WrapLayout.java

/*
Copyright 2008-2010 Gephi
Authors : Mathieu Bastian <mathieu.bastian@gephi.org>
Website : http://www.gephi.org

This file is part of Gephi.

Gephi is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

Gephi 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 Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with Gephi.  If not, see <http://www.gnu.org/licenses/>.
*/
package org.gephi.ui.components;

import java.awt.*;

/**
 *  FlowLayout subclass that fully supports wrapping of components.
 */
public class WrapLayout extends FlowLayout {

    private Dimension preferredLayoutSize;

    /**
     * Constructs a new <code>WrapLayout</code> with a left
     * alignment and a default 5-unit horizontal and vertical gap.
     */
    public WrapLayout() {
        super();
    }

    /**
     * Constructs a new <code>FlowLayout</code> with the specified
     * alignment and a default 5-unit horizontal and vertical gap.
     * The value of the alignment argument must be one of
     * <code>WrapLayout</code>, <code>WrapLayout</code>,
     * or <code>WrapLayout</code>.
     * @param align the alignment value
     */
    public WrapLayout(int align) {
        super(align);
    }

    /**
     * Creates a new flow layout manager with the indicated alignment
     * and the indicated horizontal and vertical gaps.
     * <p>
     * The value of the alignment argument must be one of
     * <code>WrapLayout</code>, <code>WrapLayout</code>,
     * or <code>WrapLayout</code>.
     * @param align the alignment value
     * @param hgap the horizontal gap between components
     * @param vgap the vertical gap between components
     */
    public WrapLayout(int align, int hgap, int vgap) {
        super(align, hgap, vgap);
    }

    /**
     * Returns the preferred dimensions for this layout given the
     * <i>visible</i> components in the specified target container.
     * @param target the component which needs to be laid out
     * @return the preferred dimensions to lay out the
     * subcomponents of the specified container
     */
    @Override
    public Dimension preferredLayoutSize(Container target) {
        return layoutSize(target, true);
    }

    /**
     * Returns the minimum dimensions needed to layout the <i>visible</i>
     * components contained in the specified target container.
     * @param target the component which needs to be laid out
     * @return the minimum dimensions to lay out the
     * subcomponents of the specified container
     */
    @Override
    public Dimension minimumLayoutSize(Container target) {
        return layoutSize(target, false);
    }

    /**
     * Returns the minimum or preferred dimension needed to layout the target
     * container.
     *
     * @param target target to get layout size for
     * @param preferred should preferred size be calculated
     * @return the dimension to layout the target container
     */
    private Dimension layoutSize(Container target, boolean preferred) {
        synchronized (target.getTreeLock()) {
            //  Each row must fit with the width allocated to the containter.
            //  When the container width = 0, the preferred width of the container
            //  has not yet been calculated so lets ask for the maximum.

            int targetWidth = target.getSize().width;

            if (targetWidth == 0) {
                targetWidth = Integer.MAX_VALUE;
            }

            int hgap = getHgap();
            int vgap = getVgap();
            Insets insets = target.getInsets();
            int horizontalInsetsAndGap = insets.left + insets.right + (hgap * 2);
            int maxWidth = targetWidth - horizontalInsetsAndGap;

            //  Fit components into the allowed width

            Dimension dim = new Dimension(0, 0);
            int rowWidth = 0;
            int rowHeight = 0;

            int nmembers = target.getComponentCount();

            for (int i = 0; i < nmembers; i++) {
                Component m = target.getComponent(i);

                if (m.isVisible()) {
                    Dimension d = preferred ? m.getPreferredSize() : m.getMinimumSize();

                    //  Can't add the component to current row. Start a new row.

                    if (rowWidth + d.width > maxWidth) {
                        addRow(dim, rowWidth, rowHeight);
                        rowWidth = 0;
                        rowHeight = 0;
                    }

                    //  Add a horizontal gap for all components after the first

                    if (rowWidth != 0) {
                        rowWidth += hgap;
                    }

                    rowWidth += d.width;
                    rowHeight = Math.max(rowHeight, d.height);
                }
            }

            addRow(dim, rowWidth, rowHeight);

            dim.width += horizontalInsetsAndGap;
            dim.height += insets.top + insets.bottom + vgap * 2;

            //	When using a scroll pane or the DecoratedLookAndFeel we need to
            //  make sure the preferred size is less than the size of the
            //  target containter so shrinking the container size works
            //  correctly. Removing the horizontal gap is an easy way to do this.

            dim.width -= (hgap + 1);

            return dim;
        }
    }

    /**
     *  Layout the components in the Container using the layout logic of the
     *  parent FlowLayout class.
     *
     *	@param target the Container using this WrapLayout
     */
    @Override
    public void layoutContainer(Container target) {
        Dimension size = preferredLayoutSize(target);

        //  When a frame is minimized or maximized the preferred size of the
        //  Container is assumed not to change. Therefore we need to force a
        //  validate() to make sure that space, if available, is allocated to
        //  the panel using a WrapLayout.

        if (size.equals(preferredLayoutSize)) {
            super.layoutContainer(target);
        } else {
            preferredLayoutSize = size;
            Container top = target;

            while (top.getParent() != null) {
                top = top.getParent();
            }

            top.validate();
        }
    }

    /*
     *  A new row has been completed. Use the dimensions of this row
     *  to update the preferred size for the container.
     *
     *  @param dim update the width and height when appropriate
     *  @param rowWidth the width of the row to add
     *  @param rowHeight the height of the row to add
     */
    private void addRow(Dimension dim, int rowWidth, int rowHeight) {
        dim.width = Math.max(dim.width, rowWidth);

        if (dim.height > 0) {
            dim.height += getVgap();
        }

        dim.height += rowHeight;
    }
}