QGradient

The QGradient class is used in combination with QBrush to specify gradient fills. More

Inheritance diagram of PySide2.QtGui.QGradient

Inherited by: QConicalGradient, QLinearGradient, QRadialGradient

Synopsis

Functions

Detailed Description

Qt currently supports three types of gradient fills:

  • Linear gradients interpolate colors between start and end points.

  • Simple radial gradients interpolate colors between a focal point and end points on a circle surrounding it.

  • Extended radial gradients interpolate colors between a center and a focal circle.

  • Conical gradients interpolate colors around a center point.

A gradient’s type can be retrieved using the type() function. Each of the types is represented by a subclass of QGradient :

QLinearGradient

QRadialGradient

QConicalGradient

qgradient-linear1

qgradient-radial2

qgradient-conical3

The colors in a gradient are defined using stop points of the QGradientStop type; i.e., a position and a color. Use the setColorAt() function to define a single stop point. Alternatively, use the setStops() function to define several stop points in one go. Note that the latter function replaces the current set of stop points.

It is the gradient’s complete set of stop points (accessible through the stops() function) that describes how the gradient area should be filled. If no stop points have been specified, a gradient of black at 0 to white at 1 is used.

A diagonal linear gradient from black at (100, 100) to white at (200, 200) could be specified like this:

QLinearGradient linearGrad(QPointF(100, 100), QPointF(200, 200));
linearGrad.setColorAt(0, Qt::black);
linearGrad.setColorAt(1, Qt::white);

A gradient can have an arbitrary number of stop points. The following would create a radial gradient starting with red in the center, blue and then green on the edges:

QRadialGradient radialGrad(QPointF(100, 100), 100);
radialGrad.setColorAt(0, Qt::red);
radialGrad.setColorAt(0.5, Qt::blue);
radialGrad.setColorAt(1, Qt::green);

It is possible to repeat or reflect the gradient outside its area by specifiying the spread method using the setSpread() function. The default is to pad the outside area with the color at the closest stop point. The currently set spread method can be retrieved using the spread() function. The Spread enum defines three different methods:

qradialgradient-pad4

qradialgradient-repeat5

qradialgradient-reflect6

PadSpread

RepeatSpread

ReflectSpread

Note that the setSpread() function only has effect for linear and radial gradients. The reason is that the conical gradient is closed by definition, i.e. the conical gradient fills the entire circle from 0 - 360 degrees, while the boundary of a radial or a linear gradient can be specified through its radius or final stop points, respectively.

The gradient coordinates can be specified in logical coordinates, relative to device coordinates, or relative to object bounding box coordinates. The coordinate mode can be set using the setCoordinateMode() function. The default is LogicalMode , where the gradient coordinates are specified in the same way as the object coordinates. To retrieve the currently set coordinate mode use coordinateMode() .

See also

The Gradients Example QBrush

class QGradient

QGradient(arg__1)

QGradient(QGradient)

param arg__1

Preset

param QGradient

QGradient

Constructs a gradient based on a predefined preset .

The coordinate mode of the resulting gradient is ObjectMode , allowing the preset to be applied to arbitrary object sizes.

PySide2.QtGui.QGradient.Type

Specifies the type of gradient.

Constant

Description

QGradient.LinearGradient

Interpolates colors between start and end points ( QLinearGradient ).

QGradient.RadialGradient

Interpolate colors between a focal point and end points on a circle surrounding it ( QRadialGradient ).

QGradient.ConicalGradient

Interpolate colors around a center point ( QConicalGradient ).

QGradient.NoGradient

No gradient is used.

See also

type()

PySide2.QtGui.QGradient.Spread

Specifies how the area outside the gradient area should be filled.

Constant

Description

QGradient.PadSpread

The area is filled with the closest stop color. This is the default.

QGradient.RepeatSpread

The gradient is repeated outside the gradient area.

QGradient.ReflectSpread

The gradient is reflected outside the gradient area.

PySide2.QtGui.QGradient.CoordinateMode

This enum specifies how gradient coordinates map to the paint device on which the gradient is used.

Constant

Description

QGradient.LogicalMode

This is the default mode. The gradient coordinates are specified logical space just like the object coordinates.

QGradient.ObjectMode

In this mode the gradient coordinates are relative to the bounding rectangle of the object being drawn, with (0,0) in the top left corner, and (1,1) in the bottom right corner of the object’s bounding rectangle. This value was added in Qt 5.12.

QGradient.StretchToDeviceMode

In this mode the gradient coordinates are relative to the bounding rectangle of the paint device, with (0,0) in the top left corner, and (1,1) in the bottom right corner of the paint device.

QGradient.ObjectBoundingMode

This mode is the same as , except that the { transform() } {brush transform}, if any, is applied relative to the logical space instead of the object space. This enum value is deprecated and should not be used in new code.

PySide2.QtGui.QGradient.InterpolationMode

Constant

Description

QGradient.ComponentInterpolation

The color components and the alpha component are independently linearly interpolated.

QGradient.ColorInterpolation

The colors are linearly interpolated in premultiplied color space.

PySide2.QtGui.QGradient.Preset

This enum specifies a set of predefined presets for QGradient , based on the gradients from https://webgradients.com/.

New in version 5.12.

PySide2.QtGui.QGradient.coordinateMode()
Return type

CoordinateMode

Returns the coordinate mode of this gradient. The default mode is LogicalMode .

PySide2.QtGui.QGradient.interpolationMode()
Return type

InterpolationMode

Returns the interpolation mode of this gradient. The default mode is .

PySide2.QtGui.QGradient.__ne__(other)
Parameters

otherQGradient

Return type

bool

Returns true if the gradient is the same as the other gradient specified; otherwise returns false .

See also

operator==()

PySide2.QtGui.QGradient.__eq__(gradient)
Parameters

gradientQGradient

Return type

bool

Returns true if the gradient is the same as the other gradient specified; otherwise returns false .

See also

operator!=()

PySide2.QtGui.QGradient.setColorAt(pos, color)
Parameters
  • posqreal

  • colorQColor

Creates a stop point at the given position with the given color . The given position must be in the range 0 to 1.

See also

setStops() stops()

PySide2.QtGui.QGradient.setCoordinateMode(mode)
Parameters

modeCoordinateMode

Sets the coordinate mode of this gradient to mode . The default mode is LogicalMode .

See also

coordinateMode()

PySide2.QtGui.QGradient.setInterpolationMode(mode)
Parameters

modeInterpolationMode

Sets the interpolation mode of this gradient to mode . The default mode is .

PySide2.QtGui.QGradient.setSpread(spread)
Parameters

spreadSpread

Specifies the spread method that should be used for this gradient.

Note that this function only has effect for linear and radial gradients.

See also

spread()

PySide2.QtGui.QGradient.setStops(stops)
Parameters

stops

Replaces the current set of stop points with the given stopPoints . The positions of the points must be in the range 0 to 1, and must be sorted with the lowest point first.

PySide2.QtGui.QGradient.spread()
Return type

Spread

Returns the spread method use by this gradient. The default is PadSpread .

See also

setSpread()

PySide2.QtGui.QGradient.stops()
Return type

Returns the stop points for this gradient.

If no stop points have been specified, a gradient of black at 0 to white at 1 is used.

PySide2.QtGui.QGradient.type()
Return type

Type

Returns the type of gradient.