Java tutorial
/* * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.border; import java.awt.Graphics; import java.awt.Insets; import java.awt.Rectangle; import java.awt.Component; import java.io.Serializable; /** * A class that implements an empty border with no size. * This provides a convenient base class from which other border * classes can be easily derived. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author David Kloba */ @SuppressWarnings("serial") public abstract class AbstractBorder implements Border, Serializable { /** * This default implementation does no painting. * @param c the component for which this border is being painted * @param g the paint graphics * @param x the x position of the painted border * @param y the y position of the painted border * @param width the width of the painted border * @param height the height of the painted border */ public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) { } /** * This default implementation returns a new {@link Insets} object * that is initialized by the {@link #getBorderInsets(Component,Insets)} * method. * By default the {@code top}, {@code left}, {@code bottom}, * and {@code right} fields are set to {@code 0}. * * @param c the component for which this border insets value applies * @return a new {@link Insets} object */ public Insets getBorderInsets(Component c) { return getBorderInsets(c, new Insets(0, 0, 0, 0)); } /** * Reinitializes the insets parameter with this Border's current Insets. * @param c the component for which this border insets value applies * @param insets the object to be reinitialized * @return the <code>insets</code> object */ public Insets getBorderInsets(Component c, Insets insets) { insets.left = insets.top = insets.right = insets.bottom = 0; return insets; } /** * This default implementation returns false. * @return false */ public boolean isBorderOpaque() { return false; } /** * This convenience method calls the static method. * @param c the component for which this border is being computed * @param x the x position of the border * @param y the y position of the border * @param width the width of the border * @param height the height of the border * @return a <code>Rectangle</code> containing the interior coordinates */ public Rectangle getInteriorRectangle(Component c, int x, int y, int width, int height) { return getInteriorRectangle(c, this, x, y, width, height); } /** * Returns a rectangle using the arguments minus the * insets of the border. This is useful for determining the area * that components should draw in that will not intersect the border. * @param c the component for which this border is being computed * @param b the <code>Border</code> object * @param x the x position of the border * @param y the y position of the border * @param width the width of the border * @param height the height of the border * @return a <code>Rectangle</code> containing the interior coordinates */ public static Rectangle getInteriorRectangle(Component c, Border b, int x, int y, int width, int height) { Insets insets; if (b != null) insets = b.getBorderInsets(c); else insets = new Insets(0, 0, 0, 0); return new Rectangle(x + insets.left, y + insets.top, width - insets.right - insets.left, height - insets.top - insets.bottom); } /** * Returns the baseline. A return value less than 0 indicates the border * does not have a reasonable baseline. * <p> * The default implementation returns -1. Subclasses that support * baseline should override appropriately. If a value >= 0 is * returned, then the component has a valid baseline for any * size >= the minimum size and <code>getBaselineResizeBehavior</code> * can be used to determine how the baseline changes with size. * * @param c <code>Component</code> baseline is being requested for * @param width the width to get the baseline for * @param height the height to get the baseline for * @return the baseline or < 0 indicating there is no reasonable * baseline * @throws IllegalArgumentException if width or height is < 0 * @see java.awt.Component#getBaseline(int,int) * @see java.awt.Component#getBaselineResizeBehavior() * @since 1.6 */ public int getBaseline(Component c, int width, int height) { if (width < 0 || height < 0) { throw new IllegalArgumentException("Width and height must be >= 0"); } return -1; } /** * Returns an enum indicating how the baseline of a component * changes as the size changes. This method is primarily meant for * layout managers and GUI builders. * <p> * The default implementation returns * <code>BaselineResizeBehavior.OTHER</code>, subclasses that support * baseline should override appropriately. Subclasses should * never return <code>null</code>; if the baseline can not be * calculated return <code>BaselineResizeBehavior.OTHER</code>. Callers * should first ask for the baseline using * <code>getBaseline</code> and if a value >= 0 is returned use * this method. It is acceptable for this method to return a * value other than <code>BaselineResizeBehavior.OTHER</code> even if * <code>getBaseline</code> returns a value less than 0. * * @param c <code>Component</code> to return baseline resize behavior for * @return an enum indicating how the baseline changes as the border is * resized * @see java.awt.Component#getBaseline(int,int) * @see java.awt.Component#getBaselineResizeBehavior() * @since 1.6 */ public Component.BaselineResizeBehavior getBaselineResizeBehavior(Component c) { if (c == null) { throw new NullPointerException("Component must be non-null"); } return Component.BaselineResizeBehavior.OTHER; } /* * Convenience function for determining ComponentOrientation. * Helps us avoid having Munge directives throughout the code. */ static boolean isLeftToRight(Component c) { return c.getComponentOrientation().isLeftToRight(); } }