/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.swing;

import java.awt.*;

import java.beans.ConstructorProperties;

import java.io.Serializable;

/**

 * A layout manager to arrange components over the top

 * of each other.  The requested size of the container

 * will be the largest requested size of the children,

 * taking alignment needs into consideration.

 *

 * The alignment is based upon what is needed to properly

 * fit the children in the allocation area.  The children

 * will be placed such that their alignment points are all

 * on top of each other.

 * <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}.

 *

 * @author   Timothy Prinzing

 * @since 1.2

 */

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

public class OverlayLayout implements LayoutManager2,Serializable {

    /**

     * Constructs a layout manager that performs overlay

     * arrangement of the children.  The layout manager

     * created is dedicated to the given container.

     *

     * @param target  the container to do layout against

     */

    @ConstructorProperties({"target"})

    public OverlayLayout(Container target) {

        this.target = target;

    }

    /**

     * Returns the container that uses this layout manager.

     *

     * @return the container that uses this layout manager

     *

     * @since 1.6

     */

    public final Container getTarget() {

        return this.target;

    }

    /**

     * Indicates a child has changed its layout related information,

     * which causes any cached calculations to be flushed.

     *

     * @param target the container

     */

    public void invalidateLayout(Container target) {

        checkContainer(target);

        xChildren = null;

        yChildren = null;

        xTotal = null;

        yTotal = null;

    }

    /**

     * Adds the specified component to the layout. Used by

     * this class to know when to invalidate layout.

     *

     * @param name the name of the component

     * @param comp the component to be added

     */

    public void addLayoutComponent(String name, Component comp) {

        invalidateLayout(comp.getParent());

    }

    /**

     * Removes the specified component from the layout. Used by

     * this class to know when to invalidate layout.

     *

     * @param comp the component to remove

     */

    public void removeLayoutComponent(Component comp) {

        invalidateLayout(comp.getParent());

    }

    /**

     * Adds the specified component to the layout, using the specified

     * constraint object. Used by this class to know when to invalidate

     * layout.

     *

     * @param comp the component to be added

     * @param constraints  where/how the component is added to the layout.

     */

    public void addLayoutComponent(Component comp, Object constraints) {

        invalidateLayout(comp.getParent());

    }

    /**

     * Returns the preferred dimensions for this layout given the components

     * in the specified target container.  Recomputes the layout if it

     * has been invalidated.  Factors in the current inset setting returned

     * by getInsets().

     *

     * @param target the component which needs to be laid out

     * @return a Dimension object containing the preferred dimensions

     * @see #minimumLayoutSize

     */

    public Dimension preferredLayoutSize(Container target) {

        checkContainer(target);

        checkRequests();

        Dimension size = new Dimension(xTotal.preferred, yTotal.preferred);

        Insets insets = target.getInsets();

        size.width += insets.left + insets.right;

        size.height += insets.top + insets.bottom;

        return size;

    }

    /**

     * Returns the minimum dimensions needed to lay out the components

     * contained in the specified target container.  Recomputes the layout

     * if it has been invalidated, and factors in the current inset setting.

     *

     * @param target the component which needs to be laid out

     * @return a Dimension object containing the minimum dimensions

     * @see #preferredLayoutSize

     */

    public Dimension minimumLayoutSize(Container target) {

        checkContainer(target);

        checkRequests();

        Dimension size = new Dimension(xTotal.minimum, yTotal.minimum);

        Insets insets = target.getInsets();

        size.width += insets.left + insets.right;

        size.height += insets.top + insets.bottom;

        return size;

    }

    /**

     * Returns the maximum dimensions needed to lay out the components

     * contained in the specified target container.  Recomputes the

     * layout if it has been invalidated, and factors in the inset setting

     * returned by <code>getInset</code>.

     *

     * @param target the component that needs to be laid out

     * @return a <code>Dimension</code> object containing the maximum

     *         dimensions

     * @see #preferredLayoutSize

     */

    public Dimension maximumLayoutSize(Container target) {

        checkContainer(target);

        checkRequests();

        Dimension size = new Dimension(xTotal.maximum, yTotal.maximum);

        Insets insets = target.getInsets();

        size.width += insets.left + insets.right;

        size.height += insets.top + insets.bottom;

        return size;

    }

    /**

     * Returns the alignment along the x axis for the container.

     *

     * @param target the container

     * @return the alignment >= 0.0f && <= 1.0f

     */

    public float getLayoutAlignmentX(Container target) {

        checkContainer(target);

        checkRequests();

        return xTotal.alignment;

    }

    /**

     * Returns the alignment along the y axis for the container.

     *

     * @param target the container

     * @return the alignment >= 0.0f && <= 1.0f

     */

    public float getLayoutAlignmentY(Container target) {

        checkContainer(target);

        checkRequests();

        return yTotal.alignment;

    }

    /**

     * Called by the AWT when the specified container needs to be laid out.

     *

     * @param target  the container to lay out

     *

     * @exception AWTError  if the target isn't the container specified to the

     *                      constructor

     */

    public void layoutContainer(Container target) {

        checkContainer(target);

        checkRequests();

        int nChildren = target.getComponentCount();

        int[] xOffsets = new int[nChildren];

        int[] xSpans = new int[nChildren];

        int[] yOffsets = new int[nChildren];

        int[] ySpans = new int[nChildren];

        // determine the child placements

        Dimension alloc = target.getSize();

        Insets in = target.getInsets();

        alloc.width -= in.left + in.right;

        alloc.height -= in.top + in.bottom;

        SizeRequirements.calculateAlignedPositions(alloc.width, xTotal,

                                                   xChildren, xOffsets,

                                                   xSpans);

        SizeRequirements.calculateAlignedPositions(alloc.height, yTotal,

                                                   yChildren, yOffsets,

                                                   ySpans);

        // flush changes to the container

        for (int i = 0; i < nChildren; i++) {

            Component c = target.getComponent(i);

            c.setBounds(in.left + xOffsets[i], in.top + yOffsets[i],

                        xSpans[i], ySpans[i]);

        }

    }

    void checkContainer(Container target) {

        if (this.target != target) {

            throw new AWTError("OverlayLayout can't be shared");

        }

    }

    void checkRequests() {

        if (xChildren == null || yChildren == null) {

            // The requests have been invalidated... recalculate

            // the request information.

            int n = target.getComponentCount();

            xChildren = new SizeRequirements[n];

            yChildren = new SizeRequirements[n];

            for (int i = 0; i < n; i++) {

                Component c = target.getComponent(i);

                Dimension min = c.getMinimumSize();

                Dimension typ = c.getPreferredSize();

                Dimension max = c.getMaximumSize();

                xChildren[i] = new SizeRequirements(min.width, typ.width,

                                                    max.width,

                                                    c.getAlignmentX());

                yChildren[i] = new SizeRequirements(min.height, typ.height,

                                                    max.height,

                                                    c.getAlignmentY());

            }

            xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren);

            yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren);

        }

    }

    private Container target;

    private SizeRequirements[] xChildren;

    private SizeRequirements[] yChildren;

    private SizeRequirements xTotal;

    private SizeRequirements yTotal;

}