com.facebook.litho.dataflow

Class ValueNode

java.lang.Object

com.facebook.litho.dataflow.ValueNode

Direct Known Subclasses:

AnimatedPropertyNode, ConstantNode, InterpolatorNode, MappingNode, SimpleNode, SpringNode, TimingNode

public abstract class ValueNode
extends Object

A single node in a DataFlowGraph. Nodes are added to a DataFlowGraph using by creating a GraphBinding and calling GraphBinding.addBinding(com.facebook.litho.dataflow.ValueNode, com.facebook.litho.dataflow.ValueNode, java.lang.String). The nodes will actually be added to the graph when GraphBinding.activate() is called.

The nodes in an active graph are visited on each frame in dependency order and given a chance to compute a new value based on frame time and their parent (dependency) nodes.

A ValueNode should be able to return its latest value at any point in time.

Sub-classes are expected to implement calculateValue(long), which handles calculating the new value for this frame based on the node's parents (i.e. nodes it depends on) and the current frame time.

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_INPUT

Constructor Summary

Constructors

Constructor and Description
ValueNode()

Method Summary

Modifier and Type	Method and Description
protected abstract float	calculateValue(long frameTimeNanos) This node should calculate and set a new value based on frame time and its parents (the nodes it depends on).
protected ValueNode	getInput()
protected ValueNode	getInput(String name)
float	getValue()
protected boolean	hasInput()
protected boolean	hasInput(String name)
void	setValue(float value) Manually sets the current value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_INPUT

public static final String DEFAULT_INPUT

See Also:

Constant Field Values

Constructor Detail

ValueNode

public ValueNode()

Method Detail

getValue

public float getValue()

Returns:

the most recently calculated value from calculateValue(long).

setValue

public void setValue(float value)

Manually sets the current value.

calculateValue

protected abstract float calculateValue(long frameTimeNanos)

This node should calculate and set a new value based on frame time and its parents (the nodes it depends on). When this is called, it's guaranteed that the parent nodes have already been updated for this frame.

getInput

protected ValueNode getInput(String name)

Returns:

the input node for the given input name

getInput

protected ValueNode getInput()

Returns:

the default input node. This should only be used for nodes that expect a single input.

hasInput

protected boolean hasInput(String name)

Returns:

whether this node has an input with the given name

hasInput

protected boolean hasInput()

Returns:

whether this node has a default input node. This should only be used for nodes that expect a single input.