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QEasingCurve Class Reference
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The QEasingCurve class provides easing curves for controlling animation. More...

Types

enum Type { Linear, InQuad, OutQuad, InOutQuad, ..., Custom }

Methods

__init__ (self, Type type = QEasingCurve.Linear)
__init__ (self, QEasingCurve other)
float amplitude (self)
callable customType (self)
float overshoot (self)
float period (self)
setAmplitude (self, float amplitude)
setCustomType (self, callable func)
setOvershoot (self, float overshoot)
setPeriod (self, float period)
setType (self, Type type)
Type type (self)
float valueForProgress (self, float progress)

Special Methods

bool __eq__ (self, QEasingCurve other)
bool __ne__ (self, QEasingCurve other)

Detailed Description

The QEasingCurve class provides easing curves for controlling animation.

Easing curves describe a function that controls how the speed of the interpolation between 0 and 1 should be. Easing curves allow transitions from one value to another to appear more natural than a simple constant speed would allow. The QEasingCurve class is usually used in conjunction with the QVariantAnimation and QPropertyAnimation classes but can be used on its own. It is usually used to accelerate the interpolation from zero velocity (ease in) or decelerate to zero velocity (ease out). Ease in and ease out can also be combined in the same easing curve.

To calculate the speed of the interpolation, the easing curve provides the function valueForProgress(), where the progress argument specifies the progress of the interpolation: 0 is the start value of the interpolation, 1 is the end value of the interpolation. The returned value is the effective progress of the interpolation. If the returned value is the same as the input value for all input values the easing curve is a linear curve. This is the default behaviour.

For example,

 QEasingCurve easing(QEasingCurve.InOutQuad);

 for(qreal t = 0.0; t < 1.0; t+=0.1)
     qWarning() << "Effective progress" << t << " is
                << easing.valueForProgress(t);

will print the effective progress of the interpolation between 0 and 1.

When using a QPropertyAnimation, the associated easing curve will be used to control the progress of the interpolation between startValue and endValue:

 QPropertyAnimation animation;
 animation.setStartValue(0);
 animation.setEndValue(1000);
 animation.setDuration(1000);
 animation.setEasingCurve(QEasingCurve.InOutQuad);

The ability to set an amplitude, overshoot, or period depends on the QEasingCurve type. Amplitude access is available to curves that behave as springs such as elastic and bounce curves. Changing the amplitude changes the height of the curve. Period access is only available to elastic curves and setting a higher period slows the rate of bounce. Only curves that have "boomerang" behaviors such as the InBack, OutBack, InOutBack, and OutInBack have overshoot settings. These curves will interpolate beyond the end points and return to the end point, acting similar to a boomerang.

The Easing Curves Example contains samples of QEasingCurve types and lets you change the curve settings.

Type Documentation

QEasingCurve.Type

The type of easing curve.

Constant	Value	Description
`QEasingCurve.Linear`	`0`	Easing curve for a linear (t) function: velocity is constant.
`QEasingCurve.InQuad`	`1`	Easing curve for a quadratic (t^2) function: accelerating from zero velocity.
`QEasingCurve.OutQuad`	`2`	Easing curve for a quadratic (t^2) function: decelerating to zero velocity.
`QEasingCurve.InOutQuad`	`3`	Easing curve for a quadratic (t^2) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInQuad`	`4`	Easing curve for a quadratic (t^2) function: deceleration until halfway, then acceleration.
`QEasingCurve.InCubic`	`5`	Easing curve for a cubic (t^3) function: accelerating from zero velocity.
`QEasingCurve.OutCubic`	`6`	Easing curve for a cubic (t^3) function: decelerating to zero velocity.
`QEasingCurve.InOutCubic`	`7`	Easing curve for a cubic (t^3) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInCubic`	`8`	Easing curve for a cubic (t^3) function: deceleration until halfway, then acceleration.
`QEasingCurve.InQuart`	`9`	Easing curve for a quartic (t^4) function: accelerating from zero velocity.
`QEasingCurve.OutQuart`	`10`	Easing curve for a quartic (t^4) function: decelerating to zero velocity.
`QEasingCurve.InOutQuart`	`11`	Easing curve for a quartic (t^4) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInQuart`	`12`	Easing curve for a quartic (t^4) function: deceleration until halfway, then acceleration.
`QEasingCurve.InQuint`	`13`	Easing curve for a quintic (t^5) easing in: accelerating from zero velocity.
`QEasingCurve.OutQuint`	`14`	Easing curve for a quintic (t^5) function: decelerating to zero velocity.
`QEasingCurve.InOutQuint`	`15`	Easing curve for a quintic (t^5) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInQuint`	`16`	Easing curve for a quintic (t^5) function: deceleration until halfway, then acceleration.
`QEasingCurve.InSine`	`17`	Easing curve for a sinusoidal (sin(t)) function: accelerating from zero velocity.
`QEasingCurve.OutSine`	`18`	Easing curve for a sinusoidal (sin(t)) function: decelerating from zero velocity.
`QEasingCurve.InOutSine`	`19`	Easing curve for a sinusoidal (sin(t)) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInSine`	`20`	Easing curve for a sinusoidal (sin(t)) function: deceleration until halfway, then acceleration.
`QEasingCurve.InExpo`	`21`	Easing curve for an exponential (2^t) function: accelerating from zero velocity.
`QEasingCurve.OutExpo`	`22`	Easing curve for an exponential (2^t) function: decelerating from zero velocity.
`QEasingCurve.InOutExpo`	`23`	Easing curve for an exponential (2^t) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInExpo`	`24`	Easing curve for an exponential (2^t) function: deceleration until halfway, then acceleration.
`QEasingCurve.InCirc`	`25`	Easing curve for a circular (sqrt(1-t^2)) function: accelerating from zero velocity.
`QEasingCurve.OutCirc`	`26`	Easing curve for a circular (sqrt(1-t^2)) function: decelerating from zero velocity.
`QEasingCurve.InOutCirc`	`27`	Easing curve for a circular (sqrt(1-t^2)) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInCirc`	`28`	Easing curve for a circular (sqrt(1-t^2)) function: deceleration until halfway, then acceleration.
`QEasingCurve.InElastic`	`29`	Easing curve for an elastic (exponentially decaying sine wave) function: accelerating from zero velocity. The peak amplitude can be set with the amplitude parameter, and the period of decay by the period parameter.
`QEasingCurve.OutElastic`	`30`	Easing curve for an elastic (exponentially decaying sine wave) function: decelerating from zero velocity. The peak amplitude can be set with the amplitude parameter, and the period of decay by the period parameter.
`QEasingCurve.InOutElastic`	`31`	Easing curve for an elastic (exponentially decaying sine wave) function: acceleration until halfway, then deceleration.
`QEasingCurve.OutInElastic`	`32`	Easing curve for an elastic (exponentially decaying sine wave) function: deceleration until halfway, then acceleration.
`QEasingCurve.InBack`	`33`	Easing curve for a back (overshooting cubic function: (s+1)t^3 - st^2) easing in: accelerating from zero velocity.
`QEasingCurve.OutBack`	`34`	Easing curve for a back (overshooting cubic function: (s+1)t^3 - st^2) easing out: decelerating to zero velocity.
`QEasingCurve.InOutBack`	`35`	Easing curve for a back (overshooting cubic function: (s+1)t^3 - st^2) easing in/out: acceleration until halfway, then deceleration.
`QEasingCurve.OutInBack`	`36`	Easing curve for a back (overshooting cubic easing: (s+1)t^3 - st^2) easing out/in: deceleration until halfway, then acceleration.
`QEasingCurve.InBounce`	`37`	Easing curve for a bounce (exponentially decaying parabolic bounce) function: accelerating from zero velocity.
`QEasingCurve.OutBounce`	`38`	Easing curve for a bounce (exponentially decaying parabolic bounce) function: decelerating from zero velocity.
`QEasingCurve.InOutBounce`	`39`	Easing curve for a bounce (exponentially decaying parabolic bounce) function easing in/out: acceleration until halfway, then deceleration.
`QEasingCurve.OutInBounce`	`40`	Easing curve for a bounce (exponentially decaying parabolic bounce) function easing out/in: deceleration until halfway, then acceleration.
`QEasingCurve.Custom`	`45`	This is returned if the user specified a custom curve type with setCustomType(). Note that you cannot call setType() with this value, but type() can return it.