SpringUtilities.java

package org.chartsy.chatsy.chat.component;

import java.awt.Component;
import java.awt.Container;
import javax.swing.Spring;
import javax.swing.SpringLayout;

/**
 *
 * @author Viorel
 */
public class SpringUtilities
{

	public static SpringLayout getLayout()
	{
		return new SpringLayout();
	}

	public static void makeGrid(Container parent,
		int rows, int cols,
		int initialX, int initialY,
		int xPad, int yPad)
	{
		SpringLayout layout;
		try
		{
            layout = (SpringLayout) parent.getLayout();
        }
		catch (ClassCastException exc)
		{
            System.err.println("The first argument to makeGrid must use SpringLayout.");
            return;
        }

		Spring xPadSpring = Spring.constant(xPad);
		Spring yPadSpring = Spring.constant(yPad);
        Spring initialXSpring = Spring.constant(initialX);
        Spring initialYSpring = Spring.constant(initialY);
        int max = rows * cols;

		Spring maxWidthSpring
			= layout.getConstraints(parent.getComponent(0)).getWidth();
        Spring maxHeightSpring
			= layout.getConstraints(parent.getComponent(0)).getWidth();
		for (int i = 1; i < max; i++)
		{
			SpringLayout.Constraints cons
				= layout.getConstraints(parent.getComponent(i));
			maxWidthSpring = Spring.max(maxWidthSpring, cons.getWidth());
			maxHeightSpring = Spring.max(maxHeightSpring, cons.getHeight());
		}

		for (int i = 0; i < max; i++)
		{
			SpringLayout.Constraints cons
				= layout.getConstraints(parent.getComponent(i));
			cons.setWidth(maxWidthSpring);
			cons.setHeight(maxHeightSpring);
		}

		SpringLayout.Constraints lastCons = null;
		SpringLayout.Constraints lastRowCons = null;
		for (int i = 0; i < max; i++)
		{
			SpringLayout.Constraints cons
				= layout.getConstraints(parent.getComponent(i));
            if (i % cols == 0)
			{
                lastRowCons = lastCons;
                cons.setX(initialXSpring);
            }
			else
			{
                cons.setX(Spring.sum(
					lastCons.getConstraint(SpringLayout.EAST),
					xPadSpring));
            }

            if (i / cols == 0)
			{
                cons.setY(initialYSpring);
            }
			else
			{
                cons.setY(Spring.sum(
					lastRowCons.getConstraint(SpringLayout.SOUTH),
					yPadSpring));
            }
            lastCons = cons;
		}

		SpringLayout.Constraints pCons = layout.getConstraints(parent);
        pCons.setConstraint(SpringLayout.SOUTH, Spring.sum(
			Spring.constant(yPad),
			lastCons.getConstraint(SpringLayout.SOUTH)));
        pCons.setConstraint(SpringLayout.EAST, Spring.sum(
			Spring.constant(xPad),
			lastCons.getConstraint(SpringLayout.EAST)));
	}

	private static SpringLayout.Constraints getConstraintsForCell(
		int row, int col,
		Container parent,
		int cols)
	{
		SpringLayout layout = (SpringLayout) parent.getLayout();
        Component c = parent.getComponent(row * cols + col);
        return layout.getConstraints(c);
	}

	public static void makeCompactGrid(Container parent,
		int rows, int cols,
		int initialX, int initialY,
		int xPad, int yPad)
	{
		SpringLayout layout;
        try
		{
            layout = (SpringLayout)parent.getLayout();
        } 
		catch (ClassCastException exc)
		{
            System.err.println("The first argument to makeCompactGrid must use SpringLayout.");
            return;
        }

        Spring x = Spring.constant(initialX);
        for (int c = 0; c < cols; c++)
		{
            Spring width = Spring.constant(0);
            for (int r = 0; r < rows; r++)
			{
                width = Spring.max(
					width,
					getConstraintsForCell(r, c, parent, cols).getWidth());
            }

            for (int r = 0; r < rows; r++)
			{
                SpringLayout.Constraints constraints 
					= getConstraintsForCell(r, c, parent, cols);
                constraints.setX(x);
                constraints.setWidth(width);
            }
            x = Spring.sum(x, Spring.sum(width, Spring.constant(xPad)));
        }

        Spring y = Spring.constant(initialY);
        for (int r = 0; r < rows; r++)
		{
            Spring height = Spring.constant(0);
            for (int c = 0; c < cols; c++)
			{
                height = Spring.max(
					height,
					getConstraintsForCell(r, c, parent, cols).getHeight());
            }

            for (int c = 0; c < cols; c++)
			{
                SpringLayout.Constraints constraints 
					= getConstraintsForCell(r, c, parent, cols);
                constraints.setY(y);
                constraints.setHeight(height);
            }
            y = Spring.sum(y, Spring.sum(height, Spring.constant(yPad)));
        }

        SpringLayout.Constraints pCons = layout.getConstraints(parent);
        pCons.setConstraint(SpringLayout.SOUTH, y);
        pCons.setConstraint(SpringLayout.EAST, x);
	}

}