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