determining minimum dimensions of an Applet

[Clayton Cramer]

I have an applet that pops up a window with several components: a JLabel, a JTextArea, and two buttons. Different callers will specify different sizes for the JTextArea, so I would like to setSize so that the Applet window shrinks to only the area that is used. This is the code that creates the components:

	  public String inputTextBox(String prompt, int rows, int columns) throws InterruptedException, BadLocationException {
		  PopupWindow popup = new PopupWindow(this);
		  popup.setVisible(true);
		  JPanel p = new JPanel();
		  p.setLayout(new BoxLayout(p, BoxLayout.PAGE_AXIS));
		  add(p);
		  JLabel promptMsg = new JLabel(prompt);
		  p.add(promptMsg);
		  JTextArea textBlock = new JTextArea(rows, columns);
		  textBlock.setText("");
		  textBlock.setBorder(BorderFactory.createLineBorder(Color.black));
		  textBlock.setLineWrap(true);
		  textBlock.setWrapStyleWord(true);
		  JScrollPane scrollPane = new JScrollPane(textBlock);
		  scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
		  textBlock.setEditable(true);
		  p.add(scrollPane);
		  JPanel buttons = new JPanel();
		  p.add(buttons);
		  addButton(buttons, "OK");
		  addButton(buttons, "Cancel");
		  setVisible(true);
		  validate();
		  while (!buttonPressed)
			  Thread.sleep(1000);
		  return (okay ? textBlock.getText() : "");
    	}

Here is the code that does the popup, and tries to resize the object:

    public class PopupWindow extends JFrame
    {
    	public final static long serialVersionUID = 1;
    	
    	public PopupWindow(Applet whatToPop)
    	{
    		add(whatToPop);
    		// Set the size of the popup window.  We should probably be a bit more 
    		// clever and figure out what size the Applet window is, and set the 
    		// size accordingly.
    		Dimension d = whatToPop.getPreferredSize();
    		System.err.println("d=" + d.toString());
    		setSize(d);
    	    // Move the window so that it at 150 x 150 pixels from the upper left.
    		// We might want to get creative and center it on the screen.
    	    this.setLocation(150, 150);
    	}
    }

Unfortunately, no method associated with the Applet seems to return the size of just the stuff that I have added. If this were a JFrame, I could use pack(), but Applet does not seem to spport this.

[Rob Camick]

Use a JApplet, not Applet.

If you build your JApplet properly by using layout managers then it should have a preferred size since it uses a content pane the same as JFrame, JDialog and JWindow.

[Clayton Cramer]

Rob Camick wrote:Use a JApplet, not Applet.

If you build your JApplet properly by using layout managers then it should have a preferred size since it uses a content pane the same as JFrame, JDialog and JWindow.

Thanks, not sure why I was using Applet instead of JApplet. I am using the BoxLayout, but the getPreferredSize method returns something very tiny--just enough room for the Java icon, the icon, maximize, and close buttons. I can enlarge it, but perhaps getPreferredSize isn't what I need? Or does BoxLayout not set these to the minimum sizes of all the components added to it?

[Rob Camick]

Post your SSCCE that demonstrates the problem.

[Paul Clapham]

No, you need a layout in which the components are all materialized. In other words, displayed on the screen. I believe I already suggested that. Why don't you do it?

[Darryl Burke]

Clayton Cramer wrote:I am using the BoxLayout, but the getPreferredSize method returns something very tiny--just enough room for the Java icon, the icon, maximize, and close buttons.

Are you sure you're talking about an Applet/JApplet? What Java icon, the icon, maximize, and close buttons?

[Darryl Burke]

Paul Clapham wrote:No, you need a layout in which the components are all materialized. In other words, displayed on the screen.

Unless I've misunderstood you, this isn't needed. Example:

import javax.swing.*;

public class PreferredSizeTest {

  public static void main(String[] args) throws Exception {
    SwingUtilities.invokeLater(new Runnable() {

      @Override
      public void run() {
        new PreferredSizeTest().makeUI();
      }
    });
  }

  public void makeUI() {
    JPanel panel = new JPanel();
    panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
    panel.add(new JLabel("Label"));
    panel.add(new JButton("Button"));
    System.out.println(panel.getPreferredSize());
  }
}

// prints:
// java.awt.Dimension[width=102,height=26]

[Clayton Cramer]

Rob Camick wrote:Post your SSCCE that demonstrates the problem.

import javax.swing.*;
import javax.swing.text.BadLocationException;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

/**
 * This applet provides support for freeform text field inputs that can be done entirely on the 
 * GUI side.  There are currently two methods that you can call here from std_lib.js: inputTextBox, 
 * and editableTextBox.  The former is for when you want the user to enter an input string; the 
 * latter is for when you have a block of text that you want the user to be able to edit.  For both, 
 * the OK and Cancel buttons control whether the string is returned to the caller or an empty string.
 * @author ccramer
 *
 */
public class textboxApplet extends JApplet implements ActionListener {
	private static final long serialVersionUID = 1;
	boolean buttonPressed = false;
	boolean okay = false;

	/**
	 * Constructor of the applet.
	 *
	 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
	 * returns true.
	 */
	public textboxApplet() {
		super();
	}

	/**
	 * Called by the browser or applet viewer to inform
	 * this applet that it is being reclaimed and that it should destroy
	 * any resources that it has allocated. The <code>stop</code> method
	 * will always be called before <code>destroy</code>. <p>
	 *
	 * A subclass of <code>Applet</code> should override this method if
	 * it has any operation that it wants to perform before it is
	 * destroyed. For example, an applet with threads would use the
	 * <code>init</code> method to create the threads and the
	 * <code>destroy</code> method to kill them. <p>
	 */
	public void destroy() {
		System.err.println("destroy entered");
		buttonPressed = false;
		okay = false;
	}

	/**
	 * Returns information about this applet. An applet should override
	 * this method to return a <code>String</code> containing information
	 * about the author, version, and copyright of the applet. <p>
	 *
	 * @return  a string containing information about the author, version, and
	 * copyright of the applet.
	 */
	public String getAppletInfo() {
		return "This is my default applet created by Eclipse";
	}
	
	/**
	 * Called by the browser or applet viewer to inform
	 * this applet that it has been loaded into the system. It is always
	 * called before the first time that the <code>start</code> method is
	 * called. <p>
	 *
	 * A subclass of <code>Applet</code> should override this method if
	 * it has initialization to perform. For example, an applet with
	 * threads would use the <code>init</code> method to create the
	 * threads and the <code>destroy</code> method to kill them. <p>
	 */
	public void init() {
		System.err.println("entering init");
		buttonPressed = false;
		try
		{
			SwingUtilities.invokeAndWait(new Runnable() 
			{
				public void run()
				{
					//add(new JLabel("hello CIS"));
				}
			});
		}
		catch (Exception e)
		{
			System.err.println("textBoxGUI didn't complete successfully");
		}
	}
	
	/**
	 * Called by the browser or applet viewer to inform
	 * this applet that it should start its execution. It is called after
	 * the <code>init</code> method and each time the applet is revisited
	 * in a Web page. <p>
	 *
	 * A subclass of <code>Applet</code> should override this method if
	 * it has any operation that it wants to perform each time the Web
	 * page containing it is visited. For example, an applet with
	 * animation might want to use the <code>start</code> method to
	 * resume animation, and the <code>stop</code> method to suspend the
	 * animation. <p>
	 */
	public void start() {
		}
	
	/**
	 * Replaces the Javascript prompt function.  It displays text in a text box, OK and Cancel buttons, 
	 * and returns a String if the user hits OK.  
	 * @param msg: 	the prompt to the user
	 * @return:		String
	 * @throws InterruptedException 
	 * @throws BadLocationException 
	 */
	  public String editableTextBox(String prompt, String defaultText, int rows, int columns) throws InterruptedException, BadLocationException {
		  PopupWindow popup = new PopupWindow(this);
		  popup.setVisible(true);
		  setLayout(new FlowLayout());
		  JPanel p = new JPanel();
		  p.setLayout(new BoxLayout(p, BoxLayout.PAGE_AXIS));
		  add(p);
		  JLabel promptMsg = new JLabel(prompt);
		  p.add(promptMsg);
		  JTextArea textBlock = new JTextArea(rows, columns);
		  textBlock.setText(defaultText);
		  textBlock.setBorder(BorderFactory.createLineBorder(Color.black));
		  textBlock.setLineWrap(true);
		  textBlock.setWrapStyleWord(true);
		  JScrollPane scrollPane = new JScrollPane(textBlock);
		  scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
		  textBlock.setEditable(true);
		  p.add(scrollPane);
		  JPanel buttons = new JPanel();
		  p.add(buttons);
		  addButton(buttons, "OK");
		  addButton(buttons, "Cancel");
		  setVisible(true);
		  validate();
		  while (!buttonPressed)
			  Thread.sleep(50);
		  return (okay ? textBlock.getText() : "");
    	}

	/**
	 * Replaces the Javascript prompt function.  It puts up an empty text box, OK and Cancel buttons, 
	 * and returns a String if the user hits OK.  
	 * @param msg: 	the prompt to the user
	 * @return:		String
	 * @throws InterruptedException 
	 * @throws BadLocationException 
	 */
	  public String inputTextBox(String prompt, int rows, int columns) throws InterruptedException, BadLocationException {
		  PopupWindow popup = new PopupWindow(this);
		  popup.setVisible(true);
		  JPanel p = new JPanel();
		  p.setLayout(new BoxLayout(p, BoxLayout.PAGE_AXIS));
		  add(p);
		  JLabel promptMsg = new JLabel(prompt);
		  p.add(promptMsg);
		  JTextArea textBlock = new JTextArea(rows, columns);
		  textBlock.setText("");
		  textBlock.setBorder(BorderFactory.createLineBorder(Color.black));
		  textBlock.setLineWrap(true);
		  textBlock.setWrapStyleWord(true);
		  JScrollPane scrollPane = new JScrollPane(textBlock);
		  scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
		  textBlock.setEditable(true);
		  p.add(scrollPane);
		  JPanel buttons = new JPanel();
		  p.add(buttons);
		  addButton(buttons, "OK");
		  addButton(buttons, "Cancel");
		  setVisible(true);
		  validate();
		  while (!buttonPressed)
			  Thread.sleep(50);
		  return (okay ? textBlock.getText() : "");
    	}

	  private void addButton(Container c, String s)
	  {
		  JButton b = new JButton(s);
		  c.add(b);
		  b.addActionListener(this);
	  }
	  
	/**
	 * Called by the browser or applet viewer to inform
	 * this applet that it should stop its execution. It is called when
	 * the Web page that contains this applet has been replaced by
	 * another page, and also just before the applet is to be destroyed. <p>
	 *
	 * A subclass of <code>Applet</code> should override this method if
	 * it has any operation that it wants to perform each time the Web
	 * page containing it is no longer visible. For example, an applet
	 * with animation might want to use the <code>start</code> method to
	 * resume animation, and the <code>stop</code> method to suspend the
	 * animation. <p>
	 */
	public void stop() {
		buttonPressed = false;
		okay = false;
	}

    public void actionPerformed(ActionEvent e) {
		String s = e.getActionCommand();
		buttonPressed = true;
		okay = s.equals("OK");
	}
    
    /**
     * Used for creating a popup window so this is obvious to the user.
     * @author ccramer
     *
     */
    public class PopupWindow extends JFrame 
    {
    	public final static long serialVersionUID = 1;
    	
    	public PopupWindow(JApplet whatToPop)
    	{
    		add(whatToPop);
    		setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
    		// Set the size of the popup window.  We should probably be a bit more 
    		// clever and figure out what size the Applet window is, and set the 
    		// size accordingly.
    		Dimension d = whatToPop.getPreferredSize();
    		System.err.println("d=" + d.toString());
    		setSize(640, 480);
    	    // Move the window so that it at 150 x 150 pixels from the upper left.
    		// We might want to get creative and center it on the screen.
    	    this.setLocation(150, 150);
    	}
    }
}

When I execute it, I get

d=java.awt.Dimension[width=1,height=1]

on the console, even though the various components are clearly much larger.

[Clayton Cramer]

Darryl Burke wrote:

Clayton Cramer wrote:I am using the BoxLayout, but the getPreferredSize method returns something very tiny--just enough room for the Java icon, the icon, maximize, and close buttons.

Are you sure you're talking about an Applet/JApplet? What Java icon, the icon, maximize, and close buttons?

Yes, to make it stand out (since it is a modal dialog for the application), I put it inside a JFrame, using this class:

    /**
     * Used for creating a popup window so this is obvious to the user.
     * @author ccramer
     *
     */
    public class PopupWindow extends JFrame 
    {
    	public final static long serialVersionUID = 1;
    	
    	public PopupWindow(JApplet whatToPop)
    	{
    		add(whatToPop);
    		setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
    		// Set the size of the popup window.  We should probably be a bit more 
    		// clever and figure out what size the Applet window is, and set the 
    		// size accordingly.
    		Dimension d = whatToPop.getPreferredSize();
    		System.err.println("d=" + d.toString());
    		setSize(640, 480);
    	    // Move the window so that it at 150 x 150 pixels from the upper left.
    		// We might want to get creative and center it on the screen.
    	    this.setLocation(150, 150);
    	}
    }

[Clayton Cramer]

Paul Clapham wrote:No, you need a layout in which the components are all materialized. In other words, displayed on the screen. I believe I already suggested that. Why don't you do it?

I did. And getPreferredSize() still returns 1, 1.

[Rob Camick]

I have no idea what you are doing. That is not an applet. I see a few methods:

a) inputTextBox(...);
b) editableTextBox(...);

Those methods are never invoked from within the applet.

When you execute the applet nothing happens.

If you want to display a frame or dialog from an applet then create a frame or dialog and display it there is no need to "add an Applet" to the frame or dialog.

[Clayton Cramer]

Rob Camick wrote:I have no idea what you are doing. That is not an applet. I see a few methods:

a) inputTextBox(...);
b) editableTextBox(...);

Those methods are never invoked from within the applet.

When you execute the applet nothing happens.

If you want to display a frame or dialog from an applet then create a frame or dialog and display it there is no need to "add an Applet" to the frame or dialog.

How unfortunate. It works great! From a JSP:

	document.write('<applet codebase="' + path + '" code="textboxApplet.class" archive="textboxApplet.jar" name="textboxApplet" width="0" height="0"></applet>');

and then I call a Javascript function:

function inputTextBox(prompt, rows, columns)
{
    var reply = document.applets["textboxApplet"].inputTextBox(prompt, rows, columns);
    return(reply);
}

This executes the inputTextBox method in the applet, bringing up a display. I admit that this is a somewhat unusual form of an applet, but it is one, and it works.

[Rob Camick]

I admit that this is a somewhat unusual form of an applet...

And based on all previous comments in your original question how are we supposed to know what you are doing?

Three people wasted time attempting to answer the question assuming your where talking about a "normal applet". Even when you where asked to post a SSCCE you still didn't post code so that we could actually invoke the applet.

You still haven't posted code we can actually use to test the applet. I don't have any more time to spend. Good luck with the answer.