Extreme Java

Tired of lose the fight against NetBeans MDR stuff, I decided to check out Code Folding. Pretty easy, indeed. I haven’t done a full code fold example, but I was able to use NB ‘editor-fold’ pseudo-tag. Considering that you have the syntax support (see NBP Tutorials), the steps are:

1. The first step is not obvious, but it is the most important step. Without it, you will never activate folding (this was hard to find out - like any other “non-layer.xml” stuff). On your SettingsInitializer, you need to add this line:

   settingsMap.put(SettingsNames.CODE_FOLDING_ENABLE, Boolean.TRUE);

2. Next, we need to tell CustomFold which tokens it must use to find the pseudo-tag. On your EditorKit, you need to implement the SyntaxUpdateTokens class and put it as a document property. Like this:

   public class MyEditorKit extends NbEditorKit {
     [ ... ]        
   
     protected void initDocument(BaseDocument doc) {
       doc.putProperty(SyntaxUpdateTokens.class, new SUT());
     }
   
     public class SUT extends SyntaxUpdateTokens {
       private List list;
   
       public void syntaxUpdateStart() {
         list = new ArrayList();
       }
   
       public List syntaxUpdateEnd() {
         return list;
       }
   
       public void syntaxUpdateToken(TokenID tid, TokenContextPath tcp,
                                     int offset, int len) {
         if (tokenID == MyTokenContext.LINE_COMMENT) {
           list.add(new TokenInfo(tid, tcp, offset, len));
         }
       }
     }
   }

3. This is a weird step. I don’t know why there’s no ready-to-go class to do this job. You need to create a three-line class to add the sidebar to the editor:

   public class MyFoldingSideBarFactory implements SideBarFactory {
     public JComponent createSideBar(JTextComponent jTextComponent) {
       return new CodeFoldingSideBar(jTextComponent);
     }
   }

4. Now, glue everything in your layer.xml, under “Editor/MIME” folder:

   <folder name="SideBar">
     <file name="mypkg-MyFoldingSideBarFactory.instance"/>
     <attr name="org-netbeans-editor-GlyphGutter.instance
           /mypkg-MyFoldingSideBarFactory.instance"
           boolvalue="true"/>
   </folder>
   <folder name="FoldManager">
     <file name="org-netbeans-editor-CustomFoldManager$Factory.instance"/>
   </folder>

Small note: implementations of FoldManager can be chained, just like the SideBar. Making it easy to add a “real” code fold based on tokens.