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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.

Warning:
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 java.beans package. Please see XMLEncoder. 
Author:
  Timothy Prinzing/**
 * 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&trade;
 * 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.
Params:
target –  the container to do layout against/**
     * 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.
Returns:
the container that uses this layout manager
Since:
1.6/**
     * 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.
Params:
target – the container/**
     * 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.
Params:
name – the name of the component
comp – the the component to be added/**
     * 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.
Params:
comp – the component to remove/**
     * 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.
Params:
comp – the component to be added
constraints –  where/how the component is added to the layout./**
     * 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().
Params:
target – the component which needs to be laid out
See Also:
minimumLayoutSize
Returns:
a Dimension object containing the preferred dimensions/**
     * 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.
Params:
target – the component which needs to be laid out
See Also:
preferredLayoutSize
Returns:
a Dimension object containing the minimum dimensions/**
     * 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 getInset.
Params:
target – the component that needs to be laid out
See Also:
preferredLayoutSize
Returns:
a Dimension object containing the maximum
        dimensions/**
     * 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.
Params:
target – the container
Returns:
the alignment >= 0.0f && <= 1.0f/**
     * Returns the alignment along the x axis for the container.
     *
     * @param target the container
     * @return the alignment &gt;= 0.0f &amp;&amp; &lt;= 1.0f
     */
    public float getLayoutAlignmentX(Container target) {
        checkContainer(target);
        checkRequests();
        return xTotal.alignment;
    }

    
Returns the alignment along the y axis for the container.
Params:
target – the container
Returns:
the alignment >= 0.0f && <= 1.0f/**
     * Returns the alignment along the y axis for the container.
     *
     * @param target the container
     * @return the alignment &gt;= 0.0f &amp;&amp; &lt;= 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.
Params:
target –  the container to lay out
Throws:
AWTError –  if the target isn't the container specified to the
                     constructor/**
     * 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;

}