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 * Copyright (c) 2010, 2016, 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 com.sun.javafx.charts;

import java.util.List;
import java.util.stream.Collectors;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.BooleanPropertyBase;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.ObjectPropertyBase;
import javafx.beans.property.StringProperty;
import javafx.beans.property.StringPropertyBase;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.geometry.Orientation;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.Label;
import javafx.scene.layout.Region;
import javafx.scene.layout.TilePane;

A chart legend that displays a list of items with symbols in a box
/**
 * A chart legend that displays a list of items with symbols in a box
 */
public class Legend extends TilePane {

    private static final int GAP = 5;

    // -------------- PRIVATE FIELDS ------------------------------------------

    private ListChangeListener<LegendItem> itemsListener = c -> {
        List<Label> labels = getItems().stream()
                                       .map(i -> i.label)
                                       .collect(Collectors.toList());
        getChildren().setAll(labels);
        if(isVisible()) requestLayout();
    };

    // -------------- PUBLIC PROPERTIES ----------------------------------------
    
The legend items should be laid out vertically in columns rather than
horizontally in rows
/** The legend items should be laid out vertically in columns rather than
     * horizontally in rows
     */
    private BooleanProperty vertical = new BooleanPropertyBase(false) {
        @Override protected void invalidated() {
            setOrientation(get() ? Orientation.VERTICAL : Orientation.HORIZONTAL);
        }

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

        @Override
        public String getName() {
             return "vertical";
        }
    };
    public final boolean isVertical() { return vertical.get(); }
    public final void setVertical(boolean value) { vertical.set(value); }
    public final BooleanProperty verticalProperty() { return vertical; }

     
The legend items to display in this legend /** The legend items to display in this legend */
    private ObjectProperty<ObservableList<LegendItem>> items = new ObjectPropertyBase<ObservableList<LegendItem>>() {
        ObservableList<LegendItem> oldItems = null;
        @Override protected void invalidated() {
            if (oldItems != null) oldItems.removeListener(itemsListener);
            getChildren().clear();
            ObservableList<LegendItem> newItems = get();
            if (newItems != null) {
                newItems.addListener(itemsListener);
                List<Label> labels = newItems.stream()
                        .map(i -> i.label)
                        .collect(Collectors.toList());
                getChildren().addAll(labels);
            }
            oldItems = newItems;
            requestLayout();
        }

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

        @Override
        public String getName() {
            return "items";
        }
    };
    public final void setItems(ObservableList<LegendItem> value) {itemsProperty().set(value);}
    public final ObservableList<LegendItem> getItems() { return items.get();}
    public final ObjectProperty<ObservableList<LegendItem>> itemsProperty() {return items;}

    // -------------- PROTECTED PROPERTIES ------------------------------------

    // -------------- CONSTRUCTORS ----------------------------------------------

    public Legend() {
        super(GAP, GAP);
        setTileAlignment(Pos.CENTER_LEFT);
        setItems(FXCollections.<LegendItem>observableArrayList());
        getStyleClass().setAll("chart-legend");
    }

    // -------------- METHODS ---------------------------------------------------

    @Override
    protected double computePrefWidth(double forHeight) {
        // Legend prefWidth is zero if there are no legend items
        return (getItems().size() > 0) ? super.computePrefWidth(forHeight) : 0;
    }

    @Override
    protected double computePrefHeight(double forWidth) {
        // Legend prefHeight is zero if there are no legend items
        return (getItems().size() > 0) ? super.computePrefHeight(forWidth) : 0;
    }

    
A item to be displayed on a Legend /** A item to be displayed on a Legend */
    public static class LegendItem {

        
Label used to represent the legend item /** Label used to represent the legend item */
        private Label label = new Label();

        
The item text /** The item text */
        private StringProperty text = new StringPropertyBase() {
            @Override protected void invalidated() {
                label.setText(get());
            }

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

            @Override
            public String getName() {
                return "text";
            }
        };
        public final String getText() { return text.getValue(); }
        public final void setText(String value) { text.setValue(value); }
        public final StringProperty textProperty() { return text; }

        
The symbol to use next to the item text, set to null for no symbol. The default is a simple square of symbolFill /** The symbol to use next to the item text, set to null for no symbol. The default is a simple square of symbolFill */
        //new Rectangle(8,8,null)
        private ObjectProperty<Node> symbol = new ObjectPropertyBase<Node>(new Region()) {
            @Override protected void invalidated() {
                Node symbol = get();
                if(symbol != null) symbol.getStyleClass().setAll("chart-legend-item-symbol");
                label.setGraphic(symbol);
            }

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

            @Override
            public String getName() {
                return "symbol";
            }
        };
        public final Node getSymbol() { return symbol.getValue(); }
        public final void setSymbol(Node value) { symbol.setValue(value); }
        public final ObjectProperty<Node> symbolProperty() { return symbol; }

        public LegendItem(String text) {
            setText(text);
            label.getStyleClass().add("chart-legend-item");
            label.setAlignment(Pos.CENTER_LEFT);
            label.setContentDisplay(ContentDisplay.LEFT);
            label.setGraphic(getSymbol());
            getSymbol().getStyleClass().setAll("chart-legend-item-symbol");
        }

        public LegendItem(String text, Node symbol) {
            this(text);
            setSymbol(symbol);
        }
    }
}