Source for javax.swing.plaf.basic.BasicHTML

   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: }