odk/examples/DevelopersGuide/Forms/TableCellTextBinding.java

   1 /*
   2  * This file is part of the LibreOffice project.
   3  *
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   7  *
   8  * This file incorporates work covered by the following license notice:
   9  *
  10  *   Licensed to the Apache Software Foundation (ASF) under one or more
  11  *   contributor license agreements. See the NOTICE file distributed
  12  *   with this work for additional information regarding copyright
  13  *   ownership. The ASF licenses this file to you under the Apache
  14  *   License, Version 2.0 (the "License"); you may not use this file
  15  *   except in compliance with the License. You may obtain a copy of
  16  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  17  */
  18 import com.sun.star.uno.Type;
  19 import com.sun.star.uno.UnoRuntime;
  20 import com.sun.star.table.XCell;
  21 import com.sun.star.util.XModifyListener;
  22 import com.sun.star.text.XTextRange;
  23
  24 /** a value binding to be connected to a form control
  25
  26     This binding synchronizes the text contained in a table cell (which you must
  27     pass upon construction) to the text in an XBindableValue.
  28
  29     Well, in real it does not synchronize both directions. The ValueBinding
  30     service has not much room for own activity: It allows notification of changes
  31     in the own value, and it allows external instances to set the current value.
  32
  33     Note that we implement this binding as a separate thread, which is (more or
  34     less permanently) polling for a new text at the cell. This is unfortunate, but
  35     sadly the Writer table cells do not support actively notifying changes in their
  36     content to other interested parties.
  37 */
  38 public class TableCellTextBinding
  39                 extends     java.lang.Thread
  40                 implements  com.sun.star.form.binding.XValueBinding,
  41                             com.sun.star.util.XModifyBroadcaster
  42 {
  43     private XTextRange  m_cellText;
  44     private Object      m_writeSignal;
  45     private String      m_newCellText;
  46     private String      m_lastKnownCellText;
  47     private boolean     m_haveNewCellText;
  48     private java.util.List<XModifyListener>  m_listeners;
  49
  50     /** Creates a new instance of TableCellTextBinding */
  51     public TableCellTextBinding( XCell cell )
  52     {
  53         m_cellText = UnoRuntime.queryInterface( XTextRange.class, cell );
  54
  55         m_newCellText = "";
  56         m_listeners = new java.util.LinkedList<XModifyListener>();
  57
  58         start();
  59     }
  60
  61     /** retrieves the list of data types which this binding can exchange
  62     */
  63     public com.sun.star.uno.Type[] getSupportedValueTypes()
  64     {
  65         try
  66         {
  67             // well, only strings here ...
  68             return new Type[] {
  69                 getStringType()
  70             };
  71         }
  72         catch( java.lang.Exception e )
  73         {
  74         }
  75         return new Type[] { };
  76     }
  77
  78     /** retrieves the current value
  79     */
  80     public Object getValue(com.sun.star.uno.Type type) throws com.sun.star.form.binding.IncompatibleTypesException
  81     {
  82         if ( !type.equals( getStringType() ) )
  83             throw new com.sun.star.form.binding.IncompatibleTypesException();
  84
  85         return m_cellText.getString();
  86     }
  87
  88     /** sets a new value
  89     */
  90     public void setValue(Object obj) throws com.sun.star.form.binding.IncompatibleTypesException
  91     {
  92         String text;
  93         try
  94         {
  95             text = (String)obj;
  96         }
  97         catch( java.lang.ClassCastException e )
  98         {
  99             throw new com.sun.star.form.binding.IncompatibleTypesException();
 100         }
 101         // remember the new text
 102         synchronized( m_newCellText )
 103         {
 104             m_newCellText = text;
 105             m_haveNewCellText = true;
 106         }
 107         // and wake up the thread which is waiting for it
 108         synchronized( m_writeSignal )
 109         {
 110             m_writeSignal.notify();
 111         }
 112     }
 113
 114     /** determines whether a given value type is supported
 115     */
 116     public boolean supportsType(com.sun.star.uno.Type type)
 117     {
 118         return type.equals( getStringType() );
 119     }
 120
 121     /** retrieves the UNO type for the string class
 122     */
 123     private static final Type getStringType()
 124     {
 125         return new com.sun.star.uno.Type( String.class );
 126     }
 127
 128     /** runs the thread
 129     */
 130     @Override
 131     public void run()
 132     {
 133         try
 134         {
 135             m_writeSignal = new Object();
 136             while ( true )
 137             {
 138                 // go sleep a while
 139                 synchronized( m_writeSignal )
 140                 {
 141                     m_writeSignal.wait( 200 );
 142                 }
 143
 144                 // if there's new text in the control, propagate it to the cell
 145                 synchronized ( m_newCellText )
 146                 {
 147                     if ( m_haveNewCellText )
 148                     {
 149                         m_cellText.setString( m_newCellText );
 150                         m_lastKnownCellText = m_newCellText;
 151                     }
 152                     m_haveNewCellText = false;
 153                 }
 154
 155                 // if there's new text in the cell, propagate it to the control
 156                 String currentCellText = m_cellText.getString();
 157                 if ( !currentCellText.equals( m_lastKnownCellText ) )
 158                 {
 159                     m_lastKnownCellText = currentCellText;
 160                     // notify the modification
 161                     synchronized( m_listeners )
 162                     {
 163                         com.sun.star.lang.EventObject eventSource = new com.sun.star.lang.EventObject( this );
 164
 165                         java.util.Iterator<XModifyListener> loop = m_listeners.iterator();
 166                         while ( loop.hasNext() )
 167                         {
 168                             loop.next().modified( eventSource );
 169                         }
 170                     }
 171                 }
 172             }
 173         }
 174         catch( java.lang.Exception e )
 175         {
 176             e.printStackTrace(System.err);
 177         }
 178     }
 179
 180     public void addModifyListener(com.sun.star.util.XModifyListener xModifyListener)
 181     {
 182         synchronized( m_listeners )
 183         {
 184             m_listeners.add( xModifyListener );
 185         }
 186     }
 187
 188     public void removeModifyListener(com.sun.star.util.XModifyListener xModifyListener)
 189     {
 190         synchronized( m_listeners )
 191         {
 192             m_listeners.remove( xModifyListener );
 193         }
 194     }
 195
 196 }