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    1   /*
    2    * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   package javax.swing.border;
   26   
   27   import java.awt.Graphics;
   28   import java.awt.Insets;
   29   import java.awt.Rectangle;
   30   import java.awt.Component;
   31   import java.io.Serializable;
   32   
   33   /**
   34    * A class that implements an empty border with no size.
   35    * This provides a convenient base class from which other border
   36    * classes can be easily derived.
   37    * <p>
   38    * <strong>Warning:</strong>
   39    * Serialized objects of this class will not be compatible with
   40    * future Swing releases. The current serialization support is
   41    * appropriate for short term storage or RMI between applications running
   42    * the same version of Swing.  As of 1.4, support for long term storage
   43    * of all JavaBeans<sup><font size="-2">TM</font></sup>
   44    * has been added to the <code>java.beans</code> package.
   45    * Please see {@link java.beans.XMLEncoder}.
   46    *
   47    * @author David Kloba
   48    */
   49   public abstract class AbstractBorder implements Border, Serializable
   50   {
   51       /**
   52        * This default implementation does no painting.
   53        * @param c the component for which this border is being painted
   54        * @param g the paint graphics
   55        * @param x the x position of the painted border
   56        * @param y the y position of the painted border
   57        * @param width the width of the painted border
   58        * @param height the height of the painted border
   59        */
   60       public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
   61       }
   62   
   63       /**
   64        * This default implementation returns a new {@link Insets} object
   65        * that is initialized by the {@link #getBorderInsets(Component,Insets)}
   66        * method.
   67        * By default the {@code top}, {@code left}, {@code bottom},
   68        * and {@code right} fields are set to {@code 0}.
   69        *
   70        * @param c  the component for which this border insets value applies
   71        * @return a new {@link Insets} object
   72        */
   73       public Insets getBorderInsets(Component c)       {
   74           return getBorderInsets(c, new Insets(0, 0, 0, 0));
   75       }
   76   
   77       /**
   78        * Reinitializes the insets parameter with this Border's current Insets.
   79        * @param c the component for which this border insets value applies
   80        * @param insets the object to be reinitialized
   81        * @return the <code>insets</code> object
   82        */
   83       public Insets getBorderInsets(Component c, Insets insets) {
   84           insets.left = insets.top = insets.right = insets.bottom = 0;
   85           return insets;
   86       }
   87   
   88       /**
   89        * This default implementation returns false.
   90        * @return false
   91        */
   92       public boolean isBorderOpaque() { return false; }
   93   
   94       /**
   95        * This convenience method calls the static method.
   96        * @param c the component for which this border is being computed
   97        * @param x the x position of the border
   98        * @param y the y position of the border
   99        * @param width the width of the border
  100        * @param height the height of the border
  101        * @return a <code>Rectangle</code> containing the interior coordinates
  102        */
  103       public Rectangle getInteriorRectangle(Component c, int x, int y, int width, int height) {
  104           return getInteriorRectangle(c, this, x, y, width, height);
  105       }
  106   
  107       /**
  108        * Returns a rectangle using the arguments minus the
  109        * insets of the border. This is useful for determining the area
  110        * that components should draw in that will not intersect the border.
  111        * @param c the component for which this border is being computed
  112        * @param b the <code>Border</code> object
  113        * @param x the x position of the border
  114        * @param y the y position of the border
  115        * @param width the width of the border
  116        * @param height the height of the border
  117        * @return a <code>Rectangle</code> containing the interior coordinates
  118        */
  119       public static Rectangle getInteriorRectangle(Component c, Border b, int x, int y, int width, int height) {
  120           Insets insets;
  121           if(b != null)
  122               insets = b.getBorderInsets(c);
  123           else
  124               insets = new Insets(0, 0, 0, 0);
  125           return new Rectangle(x + insets.left,
  126                                       y + insets.top,
  127                                       width - insets.right - insets.left,
  128                                       height - insets.top - insets.bottom);
  129       }
  130   
  131       /**
  132        * Returns the baseline.  A return value less than 0 indicates the border
  133        * does not have a reasonable baseline.
  134        * <p>
  135        * The default implementation returns -1.  Subclasses that support
  136        * baseline should override appropriately.  If a value &gt;= 0 is
  137        * returned, then the component has a valid baseline for any
  138        * size &gt;= the minimum size and <code>getBaselineResizeBehavior</code>
  139        * can be used to determine how the baseline changes with size.
  140        *
  141        * @param c <code>Component</code> baseline is being requested for
  142        * @param width the width to get the baseline for
  143        * @param height the height to get the baseline for
  144        * @return the baseline or &lt; 0 indicating there is no reasonable
  145        *         baseline
  146        * @throws IllegalArgumentException if width or height is &lt; 0
  147        * @see java.awt.Component#getBaseline(int,int)
  148        * @see java.awt.Component#getBaselineResizeBehavior()
  149        * @since 1.6
  150        */
  151       public int getBaseline(Component c, int width, int height) {
  152           if (width < 0 || height < 0) {
  153               throw new IllegalArgumentException(
  154                       "Width and height must be >= 0");
  155           }
  156           return -1;
  157       }
  158   
  159       /**
  160        * Returns an enum indicating how the baseline of a component
  161        * changes as the size changes.  This method is primarily meant for
  162        * layout managers and GUI builders.
  163        * <p>
  164        * The default implementation returns
  165        * <code>BaselineResizeBehavior.OTHER</code>, subclasses that support
  166        * baseline should override appropriately.  Subclasses should
  167        * never return <code>null</code>; if the baseline can not be
  168        * calculated return <code>BaselineResizeBehavior.OTHER</code>.  Callers
  169        * should first ask for the baseline using
  170        * <code>getBaseline</code> and if a value &gt;= 0 is returned use
  171        * this method.  It is acceptable for this method to return a
  172        * value other than <code>BaselineResizeBehavior.OTHER</code> even if
  173        * <code>getBaseline</code> returns a value less than 0.
  174        *
  175        * @param c <code>Component</code> to return baseline resize behavior for
  176        * @return an enum indicating how the baseline changes as the border is
  177        *         resized
  178        * @see java.awt.Component#getBaseline(int,int)
  179        * @see java.awt.Component#getBaselineResizeBehavior()
  180        * @since 1.6
  181        */
  182       public Component.BaselineResizeBehavior getBaselineResizeBehavior(
  183               Component c) {
  184           if (c == null) {
  185               throw new NullPointerException("Component must be non-null");
  186           }
  187           return Component.BaselineResizeBehavior.OTHER;
  188       }
  189   
  190       /*
  191        * Convenience function for determining ComponentOrientation.
  192        * Helps us avoid having Munge directives throughout the code.
  193        */
  194       static boolean isLeftToRight( Component c ) {
  195           return c.getComponentOrientation().isLeftToRight();
  196       }
  197   
  198   }

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