/*

 * Copyright (c) 1997, 2014, 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 javax.swing;

import javax.swing.border.*;

import java.awt.LayoutManager;

import java.awt.Component;

import java.awt.Container;

import java.awt.Rectangle;

import java.awt.Dimension;

import java.awt.Insets;

import java.io.Serializable;

/**

 * The layout manager used by <code>JScrollPane</code>.

 * <code>JScrollPaneLayout</code> is

 * responsible for nine components: a viewport, two scrollbars,

 * a row header, a column header, and four "corner" components.

 * <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™

 * has been added to the <code>java.beans</code> package.

 * Please see {@link java.beans.XMLEncoder}.

 *

 * @see JScrollPane

 * @see JViewport

 *

 * @author Hans Muller

 * @since 1.2

 */

@SuppressWarnings("serial") // Same-version serialization only

public class ScrollPaneLayout

    implements LayoutManager, ScrollPaneConstants, Serializable

{

    /**

     * The scrollpane's viewport child.

     * Default is an empty <code>JViewport</code>.

     * @see JScrollPane#setViewport

     */

    protected JViewport viewport;

    /**

     * The scrollpane's vertical scrollbar child.

     * Default is a <code>JScrollBar</code>.

     * @see JScrollPane#setVerticalScrollBar

     */

    protected JScrollBar vsb;

    /**

     * The scrollpane's horizontal scrollbar child.

     * Default is a <code>JScrollBar</code>.

     * @see JScrollPane#setHorizontalScrollBar

     */

    protected JScrollBar hsb;

    /**

     * The row header child.  Default is <code>null</code>.

     * @see JScrollPane#setRowHeader

     */

    protected JViewport rowHead;

    /**

     * The column header child.  Default is <code>null</code>.

     * @see JScrollPane#setColumnHeader

     */

    protected JViewport colHead;

    /**

     * The component to display in the lower left corner.

     * Default is <code>null</code>.

     * @see JScrollPane#setCorner

     */

    protected Component lowerLeft;

    /**

     * The component to display in the lower right corner.

     * Default is <code>null</code>.

     * @see JScrollPane#setCorner

     */

    protected Component lowerRight;

    /**

     * The component to display in the upper left corner.

     * Default is <code>null</code>.

     * @see JScrollPane#setCorner

     */

    protected Component upperLeft;

    /**

     * The component to display in the upper right corner.

     * Default is <code>null</code>.

     * @see JScrollPane#setCorner

     */

    protected Component upperRight;

    /**

     * The display policy for the vertical scrollbar.

     * The default is <code>ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED</code>.

     * <p>

     * This field is obsolete, please use the <code>JScrollPane</code> field instead.

     *

     * @see JScrollPane#setVerticalScrollBarPolicy

     */

    protected int vsbPolicy = VERTICAL_SCROLLBAR_AS_NEEDED;

    /**

     * The display policy for the horizontal scrollbar.

     * The default is <code>ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED</code>.

     * <p>

     * This field is obsolete, please use the <code>JScrollPane</code> field instead.

     *

     * @see JScrollPane#setHorizontalScrollBarPolicy

     */

    protected int hsbPolicy = HORIZONTAL_SCROLLBAR_AS_NEEDED;

    /**

     * This method is invoked after the ScrollPaneLayout is set as the

     * LayoutManager of a <code>JScrollPane</code>.

     * It initializes all of the internal fields that

     * are ordinarily set by <code>addLayoutComponent</code>.  For example:

     * <pre>

     * ScrollPaneLayout mySPLayout = new ScrollPanelLayout() {

     *     public void layoutContainer(Container p) {

     *         super.layoutContainer(p);

     *         // do some extra work here ...

     *     }

     * };

     * scrollpane.setLayout(mySPLayout):

     * </pre>

     *

     * @param sp an instance of the {@code JScrollPane}

     */

    public void syncWithScrollPane(JScrollPane sp) {

        viewport = sp.getViewport();

        vsb = sp.getVerticalScrollBar();

        hsb = sp.getHorizontalScrollBar();

        rowHead = sp.getRowHeader();

        colHead = sp.getColumnHeader();

        lowerLeft = sp.getCorner(LOWER_LEFT_CORNER);

        lowerRight = sp.getCorner(LOWER_RIGHT_CORNER);

        upperLeft = sp.getCorner(UPPER_LEFT_CORNER);

        upperRight = sp.getCorner(UPPER_RIGHT_CORNER);

        vsbPolicy = sp.getVerticalScrollBarPolicy();

        hsbPolicy = sp.getHorizontalScrollBarPolicy();

    }

    /**

     * Removes an existing component.  When a new component, such as

     * the left corner, or vertical scrollbar, is added, the old one,

     * if it exists, must be removed.

     * <p>

     * This method returns <code>newC</code>. If <code>oldC</code> is

     * not equal to <code>newC</code> and is non-<code>null</code>,

     * it will be removed from its parent.

     *

     * @param oldC the <code>Component</code> to replace

     * @param newC the <code>Component</code> to add

     * @return the <code>newC</code>

     */

    protected Component addSingletonComponent(Component oldC, Component newC)

    {

        if ((oldC != null) && (oldC != newC)) {

            oldC.getParent().remove(oldC);

        }

        return newC;

    }

    /**

     * Adds the specified component to the layout. The layout is

     * identified using one of:

     * <ul>

     * <li>ScrollPaneConstants.VIEWPORT

     * <li>ScrollPaneConstants.VERTICAL_SCROLLBAR

     * <li>ScrollPaneConstants.HORIZONTAL_SCROLLBAR

     * <li>ScrollPaneConstants.ROW_HEADER

     * <li>ScrollPaneConstants.COLUMN_HEADER

     * <li>ScrollPaneConstants.LOWER_LEFT_CORNER

     * <li>ScrollPaneConstants.LOWER_RIGHT_CORNER

     * <li>ScrollPaneConstants.UPPER_LEFT_CORNER

     * <li>ScrollPaneConstants.UPPER_RIGHT_CORNER

     * </ul>

     *

     * @param s the component identifier

     * @exception IllegalArgumentException if <code>s</code> is an invalid key

     */

    public void addLayoutComponent(String s, Component c)

    {

        if (s.equals(VIEWPORT)) {

            viewport = (JViewport)addSingletonComponent(viewport, c);

        }

        else if (s.equals(VERTICAL_SCROLLBAR)) {

            vsb = (JScrollBar)addSingletonComponent(vsb, c);

        }

        else if (s.equals(HORIZONTAL_SCROLLBAR)) {

            hsb = (JScrollBar)addSingletonComponent(hsb, c);

        }

        else if (s.equals(ROW_HEADER)) {

            rowHead = (JViewport)addSingletonComponent(rowHead, c);

        }

        else if (s.equals(COLUMN_HEADER)) {

            colHead = (JViewport)addSingletonComponent(colHead, c);

        }

        else if (s.equals(LOWER_LEFT_CORNER)) {

            lowerLeft = addSingletonComponent(lowerLeft, c);

        }

        else if (s.equals(LOWER_RIGHT_CORNER)) {

            lowerRight = addSingletonComponent(lowerRight, c);

        }

        else if (s.equals(UPPER_LEFT_CORNER)) {

            upperLeft = addSingletonComponent(upperLeft, c);

        }

        else if (s.equals(UPPER_RIGHT_CORNER)) {

            upperRight = addSingletonComponent(upperRight, c);

        }

        else {

            throw new IllegalArgumentException("invalid layout key " + s);

        }

    }

    /**

     * Removes the specified component from the layout.

     *

     * @param c the component to remove

     */

    public void removeLayoutComponent(Component c)

    {

        if (c == viewport) {

            viewport = null;

        }

        else if (c == vsb) {

            vsb = null;

        }

        else if (c == hsb) {

            hsb = null;

        }

        else if (c == rowHead) {

            rowHead = null;

        }

        else if (c == colHead) {

            colHead = null;

        }

        else if (c == lowerLeft) {

            lowerLeft = null;

        }

        else if (c == lowerRight) {

            lowerRight = null;

        }

        else if (c == upperLeft) {

            upperLeft = null;

        }

        else if (c == upperRight) {

            upperRight = null;

        }

    }

    /**

     * Returns the vertical scrollbar-display policy.

     *

     * @return an integer giving the display policy

     * @see #setVerticalScrollBarPolicy

     */

    public int getVerticalScrollBarPolicy() {

        return vsbPolicy;

    }

    /**

     * Sets the vertical scrollbar-display policy. The options

     * are:

     * <ul>

     * <li>ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED

     * <li>ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER

     * <li>ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS

     * </ul>

     * Note: Applications should use the <code>JScrollPane</code> version

     * of this method.  It only exists for backwards compatibility

     * with the Swing 1.0.2 (and earlier) versions of this class.

     *

     * @param x an integer giving the display policy

     * @exception IllegalArgumentException if <code>x</code> is an invalid

     *          vertical scroll bar policy, as listed above

     */

    public void setVerticalScrollBarPolicy(int x) {

        switch (x) {

        case VERTICAL_SCROLLBAR_AS_NEEDED:

        case VERTICAL_SCROLLBAR_NEVER:

        case VERTICAL_SCROLLBAR_ALWAYS:

                vsbPolicy = x;

                break;

        default:

            throw new IllegalArgumentException("invalid verticalScrollBarPolicy");

        }

    }

    /**

     * Returns the horizontal scrollbar-display policy.

     *

     * @return an integer giving the display policy

     * @see #setHorizontalScrollBarPolicy

     */

    public int getHorizontalScrollBarPolicy() {

        return hsbPolicy;

    }

    /**

     * Sets the horizontal scrollbar-display policy.

     * The options are:<ul>

     * <li>ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED

     * <li>ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER

     * <li>ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS

     * </ul>

     * Note: Applications should use the <code>JScrollPane</code> version

     * of this method.  It only exists for backwards compatibility

     * with the Swing 1.0.2 (and earlier) versions of this class.

     *

     * @param x an int giving the display policy

     * @exception IllegalArgumentException if <code>x</code> is not a valid

     *          horizontal scrollbar policy, as listed above

     */

    public void setHorizontalScrollBarPolicy(int x) {

        switch (x) {

        case HORIZONTAL_SCROLLBAR_AS_NEEDED:

        case HORIZONTAL_SCROLLBAR_NEVER:

        case HORIZONTAL_SCROLLBAR_ALWAYS:

                hsbPolicy = x;

                break;

        default:

            throw new IllegalArgumentException("invalid horizontalScrollBarPolicy");

        }

    }

    /**

     * Returns the <code>JViewport</code> object that displays the

     * scrollable contents.

     * @return the <code>JViewport</code> object that displays the scrollable contents

     * @see JScrollPane#getViewport

     */

    public JViewport getViewport() {

        return viewport;

    }

    /**

     * Returns the <code>JScrollBar</code> object that handles horizontal scrolling.

     * @return the <code>JScrollBar</code> object that handles horizontal scrolling

     * @see JScrollPane#getHorizontalScrollBar

     */

    public JScrollBar getHorizontalScrollBar() {

        return hsb;

    }

    /**

     * Returns the <code>JScrollBar</code> object that handles vertical scrolling.

     * @return the <code>JScrollBar</code> object that handles vertical scrolling

     * @see JScrollPane#getVerticalScrollBar

     */

    public JScrollBar getVerticalScrollBar() {

        return vsb;

    }

    /**

     * Returns the <code>JViewport</code> object that is the row header.

     * @return the <code>JViewport</code> object that is the row header

     * @see JScrollPane#getRowHeader

     */

    public JViewport getRowHeader() {

        return rowHead;

    }

    /**

     * Returns the <code>JViewport</code> object that is the column header.

     * @return the <code>JViewport</code> object that is the column header

     * @see JScrollPane#getColumnHeader

     */

    public JViewport getColumnHeader() {

        return colHead;

    }

    /**

     * Returns the <code>Component</code> at the specified corner.

     * @param key the <code>String</code> specifying the corner

     * @return the <code>Component</code> at the specified corner, as defined in

     *         {@link ScrollPaneConstants}; if <code>key</code> is not one of the

     *          four corners, <code>null</code> is returned

     * @see JScrollPane#getCorner

     */

    public Component getCorner(String key) {

        if (key.equals(LOWER_LEFT_CORNER)) {

            return lowerLeft;

        }

        else if (key.equals(LOWER_RIGHT_CORNER)) {

            return lowerRight;

        }

        else if (key.equals(UPPER_LEFT_CORNER)) {

            return upperLeft;

        }

        else if (key.equals(UPPER_RIGHT_CORNER)) {

            return upperRight;

        }

        else {

            return null;

        }

    }

    /**

     * The preferred size of a <code>ScrollPane</code> is the size of the insets,

     * plus the preferred size of the viewport, plus the preferred size of

     * the visible headers, plus the preferred size of the scrollbars

     * that will appear given the current view and the current

     * scrollbar displayPolicies.

     * <p>Note that the rowHeader is calculated as part of the preferred width

     * and the colHeader is calculated as part of the preferred size.

     *

     * @param parent the <code>Container</code> that will be laid out

     * @return a <code>Dimension</code> object specifying the preferred size of the

     *         viewport and any scrollbars

     * @see ViewportLayout

     * @see LayoutManager

     */

    public Dimension preferredLayoutSize(Container parent)

    {

        /* Sync the (now obsolete) policy fields with the

         * JScrollPane.

         */

        JScrollPane scrollPane = (JScrollPane)parent;

        vsbPolicy = scrollPane.getVerticalScrollBarPolicy();

        hsbPolicy = scrollPane.getHorizontalScrollBarPolicy();

        Insets insets = parent.getInsets();

        int prefWidth = insets.left + insets.right;

        int prefHeight = insets.top + insets.bottom;

        /* Note that viewport.getViewSize() is equivalent to

         * viewport.getView().getPreferredSize() modulo a null

         * view or a view whose size was explicitly set.

         */

        Dimension extentSize = null;

        Dimension viewSize = null;

        Component view = null;

        if (viewport != null) {

            extentSize = viewport.getPreferredSize();

            view = viewport.getView();

            if (view != null) {

                viewSize = view.getPreferredSize();

            } else {

                viewSize = new Dimension(0, 0);

            }

        }

        /* If there's a viewport add its preferredSize.

         */

        if (extentSize != null) {

            prefWidth += extentSize.width;

            prefHeight += extentSize.height;

        }

        /* If there's a JScrollPane.viewportBorder, add its insets.

         */

        Border viewportBorder = scrollPane.getViewportBorder();

        if (viewportBorder != null) {

            Insets vpbInsets = viewportBorder.getBorderInsets(parent);

            prefWidth += vpbInsets.left + vpbInsets.right;

            prefHeight += vpbInsets.top + vpbInsets.bottom;

        }

        /* If a header exists and it's visible, factor its

         * preferred size in.

         */