QColor Class

The QColor class provides colors based on RGB values. More…

List of all members, including inherited members

Public Types

Public Functions

Static Public Members

Detailed Description

A color is a red, green, blue and alpha value, each from 0 to 255. It can be built from components, a QRgb, a Qt::GlobalColor or a name such as "#ff8000" or "steelblue":

QColor orange(255, 128, 0);
QColor translucent = QColor::fromRgb(0, 0, 255, 128);
QColor named("#336699");

A default-constructed QColor is invalid; isValid() returns false.

See also QBrush, QPen and QImage.

Differences from Qt

Member Type Documentation

enum QColor::NameFormat

This enum selects the form of name().

enum QColor::Spec

This enum describes how a color is specified.

Member Function Documentation

QColor::QColor()

Constructs an invalid color.

See also isValid().

QColor::QColor(Qt::GlobalColor color)

Constructs a color for the predefined color.

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

Constructs a color with the components r, g, b and a, each clamped to the range 0 to 255.

QColor::QColor(QRgb rgb)

Constructs an opaque color from rgb. The alpha byte of rgb is ignored; use fromRgba() to keep it.

QColor::QColor(const QString &name)

Constructs a color from name, which is a hex form or a color name. The color is invalid if the name is not recognized.

See also setNamedColor().

QColor::QColor(const char *name)

This is an overloaded function.

Constructs a color from the Latin-1 string name.

int QColor::alpha() const

Returns the alpha component, from 0 (transparent) to 255 (opaque).

See also setAlpha() and alphaF().

qreal QColor::alphaF() const

Returns the alpha component from 0.0 to 1.0.

See also alpha() and setAlphaF().

int QColor::blue() const

Returns the blue component, from 0 to 255.

See also setBlue() and blueF().

qreal QColor::blueF() const

Returns the blue component from 0.0 to 1.0.

See also blue() and setBlueF().

QColor QColor::darker(int factor = 200) const

Returns a darker color. A factor of 200 halves the value; 100 or less returns the color unchanged.

See also lighter().

[static] QColor QColor::fromHsv(int h, int s, int v, int a = 255)

Returns the color with hue h (0 to 359), saturation s, value v and alpha a (each 0 to 255). A negative h gives a gray.

[static] QColor QColor::fromRgb(int r, int g, int b, int a = 255)

Returns the color with the components r, g, b and a.

[static] QColor QColor::fromRgb(QRgb rgb)

This is an overloaded function.

Returns the opaque color for rgb.

[static] QColor QColor::fromRgba(QRgb rgba)

Returns the color for rgba, including its alpha byte.

[static] QColor QColor::fromRgbF(qreal r, qreal g, qreal b, qreal a = 1.0)

Returns the color with the components r, g, b and a, each from 0.0 to 1.0.

[static] QColor QColor::fromString(const QString &name)

Returns the color called name, or an invalid color.

See also setNamedColor().

void QColor::getRgb(int *r, int *g, int *b, int *a = nullptr) const

Stores the components in r, g, b and, if not null, a.

See also setRgb().

int QColor::green() const

Returns the green component, from 0 to 255.

See also setGreen() and greenF().

qreal QColor::greenF() const

Returns the green component from 0.0 to 1.0.

See also green() and setGreenF().

int QColor::hue() const

Returns the hue, from 0 to 359, or -1 for a gray.

See also saturation() and value().

bool QColor::isValid() const

Returns true if the color is valid; otherwise returns false.

[static] bool QColor::isValidColor(const QString &name)

Returns true if name is a color name that setNamedColor() accepts.

QColor QColor::lighter(int factor = 150) const

Returns a lighter color. A factor of 150 makes the value 50% higher; 100 or less returns the color unchanged. Black becomes dark gray.

See also darker().

QString QColor::name(NameFormat format = HexRgb) const

Returns the name of the color in the given format: #RRGGBB for HexRgb and #AARRGGBB for HexArgb. An invalid color gives an empty string.

See also setNamedColor().

int QColor::red() const

Returns the red component, from 0 to 255.

See also setRed() and redF().

qreal QColor::redF() const

Returns the red component from 0.0 to 1.0.

See also red() and setRedF().

QRgb QColor::rgb() const

Returns the color as an opaque QRgb; the alpha component is dropped.

See also rgba().

QRgb QColor::rgba() const

Returns the color as a QRgb that includes the alpha component.

See also rgb().

int QColor::saturation() const

Returns the HSV saturation, from 0 to 255.

See also hue() and value().

void QColor::setAlpha(int alpha)

Sets the alpha component to alpha, clamped to 0 to 255. The color becomes valid.

See also alpha().

void QColor::setAlphaF(qreal alpha)

Sets the alpha component to alpha, from 0.0 to 1.0.

See also alphaF().

void QColor::setBlue(int blue)

Sets the blue component to blue, clamped to 0 to 255. The color becomes valid.

See also blue().

void QColor::setBlueF(qreal blue)

Sets the blue component to blue, from 0.0 to 1.0.

See also blueF().

void QColor::setGreen(int green)

Sets the green component to green, clamped to 0 to 255. The color becomes valid.

See also green().

void QColor::setGreenF(qreal green)

Sets the green component to green, from 0.0 to 1.0.

See also greenF().

void QColor::setNamedColor(const QString &name)

Sets the color to the one called name: #rgb, #rrggbb, #aarrggbb or a color name, in any case. The color becomes invalid if name is not recognized.

See also isValidColor() and name().

void QColor::setRed(int red)

Sets the red component to red, clamped to 0 to 255. The color becomes valid.

See also red().

void QColor::setRedF(qreal red)

Sets the red component to red, from 0.0 to 1.0.

See also redF().

void QColor::setRgb(int r, int g, int b, int a = 255)

Sets the color to the components r, g, b and a.

See also getRgb().

void QColor::setRgb(QRgb rgb)

This is an overloaded function.

Sets the color to rgb, with full opacity.

void QColor::setRgba(QRgb rgba)

Sets the color to rgba, including its alpha byte.

See also rgba().

Spec QColor::spec() const

Returns Rgb for a valid color and Invalid otherwise.

int QColor::value() const

Returns the HSV value, from 0 to 255.

See also hue() and saturation().