com.facebook.react.uimanager

Class ReactShadowNode

java.lang.Object

com.facebook.csslayout.CSSNode

com.facebook.react.uimanager.ReactShadowNode

Direct Known Subclasses:

ProgressBarShadowNode, ReactTextShadowNode

public class ReactShadowNode
extends CSSNode

Base node class for representing virtual tree of React nodes. Shadow nodes are used primarily for layouting therefore it extends CSSNode to allow that. They also help with handling Common base subclass of CSSNode for all layout nodes for react-based view. It extends CSSNode by adding additional capabilities. Instances of this class receive property updates from JS via @{link UIManagerModule}. Subclasses may use updateProperties(com.facebook.react.uimanager.CatalystStylesDiffMap) to persist some of the updated fields in the node instance that corresponds to a particular view type. Subclasses of ReactShadowNode should be created only from ViewManager that corresponds to a certain type of native view. They will be updated and accessed only from JS thread. Subclasses of ViewManager may choose to use base class ReactShadowNode or custom subclass of it if necessary. The primary use-case for ReactShadowNode nodes is to calculate layouting. Although this might be extended. For some examples please refer to ARTGroupCSSNode or ReactTextCSSNode. This class allows for the native view hierarchy to not be an exact copy of the hierarchy received from JS by keeping track of both JS children (e.g. CSSNode.getChildCount() and separately native children (e.g. getNativeChildCount()). See NativeViewHierarchyOptimizer for more information.

Nested Class Summary

Nested classes/interfaces inherited from class com.facebook.csslayout.CSSNode

CSSNode.MeasureFunction

Field Summary

Fields inherited from class com.facebook.csslayout.CSSNode

lineIndex

Constructor Summary

Constructors

Constructor and Description
ReactShadowNode()

Method Summary

Methods

Modifier and Type	Method and Description
void	addChildAt(CSSNode child, int i)
void	addNativeChildAt(ReactShadowNode child, int nativeIndex) Adds a child that the native view hierarchy will have at this index in the native view corresponding to this node.
protected void	dirty()
ReactShadowNode	getChildAt(int i)
int	getNativeChildCount()
int	getNativeOffsetForChild(ReactShadowNode child) Returns the offset within the native children owned by all layout-only nodes in the subtree rooted at this node for the given child.
ReactShadowNode	getNativeParent()
ReactShadowNode	getParent()
int	getReactTag()
ReactShadowNode	getRootNode()
int	getScreenHeight()
int	getScreenWidth()
int	getScreenX()
int	getScreenY()
ThemedReactContext	getThemedContext() Get the ThemedReactContext associated with this ReactShadowNode.
int	getTotalNativeChildren()
java.lang.String	getViewClass()
boolean	hasUpdates()
int	indexOfNativeChild(ReactShadowNode nativeChild)
boolean	isLayoutOnly()
boolean	isVirtual() Nodes that return true will be treated as "virtual" nodes.
boolean	isVirtualAnchor() Nodes that return true will be treated as a root view for the virtual nodes tree.
protected void	markUpdated()
void	markUpdateSeen()
void	onBeforeLayout() This method will be called by UIManagerModule once per batch, before calculating layout.
void	onCollectExtraUpdates(UIViewOperationQueue uiViewOperationQueue) Called after layout step at the end of the UI batch from UIManagerModule.
ReactShadowNode	removeChildAt(int i)
ReactShadowNode	removeNativeChildAt(int i)
void	setIsLayoutOnly(boolean isLayoutOnly) Sets whether this node only contributes to the layout of its children without doing any drawing or functionality itself.
protected void	setThemedContext(ThemedReactContext themedContext)
void	updateProperties(CatalystStylesDiffMap styles)

Methods inherited from class com.facebook.csslayout.CSSNode

calculateLayout, getChildCount, getLayoutDirection, getLayoutHeight, getLayoutWidth, getLayoutX, getLayoutY, getStyleDirection, getStyleHeight, getStylePadding, getStyleWidth, hasNewLayout, indexOf, isDirty, isMeasureDefined, markLayoutSeen, setAlignItems, setAlignSelf, setBorder, setDefaultPadding, setDirection, setFlex, setFlexDirection, setJustifyContent, setMargin, setMeasureFunction, setPadding, setPositionBottom, setPositionLeft, setPositionRight, setPositionTop, setPositionType, setStyleHeight, setStyleWidth, setWrap, toString, valuesEqual, valuesEqual

Methods inherited from class java.lang.Object

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

Constructor Detail

ReactShadowNode

public ReactShadowNode()

Method Detail

isVirtual

public boolean isVirtual()

Nodes that return true will be treated as "virtual" nodes. That is, nodes that are not mapped into native views (e.g. nested text node). By default this method returns false.

isVirtualAnchor

public boolean isVirtualAnchor()

Nodes that return true will be treated as a root view for the virtual nodes tree. It means that NativeViewHierarchyManager will not try to perform manageChildren operation on such views. Good example is InputText view that may have children Text nodes but this whole hierarchy will be mapped to a single android EditText view.

getViewClass

public final java.lang.String getViewClass()

hasUpdates

public final boolean hasUpdates()

markUpdateSeen

public final void markUpdateSeen()

markUpdated

protected void markUpdated()

dirty

protected void dirty()

Overrides:

dirty in class CSSNode

addChildAt

public void addChildAt(CSSNode child,
              int i)

Overrides:

addChildAt in class CSSNode

removeChildAt

public ReactShadowNode removeChildAt(int i)

Overrides:

removeChildAt in class CSSNode

onBeforeLayout

public void onBeforeLayout()

This method will be called by UIManagerModule once per batch, before calculating layout. Will be only called for nodes that are marked as updated with markUpdated() or require layouting (marked with dirty()).

updateProperties

public void updateProperties(CatalystStylesDiffMap styles)

onCollectExtraUpdates

public void onCollectExtraUpdates(UIViewOperationQueue uiViewOperationQueue)

Called after layout step at the end of the UI batch from UIManagerModule. May be used to enqueue additional ui operations for the native view. Will only be called on nodes marked as updated either with dirty() or markUpdated().

Parameters:

uiViewOperationQueue - interface for enqueueing UI operations

getReactTag

public final int getReactTag()

getRootNode

public final ReactShadowNode getRootNode()

getChildAt

public final ReactShadowNode getChildAt(int i)

Overrides:

getChildAt in class CSSNode

getParent

@Nullable
public final ReactShadowNode getParent()

Overrides:

getParent in class CSSNode

getThemedContext

public ThemedReactContext getThemedContext()

Get the ThemedReactContext associated with this ReactShadowNode. This will never change during the lifetime of a ReactShadowNode instance, but different instances can have different contexts; don't cache any calculations based on theme values globally.

setThemedContext

protected void setThemedContext(ThemedReactContext themedContext)

addNativeChildAt

public void addNativeChildAt(ReactShadowNode child,
                    int nativeIndex)

Adds a child that the native view hierarchy will have at this index in the native view corresponding to this node.

removeNativeChildAt

public ReactShadowNode removeNativeChildAt(int i)

getNativeChildCount

public int getNativeChildCount()

indexOfNativeChild

public int indexOfNativeChild(ReactShadowNode nativeChild)

getNativeParent

@Nullable
public ReactShadowNode getNativeParent()

setIsLayoutOnly

public void setIsLayoutOnly(boolean isLayoutOnly)

Sets whether this node only contributes to the layout of its children without doing any drawing or functionality itself.

isLayoutOnly

public boolean isLayoutOnly()

getTotalNativeChildren

public int getTotalNativeChildren()

getNativeOffsetForChild

public int getNativeOffsetForChild(ReactShadowNode child)

Returns the offset within the native children owned by all layout-only nodes in the subtree rooted at this node for the given child. Put another way, this returns the number of native nodes (nodes not optimized out of the native tree) that are a) to the left (visited before by a DFS) of the given child in the subtree rooted at this node and b) do not have a native parent in this subtree (which means that the given child will be a sibling of theirs in the final native hierarchy since they'll get attached to the same native parent). Basically, a view might have children that have been optimized away by NativeViewHierarchyOptimizer. Since those children will then add their native children to this view, we now have ranges of native children that correspond to single unoptimized children. The purpose of this method is to return the index within the native children that corresponds to the **start** of the native children that belong to the given child. Also, note that all of the children of a view might be optimized away, so this could return the same value for multiple different children. Example. Native children are represented by (N) where N is the no-opt child they came from. If no children are optimized away it'd look like this: (0) (1) (2) (3) ... (n) In case some children are optimized away, it might look like this: (0) (1) (1) (1) (3) (3) (4) In that case: getNativeOffsetForChild(Node 0) => 0 getNativeOffsetForChild(Node 1) => 1 getNativeOffsetForChild(Node 2) => 4 getNativeOffsetForChild(Node 3) => 4 getNativeOffsetForChild(Node 4) => 6

getScreenX

public int getScreenX()

Returns:

the x position of the corresponding view on the screen, rounded to pixels

getScreenY

public int getScreenY()

Returns:

the y position of the corresponding view on the screen, rounded to pixels

getScreenWidth

public int getScreenWidth()

Returns:

width corrected for rounding to pixels.

getScreenHeight

public int getScreenHeight()

Returns:

height corrected for rounding to pixels.