Spring

java.lang.Object
- com.facebook.litho.dataflow.springs.Spring

```
public class Spring
extends Object
```
Classical spring implementing Hooke's law with configurable friction and tension.
This code was forked from the facebook/rebound repository.

Constructor Summary

Constructors
Constructor and Description

Spring()
create a new spring

Constructors
Constructor and Description
`Spring()` create a new spring

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Spring`	`addListener(SpringListener newListener)` add a listener
`void`	`advance(double realDeltaTime)` advance the physics simulation in SOLVER_TIMESTEP_SEC sized chunks to fulfill the required realTimeDelta.
`boolean`	`currentValueIsApproximately(double value)` This method checks to see that the current spring displacement value is equal to the input, accounting for the spring's rest displacement threshold.
`void`	`destroy()` Destroys this Spring, meaning that it will be deregistered from its BaseSpringSystem so it won't be iterated anymore and will clear its set of listeners.
`double`	`getCurrentDisplacementDistance()` get the displacement of the springs current value from its rest value.
`double`	`getCurrentValue()` Get the current
`double`	`getEndValue()` get the rest value used for determining the displacement of the spring
`String`	`getId()` get the unique id for this spring
`double`	`getRestDisplacementThreshold()` get the threshold of displacement from rest below which the spring should be considered at rest
`double`	`getRestSpeedThreshold()` Returns the speed at which the spring should be considered at rest in pixels per second
`SpringConfig`	`getSpringConfig()` retrieve the spring config for this spring
`double`	`getStartValue()` Get the displacement value from the last time setCurrentValue was called.
`double`	`getVelocity()` get the velocity of the spring
`boolean`	`isAtRest()` check if the current state is at rest
`boolean`	`isOvershootClampingEnabled()` Check if overshoot clamping is enabled.
`boolean`	`isOvershooting()` Check if the spring is overshooting beyond its target.
`Spring`	`removeAllListeners()` remove all of the listeners
`Spring`	`removeListener(SpringListener listenerToRemove)` remove a listener
`Spring`	`setAtRest()` Set the spring to be at rest by making its end value equal to its current value and setting velocity to 0.
`Spring`	`setCurrentValue(double currentValue)` Set the displaced value to determine the displacement for the spring from the rest value.
`Spring`	`setCurrentValue(double currentValue, boolean setAtRest)` The full signature for setCurrentValue includes the option of not setting the spring at rest after updating its currentValue.
`Spring`	`setEndValue(double endValue)` set the rest value to determine the displacement for the spring
`Spring`	`setOvershootClampingEnabled(boolean overshootClampingEnabled)` Force the spring to clamp at its end value to avoid overshooting the target value.
`Spring`	`setRestDisplacementThreshold(double displacementFromRestThreshold)` set the threshold of displacement from rest below which the spring should be considered at rest
`Spring`	`setRestSpeedThreshold(double restSpeedThreshold)` Sets the speed at which the spring should be considered at rest.
`Spring`	`setSpringConfig(SpringConfig springConfig)` set the config class
`Spring`	`setVelocity(double velocity)` set the velocity on the spring in pixels per second
`boolean`	`systemShouldAdvance()` Check if this spring should be advanced by the system.
`boolean`	`wasAtRest()` Check if the spring was at rest in the prior iteration.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Spring
```
public Spring()
```
    create a new spring
- Method Detail
  - destroy
```
public void destroy()
```
    Destroys this Spring, meaning that it will be deregistered from its BaseSpringSystem so it won't be iterated anymore and will clear its set of listeners. Do not use the Spring after calling this, doing so may just cause an exception to be thrown.
  - getId
```
public String getId()
```
    get the unique id for this spring
    
    Returns:
    
    the unique id
  - setSpringConfig
```
public Spring setSpringConfig(SpringConfig springConfig)
```
    set the config class
    
    Parameters:
    
    springConfig - config class for the spring
    
    Returns:
    
    this Spring instance for chaining
  - getSpringConfig
```
public SpringConfig getSpringConfig()
```
    retrieve the spring config for this spring
    
    Returns:
    
    the SpringConfig applied to this spring
  - setCurrentValue
```
public Spring setCurrentValue(double currentValue)
```
    Set the displaced value to determine the displacement for the spring from the rest value. This value is retained and used to calculate the displacement ratio. The default signature also sets the Spring at rest to facilitate the common behavior of moving a spring to a new position.
    
    Parameters:
    
    currentValue - the new start and current value for the spring
    
    Returns:
    
    the spring for chaining
  - setCurrentValue
```
public Spring setCurrentValue(double currentValue,
                              boolean setAtRest)
```
    The full signature for setCurrentValue includes the option of not setting the spring at rest after updating its currentValue. Passing setAtRest false means that if the endValue of the spring is not equal to the currentValue, the physics system will start iterating to resolve the spring to the end value. This is almost never the behavior that you want, so the default setCurrentValue signature passes true.
    
    Parameters:
    
    currentValue - the new start and current value for the spring
    
    setAtRest - optionally set the spring at rest after updating its current value. see com.facebook.rebound.Spring#setAtRest()
    
    Returns:
    
    the spring for chaining
  - getStartValue
```
public double getStartValue()
```
    Get the displacement value from the last time setCurrentValue was called.
    
    Returns:
    
    displacement value
  - getCurrentValue
```
public double getCurrentValue()
```
    Get the current
    
    Returns:
    
    current value
  - getCurrentDisplacementDistance
```
public double getCurrentDisplacementDistance()
```
    get the displacement of the springs current value from its rest value.
    
    Returns:
    
    the distance displaced by
  - setEndValue
```
public Spring setEndValue(double endValue)
```
    set the rest value to determine the displacement for the spring
    
    Parameters:
    
    endValue - the endValue for the spring
    
    Returns:
    
    the spring for chaining
  - getEndValue
```
public double getEndValue()
```
    get the rest value used for determining the displacement of the spring
    
    Returns:
    
    the rest value for the spring
  - setVelocity
```
public Spring setVelocity(double velocity)
```
    set the velocity on the spring in pixels per second
    
    Parameters:
    
    velocity - velocity value
    
    Returns:
    
    the spring for chaining
  - getVelocity
```
public double getVelocity()
```
    get the velocity of the spring
    
    Returns:
    
    the current velocity
  - setRestSpeedThreshold
```
public Spring setRestSpeedThreshold(double restSpeedThreshold)
```
    Sets the speed at which the spring should be considered at rest.
    
    Parameters:
    
    restSpeedThreshold - speed pixels per second
    
    Returns:
    
    the spring for chaining
  - getRestSpeedThreshold
```
public double getRestSpeedThreshold()
```
    Returns the speed at which the spring should be considered at rest in pixels per second
    
    Returns:
    
    speed in pixels per second
  - setRestDisplacementThreshold
```
public Spring setRestDisplacementThreshold(double displacementFromRestThreshold)
```
    set the threshold of displacement from rest below which the spring should be considered at rest
    
    Parameters:
    
    displacementFromRestThreshold - displacement to consider resting below
    
    Returns:
    
    the spring for chaining
  - getRestDisplacementThreshold
```
public double getRestDisplacementThreshold()
```
    get the threshold of displacement from rest below which the spring should be considered at rest
    
    Returns:
    
    displacement to consider resting below
  - setOvershootClampingEnabled
```
public Spring setOvershootClampingEnabled(boolean overshootClampingEnabled)
```
    Force the spring to clamp at its end value to avoid overshooting the target value.
    
    Parameters:
    
    overshootClampingEnabled - whether or not to enable overshoot clamping
    
    Returns:
    
    the spring for chaining
  - isOvershootClampingEnabled
```
public boolean isOvershootClampingEnabled()
```
    Check if overshoot clamping is enabled.
    
    Returns:
    
    is overshoot clamping enabled
  - isOvershooting
```
public boolean isOvershooting()
```
    Check if the spring is overshooting beyond its target.
    
    Returns:
    
    true if the spring is overshooting its target
  - advance
```
public void advance(double realDeltaTime)
```
    advance the physics simulation in SOLVER_TIMESTEP_SEC sized chunks to fulfill the required realTimeDelta. The math is inlined inside the loop since it made a huge performance impact when there are several springs being advanced.
    
    Parameters:
    
    realDeltaTime - clock drift
  - systemShouldAdvance
```
public boolean systemShouldAdvance()
```
    Check if this spring should be advanced by the system. * The rule is if the spring is currently at rest and it was at rest in the previous advance, the system can skip this spring
    
    Returns:
    
    should the system process this spring
  - wasAtRest
```
public boolean wasAtRest()
```
    Check if the spring was at rest in the prior iteration. This is used for ensuring the ending callbacks are fired as the spring comes to a rest.
    
    Returns:
    
    true if the spring was at rest in the prior iteration
  - isAtRest
```
public boolean isAtRest()
```
    check if the current state is at rest
    
    Returns:
    
    is the spring at rest
  - setAtRest
```
public Spring setAtRest()
```
    Set the spring to be at rest by making its end value equal to its current value and setting velocity to 0.
    
    Returns:
    
    this object
  - addListener
```
public Spring addListener(SpringListener newListener)
```
    add a listener
    
    Parameters:
    
    newListener - to add
    
    Returns:
    
    the spring for chaining
  - removeListener
```
public Spring removeListener(SpringListener listenerToRemove)
```
    remove a listener
    
    Parameters:
    
    listenerToRemove - to remove
    
    Returns:
    
    the spring for chaining
  - removeAllListeners
```
public Spring removeAllListeners()
```
    remove all of the listeners
    
    Returns:
    
    the spring for chaining
  - currentValueIsApproximately
```
public boolean currentValueIsApproximately(double value)
```
    This method checks to see that the current spring displacement value is equal to the input, accounting for the spring's rest displacement threshold.
    
    Parameters:
    
    value - The value to compare the spring value to
    
    Returns:
    
    Whether the displacement value from the spring is within the bounds of the compare value, accounting for threshold

Class Spring

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Spring

Method Detail

destroy

getId

setSpringConfig

getSpringConfig

setCurrentValue

setCurrentValue

getStartValue

getCurrentValue

getCurrentDisplacementDistance

setEndValue

getEndValue

setVelocity

getVelocity

setRestSpeedThreshold

getRestSpeedThreshold

setRestDisplacementThreshold

getRestDisplacementThreshold

setOvershootClampingEnabled

isOvershootClampingEnabled

isOvershooting

advance

systemShouldAdvance

wasAtRest

isAtRest

setAtRest

addListener

removeListener

removeAllListeners

currentValueIsApproximately