Function Documentation

[since 5.68] qreal KColorUtils::chroma(const QColor &)

Calculate the chroma of a color. The range is from 0.0 (none) to 1.0 (full).

The result is computed in linear (not sRGB) color space.

This function was introduced in 5.68.

See also https://en.wikipedia.org/wiki/Colorfulness.

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

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.

QColor KColorUtils::darken(const QColor &, 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)

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.

[since 5.0] void KColorUtils::getHcy(const QColor &, qreal *hue, qreal *chroma, qreal *luma, qreal *alpha = nullptr)

Calculate hue, chroma and luma of a color in one call.

The range of hue is from 0.0 (red) to almost 1.0 (slightly blue-ish red). The range of chroma is from 0.0 (none) to 1.0 (full). The range of luma is from 0.0 (black) to 1.0 (white).

The hue, chroma and luma values are computed in linear (not sRGB) color space.

This function was introduced in 5.0.

[since 5.68] QColor KColorUtils::hcyColor(qreal hue, qreal chroma, qreal luma, qreal alpha = 1.0)

Return a QColor based on the given hue, chroma, luma and alpha values.

The range of hue is cyclical. For example, 0.0 and 1.0 are both red while -0.166667 and 0.833333 are both magenta. The range of chroma is from 0.0 (none) to 1.0 (full). Out of range values will be clamped. The range of luma is from 0.0 (black) to 1.0 (white). Out of range values will be clamped.

The hue, chroma and luma values are computed in linear (not sRGB) color space.

This function was introduced in 5.68.

[since 5.68] qreal KColorUtils::hue(const QColor &)

Calculate the hue of a color. The range is from 0.0 (red) to almost 1.0 (slightly blue-ish red).

The result is computed in linear (not sRGB) color space and may differ slightly from QColor::hue().

This function was introduced in 5.68.

See also https://en.wikipedia.org/wiki/Hue.

QColor KColorUtils::lighten(const QColor &, 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))

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.

qreal KColorUtils::luma(const QColor &)

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).

The result is computed in linear (not sRGB) color space.

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

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

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)

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.

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);

base the base color (alpha channel is ignored).

paint the color to be overlaid onto the base color.

comp the CompositionMode used to do the blending.

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

Adjust the luma and chroma components of a color. The amount is added to the corresponding component.

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.

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 withings 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.

base color to be tinted

color color with which to tint

amount how strongly to tint the base; 0.0 gives @p base, 1.0 gives @p color