const Vector &, const double &=1.0)
	Creates a color.

	Color (int, int, int, int=255)
	Create a color given integer components.

	Color (const QColor &)
	Create a color from Qt representation.

	Color (const QRgb &)
	Create a color from Qt representation.

	~Color ()
	Empty.

Color	Pow (const double &=2.2) const
	Apply gamma correction.

Color &	operator+= (const Color &)
	Overloaded operator.

Color	Scale (const Color &) const
	Scale.

Color &	*operator=** (const double &)
	Destructive scalar multiply.

Color	Clamp (const Color &=Color::Black, const Color &=Color::White) const
	Clamp a color between two bounds.

double	Luminance () const
	Compute the luminance.

unsigned long	Cast () const
	Returns a compact color format of the RGB-alpha system value of the color.

constexpr double &	operator[] (int)
	Returns the i^th channel of the spectrum.

constexpr double	operator[] (int) const
	Returns a copy of the i^th channel of the spectrum.

QColor	GetQt () const
	Create a Qt color from a color.

Static Public Member Functions
static Color	Min (const Color &, const Color &)
	Returns the minimum value of each component.

static Color	Max (const Color &, const Color &)
	Returns the maximum value of each component.

static Color	Lerp (const double &, const Color &, const Color &)
	Linear interpolation between two colors.

static Color	Get (const QVector< Color > &, const double &t)
	Compute a color in a discretized array of colors.

static QColor	LerpQt (const QColor &, const QColor &, const double &, int)
	Interpolate two Qt colors in the prescribed space.

static Color	BiCubic (const double &, const double &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &, const Color &=Color::Black, const Color &=Color::Black, const Color &=Color::Black, const Color &=Color::Black)
	Bi-cubic interpolation between four values, given partial derivatives.

static Color	Bilinear (const Color &, const Color &, const Color &, const Color &, const double &, const double &)
	Bi-linear interpolation between four colors.

static const Color	Grey (const double &)
	Grey.

Static Public Attributes
static const Color	Black
	Black.

static const Color	White
	White.

static const Color	Red
	Red.

static const Color	Blue
	Blue.

static const Color	Transparent
	Transparent.

Protected Attributes
double	c [4] = { 0.0,0.0,0.0,1.0 }
	Array of color components, with an alpha channel.

Friends
Color	operator+ (const Color &u, const Color &v)
	Overloaded sum operator.

Color	operator- (const Color &u, const Color &v)
	Overloaded difference operator.

Color	operator* (const Color &u, const double &a)
	Overloaded product by a scalar operator.

Color	operator* (const double &a, const Color &c)
	Overloaded product by a scalar operator.

Color	operator/ (const Color &c, const double &a)
	Overloaded division by a scalar operator.

std::ostream &	operator<< (std::ostream &s, const Color &c)
	Overloaded output-stream operator.

Detailed Description

Color with alpha channel in RGB space.

Colors are represented using double.

Several constructors exist, two of them may be confusing:

Color c(127,24,216); // Use constructor with integer parameters in [0,255] range.

Color c(0.5,0.1,0.84); // Use double parameters, in [0.0,1.0] range.

Color::c

double c[4]

Array of color components, with an alpha channel.

Definition color.h:17

Color::Color

Color(const double &=0.0)

Creates a greyscale color.

Definition color.h:133

Constructor & Destructor Documentation

◆ Color() [1/7]

Color::Color ( const double & v = 0.0 )

inlineexplicit

Creates a greyscale color.

Initializes all the components to the given value except the opacity coefficient wich is set to 1.0.

Parameters

v	Grey value.

◆ Color() [2/7]

Color::Color ( unsigned long x )

inlineexplicit

Creates a color given a compact color representation.

Parameters

x	Color compacted into an unsigned long.

◆ Color() [3/7]

Color::Color	(	const double &	r,
		const double &	g,
		const double &	b,
		const double &	a = 1.0 )

inlineexplicit

Creates a color given each of these components.

Parameters

r,g,b	Red, green and blue components.
a	Alpha channel, set to 1.0 (opaque) as default.

◆ Color() [4/7]

Color::Color	(	const Vector &	v,
		const double &	a = 1.0 )

inlineexplicit

Creates a color.

Parameters

v	Vector, coordinates interpreted as red, green and blue components.
a	Alpha channel, set to 1.0 (opaque) as default.

◆ Color() [5/7]

Color::Color	(	int	r,
		int	g,
		int	b,
		int	a = 255 )

inlineexplicit

Create a color given integer components.

Parameters

r,g,b	Red, green and blue components.
a	Alpha channel, set to 255 (opaque) as default.

◆ Color() [6/7]

Color::Color ( const QColor & c )

explicit

Create a color from Qt representation.

Parameters

c	Color in Qt.

◆ Color() [7/7]

Color::Color ( const QRgb & c )

explicit

Create a color from Qt representation.

Parameters

c	Color in Qt.

Member Function Documentation

◆ BiCubic()

Color Color::BiCubic	(	const double &	u,
		const double &	v,
		const Color &	a00,
		const Color &	a10,
		const Color &	a11,
		const Color &	a01,
		const Color &	u00,
		const Color &	u10,
		const Color &	u11,
		const Color &	u01,
		const Color &	v00,
		const Color &	v10,
		const Color &	v11,
		const Color &	v01,
		const Color &	x00 = Color::Black,
		const Color &	x10 = Color::Black,
		const Color &	x11 = Color::Black,
		const Color &	x01 = Color::Black )

static

Bi-cubic interpolation between four values, given partial derivatives.

The values are given in trigonometric order.

See also: Math::BiCubic

Parameters

u,v	Interpolation coefficients.
a00,a10,a11,a01	Interpolated values.
u00,u10,u11,u01,v00,v10,v11,v01	Partial derivatives with respect to u and v.
x00,x10,x11,x01	Cross derivatives.

◆ Bilinear()

Color Color::Bilinear	(	const Color &	a00,
		const Color &	a10,
		const Color &	a11,
		const Color &	a01,
		const double &	u,
		const double &	v )

static

Bi-linear interpolation between four colors.

See also: Math::Bilinear

Parameters

a00,a10,a11,a01	Interpolated colors.
u,v	Interpolation coefficients.

◆ Clamp()

Color Color::Clamp	(	const Color &	a = Color::Black,
		const Color &	b = Color::White ) const

inline

Clamp a color between two bounds.

Parameters

a,b	Color bounds.

◆ Get()

Color Color::Get	(	const QVector< Color > &	c,
		const double &	t )

static

Compute a color in a discretized array of colors.

Parameters

c	Array of colors.
t	Interpolation factor.

◆ GetQt()

QColor Color::GetQt ( ) const

inline

Create a Qt color from a color.

Example how to write a pixel with a given color in an image:

QImage image;
Color c;
image.setPixel(i, j, c.GetQt().rgb());

◆ Grey()

const Color Color::Grey ( const double & g )

inlinestatic

Grey.

Same as Color(const double&)

Parameters

g	Grey level.

◆ Lerp()

Color Color::Lerp	(	const double &	t,
		const Color &	a,
		const Color &	b )

inlinestatic

Linear interpolation between two colors.

Interpolation is performed in RGB space.

Note that the following lines are equivalent:

Color a,b;
double t;
Color c=(1.0-t)*a+t*b;
Color c=Lerp(t,a,b);

◆ LerpQt()

QColor Color::LerpQt	(	const QColor &	a,
		const QColor &	b,
		const double &	t,
		int	s )

static

Interpolate two Qt colors in the prescribed space.

The color space can be QColor::Rgb, QColor::Hsv, QColor::Cmyk or QColor::Hsl.

Parameters

a,b	Colors.
t	Interpolation parameter.
s	Color space.

◆ Max()

Color Color::Max	(	const Color &	a,
		const Color &	b )

static

Returns the maximum value of each component.

Parameters

a,b	Argument colors.

◆ Min()

Color Color::Min	(	const Color &	a,
		const Color &	b )

static

Returns the minimum value of each component.

Parameters

a,b	Argument colors.

◆ operator[]() [1/2]

double & Color::operator[] ( int i )

inlineconstexpr

Returns the i^th channel of the spectrum.

Parameters

i	nummber of the channel queried (default=last)

◆ operator[]() [2/2]

double Color::operator[] ( int i ) const

inlineconstexpr

Returns a copy of the i^th channel of the spectrum.

Parameters

i	nummber of the channel queried (default=last)

◆ Pow()

Color Color::Pow ( const double & gamma = 2.2 ) const

Apply gamma correction.

Parameters

gamma Exponential coefficient.

◆ Scale()

Color Color::Scale ( const Color & v ) const

inline

Scale.

Parameters

v Color.

Friends And Related Symbol Documentation

◆ operator*

Color operator*	(	const double &	a,
		const Color &	c )

friend

Overloaded product by a scalar operator.

Parameters

c	Color.
a	Scalar.

◆ operator/

Color operator/	(	const Color &	c,
		const double &	a )

friend

Overloaded division by a scalar operator.

Parameters

c	Color.
a	Scalar.

◆ operator<<

std::ostream & operator<<	(	std::ostream &	s,
		const Color &	c )

friend

Overloaded output-stream operator.

Parameters

c	Color.
s	Stream.

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ Color() [1/7]

◆ Color() [2/7]

◆ Color() [3/7]

◆ Color() [4/7]

◆ Color() [5/7]

◆ Color() [6/7]

◆ Color() [7/7]

Member Function Documentation

◆ BiCubic()

◆ Bilinear()

◆ Clamp()

◆ Get()

◆ GetQt()

◆ Grey()

◆ Lerp()

◆ LerpQt()

◆ Max()

◆ Min()

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ Pow()

◆ Scale()

Friends And Related Symbol Documentation

◆ operator*

◆ operator/

◆ operator<<