FormLayout.java

/* 
 * AP(r) Computer Science GridWorld Case Study:
 * Copyright(c) 2005-2006 Cay S. Horstmann (http://horstmann.com)
 *
 * This code is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.
 *
 * 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 for more details.
 * 
 * @author Cay Horstmann
 */

package info.gridworld.gui;

import java.awt.*;

/**
 * A layout manager that lays out components along a central axis <br />
 * This code is not tested on the AP CS A and AB exams. It contains GUI
 * implementation details that are not intended to be understood by AP CS
 * students.
 */
public class FormLayout implements LayoutManager
{
    public Dimension preferredLayoutSize(Container parent)
    {
        Component[] components = parent.getComponents();
        left = 0;
        right = 0;
        height = 0;
        for (int i = 0; i < components.length; i += 2)
        {
            Component cleft = components[i];
            Component cright = components[i + 1];

            Dimension dleft = cleft.getPreferredSize();
            Dimension dright = cright.getPreferredSize();
            left = Math.max(left, dleft.width);
            right = Math.max(right, dright.width);
            height = height + Math.max(dleft.height, dright.height);
        }
        return new Dimension(left + GAP + right, height);
    }

    public Dimension minimumLayoutSize(Container parent)
    {
        return preferredLayoutSize(parent);
    }

    public void layoutContainer(Container parent)
    {
        preferredLayoutSize(parent); // sets left, right

        Component[] components = parent.getComponents();

        Insets insets = parent.getInsets();
        int xcenter = insets.left + left;
        int y = insets.top;

        for (int i = 0; i < components.length; i += 2)
        {
            Component cleft = components[i];
            Component cright = components[i + 1];

            Dimension dleft = cleft.getPreferredSize();
            Dimension dright = cright.getPreferredSize();

            int height = Math.max(dleft.height, dright.height);

            cleft.setBounds(xcenter - dleft.width, y + (height - dleft.height)
                    / 2, dleft.width, dleft.height);

            cright.setBounds(xcenter + GAP, y + (height - dright.height) / 2,
                    dright.width, dright.height);
            y += height;
        }
    }

    public void addLayoutComponent(String name, Component comp)
    {
    }

    public void removeLayoutComponent(Component comp)
    {
    }

    private int left;
    private int right;
    private int height;
    private static final int GAP = 6;
}