package horstmann.ch05_layout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;

/**
   A layout manager that lays out components along a central axis
 */
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;
}