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

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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package javax.swing;

import java.awt.Component;

import java.awt.Container;

import java.awt.Dimension;

import java.awt.Insets;

import java.awt.LayoutManager2;

import java.util.*;

import static java.awt.Component.BaselineResizeBehavior;

import static javax.swing.LayoutStyle.ComponentPlacement;

import static javax.swing.SwingConstants.HORIZONTAL;

import static javax.swing.SwingConstants.VERTICAL;

/**

 * {@code GroupLayout} is a {@code LayoutManager} that hierarchically

 * groups components in order to position them in a {@code Container}.

 * {@code GroupLayout} is intended for use by builders, but may be

 * hand-coded as well.

 * Grouping is done by instances of the {@link Group Group} class. {@code

 * GroupLayout} supports two types of groups. A sequential group

 * positions its child elements sequentially, one after another. A

 * parallel group aligns its child elements in one of four ways.

 * <p>

 * Each group may contain any number of elements, where an element is

 * a {@code Group}, {@code Component}, or gap. A gap can be thought

 * of as an invisible component with a minimum, preferred and maximum

 * size. In addition {@code GroupLayout} supports a preferred gap,

 * whose value comes from {@code LayoutStyle}.

 * <p>

 * Elements are similar to a spring. Each element has a range as

 * specified by a minimum, preferred and maximum.  Gaps have either a

 * developer-specified range, or a range determined by {@code

 * LayoutStyle}. The range for {@code Component}s is determined from

 * the {@code Component}'s {@code getMinimumSize}, {@code

 * getPreferredSize} and {@code getMaximumSize} methods. In addition,

 * when adding {@code Component}s you may specify a particular range

 * to use instead of that from the component. The range for a {@code

 * Group} is determined by the type of group. A {@code ParallelGroup}'s

 * range is the maximum of the ranges of its elements. A {@code

 * SequentialGroup}'s range is the sum of the ranges of its elements.

 * <p>

 * {@code GroupLayout} treats each axis independently.  That is, there

 * is a group representing the horizontal axis, and a group

 * representing the vertical axis.  The horizontal group is

 * responsible for determining the minimum, preferred and maximum size

 * along the horizontal axis as well as setting the x and width of the

 * components contained in it. The vertical group is responsible for

 * determining the minimum, preferred and maximum size along the

 * vertical axis as well as setting the y and height of the

 * components contained in it. Each {@code Component} must exist in both

 * a horizontal and vertical group, otherwise an {@code IllegalStateException}

 * is thrown during layout, or when the minimum, preferred or

 * maximum size is requested.

 * <p>

 * The following diagram shows a sequential group along the horizontal

 * axis. The sequential group contains three components. A parallel group

 * was used along the vertical axis.

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

 * <img src="doc-files/groupLayout.1.gif">

 * <p>

 * To reinforce that each axis is treated independently the diagram shows

 * the range of each group and element along each axis. The

 * range of each component has been projected onto the axes,

 * and the groups are rendered in blue (horizontal) and red (vertical).

 * For readability there is a gap between each of the elements in the

 * sequential group.

 * <p>

 * The sequential group along the horizontal axis is rendered as a solid

 * blue line. Notice the sequential group is the sum of the children elements

 * it contains.

 * <p>

 * Along the vertical axis the parallel group is the maximum of the height

 * of each of the components. As all three components have the same height,

 * the parallel group has the same height.

 * <p>

 * The following diagram shows the same three components, but with the

 * parallel group along the horizontal axis and the sequential group along

 * the vertical axis.

 * <p>

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

 * <img src="doc-files/groupLayout.2.gif">

 * <p>

 * As {@code c1} is the largest of the three components, the parallel

 * group is sized to {@code c1}. As {@code c2} and {@code c3} are smaller

 * than {@code c1} they are aligned based on the alignment specified

 * for the component (if specified) or the default alignment of the

 * parallel group. In the diagram {@code c2} and {@code c3} were created

 * with an alignment of {@code LEADING}. If the component orientation were

 * right-to-left then {@code c2} and {@code c3} would be positioned on

 * the opposite side.

 * <p>

 * The following diagram shows a sequential group along both the horizontal

 * and vertical axis.

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

 * <img src="doc-files/groupLayout.3.gif">

 * <p>

 * {@code GroupLayout} provides the ability to insert gaps between

 * {@code Component}s. The size of the gap is determined by an

 * instance of {@code LayoutStyle}. This may be turned on using the

 * {@code setAutoCreateGaps} method.  Similarly, you may use

 * the {@code setAutoCreateContainerGaps} method to insert gaps

 * between components that touch the edge of the parent container and the

 * container.

 * <p>

 * The following builds a panel consisting of two labels in

 * one column, followed by two textfields in the next column:

 * <pre>

 *   JComponent panel = ...;

 *   GroupLayout layout = new GroupLayout(panel);

 *   panel.setLayout(layout);

 *

 *   // Turn on automatically adding gaps between components

 *   layout.setAutoCreateGaps(true);

 *

 *   // Turn on automatically creating gaps between components that touch

 *   // the edge of the container and the container.

 *   layout.setAutoCreateContainerGaps(true);

 *

 *   // Create a sequential group for the horizontal axis.

 *

 *   GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup();

 *

 *   // The sequential group in turn contains two parallel groups.

 *   // One parallel group contains the labels, the other the text fields.

 *   // Putting the labels in a parallel group along the horizontal axis

 *   // positions them at the same x location.

 *   //

 *   // Variable indentation is used to reinforce the level of grouping.

 *   hGroup.addGroup(layout.createParallelGroup().

 *            addComponent(label1).addComponent(label2));

 *   hGroup.addGroup(layout.createParallelGroup().

 *            addComponent(tf1).addComponent(tf2));

 *   layout.setHorizontalGroup(hGroup);

 *

 *   // Create a sequential group for the vertical axis.

 *   GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup();

 *

 *   // The sequential group contains two parallel groups that align

 *   // the contents along the baseline. The first parallel group contains

 *   // the first label and text field, and the second parallel group contains

 *   // the second label and text field. By using a sequential group

 *   // the labels and text fields are positioned vertically after one another.

 *   vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE).

 *            addComponent(label1).addComponent(tf1));

 *   vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE).

 *            addComponent(label2).addComponent(tf2));

 *   layout.setVerticalGroup(vGroup);

 * </pre>

 * <p>

 * When run the following is produced.

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

 * <img src="doc-files/groupLayout.example.png">

 * <p>

 * This layout consists of the following.

 * <ul><li>The horizontal axis consists of a sequential group containing two

 *         parallel groups.  The first parallel group contains the labels,

 *         and the second parallel group contains the text fields.

 *     <li>The vertical axis consists of a sequential group

 *         containing two parallel groups.  The parallel groups are configured

 *         to align their components along the baseline. The first parallel

 *         group contains the first label and first text field, and

 *         the second group consists of the second label and second

 *         text field.

 * </ul>

 * There are a couple of things to notice in this code:

 * <ul>

 *   <li>You need not explicitly add the components to the container; this

 *       is indirectly done by using one of the {@code add} methods of

 *       {@code Group}.

 *   <li>The various {@code add} methods return

 *       the caller.  This allows for easy chaining of invocations.  For

 *       example, {@code group.addComponent(label1).addComponent(label2);} is

 *       equivalent to

 *       {@code group.addComponent(label1); group.addComponent(label2);}.

 *   <li>There are no public constructors for {@code Group}s; instead

 *       use the create methods of {@code GroupLayout}.

 * </ul>

 *

 * @author Tomas Pavek

 * @author Jan Stola

 * @author Scott Violet

 * @since 1.6

 */

public class GroupLayout implements LayoutManager2 {

    // Used in size calculations

    private static final int MIN_SIZE = 0;

    private static final int PREF_SIZE = 1;

    private static final int MAX_SIZE = 2;

    // Used by prepare, indicates min, pref or max isn't going to be used.

    private static final int SPECIFIC_SIZE = 3;

    private static final int UNSET = Integer.MIN_VALUE;

    /**

     * Indicates the size from the component or gap should be used for a

     * particular range value.

     *

     * @see Group

     */

    public static final int DEFAULT_SIZE = -1;

    /**

     * Indicates the preferred size from the component or gap should

     * be used for a particular range value.

     *

     * @see Group

     */

    public static final int PREFERRED_SIZE = -2;

    // Whether or not we automatically try and create the preferred

    // padding between components.

    private boolean autocreatePadding;

    // Whether or not we automatically try and create the preferred

    // padding between components the touch the edge of the container and

    // the container.

    private boolean autocreateContainerPadding;

    /**

     * Group responsible for layout along the horizontal axis.  This is NOT

     * the user specified group, use getHorizontalGroup to dig that out.

     */

    private Group horizontalGroup;

    /**

     * Group responsible for layout along the vertical axis.  This is NOT

     * the user specified group, use getVerticalGroup to dig that out.

     */

    private Group verticalGroup;

    // Maps from Component to ComponentInfo.  This is used for tracking

    // information specific to a Component.

    private Map<Component,ComponentInfo> componentInfos;

    // Container we're doing layout for.

    private Container host;

    // Used by areParallelSiblings, cached to avoid excessive garbage.

    private Set<Spring> tmpParallelSet;

    // Indicates Springs have changed in some way since last change.

    private boolean springsChanged;

    // Indicates invalidateLayout has been invoked.

    private boolean isValid;

    // Whether or not any preferred padding (or container padding) springs

    // exist

    private boolean hasPreferredPaddingSprings;

    /**

     * The LayoutStyle instance to use, if null the sharedInstance is used.

     */

    private LayoutStyle layoutStyle;

    /**

     * If true, components that are not visible are treated as though they

     * aren't there.

     */

    private boolean honorsVisibility;

    /**

     * Enumeration of the possible ways {@code ParallelGroup} can align

     * its children.

     *

     * @see #createParallelGroup(Alignment)

     * @since 1.6

     */

    public enum Alignment {

        /**

         * Indicates the elements should be

         * aligned to the origin.  For the horizontal axis with a left to

         * right orientation this means aligned to the left edge. For the

         * vertical axis leading means aligned to the top edge.

         *

         * @see #createParallelGroup(Alignment)

         */

        LEADING,

        /**

         * Indicates the elements should be aligned to the end of the

         * region.  For the horizontal axis with a left to right

         * orientation this means aligned to the right edge. For the

         * vertical axis trailing means aligned to the bottom edge.

         *

         * @see #createParallelGroup(Alignment)

         */

        TRAILING,

        /**

         * Indicates the elements should be centered in

         * the region.

         *

         * @see #createParallelGroup(Alignment)

         */

        CENTER,

        /**

         * Indicates the elements should be aligned along

         * their baseline.

         *

         * @see #createParallelGroup(Alignment)

         * @see #createBaselineGroup(boolean,boolean)

         */

        BASELINE

    }

    private static void checkSize(int min, int pref, int max,

            boolean isComponentSpring) {

        checkResizeType(min, isComponentSpring);

        if (!isComponentSpring && pref < 0) {

            throw new IllegalArgumentException("Pref must be >= 0");

        } else if (isComponentSpring) {

            checkResizeType(pref, true);

        }

        checkResizeType(max, isComponentSpring);

        checkLessThan(min, pref);

        checkLessThan(pref, max);

    }

    private static void checkResizeType(int type, boolean isComponentSpring) {

        if (type < 0 && ((isComponentSpring && type != DEFAULT_SIZE &&

                type != PREFERRED_SIZE) ||

                (!isComponentSpring && type != PREFERRED_SIZE))) {

            throw new IllegalArgumentException("Invalid size");

        }

    }

    private static void checkLessThan(int min, int max) {

        if (min >= 0 && max >= 0 && min > max) {

            throw new IllegalArgumentException(

                    "Following is not met: min<=pref<=max");

        }

    }

    /**

     * Creates a {@code GroupLayout} for the specified {@code Container}.

     *

     * @param host the {@code Container} the {@code GroupLayout} is

     *        the {@code LayoutManager} for

     * @throws IllegalArgumentException if host is {@code null}

     */

    public GroupLayout(Container host) {

        if (host == null) {

            throw new IllegalArgumentException("Container must be non-null");

        }

        honorsVisibility = true;

        this.host = host;

        setHorizontalGroup(createParallelGroup(Alignment.LEADING, true));

        setVerticalGroup(createParallelGroup(Alignment.LEADING, true));

        componentInfos = new HashMap<Component,ComponentInfo>();

        tmpParallelSet = new HashSet<Spring>();

    }

    /**

     * positioning components. A value of {@code true} indicates that

     * non-visible components should not be treated as part of the

     * layout. A value of {@code false} indicates that components should be

     * positioned and sized regardless of visibility.

     * <p>

     * A value of {@code false} is useful when the visibility of components

     * is dynamically adjusted and you don't want surrounding components and

     * the sizing to change.

     * <p>

     * The specified value is used for components that do not have an

     * explicit visibility specified.

     * <p>

     * The default is {@code true}.

     *

     *                         sizing and positioning components

     * @see #setHonorsVisibility(Component,Boolean)

     */

    public void setHonorsVisibility(boolean honorsVisibility) {

        if (this.honorsVisibility != honorsVisibility) {

            this.honorsVisibility = honorsVisibility;

            springsChanged = true;

            isValid = false;

            invalidateHost();

        }

    }

    /**

     * positioning components.

     *

     *         positioning components

     */

    public boolean getHonorsVisibility() {

        return honorsVisibility;

    }

    /**

     * sizing and positioning. A value of {@code Boolean.TRUE}

     * indicates that if {@code component} is not visible it should

     * not be treated as part of the layout. A value of {@code false}

     * indicates that {@code component} is positioned and sized

     * regardless of it's visibility.  A value of {@code null}

     * indicates the value specified by the single argument method {@code

     * setHonorsVisibility} should be used.

     * <p>

     * If {@code component} is not a child of the {@code Container} this

     * {@code Container}.

     *

     * @param component the component

     *              considered for sizing and positioning

     * @throws IllegalArgumentException if {@code component} is {@code null}

     * @see #setHonorsVisibility(Component,Boolean)

     */

    public void setHonorsVisibility(Component component,

            Boolean honorsVisibility) {

        if (component == null) {

            throw new IllegalArgumentException("Component must be non-null");

        }

        getComponentInfo(component).setHonorsVisibility(honorsVisibility);

        springsChanged = true;

        isValid = false;

        invalidateHost();

    }

    /**

     * Sets whether a gap between components should automatically be

     * created.  For example, if this is {@code true} and you add two

     * components to a {@code SequentialGroup} a gap between the

     * two components is automatically be created.  The default is

     * {@code false}.

     *

     * @param autoCreatePadding whether a gap between components is

     *        automatically created

     */

    public void setAutoCreateGaps(boolean autoCreatePadding) {

        if (this.autocreatePadding != autoCreatePadding) {

            this.autocreatePadding = autoCreatePadding;

            invalidateHost();

        }

    }

    /**

     * Returns {@code true} if gaps between components are automatically

     * created.

     *

     * @return {@code true} if gaps between components are automatically

     *         created

     */

    public boolean getAutoCreateGaps() {

        return autocreatePadding;

    }

    /**

     * Sets whether a gap between the container and components that

     * touch the border of the container should automatically be

     * created. The default is {@code false}.

     *

     * @param autoCreateContainerPadding whether a gap between the container and

     *        components that touch the border of the container should

     *        automatically be created

     */

    public void setAutoCreateContainerGaps(boolean autoCreateContainerPadding){

        if (this.autocreateContainerPadding != autoCreateContainerPadding) {

            this.autocreateContainerPadding = autoCreateContainerPadding;

            horizontalGroup = createTopLevelGroup(getHorizontalGroup());

            verticalGroup = createTopLevelGroup(getVerticalGroup());

            invalidateHost();

        }

    }

    /**

     * Returns {@code true} if gaps between the container and components that

     * border the container are automatically created.

     *

     * @return {@code true} if gaps between the container and components that

     *         border the container are automatically created

     */

    public boolean getAutoCreateContainerGaps() {

        return autocreateContainerPadding;

    }

    /**

     * Sets the {@code Group} that positions and sizes

     * components along the horizontal axis.

     *

     * @param group the {@code Group} that positions and sizes

     *        components along the horizontal axis

     * @throws IllegalArgumentException if group is {@code null}

     */

    public void setHorizontalGroup(Group group) {

        if (group == null) {

            throw new IllegalArgumentException("Group must be non-null");

        }

        horizontalGroup = createTopLevelGroup(group);

        invalidateHost();