KColorUtils Namespace Reference

Functions
qreal	contrastRatio (const QColor &, const QColor &)
QColor	darken (const QColor &, qreal amount=0.5, qreal chromaGain=1.0)
QColor	lighten (const QColor &, qreal amount=0.5, qreal chromaInverseGain=1.0)
qreal	luma (const QColor &)
QColor	mix (const QColor &c1, const QColor &c2, qreal bias=0.5)
QColor	overlayColors (const QColor &base, const QColor &paint, QPainter::CompositionMode comp=QPainter::CompositionMode_SourceOver)
QColor	shade (const QColor &, qreal lumaAmount, qreal chromaAmount=0.0)
QColor	tint (const QColor &base, const QColor &color, qreal amount=0.3)

Detailed Description

A set of methods used to work with colors.

Function Documentation

qreal KColorUtils::contrastRatio	(	const QColor &	c1,
		const QColor &	c2
	)

Calculate the contrast ratio between two colors, according to the W3C/WCAG2.0 algorithm, (Lmax + 0.05)/(Lmin + 0.05), where Lmax and Lmin are the luma values of the lighter color and the darker color, respectively.

A contrast ration of 5:1 (result == 5.0) is the minimum for "normal" text to be considered readable (large text can go as low as 3:1). The ratio ranges from 1:1 (result == 1.0) to 21:1 (result == 21.0).

See also

KColorUtils::luma

Definition at line 50 of file kcolorutils.cpp.

QColor KColorUtils::darken	(	const QColor &	color,
		qreal	amount = 0.5,
		qreal	chromaGain = 1.0
	)

Adjust the luma of a color by changing its distance from black.

• amount == 1.0 gives black
• amount == 0.5 results in a color whose luma is halfway between 0.0 and that of the original color
• amount == 0.0 gives the original color
• amount == -1.0 gives a color that is 'twice as far from black' as the original color, that is luma(result) == 2*luma(color)

Parameters

amount	factor by which to adjust the luma component of the color
chromaGain	(optional) factor by which to adjust the chroma component of the color; 1.0 means no change, 0.0 minimizes chroma

See also

KColorUtils::shade

Definition at line 63 of file kcolorutils.cpp.

QColor KColorUtils::lighten	(	const QColor &	color,
		qreal	amount = 0.5,
		qreal	chromaInverseGain = 1.0
	)

Adjust the luma of a color by changing its distance from white.

• amount == 1.0 gives white
• amount == 0.5 results in a color whose luma is halfway between 1.0 and that of the original color
• amount == 0.0 gives the original color
• amount == -1.0 gives a color that is 'twice as far from white' as the original color, that is luma(result) == 1.0 - 2*(1.0 - luma(color))

Parameters

amount	factor by which to adjust the luma component of the color
chromaInverseGain	(optional) factor by which to adjust the chroma component of the color; 1.0 means no change, 0.0 maximizes chroma

See also

KColorUtils::shade

Definition at line 55 of file kcolorutils.cpp.

qreal KColorUtils::luma

(

const QColor &

color

)

Calculate the luma of a color.

Luma is weighted sum of gamma-adjusted R'G'B' components of a color. The result is similar to qGray. The range is from 0.0 (black) to 1.0 (white).

KColorUtils::darken(), KColorUtils::lighten() and KColorUtils::shade() operate on the luma of a color.

See also

http://en.wikipedia.org/wiki/Luma_(video)

Definition at line 37 of file kcolorutils.cpp.

QColor KColorUtils::mix	(	const QColor &	c1,
		const QColor &	c2,
		qreal	bias = 0.5
	)

Blend two colors into a new color by linear combination.

QColor lighter = KColorUtils::mix(myColor, Qt::white)

Parameters

c1	first color.
c2	second color.
bias	weight to be used for the mix. bias <= 0 gives c1, bias >= 1 gives c2. bias == 0.5 gives a 50% blend of c1 and c2.

Definition at line 110 of file kcolorutils.cpp.

QColor KColorUtils::overlayColors	(	const QColor &	base,
		const QColor &	paint,
		QPainter::CompositionMode	comp = QPainter::CompositionMode_SourceOver
	)

Blend two colors into a new color by painting the second color over the first using the specified composition mode.

QColor white(Qt::white);
white.setAlphaF(0.5);
QColor lighter = KColorUtils::overlayColors(myColor, white);

Parameters

base	the base color (alpha channel is ignored).
paint	the color to be overlayed onto the base color.
comp	the CompositionMode used to do the blending.

Definition at line 124 of file kcolorutils.cpp.

QColor KColorUtils::shade	(	const QColor &	color,
		qreal	lumaAmount,
		qreal	chromaAmount = 0.0
	)

Adjust the luma and chroma components of a color.

The amount is added to the corresponding component.

Parameters

lumaAmount	amount by which to adjust the luma component of the color; 0.0 results in no change, -1.0 turns anything black, 1.0 turns anything white
chromaAmount	(optional) amount by which to adjust the chroma component of the color; 0.0 results in no change, -1.0 minimizes chroma, 1.0 maximizes chroma

See also

KColorUtils::luma

Definition at line 71 of file kcolorutils.cpp.

QColor KColorUtils::tint	(	const QColor &	base,
		const QColor &	color,
		qreal	amount = 0.3
	)

Create a new color by tinting one color with another.

This function is meant for creating additional colors withing the same class (background, foreground) from colors in a different class. Therefore when amount is low, the luma of base is mostly preserved, while the hue and chroma of color is mostly inherited.

Parameters

base	color to be tinted
color	color with which to tint
amount	how strongly to tint the base; 0.0 gives base, 1.0 gives color

Definition at line 87 of file kcolorutils.cpp.