JScrollPane issues - no autoscroll wished

[Flo]

Hello.
Currently I'm working on a simple IDE. I came up with a pretty good codeeditor but unfortunately there is a tiny problem with the JScrollPane.
A JTextPane is embedded in a JPanel which is the ViewPortView of the JScrollPane.
And with that there come major scrolling problems. When you enter a lot of rows then scroll to the top and enter letters there, the JScrollPane just scrolls to the very end of the JTextPane.

Here is my code:

/**
 * Editorfeld mit Zeilennummerierung und Syntax-Highlighting
 */
class JEditorNumbered extends JScrollPane implements DocumentListener
{    
    // Private Datenfelder
    JTextPane textPane = new JTextPane();    
    JTextPane lineBar = new JTextPane();
    
    String[] commands = {"mov ", "add ", "sub ", "not ", "xor ", "or ", "and ", "jmp ", "jmpg ", "jmpe ", "jmpl ", "swap ", "load ", "store ", "cmp ", "nop", "reset", "addo ", "db ", "var ", "set ", "#include "};
    String[] keywords = {"PortA", "PortB", "PortC", "Akku", "HL"};
    
    
    /**
     * Text bekommen
     * @return der Text
     */
    public String getText(){return textPane.getText();}
    
    
    /**
     * Text setzen
     * @param text 
     */
    public void setText(String text){textPane.setText(text);}
    
    /**
     * Aktivieren/Deaktivieren
     * @param b 
     */
    @Override
    public void setEnabled(boolean b){super.setEnabled(b); textPane.setEnabled(b);}
    
    
    /**
     * Ein Dokumentlistener hinzufügen
     * @param listener 
     */
    public void addDocumentListener(DocumentListener listener){textPane.getDocument().addDocumentListener(listener); }
    
    
    
    /**
     * Konstruktor
     */
    public JEditorNumbered()
    {
        super();
        
        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());
        panel.add(textPane,BorderLayout.CENTER);
        panel.add(lineBar,BorderLayout.WEST); 	
        
        lineBar.setBorder(BorderFactory.createMatteBorder(0, 0, 0, 1, Color.LIGHT_GRAY));
        lineBar.setEnabled(false);
        lineBar.setText(" 0 ");
        
        textPane.getDocument().addDocumentListener(this); 
        textPane.setMargin(new Insets(0,10,0,0));
        
         this.setViewportView(panel);
        setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        
        Style style = textPane.addStyle("Normal", null);
        StyleConstants.setForeground(style, Color.BLACK);
        StyleConstants.setItalic(style, false);
        StyleConstants.setBold(style, false);
        
        style = textPane.addStyle("Befehl", null);
        StyleConstants.setForeground(style, Color.BLUE);
        StyleConstants.setBold(style, true);
        
        style = textPane.addStyle("Schlusselworter", null);
        StyleConstants.setForeground(style, Color.darkGray);
        StyleConstants.setBold(style, true);
        
        style = textPane.addStyle("Labels", null);
        StyleConstants.setForeground(style, Color.RED);
        StyleConstants.setBold(style, true);
        
        style = textPane.addStyle("Address", null);
        StyleConstants.setForeground(style, Color.RED);
        
        style = textPane.addStyle("String", null);
        StyleConstants.setForeground(style, new Color(0,0.5f,0));
        StyleConstants.setBold(style, true);
        
        style = textPane.addStyle("Kommentar", null);
        StyleConstants.setForeground(style, new Color(0.5f,0.5f,0.5f));
    }
    
    
    public void saveToFile(String path) throws IOException
    {
        BufferedWriter  out = new BufferedWriter(new FileWriter(path));
        out.write(textPane.getText());
        out.close();
    }

    public void readFromFile(String path) throws IOException
    {
        Scanner sc = new Scanner(new FileInputStream(path)); 
        String text = "";
        while(sc.hasNextLine())
        {
            text += sc.nextLine()+"\r\n";
        }
        
        sc.close();
        
        setText(text);
    }
    
    
    @Override
    public void changedUpdate(DocumentEvent e) {
        
    }

    @Override
    public void removeUpdate(DocumentEvent e) {
        insertUpdate(e);
    }

    @Override
    public void insertUpdate(DocumentEvent e) {
               
        
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                StyledDocument doc = textPane.getStyledDocument();
                doc.setCharacterAttributes(0, textPane.getText().length(), textPane.getStyle("Normal"), true);
                
                Scanner sc = new Scanner(textPane.getText());
                String numbers = "";		
                int lineNr = 0;
                int offsetToRow = 0;
                
                while(sc.hasNextLine())
                {
                    numbers = numbers + " " + (lineNr++) + " \n";
                    String line = sc.nextLine();
                    
                    
                    // Highlighting
                    int start;
                    int pos;
                    int end;

                    // COMMANDS
                    for(int i=0;i<commands.length;i++)
                    {
                        start = 0;
            
                        while(true)
                        {
                            pos = line.indexOf(commands[i], start);

                            if(pos == -1)
                                break;

                            int len = commands[i].length();
                            doc.setCharacterAttributes(offsetToRow + pos, len, textPane.getStyle("Befehl"), true);  
                            start += len;
                        }
                    }
                    
                    // <editor-fold defaultstate="collapsed" desc="Filter">
                    // KEYWORDS
                    for(int i=0;i<keywords.length;i++)
                    {
                        start = 0;
            
                        while(true)
                        {
                            pos = line.indexOf(keywords[i], start);

                            if(pos == -1)
                                break;

                            int len = keywords[i].length();
                            doc.setCharacterAttributes(offsetToRow + pos, len, textPane.getStyle("Schlusselworter"), true);  
                            start += len;
                        }
                    }
                    
                    // LABELS
                    start = line.indexOf(":");
                    if(start != -1)
                    {
                        doc.setCharacterAttributes(offsetToRow, start+1, textPane.getStyle("Labels"), true);  
                    }
                    
                    
                    // ADRESSES
                    start = 0;
                    end = 0;
                    while(true)
                    {
                        start = line.indexOf("[", start);
                        end = line.indexOf("]", end);
                        if(start != -1 && end != -1)
                        {
                            doc.setCharacterAttributes(offsetToRow+start, end-start+1, textPane.getStyle("Address"), true);
                        }else{
                            break;
                        } 
                        start++; end++;
                    }
                    
                    
                    // STRING
                    start = 0;
                    end = 0;
                    while(true)
                    {
                        start = line.indexOf("\"", end);
                        end = line.indexOf("\"", start+1);
                        if(start != -1 && end != -1)
                        {
                            doc.setCharacterAttributes(offsetToRow+start, end-start+1, textPane.getStyle("String"), true);
                        }else{
                            break;
                        } 
                        start++; end++;
                    }
                    
                    
                    
                    // COMMENT
                    start = line.indexOf("//");
                    if(start != -1)
                    {                     
                        doc.setCharacterAttributes(offsetToRow+start, line.length()-start+1, textPane.getStyle("Kommentar"), true);
                    }
                    
                    //</editor-fold>
                                        
                    offsetToRow += line.length()+1;
                }
                
                sc.close();

                
                if(textPane.getText().length()>0)
                    if(textPane.getText().charAt(textPane.getText().length()-1) == '\n')
                        numbers = numbers + " " + (lineNr) + " \n";

                lineBar.setText(numbers);
            }
        });
        
    }
    
}

Maybe some of you know this issue and the fitting solution.

Flo

[Flo]

Ok I found the Problem.
When you refresh the line numbers then the scrollbar automatically goes down.
How can I change these without interfering with the scrollbar?
I tried:

        float prozent = getVerticalScrollBar().getValue() / (float)getVerticalScrollBar().getMaximum();
        
        lineBar.setText(numbers);
        
        this.getVerticalScrollBar().setValue( (int)(getVerticalScrollBar().getMaximum()*prozent) );

It works but it looks not nice. The scrollbar is flickering and the edited line is shown in the very top of the viewport.

Has anybody an idee?

[camickr]

Instead of using a separate text pane for the line numbers you should create a custom component that is used as the row header view of the scroll pane.

Text Component Line Number « Java Tips Weblog is a component that was designed for this purpose.

[Flo]

This is perfect!
Thanks a lot!