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	/*
	* Copyright (c) 1997, 2013, 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
	*/
	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 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;

	}

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