JDK8/Java8源码在线阅读

/*
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 * 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 javax.swing.plaf.basic;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Color;

import javax.swing.*;
import javax.swing.plaf.UIResource;

/**
 * JButton object that draws a scaled Arrow in one of the cardinal directions.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author David Kloba
 */
public class BasicArrowButton extends JButton implements SwingConstants
{
        /**
         * The direction of the arrow. One of
         * {@code SwingConstants.NORTH}, {@code SwingConstants.SOUTH},
         * {@code SwingConstants.EAST} or {@code SwingConstants.WEST}.
         */
        protected int direction;

        private Color shadow;
        private Color darkShadow;
        private Color highlight;

        /**
         * Creates a {@code BasicArrowButton} whose arrow
         * is drawn in the specified direction and with the specified
         * colors.
         *
         * @param direction the direction of the arrow; one of
         *        {@code SwingConstants.NORTH}, {@code SwingConstants.SOUTH},
         *        {@code SwingConstants.EAST} or {@code SwingConstants.WEST}
         * @param background the background color of the button
         * @param shadow the color of the shadow
         * @param darkShadow the color of the dark shadow
         * @param highlight the color of the highlight
         * @since 1.4
         */
        public BasicArrowButton(int direction, Color background, Color shadow,
                         Color darkShadow, Color highlight) {
            super();
            setRequestFocusEnabled(false);
            setDirection(direction);
            setBackground(background);
            this.shadow = shadow;
            this.darkShadow = darkShadow;
            this.highlight = highlight;
        }

        /**
         * Creates a {@code BasicArrowButton} whose arrow
         * is drawn in the specified direction.
         *
         * @param direction the direction of the arrow; one of
         *        {@code SwingConstants.NORTH}, {@code SwingConstants.SOUTH},
         *        {@code SwingConstants.EAST} or {@code SwingConstants.WEST}
         */
        public BasicArrowButton(int direction) {
            this(direction, UIManager.getColor("control"), UIManager.getColor("controlShadow"),
                 UIManager.getColor("controlDkShadow"), UIManager.getColor("controlLtHighlight"));
        }

        /**
         * Returns the direction of the arrow.
         */
        public int getDirection() {
            return direction;
        }

        /**
         * Sets the direction of the arrow.
         *
         * @param direction the direction of the arrow; one of
         *        of {@code SwingConstants.NORTH},
         *        {@code SwingConstants.SOUTH},
         *        {@code SwingConstants.EAST} or {@code SwingConstants.WEST}
         */
        public void setDirection(int direction) {
            this.direction = direction;
        }

        public void paint(Graphics g) {
            Color origColor;
            boolean isPressed, isEnabled;
            int w, h, size;

            w = getSize().width;
            h = getSize().height;
            origColor = g.getColor();
            isPressed = getModel().isPressed();
            isEnabled = isEnabled();

            g.setColor(getBackground());
            g.fillRect(1, 1, w-2, h-2);

            /// Draw the proper Border
            if (getBorder() != null && !(getBorder() instanceof UIResource)) {
                paintBorder(g);
            } else if (isPressed) {
                g.setColor(shadow);
                g.drawRect(0, 0, w-1, h-1);
            } else {
                // Using the background color set above
                g.drawLine(0, 0, 0, h-1);
                g.drawLine(1, 0, w-2, 0);

                g.setColor(highlight);    // inner 3D border
                g.drawLine(1, 1, 1, h-3);
                g.drawLine(2, 1, w-3, 1);

                g.setColor(shadow);       // inner 3D border
                g.drawLine(1, h-2, w-2, h-2);
                g.drawLine(w-2, 1, w-2, h-3);

                g.setColor(darkShadow);     // black drop shadow  __|
                g.drawLine(0, h-1, w-1, h-1);
                g.drawLine(w-1, h-1, w-1, 0);
            }

            // If there's no room to draw arrow, bail
            if(h < 5 || w < 5)      {
                g.setColor(origColor);
                return;
            }

            if (isPressed) {
                g.translate(1, 1);
            }

            // Draw the arrow
            size = Math.min((h - 4) / 3, (w - 4) / 3);
            size = Math.max(size, 2);
            paintTriangle(g, (w - size) / 2, (h - size) / 2,
                                size, direction, isEnabled);

            // Reset the Graphics back to it's original settings
            if (isPressed) {
                g.translate(-1, -1);
            }
            g.setColor(origColor);

        }

        /**
         * Returns the preferred size of the {@code BasicArrowButton}.
         *
         * @return the preferred size
         */
        public Dimension getPreferredSize() {
            return new Dimension(16, 16);
        }

        /**
         * Returns the minimum size of the {@code BasicArrowButton}.
         *
         * @return the minimum size
         */
        public Dimension getMinimumSize() {
            return new Dimension(5, 5);
        }

        /**
         * Returns the maximum size of the {@code BasicArrowButton}.
         *
         * @return the maximum size
         */
        public Dimension getMaximumSize() {
            return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE);
        }

        /**
         * Returns whether the arrow button should get the focus.
         * {@code BasicArrowButton}s are used as a child component of
         * composite components such as {@code JScrollBar} and
         * {@code JComboBox}. Since the composite component typically gets the
         * focus, this method is overriden to return {@code false}.
         *
         * @return {@code false}
         */
        public boolean isFocusTraversable() {
          return false;
        }

        /**
         * Paints a triangle.
         *
         * @param g the {@code Graphics} to draw to
         * @param x the x coordinate
         * @param y the y coordinate
         * @param size the size of the triangle to draw
         * @param direction the direction in which to draw the arrow;
         *        one of {@code SwingConstants.NORTH},
         *        {@code SwingConstants.SOUTH}, {@code SwingConstants.EAST} or
         *        {@code SwingConstants.WEST}
         * @param isEnabled whether or not the arrow is drawn enabled
         */
        public void paintTriangle(Graphics g, int x, int y, int size,
                                        int direction, boolean isEnabled) {
            Color oldColor = g.getColor();
            int mid, i, j;

            j = 0;
            size = Math.max(size, 2);
            mid = (size / 2) - 1;

            g.translate(x, y);
            if(isEnabled)
                g.setColor(darkShadow);
            else
                g.setColor(shadow);

            switch(direction)       {
            case NORTH:
                for(i = 0; i < size; i++)      {
                    g.drawLine(mid-i, i, mid+i, i);
                }
                if(!isEnabled)  {
                    g.setColor(highlight);
                    g.drawLine(mid-i+2, i, mid+i, i);
                }
                break;
            case SOUTH:
                if(!isEnabled)  {
                    g.translate(1, 1);
                    g.setColor(highlight);
                    for(i = size-1; i >= 0; i--)   {
                        g.drawLine(mid-i, j, mid+i, j);
                        j++;
                    }
                    g.translate(-1, -1);
                    g.setColor(shadow);
                }

                j = 0;
                for(i = size-1; i >= 0; i--)   {

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