source: josm/src/org/openstreetmap/josm/gui/GBC.java@ 6

package org.openstreetmap.josm.gui;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.Insets;

import javax.swing.Box;

/**
 * A wrapper for GridBagConstraints which has sane default static creators and
 * member functions to chain calling.
 * 
 * @author imi
 */
public class GBC extends GridBagConstraints {

        /**
         * Use public static creator functions to create an GBC.
         */
        private GBC() {}
        
        /**
         * Create a standard constraint (which is not the last).
         * @return A standard constraint with no filling.
         */
        public static GBC std() {
                GBC c = new GBC();
                c.anchor = WEST;
                return c;
        }
        
        /**
         * Create the constraint for the last elements on a line.
         * @return A constraint which indicates the last item on a line.
         */
        public static GBC eol() {
                GBC c = std();
                c.gridwidth = REMAINDER;
                return c;
        }
        
        /**
         * Try to fill both, horizontal and vertical
         * @return This constraint for chaining.
         */
        public GBC fill() {
                return fill(BOTH);
        }

        /**
         * Set fill to the given value
         * @param value The filling value, either NONE, HORIZONTAL, VERTICAL or BOTH
         * @return This constraint for chaining.
         */
        public GBC fill(int value) {
                fill = value;
                if (value == HORIZONTAL || value == BOTH)
                        weightx = 1.0;
                if (value == VERTICAL || value == BOTH)
                        weighty = 1.0;
                return this;
        }
        
        /**
         * Set the anchor of this GBC to a.
         * @param a The new anchor, e.g. GBC.CENTER or GBC.EAST.
         * @return This constraint for chaining.
         */
        public GBC anchor(int a) {
                anchor = a;
                return this;
        }

        /**
         * Adds insets to this GBC.
         * @param left          The left space of the insets
         * @param top           The top space of the insets
         * @param right         The right space of the insets
         * @param bottom        The bottom space of the insets
         * @return This constraint for chaining.
         */
        public GBC insets(int left, int top, int right, int bottom) {
                insets = new Insets(top, left, bottom, right);
                return this;
        }
        
        /**
         * This is a helper to easily create a glue with a minimum default value.
         * @param x If higher than 0, this will be a horizontal glue with x as minimum
         *              horizontal strut.
         * @param y If higher than 0, this will be a vertical glue with y as minimum
         *              vertical strut.
         */
        public static Component glue(int x, int y) {
                short maxx = x > 0 ? Short.MAX_VALUE : 0;
                short maxy = y > 0 ? Short.MAX_VALUE : 0;
                return new Box.Filler(new Dimension(x,y), new Dimension(x,y), new Dimension(maxx,maxy));
        }
}