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 * Copyright (c) 2009, 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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package javafx.scene.layout;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javafx.beans.property.ObjectProperty;
import javafx.css.CssMetaData;
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.EnumConverter;
import javafx.css.Styleable;
import javafx.geometry.HPos;
import javafx.util.Callback;

StackPane lays out its children in a back-to-front stack.

The z-order of the children is defined by the order of the children list
with the 0th child being the bottom and last child on top.  If a border and/or
padding have been set, the children will be laid out within those insets.

The stackpane will attempt to resize each child to fill its content area.
If the child could not be sized to fill the stackpane (either because it was
not resizable or its max size prevented it) then it will be aligned within
the area using the alignment property, which defaults to Pos.CENTER.

StackPane example:

    StackPane stack = new StackPane();
    stack.getChildren().addAll(new Rectangle(100,100,Color.BLUE), new Label("Go!"));


StackPane lays out each managed child regardless of the child's
visible property value; unmanaged children are ignored.
 StackPane may be styled with backgrounds and borders using CSS. See Region for details.
Resizable Range

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


StackPane Resize Table
width
height
minimum
left/right insets plus the largest of the children's min widths.
top/bottom insets plus the largest of the children's min heights.
preferred
left/right insets plus the largest of the children's pref widths.
top/bottom insets plus the largest of the children's pref heights.
maximum
Double.MAX_VALUE
Double.MAX_VALUE


A stackpane'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.

StackPane 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:
     // ensure stackpane is never resized beyond it's preferred size
    stackpane.setMaxSize(Region.USE_PREF_SIZE, Region.USE_PREF_SIZE);

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

StackPane 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 stackpane.
Optional Layout Constraints

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


StackPane Constraint Table
Constraint
Type
Description
alignment
javafx.geometry.Pos
The alignment of the child within the stackpane.
margin
javafx.geometry.Insets
Margin space around the outside of the child.


Examples:
     // Align the title Label at the bottom-center of the stackpane
    Label title = new Label();
    StackPane.setAlignment(title, Pos.BOTTOM_CENTER);
    stackpane.getChildren.addAll(new ImageView(...), title);
    // Create an 8 pixel margin around a listview in the stackpane
    ListView list = new ListView();
    StackPane.setMargin(list, new Insets(8,8,8,8);
    stackpane.getChildren().add(list);

Since:
JavaFX 2.0/**
 *
 * StackPane lays out its children in a back-to-front stack.
 * <p>
 * The z-order of the children is defined by the order of the children list
 * with the 0th child being the bottom and last child on top.  If a border and/or
 * padding have been set, the children will be laid out within those insets.
 * <p>
 * The stackpane will attempt to resize each child to fill its content area.
 * If the child could not be sized to fill the stackpane (either because it was
 * not resizable or its max size prevented it) then it will be aligned within
 * the area using the alignment property, which defaults to Pos.CENTER.
 * <p>
 * StackPane example:
 * <pre>{@code
 *     StackPane stack = new StackPane();
 *     stack.getChildren().addAll(new Rectangle(100,100,Color.BLUE), new Label("Go!"));
 * }</pre>
 * <p>
 * StackPane lays out each managed child regardless of the child's
 * visible property value; unmanaged children are ignored.</p>
 * <p>
 * StackPane may be styled with backgrounds and borders using CSS.  See
 * {@link javafx.scene.layout.Region Region} for details.</p>
 *
 * <h3>Resizable Range</h3>
 *
 * <p>
 * A stackpane's parent will resize the stackpane within the stackpane's resizable range
 * during layout.   By default the stackpane computes this range based on its content
 * as outlined in the table below.
 * </p>
 *
 * <table border="1">
 * <caption>StackPane 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 largest of the children's min widths.</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 largest of the children's pref widths.</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>
 * A stackpane'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>
 * StackPane 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>     // ensure stackpane is never resized beyond it's preferred size
 *     <b>stackpane.setMaxSize(Region.USE_PREF_SIZE, Region.USE_PREF_SIZE);</b>
 * </code></pre>
 * Applications may restore the computed values by setting these properties back
 * to USE_COMPUTED_SIZE.
 *
 * <p>
 * StackPane 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 stackpane.</p>
 *
 * <h3>Optional Layout Constraints</h3>
 *
 * <p>
 * An application may set constraints on individual children to customize StackPane's layout.
 * For each constraint, StackPane provides a static method for setting it on the child.
 * </p>
 *
 * <table border="1">
 * <caption>StackPane Constraint Table</caption>
 * <tr><th>Constraint</th><th scope="col">Type</th><th scope="col">Description</th></tr>
 * <tr><th scope="row">alignment</th><td>javafx.geometry.Pos</td><td>The alignment of the child within the stackpane.</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>
 * Examples:
 * <pre><code>     // Align the title Label at the bottom-center of the stackpane
 *     Label title = new Label();
 *     <b>StackPane.setAlignment(title, Pos.BOTTOM_CENTER);</b>
 *     stackpane.getChildren.addAll(new ImageView(...), title);
 *
 *     // Create an 8 pixel margin around a listview in the stackpane
 *     ListView list = new ListView();
 *     <b>StackPane.setMargin(list, new Insets(8,8,8,8);</b>
 *     stackpane.getChildren().add(list);
 * </code></pre>
 *
 * @since JavaFX 2.0
 */

public class StackPane extends Pane {

    private boolean biasDirty = true;
    private Orientation bias;

    
 BEGIN static methods
/********************************************************************
     *  BEGIN static methods
     ********************************************************************/

    private static final String MARGIN_CONSTRAINT = "stackpane-margin";
    private static final String ALIGNMENT_CONSTRAINT = "stackpane-alignment";

   
Sets the alignment for the child when contained by a stackpane.
If set, will override the stackpane's default alignment.
Setting the value to null will remove the constraint.
Params:
child – the child node of a stackpane
value – the alignment position for the child/**
     * Sets the alignment for the child when contained by a stackpane.
     * If set, will override the stackpane's default alignment.
     * Setting the value to null will remove the constraint.
     * @param child the child node of a stackpane
     * @param value the alignment position for the child
     */
    public static void setAlignment(Node child, Pos value) {
        setConstraint(child, ALIGNMENT_CONSTRAINT, value);
    }

    
Returns the child's alignment constraint if set.
Params:
child – the child node of a stackpane
Returns:
the alignment position for the child or null if no alignment was set/**
     * Returns the child's alignment constraint if set.
     * @param child the child node of a stackpane
     * @return the alignment position for the child or null if no alignment was set
     */
    public static Pos getAlignment(Node child) {
        return (Pos)getConstraint(child, ALIGNMENT_CONSTRAINT);
    }

    
Sets the margin for the child when contained by a stackpane.
If set, the stackpane will layout the child with the margin space around it.
Setting the value to null will remove the constraint.
Params:
child – the child node of a stackpane
value – the margin of space around the child/**
     * Sets the margin for the child when contained by a stackpane.
     * If set, the stackpane will layout the child with the margin space around it.
     * Setting the value to null will remove the constraint.
     * @param child the child node of a stackpane
     * @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 constraints if set.
Params:
child – the child node of a stackpane
Returns:
the margin for the child or null if no margin was set/**
     * Returns the child's margin constraints if set.
     * @param child the child node of a stackpane
     * @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 stackpane constraints from the child node.
Params:
child – the child node/**
     * Removes all stackpane constraints from the child node.
     * @param child the child node
     */
    public static void clearConstraints(Node child) {
        setAlignment(child, null);
        setMargin(child, null);
    }
    /********************************************************************
     *  END static methods
     ********************************************************************/

    
Creates a StackPane layout with default CENTER alignment.
/**
     * Creates a StackPane layout with default CENTER alignment.
     */
    public StackPane() {
        super();
    }

    
Creates a StackPane layout with default CENTER alignment.
Params:
children – The initial set of children for this pane.
Since:
JavaFX 8.0/**
     * Creates a StackPane layout with default CENTER alignment.
     * @param children The initial set of children for this pane.
     * @since JavaFX 8.0
     */
    public StackPane(Node... children) {
        super();
        getChildren().addAll(children);
    }

    
The default alignment of children within the stackpane's width and height.
This may be overridden on individual children by setting the child's
alignment constraint.
Returns:
the alignment of children within this stackpane/**
     * The default alignment of children within the stackpane's width and height.
     * This may be overridden on individual children by setting the child's
     * alignment constraint.
     * @return the alignment of children within this stackpane
     */
    public final ObjectProperty<Pos> alignmentProperty() {
        if (alignment == null) {
            alignment = new StyleableObjectProperty<Pos>(Pos.CENTER) {
                @Override
                public void invalidated() {
                    requestLayout();
                }

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

                @Override
                public Object getBean() {
                    return StackPane.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.CENTER : alignment.get(); }
    private Pos getAlignmentInternal() {
        Pos localPos = getAlignment();
        return localPos == null ? Pos.CENTER : localPos;
    }

    
Returns:
the first non-null contentBias of its managed children or null if no managed children
have a content bias./**
     *
     * @return the first non-null contentBias of its managed children or null if no managed children
     * have 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) {
        List<Node>managed = getManagedChildren();
        return getInsets().getLeft() +
               computeMaxMinAreaWidth(managed, marginAccessor, height, true) +
               getInsets().getRight();
    }

    @Override protected double computeMinHeight(double width) {
        List<Node>managed = getManagedChildren();
        return getInsets().getTop() +
               computeMaxMinAreaHeight(managed, marginAccessor, getAlignmentInternal().getVpos(), width) +
               getInsets().getBottom();
    }

    @Override protected double computePrefWidth(double height) {
        List<Node>managed = getManagedChildren();
        Insets padding = getInsets();
        return padding.getLeft() +
               computeMaxPrefAreaWidth(managed, marginAccessor,
                                       (height == -1) ? -1 : (height - padding.getTop() - padding.getBottom()), true) +
               padding.getRight();
    }

    @Override protected double computePrefHeight(double width) {
        List<Node>managed = getManagedChildren();
        Insets padding = getInsets();
        return padding.getTop() +
               computeMaxPrefAreaHeight(managed, marginAccessor,
                                        (width == -1) ? -1 : (width - padding.getLeft() - padding.getRight()),
                                        getAlignmentInternal().getVpos()) +
               padding.getBottom();
    }


    @Override public void requestLayout() {
        biasDirty = true;
        bias = null;
        super.requestLayout();
    }

    @Override protected void layoutChildren() {
        List<Node> managed = getManagedChildren();
        Pos align = getAlignmentInternal();
        HPos alignHpos = align.getHpos();
        VPos alignVpos = align.getVpos();
        final double width = getWidth();
        double height = getHeight();
        double top = getInsets().getTop();
        double right = getInsets().getRight();
        double left = getInsets().getLeft();
        double bottom = getInsets().getBottom();
        double contentWidth = width - left - right;
        double contentHeight = height - top - bottom;
        double baselineOffset = alignVpos == VPos.BASELINE ?
                getAreaBaselineOffset(managed, marginAccessor, i -> width, contentHeight, true)
                                    : 0;
        for (int i = 0, size = managed.size(); i < size; i++) {
            Node child = managed.get(i);
            Pos childAlignment = StackPane.getAlignment(child);
            layoutInArea(child, left, top,
                           contentWidth, contentHeight,
                           baselineOffset, getMargin(child),
                           childAlignment != null? childAlignment.getHpos() : alignHpos,
                           childAlignment != null? childAlignment.getVpos() : alignVpos);
        }
    }

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

     /*
      * Super-lazy instantiation pattern from Bill Pugh.
      */
     private static class StyleableProperties {
         private static final CssMetaData<StackPane,Pos> ALIGNMENT =
             new CssMetaData<StackPane,Pos>("-fx-alignment",
                 new EnumConverter<Pos>(Pos.class),
                 Pos.CENTER) {

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

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

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

}