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 * Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package javafx.scene.layout;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.ObjectProperty;
import javafx.css.CssMetaData;
import javafx.css.StyleableBooleanProperty;
import javafx.css.StyleableDoubleProperty;
import javafx.css.StyleableObjectProperty;
import javafx.css.StyleableProperty;
import javafx.geometry.Insets;
import javafx.geometry.Orientation;
import javafx.geometry.Pos;
import javafx.geometry.VPos;
import javafx.scene.Node;
import javafx.css.converter.BooleanConverter;
import javafx.css.converter.EnumConverter;
import javafx.css.converter.SizeConverter;
import javafx.css.Styleable;
import javafx.geometry.HPos;
import javafx.util.Callback;



HBox lays out its children in a single horizontal row.
If the hbox has a border and/or padding set, then the contents will be laid
out within those insets.

HBox example:

    HBox hbox = new HBox(8); // spacing = 8
    hbox.getChildren().addAll(new Label("Name:), new TextBox());

HBox will resize children (if resizable) to their preferred widths and uses its
fillHeight property to determine whether to resize their heights to
fill its own height or keep their heights to their preferred (fillHeight defaults to true).
The alignment of the content is controlled by the alignment property,
which defaults to Pos.TOP_LEFT.

If an hbox is resized larger than its preferred width, by default it will keep
children to their preferred widths, leaving the extra space unused.  If an
application wishes to have one or more children be allocated that extra space
it may optionally set an hgrow constraint on the child.  See "Optional Layout
Constraints" for details.

HBox lays out each managed child regardless of the child's
visible property value; unmanaged children are ignored.
Resizable Range

An hbox's parent will resize the hbox within the hbox's resizable range
during layout.   By default the hbox computes this range based on its content
as outlined in the table below.


HBox Resize Table
width
height
minimum
left/right insets plus the sum of each child's min width plus spacing between each child.
top/bottom insets plus the largest of the children's min heights.
preferred
left/right insets plus the sum of each child's pref width plus spacing between each child.
top/bottom insets plus the largest of the children's pref heights.
maximum
Double.MAX_VALUE
Double.MAX_VALUE


An hbox's unbounded maximum width and height are an indication to the parent that
it may be resized beyond its preferred size to fill whatever space is assigned
to it.

HBox provides properties for setting the size range directly.  These
properties default to the sentinel value USE_COMPUTED_SIZE, however the
application may set them to other values as needed:

    hbox.setPrefWidth(400);

Applications may restore the computed values by setting these properties back
to USE_COMPUTED_SIZE.

HBox does not clip its content by default, so it is possible that children's
bounds may extend outside its own bounds if a child's min size prevents it from
being fit within the hbox.
Optional Layout Constraints

An application may set constraints on individual children to customize HBox's layout.
For each constraint, HBox provides a static method for setting it on the child.


HBox Constraint Table
Constraint
Type
Description
hgrow
javafx.scene.layout.Priority
The horizontal grow priority for the child.
margin
javafx.geometry.Insets
Margin space around the outside of the child.


For example, if an hbox needs the TextField to be allocated all extra space:

    HBox hbox = new HBox();
    TextField field = new TextField();
    HBox.setHgrow(field, Priority.ALWAYS);
    hbox.getChildren().addAll(new Label("Search:"), field, new Button("Go"));

If more than one child has the same grow priority set, then the hbox will
allocate equal amounts of space to each.  HBox will only grow a child up to
its maximum width, so if the child has a max width other than Double.MAX_VALUE,
the application may need to override the max to allow it to grow.
For example:

    HBox hbox = new HBox();
    Button button1 = new Button("Add");
    Button button2 = new Button("Remove");
    HBox.setHgrow(button1, Priority.ALWAYS);
    HBox.setHgrow(button2, Priority.ALWAYS);
    button1.setMaxWidth(Double.MAX_VALUE);
    button2.setMaxWidth(Double.MAX_VALUE);
    hbox.getChildren().addAll(button1, button2);

Since:
JavaFX 2.0/**
 * HBox lays out its children in a single horizontal row.
 * If the hbox has a border and/or padding set, then the contents will be laid
 * out within those insets.
 * <p>
 * HBox example:
 * <pre>{@code
 *     HBox hbox = new HBox(8); // spacing = 8
 *     hbox.getChildren().addAll(new Label("Name:), new TextBox());
 * }</pre>
 *
 * HBox will resize children (if resizable) to their preferred widths and uses its
 * fillHeight property to determine whether to resize their heights to
 * fill its own height or keep their heights to their preferred (fillHeight defaults to true).
 * The alignment of the content is controlled by the alignment property,
 * which defaults to Pos.TOP_LEFT.
 * <p>
 * If an hbox is resized larger than its preferred width, by default it will keep
 * children to their preferred widths, leaving the extra space unused.  If an
 * application wishes to have one or more children be allocated that extra space
 * it may optionally set an hgrow constraint on the child.  See "Optional Layout
 * Constraints" for details.
 * <p>
 * HBox lays out each managed child regardless of the child's
 * visible property value; unmanaged children are ignored.</p>
 *
 * <h2>Resizable Range</h2>
 *
 * <p>
 * An hbox's parent will resize the hbox within the hbox's resizable range
 * during layout.   By default the hbox computes this range based on its content
 * as outlined in the table below.
 * </p>
 * <table border="1">
 * <caption>HBox Resize Table</caption>
 * <tr><td></td><th scope="col">width</th><th scope="col">height</th></tr>
 * <tr><th scope="row">minimum</th>
 * <td>left/right insets plus the sum of each child's min width plus spacing between each child.</td>
 * <td>top/bottom insets plus the largest of the children's min heights.</td></tr>
 * <tr><th scope="row">preferred</th>
 * <td>left/right insets plus the sum of each child's pref width plus spacing between each child.</td>
 * <td>top/bottom insets plus the largest of the children's pref heights.</td></tr>
 * <tr><th scope="row">maximum</th>
 * <td>Double.MAX_VALUE</td><td>Double.MAX_VALUE</td></tr>
 * </table>
 * <p>
 * An hbox's unbounded maximum width and height are an indication to the parent that
 * it may be resized beyond its preferred size to fill whatever space is assigned
 * to it.
 * <p>
 * HBox provides properties for setting the size range directly.  These
 * properties default to the sentinel value USE_COMPUTED_SIZE, however the
 * application may set them to other values as needed:
 * <pre><code>
 *     <b>hbox.setPrefWidth(400);</b>
 * </code></pre>
 * Applications may restore the computed values by setting these properties back
 * to USE_COMPUTED_SIZE.
 * <p>
 * HBox does not clip its content by default, so it is possible that children's
 * bounds may extend outside its own bounds if a child's min size prevents it from
 * being fit within the hbox.</p>
 *
 * <h2>Optional Layout Constraints</h2>
 *
 * <p>
 * An application may set constraints on individual children to customize HBox's layout.
 * For each constraint, HBox provides a static method for setting it on the child.
 * </p>
 *
 * <table border="1">
 * <caption>HBox Constraint Table</caption>
 * <tr><th scope="col">Constraint</th><th scope="col">Type</th><th scope="col">Description</th></tr>
 * <tr><th scope="row">hgrow</th><td>javafx.scene.layout.Priority</td><td>The horizontal grow priority for the child.</td></tr>
 * <tr><th scope="row">margin</th><td>javafx.geometry.Insets</td><td>Margin space around the outside of the child.</td></tr>
 * </table>
 * <p>
 * For example, if an hbox needs the TextField to be allocated all extra space:
 * <pre><code>
 *     HBox hbox = new HBox();
 *     TextField field = new TextField();
 *     <b>HBox.setHgrow(field, Priority.ALWAYS);</b>
 *     hbox.getChildren().addAll(new Label("Search:"), field, new Button("Go"));
 * </code></pre>
 *
 * If more than one child has the same grow priority set, then the hbox will
 * allocate equal amounts of space to each.  HBox will only grow a child up to
 * its maximum width, so if the child has a max width other than Double.MAX_VALUE,
 * the application may need to override the max to allow it to grow.
 * For example:
 * <pre><code>
 *     HBox hbox = new HBox();
 *     Button button1 = new Button("Add");
 *     Button button2 = new Button("Remove");
 *     <b>HBox.setHgrow(button1, Priority.ALWAYS);
 *     HBox.setHgrow(button2, Priority.ALWAYS);
 *     button1.setMaxWidth(Double.MAX_VALUE);
 *     button2.setMaxWidth(Double.MAX_VALUE);</b>
 *     hbox.getChildren().addAll(button1, button2);
 * </code></pre>
 * @since JavaFX 2.0
 */
public class HBox extends Pane {

    private boolean biasDirty = true;
    private double minBaselineComplement = Double.NaN;
    private double prefBaselineComplement = Double.NaN;
    private Orientation bias;
    private double[][] tempArray;

    
 BEGIN static methods
/********************************************************************
     *  BEGIN static methods
     ********************************************************************/
    private static final String MARGIN_CONSTRAINT = "hbox-margin";
    private static final String HGROW_CONSTRAINT = "hbox-hgrow";

    
Sets the horizontal grow priority for the child when contained by an hbox.
If set, the hbox will use the priority to allocate additional space if the
hbox is resized larger than it's preferred width.
If multiple hbox children have the same horizontal grow priority, then the
extra space will be split evenly between them.
If no horizontal grow priority is set on a child, the hbox will never
allocate it additional horizontal space if available.
Setting the value to null will remove the constraint.
Params:
child – the child of an hbox
value – the horizontal grow priority for the child/**
     * Sets the horizontal grow priority for the child when contained by an hbox.
     * If set, the hbox will use the priority to allocate additional space if the
     * hbox is resized larger than it's preferred width.
     * If multiple hbox children have the same horizontal grow priority, then the
     * extra space will be split evenly between them.
     * If no horizontal grow priority is set on a child, the hbox will never
     * allocate it additional horizontal space if available.
     * Setting the value to null will remove the constraint.
     * @param child the child of an hbox
     * @param value the horizontal grow priority for the child
     */
    public static void setHgrow(Node child, Priority value) {
        setConstraint(child, HGROW_CONSTRAINT, value);
    }

    
Returns the child's hgrow constraint if set.
Params:
child – the child node of an hbox
Returns:
the horizontal grow priority for the child or null if no priority was set/**
     * Returns the child's hgrow constraint if set.
     * @param child the child node of an hbox
     * @return the horizontal grow priority for the child or null if no priority was set
     */
    public static Priority getHgrow(Node child) {
        return (Priority)getConstraint(child, HGROW_CONSTRAINT);
    }

    
Sets the margin for the child when contained by an hbox.
If set, the hbox will layout the child with the margin space around it.
Setting the value to null will remove the constraint.
Params:
child – the child mode of the hbox
value – the margin of space around the child/**
     * Sets the margin for the child when contained by an hbox.
     * If set, the hbox will layout the child with the margin space around it.
     * Setting the value to null will remove the constraint.
     * @param child the child mode of the hbox
     * @param value the margin of space around the child
     */
    public static void setMargin(Node child, Insets value) {
        setConstraint(child, MARGIN_CONSTRAINT, value);
    }

    
Returns the child's margin constraint if set.
Params:
child – the child node of an hbox
Returns:
the margin for the child or null if no margin was set/**
     * Returns the child's margin constraint if set.
     * @param child the child node of an hbox
     * @return the margin for the child or null if no margin was set
     */
    public static Insets getMargin(Node child) {
        return (Insets)getConstraint(child, MARGIN_CONSTRAINT);
    }

    private static final Callback<Node, Insets> marginAccessor = n -> getMargin(n);

    
Removes all hbox constraints from the child node.
Params:
child – the child node/**
     * Removes all hbox constraints from the child node.
     * @param child the child node
     */
    public static void clearConstraints(Node child) {
        setHgrow(child, null);
        setMargin(child, null);
    }

    /********************************************************************
     *  END static methods
     ********************************************************************/

    
Creates an HBox layout with spacing = 0.
/**
     * Creates an HBox layout with spacing = 0.
     */
    public HBox() {
        super();
    }

    
Creates an HBox layout with the specified spacing between children.
Params:
spacing – the amount of horizontal space between each child/**
     * Creates an HBox layout with the specified spacing between children.
     * @param spacing the amount of horizontal space between each child
     */
    public HBox(double spacing) {
        this();
        setSpacing(spacing);
    }

    
Creates an HBox layout with spacing = 0.
Params:
children – The initial set of children for this pane.
Since:
JavaFX 8.0/**
     * Creates an HBox layout with spacing = 0.
     * @param children The initial set of children for this pane.
     * @since JavaFX 8.0
     */
    public HBox(Node... children) {
        super();
        getChildren().addAll(children);
    }

    
Creates an HBox layout with the specified spacing between children.
Params:
spacing – the amount of horizontal space between each child
children – The initial set of children for this pane.
Since:
JavaFX 8.0/**
     * Creates an HBox layout with the specified spacing between children.
     * @param spacing the amount of horizontal space between each child
     * @param children The initial set of children for this pane.
     * @since JavaFX 8.0
     */
    public HBox(double spacing, Node... children) {
        this();
        setSpacing(spacing);
        getChildren().addAll(children);
    }

    
The amount of horizontal space between each child in the hbox.
Returns:
the amount of horizontal space between each child in the hbox/**
     * The amount of horizontal space between each child in the hbox.
     * @return the amount of horizontal space between each child in the hbox
     */
    public final DoubleProperty spacingProperty() {
        if (spacing == null) {
            spacing = new StyleableDoubleProperty() {
                @Override
                public void invalidated() {
                    requestLayout();
                }

                @Override
                public CssMetaData getCssMetaData () {
                    return StyleableProperties.SPACING;
                }

                @Override
                public Object getBean() {
                    return HBox.this;
                }

                @Override
                public String getName() {
                    return "spacing";
                }
            };
        }
        return spacing;
    }

    private DoubleProperty spacing;
    public final void setSpacing(double value) { spacingProperty().set(value); }
    public final double getSpacing() { return spacing == null ? 0 : spacing.get(); }

    
The overall alignment of children within the hbox's width and height.
Returns:
the overall alignment of children within the hbox's width and
height/**
     * The overall alignment of children within the hbox's width and height.
     * @return the overall alignment of children within the hbox's width and
     * height
     */
    public final ObjectProperty<Pos> alignmentProperty() {
        if (alignment == null) {
            alignment = new StyleableObjectProperty<Pos>(Pos.TOP_LEFT) {
                @Override
                public void invalidated() {
                    requestLayout();
                }

                @Override
                public CssMetaData<HBox, Pos> getCssMetaData() {
                    return StyleableProperties.ALIGNMENT;
                }

                @Override
                public Object getBean() {
                    return HBox.this;
                }

                @Override
                public String getName() {
                    return "alignment";
                }
            };
        }
        return alignment;
    }

    private ObjectProperty<Pos> alignment;
    public final void setAlignment(Pos value) { alignmentProperty().set(value); }
    public final Pos getAlignment() { return alignment == null ? Pos.TOP_LEFT : alignment.get(); }
    private Pos getAlignmentInternal() {
        Pos localPos = getAlignment();
        return localPos == null ? Pos.TOP_LEFT : localPos;
    }

    
Whether or not resizable children will be resized to fill the full height of the hbox
or be resized to their preferred height and aligned according to the alignment
vpos value.   Note that if the hbox vertical alignment is set to BASELINE, then this
property will be ignored and children will be resized to their preferred heights.
Returns:
true if resizable children will be resized to fill the full
height of the hbox/**
     * Whether or not resizable children will be resized to fill the full height of the hbox
     * or be resized to their preferred height and aligned according to the <code>alignment</code>
     * vpos value.   Note that if the hbox vertical alignment is set to BASELINE, then this
     * property will be ignored and children will be resized to their preferred heights.
     * @return true if resizable children will be resized to fill the full
     * height of the hbox
     */
    public final BooleanProperty fillHeightProperty() {
        if (fillHeight == null) {
            fillHeight = new StyleableBooleanProperty(true) {
                @Override
                public void invalidated() {
                    requestLayout();
                }

                @Override
                public CssMetaData<HBox, Boolean> getCssMetaData() {
                    return StyleableProperties.FILL_HEIGHT;
                }

                @Override
                public Object getBean() {
                    return HBox.this;
                }

                @Override
                public String getName() {
                    return "fillHeight";
                }
            };
        }
        return fillHeight;
    }

    private BooleanProperty fillHeight;
    public final void setFillHeight(boolean value) { fillHeightProperty().set(value); }
    public final boolean isFillHeight() { return fillHeight == null ? true : fillHeight.get(); }

    private boolean shouldFillHeight() {
        return isFillHeight() && getAlignmentInternal().getVpos() != VPos.BASELINE;
    }

    
Returns:
null unless one of its children has a content bias./**
     *
     * @return null unless one of its children has a content bias.
     */
    @Override public Orientation getContentBias() {
        if (biasDirty) {
            bias = null;
            final List<Node> children = getManagedChildren();
            for (Node child : children) {
                Orientation contentBias = child.getContentBias();
                if (contentBias != null) {
                    bias = contentBias;
                    if (contentBias == Orientation.HORIZONTAL) {
                        break;
                    }
                }
            }
            biasDirty = false;
        }
        return bias;
    }

    @Override protected double computeMinWidth(double height) {
        Insets insets = getInsets();
        return snapSpaceX(insets.getLeft()) +
               computeContentWidth(getManagedChildren(), height, true) +
               snapSpaceX(insets.getRight());
    }

    @Override protected double computeMinHeight(double width) {
        Insets insets = getInsets();
        List<Node>managed = getManagedChildren();
        double contentHeight = 0;
        if (width != -1 && getContentBias() != null) {
            double prefWidths[][] = getAreaWidths(managed, -1, false);
            adjustAreaWidths(managed, prefWidths, width, -1);
            contentHeight = computeMaxMinAreaHeight(managed, marginAccessor, prefWidths[0], getAlignmentInternal().getVpos());
        } else {
            contentHeight = computeMaxMinAreaHeight(managed, marginAccessor, getAlignmentInternal().getVpos());
        }
        return snapSpaceY(insets.getTop()) +
               contentHeight +
               snapSpaceY(insets.getBottom());
    }

    @Override protected double computePrefWidth(double height) {
        Insets insets = getInsets();
        return snapSpaceX(insets.getLeft()) +
               computeContentWidth(getManagedChildren(), height, false) +
               snapSpaceX(insets.getRight());
    }

    @Override protected double computePrefHeight(double width) {
        Insets insets = getInsets();
        List<Node>managed = getManagedChildren();
        double contentHeight = 0;
        if (width != -1 && getContentBias() != null) {
            double prefWidths[][] = getAreaWidths(managed, -1, false);
            adjustAreaWidths(managed, prefWidths, width, -1);
            contentHeight = computeMaxPrefAreaHeight(managed, marginAccessor, prefWidths[0], getAlignmentInternal().getVpos());
        } else {
            contentHeight = computeMaxPrefAreaHeight(managed, marginAccessor, getAlignmentInternal().getVpos());
        }
        return snapSpaceY(insets.getTop()) +
               contentHeight +
               snapSpaceY(insets.getBottom());
    }

    private double[][] getAreaWidths(List<Node>managed, double height, boolean minimum) {
        // height could be -1
        double[][] temp = getTempArray(managed.size());
        final double insideHeight = height == -1? -1 : height -
                                     snapSpaceY(getInsets().getTop()) - snapSpaceY(getInsets().getBottom());
        final boolean shouldFillHeight = shouldFillHeight();
        for (int i = 0, size = managed.size(); i < size; i++) {
            Node child = managed.get(i);
            Insets margin = getMargin(child);
            if (minimum) {
                temp[0][i] = computeChildMinAreaWidth(child, getMinBaselineComplement(), margin, insideHeight, shouldFillHeight);
            } else {
                temp[0][i] = computeChildPrefAreaWidth(child, getPrefBaselineComplement(), margin, insideHeight, shouldFillHeight);
            }
        }
        return temp;
    }

    private double adjustAreaWidths(List<Node>managed, double areaWidths[][], double width, double height) {
        Insets insets = getInsets();
        double top = snapSpaceY(insets.getTop());
        double bottom = snapSpaceY(insets.getBottom());

        double contentWidth = sum(areaWidths[0], managed.size()) + (managed.size()-1)*snapSpaceX(getSpacing());
        double extraWidth = width -
                snapSpaceX(insets.getLeft()) - snapSpaceX(insets.getRight()) - contentWidth;

        if (extraWidth != 0) {
            final double refHeight = shouldFillHeight() && height != -1? height - top - bottom : -1;
            double remaining = growOrShrinkAreaWidths(managed, areaWidths, Priority.ALWAYS, extraWidth, refHeight);
            remaining = growOrShrinkAreaWidths(managed, areaWidths, Priority.SOMETIMES, remaining, refHeight);
            contentWidth += (extraWidth - remaining);
        }
        return contentWidth;
    }

    private double growOrShrinkAreaWidths(List<Node>managed, double areaWidths[][], Priority priority, double extraWidth, double height) {
        final boolean shrinking = extraWidth < 0;
        int adjustingNumber = 0;

        double[] usedWidths = areaWidths[0];
        double[] temp = areaWidths[1];
        final boolean shouldFillHeight = shouldFillHeight();

        if (shrinking) {
            adjustingNumber = managed.size();
            for (int i = 0, size = managed.size(); i < size; i++) {
                final Node child = managed.get(i);
                temp[i] = computeChildMinAreaWidth(child, getMinBaselineComplement(), getMargin(child), height, shouldFillHeight);
            }
        } else {
            for (int i = 0, size = managed.size(); i < size; i++) {
                final Node child = managed.get(i);
                if (getHgrow(child) == priority) {
                    temp[i] = computeChildMaxAreaWidth(child, getMinBaselineComplement(), getMargin(child), height, shouldFillHeight);
                    adjustingNumber++;
                } else {
                    temp[i] = -1;
                }
            }
        }

        double available = extraWidth; // will be negative in shrinking case
        outer:while (Math.abs(available) > 1 && adjustingNumber > 0) {
            final double portion = snapPortionX(available / adjustingNumber); // negative in shrinking case
            for (int i = 0, size = managed.size(); i < size; i++) {
                if (temp[i] == -1) {
                    continue;
                }
                final double limit = temp[i] - usedWidths[i]; // negative in shrinking case
                final double change = Math.abs(limit) <= Math.abs(portion)? limit : portion;
                usedWidths[i] += change;
                available -= change;
                if (Math.abs(available) < 1) {
                    break outer;
                }
                if (Math.abs(change) < Math.abs(portion)) {
                    temp[i] = -1;
                    adjustingNumber--;
                }
            }
        }

        return available; // might be negative in shrinking case
    }

    private double computeContentWidth(List<Node> managedChildren, double height, boolean minimum) {
        return sum(getAreaWidths(managedChildren, height, minimum)[0], managedChildren.size())
                + (managedChildren.size()-1)*snapSpaceX(getSpacing());
    }

    private static double sum(double[] array, int size) {
        int i = 0;
        double res = 0;
        while (i != size) {
            res += array[i++];
        }
        return res;
    }

    @Override public void requestLayout() {
        biasDirty = true;
        bias = null;
        minBaselineComplement = Double.NaN;
        prefBaselineComplement = Double.NaN;
        baselineOffset = Double.NaN;
        super.requestLayout();
    }

    private double getMinBaselineComplement() {
        if (Double.isNaN(minBaselineComplement)) {
            if (getAlignmentInternal().getVpos() == VPos.BASELINE) {
                minBaselineComplement = getMinBaselineComplement(getManagedChildren());
            } else {
                minBaselineComplement = -1;
            }
        }
        return minBaselineComplement;
    }

    private double getPrefBaselineComplement() {
        if (Double.isNaN(prefBaselineComplement)) {
            if (getAlignmentInternal().getVpos() == VPos.BASELINE) {
                prefBaselineComplement = getPrefBaselineComplement(getManagedChildren());
            } else {
                prefBaselineComplement = -1;
            }
        }
        return prefBaselineComplement;
    }

    private double baselineOffset = Double.NaN;

    @Override
    public double getBaselineOffset() {
        List<Node> managed = getManagedChildren();
        if (managed.isEmpty()) {
            return BASELINE_OFFSET_SAME_AS_HEIGHT;
        }
        if (Double.isNaN(baselineOffset)) {
            VPos vpos = getAlignmentInternal().getVpos();
            if (vpos == VPos.BASELINE) {
                double max = 0;
                for (int i =0, sz = managed.size(); i < sz; ++i) {
                    final Node child = managed.get(i);
                    double offset = child.getBaselineOffset();
                    if (offset == BASELINE_OFFSET_SAME_AS_HEIGHT) {
                        baselineOffset = BASELINE_OFFSET_SAME_AS_HEIGHT;
                        break;
                    } else {
                        Insets margin = getMargin(child);
                        double top = margin != null ? margin.getTop() : 0;
                        max = Math.max(max, top + child.getLayoutBounds().getMinY() + offset);
                    }
                }
                baselineOffset = max + snappedTopInset();
            } else {
                baselineOffset = BASELINE_OFFSET_SAME_AS_HEIGHT;
            }
        }
        return baselineOffset;
    }

    @Override protected void layoutChildren() {
        List<Node> managed = getManagedChildren();
        Insets insets = getInsets();
        Pos align = getAlignmentInternal();
        HPos alignHpos = align.getHpos();
        VPos alignVpos = align.getVpos();
        double width = getWidth();
        double height = getHeight();
        double top = snapSpaceY(insets.getTop());
        double left = snapSpaceX(insets.getLeft());
        double bottom = snapSpaceY(insets.getBottom());
        double right = snapSpaceX(insets.getRight());
        double space = snapSpaceX(getSpacing());
        boolean shouldFillHeight = shouldFillHeight();

        final double[][] actualAreaWidths = getAreaWidths(managed, height, false);
        double contentWidth = adjustAreaWidths(managed, actualAreaWidths, width, height);
        double contentHeight = height - top - bottom;

        double x = left + computeXOffset(width - left - right, contentWidth, align.getHpos());
        double y = top;
        double baselineOffset = -1;
        if (alignVpos == VPos.BASELINE) {
            double baselineComplement = getMinBaselineComplement();
            baselineOffset = getAreaBaselineOffset(managed, marginAccessor, i -> actualAreaWidths[0][i],
                    contentHeight, shouldFillHeight, baselineComplement);
        }

        for (int i = 0, size = managed.size(); i < size; i++) {
            Node child = managed.get(i);
            Insets margin = getMargin(child);
            layoutInArea(child, x, y, actualAreaWidths[0][i], contentHeight,
                    baselineOffset, margin, true, shouldFillHeight,
                    alignHpos, alignVpos);
            x += actualAreaWidths[0][i] + space;
        }
    }

    private double[][] getTempArray(int size) {
        if (tempArray == null) {
            tempArray = new double[2][size]; // First array for the result, second for temporary computations
        } else if (tempArray[0].length < size) {
            tempArray = new double[2][Math.max(tempArray.length * 3, size)];
        }
        return tempArray;

    }

    
                                                                        *
                        Stylesheet Handling                             *
                                                                        *
/***************************************************************************
     *                                                                         *
     *                         Stylesheet Handling                             *
     *                                                                         *
     **************************************************************************/

     /*
      * Super-lazy instantiation pattern from Bill Pugh.
      */
     private static class StyleableProperties {

         private static final CssMetaData<HBox,Pos> ALIGNMENT =
             new CssMetaData<HBox,Pos>("-fx-alignment",
                 new EnumConverter<Pos>(Pos.class),
                 Pos.TOP_LEFT) {

            @Override
            public boolean isSettable(HBox node) {
                return node.alignment == null || !node.alignment.isBound();
            }

            @Override
            public StyleableProperty<Pos> getStyleableProperty(HBox node) {
                return (StyleableProperty<Pos>)node.alignmentProperty();
            }

         };

         private static final CssMetaData<HBox,Boolean> FILL_HEIGHT =
             new CssMetaData<HBox,Boolean>("-fx-fill-height",
                 BooleanConverter.getInstance(), Boolean.TRUE) {

            @Override
            public boolean isSettable(HBox node) {
                return node.fillHeight == null ||
                        !node.fillHeight.isBound();
            }

            @Override
            public StyleableProperty<Boolean> getStyleableProperty(HBox node) {
                return (StyleableProperty<Boolean>)node.fillHeightProperty();
            }

         };

         private static final CssMetaData<HBox,Number> SPACING =
             new CssMetaData<HBox,Number>("-fx-spacing",
                 SizeConverter.getInstance(), 0.0){

            @Override
            public boolean isSettable(HBox node) {
                return node.spacing == null || !node.spacing.isBound();
            }

            @Override
            public StyleableProperty<Number> getStyleableProperty(HBox node) {
                return (StyleableProperty<Number>)node.spacingProperty();
            }

         };

         private static final List<CssMetaData<? extends Styleable, ?>> STYLEABLES;
         static {
            final List<CssMetaData<? extends Styleable, ?>> styleables =
                new ArrayList<CssMetaData<? extends Styleable, ?>>(Pane.getClassCssMetaData());
            styleables.add(FILL_HEIGHT);
            styleables.add(ALIGNMENT);
            styleables.add(SPACING);
            STYLEABLES = Collections.unmodifiableList(styleables);
         }
    }

    
Returns:
The CssMetaData associated with this class, which may include the
CssMetaData of its superclasses.
Since:
JavaFX 8.0/**
     * @return The CssMetaData associated with this class, which may include the
     * CssMetaData of its superclasses.
     * @since JavaFX 8.0
     */
    public static List<CssMetaData<? extends Styleable, ?>> getClassCssMetaData() {
        return StyleableProperties.STYLEABLES;
    }

    
{@inheritDoc}
Since:
JavaFX 8.0/**
     * {@inheritDoc}
     *
     * @since JavaFX 8.0
     */


    @Override
    public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() {
        return getClassCssMetaData();
    }

}