eclipseprojects/eu.etaxonomy.taxeditor/src/eu/etaxonomy/taxeditor/editor/LineBreakListener.java

   1 /**
   2 * Copyright (C) 2007 EDIT
   3 * European Distributed Institute of Taxonomy
   4 * http://www.e-taxonomy.eu
   5 *
   6 * The contents of this file are subject to the Mozilla Public License Version 1.1
   7 * See LICENSE.TXT at the top of this package for the full license terms.
   8 */
   9
  10 package eu.etaxonomy.taxeditor.editor;
  11
  12 import java.util.ArrayList;
  13 import java.util.Collection;
  14 import java.util.Scanner;
  15
  16 import org.apache.log4j.Logger;
  17 import org.eclipse.swt.custom.StyledText;
  18 import org.eclipse.swt.events.KeyEvent;
  19 import org.eclipse.swt.events.KeyListener;
  20 import org.eclipse.swt.events.VerifyEvent;
  21 import org.eclipse.swt.events.VerifyListener;
  22
  23 /**
  24  * Checks text entered into a StyledText widget for line breaks, sends
  25  * split text to abstract method handleSplitText().
  26  *  <p>
  27  * VerifyListener interface methods break up the text into lines. Each line is sent individually
  28  * to the handleSplitText() method when the KeyListener interface method keyReleased() is called.
  29  * This is because if the StyledText widget is disposed before the key is released, an SWT
  30  * exception occurs.
  31  * <p>
  32  * The listener should be set on the StyledText widget as follows:
  33  * <code><pre>
  34  *              StyledText styledText = new SourceViewer().getTextWidget();
  35  *              LineBreakListener lineBreakListener = new LineBreakListener() {
  36  *                      public void handleSplitText(String text) {
  37  *                              ... some operation ...
  38  *                      }
  39  *              };
  40  *
  41  *              styledText.addVerifyListener(lineBreakListener);
  42  *              styledText.addKeyListener(lineBreakListener);
  43  * </pre></code>
  44  *
  45  * @author p.ciardelli
  46  * @created 19.05.2008
  47  * @version 1.0
  48  */
  49 public abstract class LineBreakListener implements VerifyListener, KeyListener {
  50         private static final Logger logger = Logger
  51                         .getLogger(LineBreakListener.class);
  52
  53         Collection<String> splitTexts;
  54
  55         /**
  56          * Checks for 3 conditions of name viewer text:
  57          *   1) no line breaks in text
  58          *   2) line break at the end of the text
  59          *   3) line break in the middle of the text
  60          *
  61          * @see org.eclipse.swt.events.VerifyListener#verifyText(org.eclipse.swt.events.VerifyEvent)
  62          */
  63         public void verifyText(VerifyEvent e) {
  64
  65                 String verifyText = e.text;
  66
  67                 StyledText styledText = (StyledText) e.widget;
  68                 String widgetText = styledText.getText();
  69                 int cursorPosition = styledText.getCaretOffset();
  70
  71                 // If no line break in verifyText, Parse text normally
  72                 if (!verifyText.contains(System.getProperty("line.separator"))) {
  73                         return;
  74                 }
  75
  76                 // Don't add verifyText without further processing
  77                 e.doit = false;
  78
  79                 // Initialize split text collection
  80                 splitTexts = new ArrayList<String>();
  81
  82                 // If user has entered return at the end of the line,
  83                 //  make a new, empty synonym
  84                 if (widgetText.length() == cursorPosition &&
  85                                 verifyText.equals(System.getProperty("line.separator"))) {
  86                         splitTexts.add("");
  87                         return;
  88                 }
  89
  90                 // Concatenate old and new texts
  91                 String textForSplitting = widgetText.substring(0, cursorPosition)
  92                                 + verifyText
  93                                 + widgetText.substring(cursorPosition);
  94
  95                 // Split on line breaks
  96                 Scanner scanner = new Scanner( textForSplitting );
  97                 scanner.useDelimiter (System.getProperty("line.separator"));
  98
  99                 // Put first string into name viewer
 100                 styledText.setText(scanner.next());
 101
 102                 // Start new synonyms with the rest
 103                 while (scanner.hasNext()) {
 104                         splitTexts.add(scanner.next());
 105                 }
 106         }
 107
 108
 109         public void keyPressed(KeyEvent e) {}
 110
 111
 112         public void keyReleased(KeyEvent e) {
 113                 if (splitTexts != null) {
 114                         for (String text : splitTexts) {
 115                                 handleSplitText(text);
 116                         }
 117                         splitTexts = null;
 118                 }
 119         }
 120
 121         abstract public void handleSplitText(String text);
 122 }