eclipseprojects/eu.etaxonomy.taxeditor/src/eu/etaxonomy/taxeditor/editor/EmptyTextViewerPrompt.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 org.apache.log4j.Logger;
  13 import org.eclipse.jface.text.DocumentEvent;
  14 import org.eclipse.jface.text.IDocument;
  15 import org.eclipse.jface.text.IDocumentListener;
  16 import org.eclipse.jface.text.TextViewer;
  17 import org.eclipse.swt.custom.StyledText;
  18 import org.eclipse.swt.events.DisposeEvent;
  19 import org.eclipse.swt.events.DisposeListener;
  20 import org.eclipse.swt.events.FocusEvent;
  21 import org.eclipse.swt.events.FocusListener;
  22 import org.eclipse.swt.graphics.Font;
  23
  24 import eu.etaxonomy.taxeditor.ITaxEditorConstants;
  25 import eu.etaxonomy.taxeditor.TaxEditorPlugin;
  26
  27 /**
  28  * Displays a message such as "Click here to start entering
  29  * data" when <code>document</code> is empty.
  30  *
  31  * @author p.ciardelli
  32  * @created 15.09.2008
  33  * @version 1.0
  34  */
  35 public class EmptyTextViewerPrompt implements IDocumentListener {
  36         private static final Logger logger = Logger
  37                         .getLogger(EmptyTextViewerPrompt.class);
  38
  39         private IDocument document;
  40         private StyledText textControl;
  41         private String prompt;
  42         private FocusListener focusListener = null;
  43
  44         private Font textFont;
  45         private Font promptFont = TaxEditorPlugin.getDefault()
  46                         .getFont(ITaxEditorConstants.DEFAULT_PROMPT_FONT);
  47
  48         public EmptyTextViewerPrompt(TextViewer textViewer, String prompt) {
  49
  50                 this.document = textViewer.getDocument();
  51                 this.textControl = textViewer.getTextWidget();
  52                 this.prompt = prompt;
  53
  54                 this.textFont = textControl.getFont();
  55
  56                 documentChanged(null);
  57         }
  58
  59         /**
  60          * Override <code>prompt</code>'s default font.
  61          *
  62          * @param font
  63          */
  64         public void setPromptFont(Font font) {
  65                 this.promptFont = font;
  66         }
  67
  68         /**
  69          * Adds a focus listener to the <code>textControl</code>, which hides
  70          * the <code>prompt</code> if the cursor is in the <code>textControl</code>,
  71          * and shows it if the cursor is elsewhere.
  72          */
  73         private void createPrompt() {
  74
  75                 textControl.setFont(promptFont);
  76                 document.set(prompt);
  77
  78                 focusListener = new FocusListener() {
  79
  80                         public void focusGained(FocusEvent e) {
  81                                 if (document.get().equals(prompt)) {
  82                                         textControl.setFont(textFont);
  83                                         document.set("");
  84                                 }
  85                         }
  86
  87                         public void focusLost(FocusEvent e) {
  88                                 if (document.getLength() == 0) {
  89                                         textControl.setFont(promptFont);
  90                                         document.set(prompt);
  91                                 }
  92                         }
  93
  94                 };
  95                 textControl.addFocusListener(focusListener);
  96                 textControl.addDisposeListener(new DisposeListener() {
  97
  98
  99                         public void widgetDisposed(DisposeEvent e) {
 100                                 focusListener = null;
 101                         }
 102
 103                 });
 104         }
 105
 106         /**
 107          * Removes focus listener from <code>textControl</code>, turning off
 108          * the showing of <code>prompt</code>.
 109          */
 110         private void removePrompt() {
 111                 if (focusListener != null) {
 112                         textControl.removeFocusListener(focusListener);
 113                         focusListener = null;
 114                 }
 115         }
 116
 117         /* (non-Javadoc)
 118          * @see org.eclipse.jface.text.IDocumentListener#documentAboutToBeChanged(org.eclipse.jface.text.DocumentEvent)
 119          */
 120         public void documentAboutToBeChanged(DocumentEvent event) {}
 121
 122         /* (non-Javadoc)
 123          * @see org.eclipse.jface.text.IDocumentListener#documentChanged(org.eclipse.jface.text.DocumentEvent)
 124          */
 125         public void documentChanged(DocumentEvent event) {
 126
 127                 if (document.get().equals(prompt)) {
 128                         return;
 129                 }
 130
 131                 if (document.getLength() == 0) {
 132                         createPrompt();
 133                 } else {
 134                         removePrompt();
 135                 }
 136         }
 137 }