QVariantAnimation¶

The QVariantAnimation class provides a base class for animations. More…

Inherited by: QPropertyAnimation

New in version 4.6.

Synopsis¶

Functions¶

def currentValue ()
def easingCurve ()
def endValue ()
def keyValueAt (step)
def keyValues ()
def setDuration (msecs)
def setEasingCurve (easing)
def setEndValue (value)
def setKeyValueAt (step, value)
def setKeyValues (values)
def setStartValue (value)
def startValue ()

Virtual functions¶

def interpolated (from, to, progress)
def updateCurrentValue (value)

Signals¶

def valueChanged (value)

Detailed Description¶

This class is part of The Animation Framework . It serves as a base class for property and item animations, with functions for shared functionality.

The class performs interpolation over QVariant s, but leaves using the interpolated values to its subclasses. Currently, Qt provides QPropertyAnimation , which animates Qt properties . See the QPropertyAnimation class description if you wish to animate such properties.

You can then set start and end values for the property by calling setStartValue() and setEndValue() , and finally call start() to start the animation. QVariantAnimation will interpolate the property of the target object and emit valueChanged() . To react to a change in the current value you have to reimplement the updateCurrentValue() virtual function or connect to said signal.

It is also possible to set values at specified steps situated between the start and end value. The interpolation will then touch these points at the specified steps. Note that the start and end values are defined as the key values at 0.0 and 1.0.

There are two ways to affect how QVariantAnimation interpolates the values. You can set an easing curve by calling setEasingCurve() , and configure the duration by calling setDuration() . You can change how the QVariant s are interpolated by creating a subclass of QVariantAnimation , and reimplementing the virtual interpolated() function.

Subclassing QVariantAnimation can be an alternative if you have QVariant s that you do not wish to declare as Qt properties. Note, however, that you in most cases will be better off declaring your QVariant as a property.

Not all QVariant types are supported. Below is a list of currently supported QVariant types:

Int

UInt

Double

Float

QLine

QLineF

QPoint

QPointF

QSize

QSizeF

QRect

QRectF

QColor

If you need to interpolate other variant types, including custom types, you have to implement interpolation for these yourself. To do this, you can register an interpolator function for a given type. This function takes 3 parameters: the start value, the end value, and the current progress.

Example:
QVariant myColorInterpolator(const QColor &start, const QColor &end, qreal progress)
{
    ...
    return QColor(...);
}
...
qRegisterAnimationInterpolator<QColor>(myColorInterpolator);
Another option is to reimplement interpolated() , which returns interpolation values for the value being interpolated.

See also

QPropertyAnimation QAbstractAnimation The Animation Framework

class QVariantAnimation([parent=None])¶

param parent

QObject

Construct a QVariantAnimation object. parent is passed to QAbstractAnimation ‘s constructor.

PySide2.QtCore.QVariantAnimation.currentValue()¶

Return type: object

PySide2.QtCore.QVariantAnimation.easingCurve()¶

Return type: QEasingCurve

See also

setEasingCurve()

PySide2.QtCore.QVariantAnimation.endValue()¶

Return type: object

See also

setEndValue()

PySide2.QtCore.QVariantAnimation.interpolated(from, to, progress)¶

Parameters

from – object
to – object
progress – qreal

Return type

object

This virtual function returns the linear interpolation between variants from and to , at progress , usually a value between 0 and 1. You can reimplement this function in a subclass of QVariantAnimation to provide your own interpolation algorithm.

Note that in order for the interpolation to work with a QEasingCurve that return a value smaller than 0 or larger than 1 (such as InBack ) you should make sure that it can extrapolate. If the semantic of the datatype does not allow extrapolation this function should handle that gracefully.

You should call the QVariantAnimation implementation of this function if you want your class to handle the types already supported by Qt (see class QVariantAnimation description for a list of supported types).

See also

QEasingCurve

PySide2.QtCore.QVariantAnimation.keyValueAt(step)¶

Parameters: step – qreal
Return type: object

Returns the key frame value for the given step . The given step must be in the range 0 to 1. If there is no KeyValue for step , it returns an invalid QVariant .

See also

keyValues() setKeyValueAt()

PySide2.QtCore.QVariantAnimation.keyValues()¶