# Class Parent

java.lang.Object
javafx.scene.Node
javafx.scene.Parent

All Implemented Interfaces:
  `Styleable, EventTarget`

Direct Known Subclasses:
  `Group, Region, WebView`

public abstract non-sealed class Parent extends Node
The base class for all nodes that have children in the scene graph.

This class handles all hierarchical scene graph operations, including adding/removing child nodes, marking branches dirty for layout and rendering, picking, bounds calculations, and executing the layout pass on each pulse.

There are two direct concrete Parent subclasses

- `Group` effects and transforms to be applied to a collection of child nodes.
- `Region` class for nodes that can be styled with CSS and layout children.

Since:
  JavaFX 2.0

- ## Property Summary

  Properties
  Type
  Property
  Description
  `final ReadOnlyBooleanProperty`
  `needsLayout`
  Indicates that this Node and its subnodes requires a layout pass on the next pulse.

  ### Properties declared in class Node

  `accessibleHelp, accessibleRoleDescription, accessibleRole, accessibleText, blendMode, boundsInLocal, boundsInParent, cacheHint, cache, clip, cursor, depthTest, disabled, disable, effectiveNodeOrientation, effect, eventDispatcher, focused, focusTraversable, focusVisible, focusWithin, hover, id, inputMethodRequests, layoutBounds, layoutX, layoutY, localToParentTransform, localToSceneTransform, managed, mouseTransparent, nodeOrientation, onContextMenuRequested, onDragDetected, onDragDone, onDragDropped, onDragEntered, onDragExited, onDragOver, onInputMethodTextChanged, onKeyPressed, onKeyReleased, onKeyTyped, onMouseClicked, onMouseDragDone, onMouseDragEntered, onMouseDragExited, onMouseDragged, onMouseDragOver, onMouseDragReleased, onMouseEntered, onMouseExited, onMouseMoved, onMousePressed, onMouseReleased, onRotate, onRotationFinished, onRotationStarted, onScrollFinished, onScroll, onScrollStarted, onSwipeDown, onSwipeLeft, onSwipeRight, onSwipeUp, onTouchMoved, onTouchPressed, onTouchReleased, onTouchStationary, onZoomFinished, onZoom, onZoomStarted, opacity, parent, pickOnBounds, pressed, rotate, rotationAxis, scaleX, scaleY, scaleZ, scene, style, translateX, translateY, translateZ, viewOrder, visible`

- ## Field Summary

  ### Fields declared in class Node

  `BASELINE_OFFSET_SAME_AS_HEIGHT`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `Parent()`
  Constructs a new `Parent`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected double`
  `computeMinHeight(double width)`
  Calculates the min height of this `Parent`.
  `protected double`
  `computeMinWidth(double height)`
  Calculates the minimum width of this `Parent`.
  `protected double`
  `computePrefHeight(double width)`
  Calculates the preferred height of this `Parent`.
  `protected double`
  `computePrefWidth(double height)`
  Calculates the preferred width of this `Parent`.
  `double`
  `getBaselineOffset()`
  Calculates the baseline offset based on the first managed child.
  `protected ObservableList<Node>`
  `getChildren()`
  Gets the list of children of this `Parent`.
  `ObservableList<Node>`
  `getChildrenUnmodifiable()`
  Gets the list of children of this `Parent` as a read-only list.
  `protected <E extends Node>
  List<E>`
  `getManagedChildren()`
  Gets the list of all managed children of this `Parent`.
  `final ObservableList<String>`
  `getStylesheets()`
  Gets an observable list of string URLs linking to the stylesheets to use with this Parent's contents.
  `final boolean`
  `isNeedsLayout()`
  Gets the value of the `needsLayout` property.
  `final void`
  `layout()`
  Executes a top-down layout pass on the scene graph under this parent.
  `protected void`
  `layoutChildren()`
  Invoked during the layout pass to layout the children in this `Parent`.
  `final ReadOnlyBooleanProperty`
  `needsLayoutProperty()`
  Indicates that this Node and its subnodes requires a layout pass on the next pulse.
  `void`
  `requestLayout()`
  Requests a layout pass to be performed before the next scene is rendered.
  `protected final void`
  `requestParentLayout()`
  Requests a layout pass of the parent to be performed before the next scene is rendered.
  `protected final void`
  `setNeedsLayout(boolean value)`
  Sets the value of the `needsLayout` property.
  `protected void`
  `updateBounds()`
  Updates the bounds of this `Parent` and its children.

  ### Methods declared in class Node

  `accessibleHelpProperty, accessibleRoleDescriptionProperty, accessibleRoleProperty, accessibleTextProperty, addEventFilter, addEventHandler, applyCss, autosize, blendModeProperty, boundsInLocalProperty, boundsInParentProperty, buildEventDispatchChain, cacheHintProperty, cacheProperty, clipProperty, computeAreaInScreen, contains, contains, cursorProperty, depthTestProperty, disabledProperty, disableProperty, effectiveNodeOrientationProperty, effectProperty, eventDispatcherProperty, executeAccessibleAction, fireEvent, focusedProperty, focusTraversableProperty, focusVisibleProperty, focusWithinProperty, getAccessibleHelp, getAccessibleRole, getAccessibleRoleDescription, getAccessibleText, getBlendMode, getBoundsInLocal, getBoundsInParent, getCacheHint, getClassCssMetaData, getClip, getContentBias, getCssMetaData, getCursor, getDepthTest, getEffect, getEffectiveNodeOrientation, getEventDispatcher, getId, getInitialCursor, getInitialFocusTraversable, getInputMethodRequests, getLayoutBounds, getLayoutX, getLayoutY, getLocalToParentTransform, getLocalToSceneTransform, getNodeOrientation, getOnContextMenuRequested, getOnDragDetected, getOnDragDone, getOnDragDropped, getOnDragEntered, getOnDragExited, getOnDragOver, getOnInputMethodTextChanged, getOnKeyPressed, getOnKeyReleased, getOnKeyTyped, getOnMouseClicked, getOnMouseDragDone, getOnMouseDragEntered, getOnMouseDragExited, getOnMouseDragged, getOnMouseDragOver, getOnMouseDragReleased, getOnMouseEntered, getOnMouseExited, getOnMouseMoved, getOnMousePressed, getOnMouseReleased, getOnRotate, getOnRotationFinished, getOnRotationStarted, getOnScroll, getOnScrollFinished, getOnScrollStarted, getOnSwipeDown, getOnSwipeLeft, getOnSwipeRight, getOnSwipeUp, getOnTouchMoved, getOnTouchPressed, getOnTouchReleased, getOnTouchStationary, getOnZoom, getOnZoomFinished, getOnZoomStarted, getOpacity, getParent, getProperties, getPseudoClassStates, getRotate, getRotationAxis, getScaleX, getScaleY, getScaleZ, getScene, getStyle, getStyleableParent, getStyleClass, getTransforms, getTranslateX, getTranslateY, getTranslateZ, getTypeSelector, getUserData, getViewOrder, hasProperties, hoverProperty, idProperty, inputMethodRequestsProperty, intersects, intersects, isCache, isDisable, isDisabled, isFocused, isFocusTraversable, isFocusVisible, isFocusWithin, isHover, isManaged, isMouseTransparent, isPickOnBounds, isPressed, isResizable, isVisible, layoutBoundsProperty, layoutXProperty, layoutYProperty, localToParent, localToParent, localToParent, localToParent, localToParent, localToParentTransformProperty, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToSceneTransformProperty, localToScreen, localToScreen, localToScreen, localToScreen, localToScreen, lookup, lookupAll, managedProperty, maxHeight, maxWidth, minHeight, minWidth, mouseTransparentProperty, nodeOrientationProperty, notifyAccessibleAttributeChanged, onContextMenuRequestedProperty, onDragDetectedProperty, onDragDoneProperty, onDragDroppedProperty, onDragEnteredProperty, onDragExitedProperty, onDragOverProperty, onInputMethodTextChangedProperty, onKeyPressedProperty, onKeyReleasedProperty, onKeyTypedProperty, onMouseClickedProperty, onMouseDragDoneProperty, onMouseDragEnteredProperty, onMouseDragExitedProperty, onMouseDraggedProperty, onMouseDragOverProperty, onMouseDragReleasedProperty, onMouseEnteredProperty, onMouseExitedProperty, onMouseMovedProperty, onMousePressedProperty, onMouseReleasedProperty, onRotateProperty, onRotationFinishedProperty, onRotationStartedProperty, onScrollFinishedProperty, onScrollProperty, onScrollStartedProperty, onSwipeDownProperty, onSwipeLeftProperty, onSwipeRightProperty, onSwipeUpProperty, onTouchMovedProperty, onTouchPressedProperty, onTouchReleasedProperty, onTouchStationaryProperty, onZoomFinishedProperty, onZoomProperty, onZoomStartedProperty, opacityProperty, parentProperty, parentToLocal, parentToLocal, parentToLocal, parentToLocal, parentToLocal, pickOnBoundsProperty, prefHeight, prefWidth, pressedProperty, pseudoClassStateChanged, queryAccessibleAttribute, relocate, removeEventFilter, removeEventHandler, requestFocus, requestFocusTraversal, resize, resizeRelocate, rotateProperty, rotationAxisProperty, scaleXProperty, scaleYProperty, scaleZProperty, sceneProperty, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, screenToLocal, screenToLocal, screenToLocal, setAccessibleHelp, setAccessibleRole, setAccessibleRoleDescription, setAccessibleText, setBlendMode, setCache, setCacheHint, setClip, setCursor, setDepthTest, setDisable, setDisabled, setEffect, setEventDispatcher, setEventHandler, setFocused, setFocusTraversable, setHover, setId, setInputMethodRequests, setLayoutX, setLayoutY, setManaged, setMouseTransparent, setNodeOrientation, setOnContextMenuRequested, setOnDragDetected, setOnDragDone, setOnDragDropped, setOnDragEntered, setOnDragExited, setOnDragOver, setOnInputMethodTextChanged, setOnKeyPressed, setOnKeyReleased, setOnKeyTyped, setOnMouseClicked, setOnMouseDragDone, setOnMouseDragEntered, setOnMouseDragExited, setOnMouseDragged, setOnMouseDragOver, setOnMouseDragReleased, setOnMouseEntered, setOnMouseExited, setOnMouseMoved, setOnMousePressed, setOnMouseReleased, setOnRotate, setOnRotationFinished, setOnRotationStarted, setOnScroll, setOnScrollFinished, setOnScrollStarted, setOnSwipeDown, setOnSwipeLeft, setOnSwipeRight, setOnSwipeUp, setOnTouchMoved, setOnTouchPressed, setOnTouchReleased, setOnTouchStationary, setOnZoom, setOnZoomFinished, setOnZoomStarted, setOpacity, setPickOnBounds, setPressed, setRotate, setRotationAxis, setScaleX, setScaleY, setScaleZ, setStyle, setTranslateX, setTranslateY, setTranslateZ, setUserData, setViewOrder, setVisible, snapshot, snapshot, startDragAndDrop, startFullDrag, styleProperty, toBack, toFront, toString, translateXProperty, translateYProperty, translateZProperty, usesMirroring, viewOrderProperty, visibleProperty`

  ### Methods declared in class Object

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

  ### Methods declared in interface Styleable

  `getStyleableNode`

- ## Property Details

  - ### needsLayout

    public final ReadOnlyBooleanProperty needsLayoutProperty
    Indicates that this Node and its subnodes requires a layout pass on the next pulse.
    See Also:
      - `isNeedsLayout()`
      - `setNeedsLayout(boolean)`
      - `needsLayoutProperty()`

- ## Constructor Details

  - ### Parent

    protected Parent()
    Constructs a new `Parent`.

- ## Method Details

  - ### getChildren

    protected ObservableList<Node> getChildren()
    Gets the list of children of this `Parent`.

    See the class documentation for `Node` for scene graph structure restrictions on setting a `Parent`'s children list. If these restrictions are violated by a change to the list of children, the change is ignored and the previous value of the children list is restored. An `IllegalArgumentException` is thrown in this case.

    If this `Parent` node is attached to a `Scene` attached to a `Window`, that is, showing (`Window.isShowing()`), then its list of children must only be modified on the JavaFX Application Thread. An `IllegalStateException` is thrown if this restriction is violated.

    Note to subclasses: if you override this method, you must return from your implementation the result of calling this super method. The actual list instance returned from any getChildren() implementation must be the list owned and managed by this Parent. The only typical purpose for overriding this method is to promote the method to be public.

    Returns:
      the list of children of this `Parent`.

  - ### getChildrenUnmodifiable

    public ObservableList<Node> getChildrenUnmodifiable()
    Gets the list of children of this `Parent` as a read-only list.
    Returns:
      read-only access to this parent's children ObservableList

  - ### getManagedChildren

    protected <E extends Node> List<E> getManagedChildren()
    Gets the list of all managed children of this `Parent`.
    Type Parameters:
      `E` - the type of the children nodes
    Returns:
      list of all managed children in this parent

  - ### setNeedsLayout

    protected final void setNeedsLayout(boolean value)
    Sets the value of the `needsLayout` property.
    Property description:
      Indicates that this Node and its subnodes requires a layout pass on the next pulse.
    Parameters:
      `value` - the value for the `needsLayout` property
    See Also:
      - `isNeedsLayout()`
      - `needsLayoutProperty()`

  - ### isNeedsLayout

    public final boolean isNeedsLayout()
    Gets the value of the `needsLayout` property.
    Property description:
      Indicates that this Node and its subnodes requires a layout pass on the next pulse.
    Returns:
      the value of the `needsLayout` property
    See Also:
      - `setNeedsLayout(boolean)`
      - `needsLayoutProperty()`

  - ### needsLayoutProperty

    public final ReadOnlyBooleanProperty needsLayoutProperty()
    Indicates that this Node and its subnodes requires a layout pass on the next pulse.
    Returns:
      the `needsLayout` property
    See Also:
      - `isNeedsLayout()`
      - `setNeedsLayout(boolean)`

  - ### requestLayout

    public void requestLayout()
    Requests a layout pass to be performed before the next scene is rendered. This is batched up asynchronously to happen once per "pulse", or frame of animation.

    If this parent is either a scene root or unmanaged, then it will be added directly to the scene's dirty layout list, otherwise requestParentLayout will be invoked.

    Since:
      JavaFX 8.0

  - ### requestParentLayout

    protected final void requestParentLayout()
    Requests a layout pass of the parent to be performed before the next scene is rendered. This is batched up asynchronously to happen once per "pulse", or frame of animation.

    This may be used when the current parent have changed it's min/max/preferred width/height, but doesn't know yet if the change will lead to it's actual size change. This will be determined when it's parent recomputes the layout with the new hints.

  - ### computePrefWidth

    protected double computePrefWidth(double height)
    Calculates the preferred width of this `Parent`. The default implementation calculates this width as the width of the area occupied by its managed children when they are positioned at their current positions at their preferred widths.
    Parameters:
      `height` - the height that should be used if preferred width depends on it
    Returns:
      the calculated preferred width

  - ### computePrefHeight

    protected double computePrefHeight(double width)
    Calculates the preferred height of this `Parent`. The default implementation calculates this height as the height of the area occupied by its managed children when they are positioned at their current positions at their preferred heights.
    Parameters:
      `width` - the width that should be used if preferred height depends on it
    Returns:
      the calculated preferred height

  - ### computeMinWidth

    protected double computeMinWidth(double height)
    Calculates the minimum width of this `Parent`. The default implementation simply returns the pref width.
    Parameters:
      `height` - the height that should be used if min width depends on it
    Returns:
      the calculated min width
    Since:
      JavaFX 2.1

  - ### computeMinHeight

    protected double computeMinHeight(double width)
    Calculates the min height of this `Parent`. The default implementation simply returns the pref height;
    Parameters:
      `width` - the width that should be used if min height depends on it
    Returns:
      the calculated min height
    Since:
      JavaFX 2.1

  - ### getBaselineOffset

    public double getBaselineOffset()
    Calculates the baseline offset based on the first managed child. If there is no such child, returns `Node.getBaselineOffset()`.
    Overrides:
      `getBaselineOffset` in class `Node`
    Returns:
      baseline offset

  - ### layout

    public final void layout()
    Executes a top-down layout pass on the scene graph under this parent. Calling this method while the Parent is doing layout is a no-op.

  - ### layoutChildren

    protected void layoutChildren()
    Invoked during the layout pass to layout the children in this `Parent`. By default it will only set the size of managed, resizable content to their preferred sizes and does not do any node positioning.

    Subclasses should override this function to layout content as needed.

  - ### getStylesheets

    public final ObservableList<String> getStylesheets()
    Gets an observable list of string URLs linking to the stylesheets to use with this Parent's contents. See `Scene.getStylesheets()` for details.

    For additional information about using CSS with the scene graph, see the CSS Reference Guide.

    Returns:
      the list of stylesheets to use with this Parent
    Since:
      JavaFX 2.1

  - ### updateBounds

    protected void updateBounds()
    Updates the bounds of this `Parent` and its children.