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SeanSBW@gmail.com 08-30-2006 12:45 PM

JScrollPane Scrollbar issues
 
Sorry if this has been posted. I went through 3 pages of topics
looking for it, plus numerous google searches to no avail. Does anyone
know why in Java 1.5 the Horizontal scrollbar in a JScrollPane
initializes to the middle?

I've tried using:

JScrollPane pane
// more initialization, but the last call is as follows.
pane.getHorizontalScrollBar().setValue(0);

Any thoughts? I thought it might be where the visible rectangle is
set, but I am not sure. I was also wondering why too.

Thanks,

Sean


Michael Rauscher 08-30-2006 01:38 PM

Re: JScrollPane Scrollbar issues
 
SeanSBW@gmail.com schrieb:
> Sorry if this has been posted. I went through 3 pages of topics
> looking for it, plus numerous google searches to no avail. Does anyone
> know why in Java 1.5 the Horizontal scrollbar in a JScrollPane
> initializes to the middle?


It doesn't

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

public class Test {

public static final void main( String args[] ) {
JTable table = new JTable(5,5);
table.setAutoResizeMode( JTable.AUTO_RESIZE_OFF );
JScrollPane scrollPane = new JScrollPane( table );
scrollPane.setPreferredSize( new Dimension(300,200) );

JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
frame.setContentPane( scrollPane );
frame.pack();
frame.setVisible(true);
}
}

Bye
Michael

SeanSBW@gmail.com 08-30-2006 02:23 PM

Re: JScrollPane Scrollbar issues
 
Mike,

Thanks for the response. I discovered the problem, however, I'm
looking at a different situation than the simple example below. I'll
modify the ex. below to show you my issue.

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

public class Test {

public static final void main( String args[] ) {
TestPanel viewport = new TestPanel();
JScrollPane scrollPane = new JScrollPane( viewport );
scrollPane.setPreferredSize( new Dimension(300,200) );

JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
frame.setContentPane( scrollPane );
frame.pack();
frame.setVisible(true);
}
}
// Creates the ViewPort panel
class TestPanel extends JPanel
{
public TestPanel()
{
setLayout(new GridLayout(0, 6));
for (int i = 0; i < 6; i++)
{
// add new repeated panels
add(new RepeatedPanel());
}
}
}
// Repeated panel in grid formation
// ***** PROBLEM: The JTextArea inside the panel is causing
// the JScrollPane to get a different viewing area, because every
// textarea that's added to the parent JScrollPane is messing up the
scrollbar locations

class RepeatedPanel extends JPanel
{
JTextField singleLine1;
JTextField singleLine2;
JTextArea multiLine;

public TestPanel()
{
singleLine1 = new JTextField("single ex. 1");
add(singleLine1);

singleLine2 = new JTextField("single ex. 2");
add(singleLine2);

multiLine = new JTextArea("multi ex. 1");
multiLine.setLineWrap(true);
add(multiLine);
}
}

Is there a way to hide the inner JTextArea from the outside
JScrollPane, or disable it as a scrollable area? Or would it be
simpler to create a multi-line JTextField with word-wrap
and text aligned with the beginning of the field?

Thanks for your help, it is appreciated.

Michael Rauscher wrote:
> SeanSBW@gmail.com schrieb:
> > Sorry if this has been posted. I went through 3 pages of topics
> > looking for it, plus numerous google searches to no avail. Does anyone
> > know why in Java 1.5 the Horizontal scrollbar in a JScrollPane
> > initializes to the middle?

>
> It doesn't
>
> import java.awt.Dimension;
> import javax.swing.*;
>
> public class Test {
>
> public static final void main( String args[] ) {
> JTable table = new JTable(5,5);
> table.setAutoResizeMode( JTable.AUTO_RESIZE_OFF );
> JScrollPane scrollPane = new JScrollPane( table );
> scrollPane.setPreferredSize( new Dimension(300,200) );
>
> JFrame frame = new JFrame();
> frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
> frame.setContentPane( scrollPane );
> frame.pack();
> frame.setVisible(true);
> }
> }
>
> Bye
> Michael



Michael Rauscher 08-30-2006 03:43 PM

Re: JScrollPane Scrollbar issues
 
Hi,
SeanSBW@gmail.com schrieb:
> Mike,
>
> Thanks for the response. I discovered the problem, however, I'm
> looking at a different situation than the simple example below. I'll
> modify the ex. below to show you my issue.


Sorry, but I can't see your issue.

Running your example (on build 1.5.0_06-b05 - after fixing some errors
to get the code compiled) initializes the scrollbar to the left.

Bye
Michael

SeanSBW@gmail.com 08-30-2006 06:15 PM

Re: JScrollPane Scrollbar issues
 
Michael,

I saw what you meant. Sorry for the sloppy code. Here is another
version more tightly coupled to my code. The only difference is that I
removed the validate() call from my code and it still displays the same
way. If you click the update button at the bottom of the window, watch
the scrollbars, they jump to the middle and stay there. My GUI loads
that way, which is odd to me because I removed the validate() call.

import java.awt.Dimension;
import javax.swing.*;
import javax.swing.border.*;

import java.awt.*;
import java.awt.event.*;


public class Test {


public static final void main( String args[] ) {

Box displayPane = new Box(BoxLayout.PAGE_AXIS);
Dimension d = new Dimension(500,500);
int idx = 0;
TestPanel viewport = new TestPanel(idx);
displayPane.add(viewport);

JButton update = new JButton("update");
update.addActionListener(viewport);
displayPane.add(update);
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
frame.setContentPane( displayPane );
frame.pack();
frame.setVisible(true);
}
}
// Creates the ViewPort panel
class TestPanel extends JPanel implements ActionListener {

Dimension dfltSize = new Dimension(400, 150);
int offset = 36;
int og;
Dimension d = new Dimension(1200, 225);
Dimension vpSize = new Dimension(500,500);
JScrollPane scrollPane;
JPanel viewport;


public TestPanel(int idx) {
og = idx+1;
scrollPane = new
JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_AS_NEED ED,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
viewport = createPanel(idx);
add(scrollPane);
scrollPane.setPreferredSize(vpSize);
scrollPane.setMaximumSize(vpSize);
scrollPane.setMinimumSize(vpSize);
scrollPane.setViewportView(viewport);
scrollPane.validate();
}

public JPanel createPanel(int idx){
JPanel view = new JPanel();
view.setLayout(new GridLayout(0, 6));
for (int i = idx; i < idx+offset; i++) {
// add new repeated panels
RepeatedPanel tmp = new RepeatedPanel(i);
tmp.setPreferredSize(dfltSize);
tmp.setMaximumSize(dfltSize);
tmp.setMinimumSize(dfltSize);
view.add(new RepeatedPanel(i));
}
return view;
}

public void actionPerformed(ActionEvent e) {
update();
}
public void update(){
viewport = createPanel(og++);
scrollPane.setViewportView(viewport);
scrollPane.validate();
}
}

class RepeatedPanel extends JPanel {
JTextField singleLine1;
JTextField singleLine2;
JTextArea multiLine;
Border txtAreaBorder;
Dimension txtAreaSize = new Dimension(100, 100);

public RepeatedPanel(int idx) {
singleLine1 = new JTextField(Integer.toString(idx));
add(singleLine1);

singleLine2 = new JTextField(Integer.toString(idx));
add(singleLine2);

multiLine = new JTextArea(Integer.toString(idx));
multiLine.setLineWrap(true);
multiLine.setPreferredSize(txtAreaSize);
multiLine.setMaximumSize(txtAreaSize);
multiLine.setMinimumSize(txtAreaSize);
add(multiLine);

setBorder(BorderFactory.createLoweredBevelBorder() );
}
}


Michael Rauscher 08-30-2006 09:16 PM

Re: JScrollPane Scrollbar issues
 
SeanSBW@gmail.com schrieb:
> Michael,
>
> I saw what you meant. Sorry for the sloppy code. Here is another
> version more tightly coupled to my code. The only difference is that I
> removed the validate() call from my code and it still displays the same
> way. If you click the update button at the bottom of the window, watch
> the scrollbars, they jump to the middle and stay there. My GUI loads
> that way, which is odd to me because I removed the validate() call.


Ah, I see. The problem is that JComponent hands scrollRectToVisible up
the hierarchy. Solutions:

a) put multiLine into a JScrollPane or
b) override scrollRectToVisible in RepeatedPanel

Bye
Michael


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