gomp-20050608-branch/libjava/classpath/javax/swing/plaf/basic/BasicHTML.java

   1 /* BasicHTML.java -- Provides HTML support to ComponentUI implementations
   2    Copyright (C) 2006 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package javax.swing.plaf.basic;
  40
  41 import java.io.IOException;
  42 import java.io.StringReader;
  43
  44 import javax.swing.JComponent;
  45 import javax.swing.text.BadLocationException;
  46 import javax.swing.text.Element;
  47 import javax.swing.text.View;
  48 import javax.swing.text.ViewFactory;
  49 import javax.swing.text.html.HTMLDocument;
  50 import javax.swing.text.html.HTMLEditorKit;
  51
  52 /**
  53  * Provides support for HTML rendering to {@link javax.swing.plaf.ComponentUI}
  54  * implementations.
  55  *
  56  * @author Roman Kennke (kennke@aicas.com)
  57  */
  58 public class BasicHTML
  59 {
  60
  61   /**
  62    * The key that is used to store a HTML view in a JComponent's client
  63    * properties.
  64    */
  65   public static final String propertyKey = "html";
  66
  67   /**
  68    * The key that is used to store the document base in a JComponent's client
  69    * properties. The document base is used to resolve relative references
  70    * in HTML.
  71    */
  72   public static final String documentBaseKey = "html.base";
  73
  74   /**
  75    * Creates a new instance of BasicHTML. This should not be necessary since
  76    * all methods in this class are static.
  77    */
  78   public BasicHTML()
  79   {
  80     // Nothing to do here.
  81   }
  82
  83   /**
  84    * Creates a {@link View} instance that can be used by the component
  85    * <code>c</code> to render the HTML string <code>html</code>.
  86    *
  87    * @param c the component that needs to render the HTML string
  88    * @param html the HTML string to be rendered
  89    *
  90    * @return a view that can render the HTML string
  91    */
  92   public static View createHTMLView(JComponent c, String html)
  93   {
  94     // TODO: This might be wrong. Lets see if it turns out good when
  95     // the javax.swing.text.html package is in a good shape.
  96     HTMLDocument doc = new HTMLDocument();
  97     HTMLEditorKit kit = new HTMLEditorKit();
  98     StringReader reader = new StringReader(html);
  99     try
 100       {
 101         kit.read(reader, doc, 0);
 102       }
 103     catch (IOException ex)
 104       {
 105         AssertionError err = new AssertionError("unexpected IOException");
 106         err.initCause(ex);
 107         throw err;
 108       }
 109     catch (BadLocationException ex)
 110       {
 111         AssertionError err =
 112           new AssertionError("unexpected BadLocationException");
 113         err.initCause(ex);
 114         throw err;
 115       }
 116     ViewFactory vf = kit.getViewFactory();
 117     Element root = doc.getDefaultRootElement();
 118     View view = vf.create(root);
 119     return view;
 120   }
 121
 122   /**
 123    * Returns <code>true</code> if <code>s</code> is HTML, <code>false</code>
 124    * otherwise.
 125    *
 126    * @param s the string to test
 127    *
 128    * @return <code>true</code> if <code>s</code> is HTML, <code>false</code>
 129    *         otherwise
 130    */
 131   public static boolean isHTMLString(String s)
 132   {
 133     // We consider a string to be HTML if it contains both the '<' and '>'
 134     // character at least once.
 135     return s.contains("<") && s.contains(">");
 136   }
 137
 138   /**
 139    * Stores a HTML renderer in <code>c</code>'s client property if
 140    * <code>text</code> is HTML, otherwise it clears the corresponding client
 141    * property. This is useful for {@link java.swing.plaf.ComponentUI}
 142    * implementations that are shared between it's components.
 143    *
 144    * @param c the component to update the renderer for
 145    * @param text the string to be rendered
 146    */
 147   public static void updateRenderer(JComponent c, String text)
 148   {
 149     if (isHTMLString(text))
 150       c.putClientProperty(propertyKey, createHTMLView(c, text));
 151     else
 152       c.putClientProperty(propertyKey, null);
 153   }
 154 }