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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package javax.swing;

import java.awt.*;

import java.beans.ConstructorProperties;

import java.io.Serializable;

import java.io.PrintStream;

/**

 * A layout manager that allows multiple components to be laid out either

 * vertically or horizontally. The components will not wrap so, for

 * example, a vertical arrangement of components will stay vertically

 * arranged when the frame is resized.

 * <table class="borderless" style="float:right">

 * <caption>Example:</caption>

 *    <TR>

 *      <TD style="text-align:center">

 *         <P STYLE="TEXT-ALIGN:CENTER"><IMG SRC="doc-files/BoxLayout-1.gif"

 *          alt="The following text describes this graphic."

 *          WIDTH="191" HEIGHT="201" STYLE="FLOAT:BOTTOM; BORDER:0">

 *      </TD>

 *    </TR>

 * </TABLE>

 * <p>

 * Nesting multiple panels with different combinations of horizontal and

 * vertical gives an effect similar to GridBagLayout, without the

 * complexity. The diagram shows two panels arranged horizontally, each

 * of which contains 3 components arranged vertically.

 *

 * <p> The BoxLayout manager is constructed with an axis parameter that

 * specifies the type of layout that will be done. There are four choices:

 *

 * <blockquote><b>{@code X_AXIS}</b> - Components are laid out horizontally

 * from left to right.</blockquote>

 *

 * <blockquote><b>{@code Y_AXIS}</b> - Components are laid out vertically

 * from top to bottom.</blockquote>

 *

 * <blockquote><b>{@code LINE_AXIS}</b> - Components are laid out the way

 * words are laid out in a line, based on the container's

 * {@code ComponentOrientation} property. If the container's

 * {@code ComponentOrientation} is horizontal then components are laid out

 * horizontally, otherwise they are laid out vertically.  For horizontal

 * orientations, if the container's {@code ComponentOrientation} is left to

 * right then components are laid out left to right, otherwise they are laid

 * out right to left. For vertical orientations components are always laid out

 * from top to bottom.</blockquote>

 *

 * <blockquote><b>{@code PAGE_AXIS}</b> - Components are laid out the way

 * text lines are laid out on a page, based on the container's

 * {@code ComponentOrientation} property. If the container's

 * {@code ComponentOrientation} is horizontal then components are laid out

 * vertically, otherwise they are laid out horizontally.  For horizontal

 * orientations, if the container's {@code ComponentOrientation} is left to

 * right then components are laid out left to right, otherwise they are laid

 * out right to left.  For vertical orientations components are always

 * laid out from top to bottom.</blockquote>

 * <p>

 * For all directions, components are arranged in the same order as they were

 * added to the container.

 * <p>

 * BoxLayout attempts to arrange components

 * at their preferred widths (for horizontal layout)

 * or heights (for vertical layout).

 * For a horizontal layout,

 * if not all the components are the same height,

 * BoxLayout attempts to make all the components

 * as high as the highest component.

 * If that's not possible for a particular component,

 * then BoxLayout aligns that component vertically,

 * according to the component's Y alignment.

 * By default, a component has a Y alignment of 0.5,

 * which means that the vertical center of the component

 * should have the same Y coordinate as

 * the vertical centers of other components with 0.5 Y alignment.

 * <p>

 * Similarly, for a vertical layout,

 * BoxLayout attempts to make all components in the column

 * as wide as the widest component.

 * If that fails, it aligns them horizontally

 * according to their X alignments.  For {@code PAGE_AXIS} layout,

 * horizontal alignment is done based on the leading edge of the component.

 * In other words, an X alignment value of 0.0 means the left edge of a

 * component if the container's {@code ComponentOrientation} is left to

 * right and it means the right edge of the component otherwise.

 * <p>

 * Instead of using BoxLayout directly, many programs use the Box class.

 * The Box class is a lightweight container that uses a BoxLayout.

 * It also provides handy methods to help you use BoxLayout well.

 * Adding components to multiple nested boxes is a powerful way to get

 * the arrangement you want.

 * <p>

 * For further information and examples see

 * <a

 href="http://docs.oracle.com/javase/tutorial/uiswing/layout/box.html">How to Use BoxLayout</a>,

 * a section in <em>The Java Tutorial.</em>

 * <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} package.

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

 *

 * @see Box

 * @see java.awt.ComponentOrientation

 * @see JComponent#getAlignmentX

 * @see JComponent#getAlignmentY

 *

 * @author   Timothy Prinzing

 * @since 1.2

 */

@SuppressWarnings("serial")

public class BoxLayout implements LayoutManager2, Serializable {

    /**

     * Specifies that components should be laid out left to right.

     */

    public static final int X_AXIS = 0;

    /**

     * Specifies that components should be laid out top to bottom.

     */

    public static final int Y_AXIS = 1;

    /**

     * Specifies that components should be laid out in the direction of

     * a line of text as determined by the target container's

     * {@code ComponentOrientation} property.

     */

    public static final int LINE_AXIS = 2;

    /**

     * Specifies that components should be laid out in the direction that

     * lines flow across a page as determined by the target container's

     * {@code ComponentOrientation} property.

     */

    public static final int PAGE_AXIS = 3;

    /**

     * Creates a layout manager that will lay out components along the

     * given axis.

     *

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

     * @param axis  the axis to lay out components along. Can be one of:

     *              {@code BoxLayout.X_AXIS, BoxLayout.Y_AXIS,

     *              BoxLayout.LINE_AXIS} or {@code BoxLayout.PAGE_AXIS}

     *

     * @exception AWTError  if the value of {@code axis} is invalid

     */

    @ConstructorProperties({"target", "axis"})

    public BoxLayout(Container target, int axis) {

        if (axis != X_AXIS && axis != Y_AXIS &&

            axis != LINE_AXIS && axis != PAGE_AXIS) {

            throw new AWTError("Invalid axis");

        }

        this.axis = axis;

        this.target = target;

    }

    /**

     * Constructs a BoxLayout that

     * produces debugging messages.

     *

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

     * @param axis  the axis to lay out components along. Can be one of:

     *              {@code BoxLayout.X_AXIS, BoxLayout.Y_AXIS,

     *              BoxLayout.LINE_AXIS} or {@code BoxLayout.PAGE_AXIS}

     *

     * @param dbg  the stream to which debugging messages should be sent,

     *   null if none

     */

    BoxLayout(Container target, int axis, PrintStream dbg) {

        this(target, axis);

        this.dbg = dbg;

    }

    /**

     * 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;

    }

    /**

     * Returns the axis that was used to lay out components.

     * Returns one of:

     * {@code BoxLayout.X_AXIS, BoxLayout.Y_AXIS,

     * BoxLayout.LINE_AXIS} or {@code BoxLayout.PAGE_AXIS}

     *

     * @return the axis that was used to lay out components

     *

     * @since 1.6

     */

    public final int getAxis() {

        return this.axis;

    }

    /**

     * Indicates that a child has changed its layout related information,

     * and thus any cached calculations should be flushed.

     * <p>

     * This method is called by AWT when the invalidate method is called

     * on the Container.  Since the invalidate method may be called

     * asynchronously to the event thread, this method may be called

     * asynchronously.

     *

     * @param target  the affected container

     *

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

     *                      BoxLayout constructor

     */

    public synchronized void invalidateLayout(Container target) {

        checkContainer(target);

        xChildren = null;

        yChildren = null;

        xTotal = null;

        yTotal = null;

    }

    /**

     * Not used by this class.

     *

     * @param name the name of the component

     * @param comp the component

     */

    public void addLayoutComponent(String name, Component comp) {

        invalidateLayout(comp.getParent());

    }

    /**

     * Not used by this class.

     *

     * @param comp the component

     */

    public void removeLayoutComponent(Component comp) {

        invalidateLayout(comp.getParent());

    }

    /**

     * Not used by this class.

     *

     * @param comp the component

     * @param constraints constraints

     */

    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.

     *

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

     * @return the dimensions >= 0 && <= Integer.MAX_VALUE

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

     *                      BoxLayout constructor

     * @see Container

     * @see #minimumLayoutSize

     * @see #maximumLayoutSize

     */

    public Dimension preferredLayoutSize(Container target) {

        Dimension size;

        synchronized(this) {

            checkContainer(target);

            checkRequests();

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

        }

        Insets insets = target.getInsets();

        size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE);

        size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE);

        return size;

    }

    /**

     * Returns the minimum dimensions needed to lay out the components

     * contained in the specified target container.

     *

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

     * @return the dimensions >= 0 && <= Integer.MAX_VALUE

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

     *                      BoxLayout constructor

     * @see #preferredLayoutSize

     * @see #maximumLayoutSize

     */

    public Dimension minimumLayoutSize(Container target) {

        Dimension size;

        synchronized(this) {

            checkContainer(target);

            checkRequests();

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

        }

        Insets insets = target.getInsets();

        size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE);

        size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE);

        return size;

    }

    /**

     * Returns the maximum dimensions the target container can use

     * to lay out the components it contains.

     *

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

     * @return the dimensions >= 0 && <= Integer.MAX_VALUE

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

     *                      BoxLayout constructor

     * @see #preferredLayoutSize

     * @see #minimumLayoutSize

     */

    public Dimension maximumLayoutSize(Container target) {

        Dimension size;

        synchronized(this) {

            checkContainer(target);

            checkRequests();

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

        }

        Insets insets = target.getInsets();

        size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE);

        size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE);

        return size;

    }

    /**

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

     * If the box is horizontal, the default

     * alignment will be returned. Otherwise, the alignment needed

     * to place the children along the X axis will be returned.

     *

     * @param target  the container

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

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

     *                      BoxLayout constructor

     */

    public synchronized float getLayoutAlignmentX(Container target) {

        checkContainer(target);

        checkRequests();

        return xTotal.alignment;

    }

    /**

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

     * If the box is vertical, the default

     * alignment will be returned. Otherwise, the alignment needed

     * to place the children along the Y axis will be returned.

     *

     * @param target  the container

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

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

     *                      BoxLayout constructor

     */

    public synchronized float getLayoutAlignmentY(Container target) {

        checkContainer(target);

        checkRequests();

        return yTotal.alignment;

    }

    /**

     * Called by the AWT <!-- XXX CHECK! --> 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

     *                      BoxLayout constructor

     */

    public void layoutContainer(Container target) {

        checkContainer(target);

        int nChildren = target.getComponentCount();

        int[] xOffsets = new int[nChildren];

        int[] xSpans = new int[nChildren];

        int[] yOffsets = new int[nChildren];

        int[] ySpans = new int[nChildren];

        Dimension alloc = target.getSize();

        Insets in = target.getInsets();

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

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

        // Resolve axis to an absolute value (either X_AXIS or Y_AXIS)

        ComponentOrientation o = target.getComponentOrientation();

        int absoluteAxis = resolveAxis( axis, o );

        boolean ltr = (absoluteAxis != axis) ? o.isLeftToRight() : true;

        // determine the child placements

        synchronized(this) {

            checkRequests();

            if (absoluteAxis == X_AXIS) {

                SizeRequirements.calculateTiledPositions(alloc.width, xTotal,

                                                         xChildren, xOffsets,

                                                         xSpans, ltr);

                SizeRequirements.calculateAlignedPositions(alloc.height, yTotal,

                                                           yChildren, yOffsets,

                                                           ySpans);

            } else {

                SizeRequirements.calculateAlignedPositions(alloc.width, xTotal,

                                                           xChildren, xOffsets,

                                                           xSpans, ltr);

                SizeRequirements.calculateTiledPositions(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((int) Math.min((long) in.left + (long) xOffsets[i], Integer.MAX_VALUE),

                        (int) Math.min((long) in.top + (long) yOffsets[i], Integer.MAX_VALUE),

                        xSpans[i], ySpans[i]);

        }

        if (dbg != null) {

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

                Component c = target.getComponent(i);

                dbg.println(c.toString());

                dbg.println("X: " + xChildren[i]);

                dbg.println("Y: " + yChildren[i]);

            }

        }

    }

    void checkContainer(Container target) {

        if (this.target != target) {

            throw new AWTError("BoxLayout 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);

                if (!c.isVisible()) {

                    xChildren[i] = new SizeRequirements(0,0,0, c.getAlignmentX());

                    yChildren[i] = new SizeRequirements(0,0,0, c.getAlignmentY());

                    continue;

                }

                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());

            }

            // Resolve axis to an absolute value (either X_AXIS or Y_AXIS)

            int absoluteAxis = resolveAxis(axis,target.getComponentOrientation());

            if (absoluteAxis == X_AXIS) {

                xTotal = SizeRequirements.getTiledSizeRequirements(xChildren);

                yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren);

            } else {

                xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren);

                yTotal = SizeRequirements.getTiledSizeRequirements(yChildren);

            }

        }

    }

    /**

     * Given one of the 4 axis values, resolve it to an absolute axis.

     * The relative axis values, PAGE_AXIS and LINE_AXIS are converted

     * to their absolute couterpart given the target's ComponentOrientation

     * value.  The absolute axes, X_AXIS and Y_AXIS are returned unmodified.

     *

     * @param axis the axis to resolve

     * @param o the ComponentOrientation to resolve against

     * @return the resolved axis

     */

    private int resolveAxis( int axis, ComponentOrientation o ) {

        int absoluteAxis;

        if( axis == LINE_AXIS ) {

            absoluteAxis = o.isHorizontal() ? X_AXIS : Y_AXIS;

        } else if( axis == PAGE_AXIS ) {

            absoluteAxis = o.isHorizontal() ? Y_AXIS : X_AXIS;

        } else {

            absoluteAxis = axis;

        }

        return absoluteAxis;