Handling scrollpanes

[Mohan Lavu]

Hi,
I have a problem with Scrollpanes.I have a panel on which i do all the drawing with the graphics context and the panel's preferred size is set.I have a frame in which i have an instance of the above class which extends a panel and a scrollpane to which this instance is added.The scrollpanes preferred size is also set.when i execute the application i get the scrollbars as i have includes scrollbarconstants as ALWAYS.The problem is i am able to scroll up to the scrollpane's dimesnions only.can any one tell me why this is happening like this??? I am bogged down with this problem for a day..
Thank You.

[Manfred Leonhardt]

Hi Mohan,
I am not sure exactly what you have, but compare it to the code below because it works!

import java.awt.*;
import java.awt.event.*;
//
// Class to support drawing on panel.
//
class DrawingPanel extends Panel
{
  //
  // Overide the paint method so that we can see something good.
  //
  public void paint( Graphics g )
  {
    // Draw some rectangles from top down with different colors.
    Dimension dim = getSize();
    int hgt = dim.height / 4;
    Color[] colors = {Color.red, Color.green, Color.blue, Color.magenta};
    for( int i = 0; i < 4; ++i )
    {
      g.setColor( colors[i] );
      g.fillRect( 0, hgt*i, dim.width, hgt );
    }
  }
  //
  // Override preferred size so that the parent will get
  //  correct information when it requests it.
  //
  public Dimension getPreferredSize()
  {
    return( new Dimension( 1000, 4000 ) );
  }
};
//
// Top level class for this file.
//
public class ScrollFrame extends Frame
{
  DrawingPanel drawingPanel;
  ScrollPane scroll;
  //
  // Constructor for ScrollFrame
  //
  public ScrollFrame()
  {
    // Set my default size
    setSize( 600, 600 );
    // Create drawing panel add it to scrollpane and add that to me.
    drawingPanel = new DrawingPanel();
    scroll = new ScrollPane( ScrollPane.SCROLLBARS_ALWAYS );
    scroll.add( drawingPanel );
    add( scroll );
  }
  //
  // Runnable method for ScrollFrame class
  //
  public static void main(String[] args)
  {
    ScrollFrame sf = new ScrollFrame();
    sf.setVisible( true );
  }
}

Regards,
Manfred.