Using JScrollbar on a JComponent

[tdomega]

Hi,

I have a JComponent (fixed size) that shows graphics. Now I want the user to scroll the content of the component (not scroll the actual componen though)

I cant use a JScrollPance because i cant hold all the graphics in memory. I just want the user to see and use the scrollbars, capture the events and direct them to my graphics engine.

I tried JComponent.add() and JComponent.getrootPane().add() but the scrollbars dont want to show...same for the events

Any ideas how it can be done? Thanks!

[sjalle]

What scrollbars are you expecting to see ? A JComponent has no hidden scrollbar
feature.
If You use a JScrollPane the bar(s) will show if the panel you add to it exceeds the scrollpane size, and you invoke its method for user interface update.

[tdomega]

I tried to add normal JScrollBar 's to my jcomponent

here is what im trying to do:

class MyClass extends JComponent{
JScrollBar jsb;

MyClass()
{
jsb = new Scrollbar(JScrollbar.HORIZONTAL, 0,10,0,100);
this.add(jsb);
}
}

and the MyClass is added to the rootPane of my JFrame (Main Application)

...
MyClass mc = new MyClass();
this.getRootPane().add(mc);
...

Now after this i qould expect the ScrollBars to show up, but hey dont...
Makes no difference weather i setsize or setpreferredsize etc.

?!?

[sjalle]

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class ScrollFrame extends JFrame implements AdjustmentListener {
  BorderLayout borderLayout1 = new BorderLayout();
  JScrollBar vScroll = new JScrollBar();
  JScrollBar hScroll = new JScrollBar();
  public ScrollFrame() {
    try {
      jbInit();
      validate();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    ScrollFrame sf = new ScrollFrame();
    sf.setBounds(20,20,600,500);
    sf.setVisible(true);
    sf.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
  }
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(borderLayout1);
    hScroll.setOrientation(JScrollBar.HORIZONTAL);
    this.getContentPane().add(vScroll, BorderLayout.EAST);
    this.getContentPane().add(hScroll, BorderLayout.SOUTH);

    vScroll.addAdjustmentListener(this);
    hScroll.addAdjustmentListener(this);
  }
  public void adjustmentValueChanged(AdjustmentEvent e) {
    if (e.getSource()==vScroll) {
      System.out.println("vertical:"+e.getValue());
    } else if (e.getSource()==hScroll) {
      System.out.println("horizontal:"+e.getValue());
    }

  }
}

If you place your image display panel in CENTER as a JPanel extension you
could modify some drawing coordinates and do a repaint on each invokation
of the adjustmentValueChanged method.

[tdomega]

Hi, that helped, its working now =)

Big thanks !