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The QGradient class is used in combination with QBrush to specify gradient fills. More...
Inherited by QConicalGradient, QLinearGradient, and QRadialGradient.
The QGradient class is used in combination with QBrush to specify gradient fills.
Qt currently supports three types of gradient fills:
A gradient's type can be retrieved using the type function. Each of the types is represented by a subclass of QGradient:
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QLinearGradient | QRadialGradient | QConicalGradient |
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The colors in a gradient is 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 QGradient::Spread enum defines three different methods:
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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.
See also The Gradients Demo and QBrush.
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