QEasingCurve¶
The
QEasingCurve
class provides easing curves for controlling animation. More…
New in version 4.6.
Synopsis¶
Functions¶
def
__eq__
(other)def
__ne__
(other)def
addCubicBezierSegment
(c1, c2, endPoint)def
addTCBSegment
(nextPoint, t, c, b)def
amplitude
()def
customType
()def
overshoot
()def
period
()def
setAmplitude
(amplitude)def
setCustomType
(arg__1)def
setOvershoot
(overshoot)def
setPeriod
(period)def
setType
(type)def
swap
(other)def
toCubicSpline
()def
type
()def
valueForProgress
(progress)
Detailed Description¶
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 theQVariantAnimation
andQPropertyAnimation
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 theprogress
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 theInBack
,OutBack
,InOutBack
, andOutInBack
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.

class
PySide2.QtCore.
QEasingCurve
([type=Linear])¶ PySide2.QtCore.QEasingCurve(other)
 param type
 param other
Constructs an easing curve of the given
type
.

PySide2.QtCore.QEasingCurve.
Type
¶ The type of easing curve.
Constant
Description
QEasingCurve.Linear
Constant
Description
QEasingCurve.InQuad
Constant
Description
QEasingCurve.OutQuad
Constant
Description
QEasingCurve.InOutQuad
Constant
Description
QEasingCurve.OutInQuad
Constant
Description
QEasingCurve.InCubic
Constant
Description
QEasingCurve.OutCubic
Constant
Description
QEasingCurve.InOutCubic
Constant
Description
QEasingCurve.OutInCubic
Constant
Description
QEasingCurve.InQuart
Constant
Description
QEasingCurve.OutQuart
Constant
Description
QEasingCurve.InOutQuart
Constant
Description
QEasingCurve.OutInQuart
Constant
Description
QEasingCurve.InQuint
Constant
Description
QEasingCurve.OutQuint
Constant
Description
QEasingCurve.InOutQuint
Constant
Description
QEasingCurve.OutInQuint
Constant
Description
QEasingCurve.InSine
Constant
Description
QEasingCurve.OutSine
Constant
Description
QEasingCurve.InOutSine
Constant
Description
QEasingCurve.OutInSine
Constant
Description
QEasingCurve.InExpo
Constant
Description
QEasingCurve.OutExpo
Constant
Description
QEasingCurve.InOutExpo
Constant
Description
QEasingCurve.OutInExpo
Constant
Description
QEasingCurve.InCirc
Constant
Description
QEasingCurve.OutCirc
Constant
Description
QEasingCurve.InOutCirc
Constant
Description
QEasingCurve.OutInCirc
Constant
Description
QEasingCurve.InElastic
 amplitude**period
Constant
Description
QEasingCurve.OutElastic
 amplitude**period
Constant
Description
QEasingCurve.InOutElastic
Constant
Description
QEasingCurve.OutInElastic
Constant
Description
QEasingCurve.InBack
Constant
Description
QEasingCurve.OutBack
Constant
Description
QEasingCurve.InOutBack
Constant
Description
QEasingCurve.OutInBack
Constant
Description
QEasingCurve.InBounce
Constant
Description
QEasingCurve.OutBounce
Constant
Description
QEasingCurve.InOutBounce
Constant
Description
QEasingCurve.OutInBounce
Constant
Description
QEasingCurve.BezierSpline
Allows defining a custom easing curve using a cubic bezier spline
QEasingCurve.TCBSpline
Allows defining a custom easing curve using a TCB spline
QEasingCurve.Custom
This is returned if the user specified a custom curve type with
setCustomType()
. Note that you cannot callsetType()
with this value, buttype()
can return it.See also

PySide2.QtCore.QEasingCurve.
addCubicBezierSegment
(c1, c2, endPoint)¶  Parameters
endPoint –
PySide2.QtCore.QPointF
Adds a segment of a cubic bezier spline to define a custom easing curve. It is only applicable if
type()
isBezierSpline
. Note that the spline implicitly starts at (0.0, 0.0) and has to end at (1.0, 1.0) to be a valid easing curve.c1
andc2
are the control points used for drawing the curve.endPoint
is the endpoint of the curve.

PySide2.QtCore.QEasingCurve.
addTCBSegment
(nextPoint, t, c, b)¶  Parameters
nextPoint –
PySide2.QtCore.QPointF
t – float
c – float
b – float
Adds a segment of a TCB bezier spline to define a custom easing curve. It is only applicable if
type()
isTCBSpline
. The spline has to start explitly at (0.0, 0.0) and has to end at (1.0, 1.0) to be a valid easing curve. The tensiont
changes the length of the tangent vector. The continuityc
changes the sharpness in change between the tangents. The biasb
changes the direction of the tangent vector.nextPoint
is the sample position. All three parameters are valid between 1 and 1 and define the tangent of the control point. If all three parameters are 0 the resulting spline is a CatmullRom spline. The begin and endpoint always have a bias of 1 and 1, since the outer tangent is not defined.

PySide2.QtCore.QEasingCurve.
amplitude
()¶  Return type
float
Returns the amplitude. This is not applicable for all curve types. It is only applicable for bounce and elastic curves (curves of
type()
InBounce
,OutBounce
,InOutBounce
,OutInBounce
,InElastic
,OutElastic
,InOutElastic
orOutInElastic
).See also

PySide2.QtCore.QEasingCurve.
customType
()¶  Return type
object

PySide2.QtCore.QEasingCurve.
__ne__
(other)¶  Parameters
other –
PySide2.QtCore.QEasingCurve
 Return type
bool
Compare this easing curve with
other
and returnstrue
if they are not equal. It will also compare the properties of a curve.See also
operator==()

PySide2.QtCore.QEasingCurve.
__eq__
(other)¶  Parameters
other –
PySide2.QtCore.QEasingCurve
 Return type
bool
Compare this easing curve with
other
and returnstrue
if they are equal. It will also compare the properties of a curve.

PySide2.QtCore.QEasingCurve.
overshoot
()¶  Return type
float
Returns the overshoot. This is not applicable for all curve types. It is only applicable if
type()
isInBack
,OutBack
,InOutBack
orOutInBack
.See also

PySide2.QtCore.QEasingCurve.
period
()¶  Return type
float
Returns the period. This is not applicable for all curve types. It is only applicable if
type()
isInElastic
,OutElastic
,InOutElastic
orOutInElastic
.See also

PySide2.QtCore.QEasingCurve.
setAmplitude
(amplitude)¶  Parameters
amplitude – float
Sets the amplitude to
amplitude
.This will set the amplitude of the bounce or the amplitude of the elastic “spring” effect. The higher the number, the higher the amplitude.
See also

PySide2.QtCore.QEasingCurve.
setCustomType
(arg__1)¶  Parameters
arg__1 – object

PySide2.QtCore.QEasingCurve.
setOvershoot
(overshoot)¶  Parameters
overshoot – float
Sets the overshoot to
overshoot
.0 produces no overshoot, and the default value of 1.70158 produces an overshoot of 10 percent.
See also

PySide2.QtCore.QEasingCurve.
setPeriod
(period)¶  Parameters
period – float
Sets the period to
period
. Setting a small period value will give a high frequency of the curve. A large period will give it a small frequency.See also

PySide2.QtCore.QEasingCurve.
setType
(type)¶  Parameters
type –
Type
Sets the type of the easing curve to
type
.See also

PySide2.QtCore.QEasingCurve.
swap
(other)¶  Parameters
other –
PySide2.QtCore.QEasingCurve
Swaps curve
other
with this curve. This operation is very fast and never fails.

PySide2.QtCore.QEasingCurve.
toCubicSpline
()¶  Return type
Returns the
cubicBezierSpline
that defines a custom easing curve. If the easing curve does not have a custom bezier easing curve the list is empty.

PySide2.QtCore.QEasingCurve.
type
()¶  Return type
Returns the type of the easing curve.
See also

PySide2.QtCore.QEasingCurve.
valueForProgress
(progress)¶  Parameters
progress – float
 Return type
float
Return the effective progress for the easing curve at
progress
. Whereasprogress
must be between 0 and 1, the returned effective progress can be outside those bounds. For example,InBack
will return negative values in the beginning of the function.
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