/**
@author  Scott Marshall
@author  University of Glasgow, MSc IT Project 2001
@author  Building an OnLine Course in Computing Fundamentals

Multiple Choice Questions

*/

package ukacgla_HTMLMulti;

import ukacgla_HTMLMulti.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.border.*;


/**
Class includes hyperlink listener. This is not used in this implementation, but
future expansions may require it. 
*/
public class Viewer extends JPanel{

	//instance variables	
	private HTMLEditorKit edit;
	private JEditorPane html;
	private URL display;

	/**
	Editor pane constructed with a URL to display upon instantiation.
	The int size argument is used to set the size of the display area.
	*/
	public Viewer(URL display, int size){	
		this.display = display;
		html = new JTextPane();
		edit = new HTMLEditorKit();
		
		html.setEditorKit(edit);
		html.setEditable(false);
		html.addHyperlinkListener(new LinkClick());//not sure if use, but leave in anyway.


		JScrollPane jsp = new JScrollPane(html,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, 
										JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
		jsp.setPreferredSize(setDimension(size));
		jsp.setBorder(new BevelBorder(BevelBorder.LOWERED));
		displayPage(display);
		
		add("Center",jsp);
	}
		
	/** Blank editor pane constructed. No URL is displayed upon instantiation */
	public Viewer(int size){	
		html = new JTextPane();
		edit = new HTMLEditorKit();
		
		html.setEditorKit(edit);
		html.setEditable(false);
		html.addHyperlinkListener(new LinkClick());//not sure if use, but leave in anyway.


		JScrollPane jsp = new JScrollPane(html,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, 
										JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
		jsp.setPreferredSize(setDimension(size));
		jsp.setBorder(new BevelBorder(BevelBorder.LOWERED));
		add("Center",jsp);

	}
		

	/**
	Will display specified URL on the editor pane. Displays blank if no URL is specified.
	Warning - displaying text that has not been formatted as HTML causes
	CascadingStyleSheet related exceptions if the program is not restarted.
	The catch (IO Exception) is for developers - it should never be used as part of
	normal use.
	*/
	protected void displayPage(URL display){
		this.display = display;
		try	{
				html.setPage(display);
		}
		
		catch (IOException e) {
			html.setText("Error in displaying URL" + display);
		}
		html.revalidate();
		html.repaint();		

	}

	/**
	Strings must be formatted as HTML to avoid CascadingStyleSheet exceptions being
	thrown. Use the  TestUI mkHTMLString method before feeding in a string.
	*/
	protected void displayPage(String s){
		this.display = null;
		html.setText(s);
		html.revalidate();
		html.repaint();
	}


	/** Returns Dimension based on int supplied as argument. An int 1 will return a 
	Dimension of 350 x 100, an int 2 will return a Dimension of 350 x 200 */
	protected Dimension setDimension(int n)	{
	  Dimension d = new Dimension();
		if (n == 1)
			d.setSize(350,100);
		
		if (n==2)
			d.setSize(350,200);	
	
		return d;
	}


	//--------------------------HYPER LINK LISTENER FILE------------------------------------

	/**
	LinkClick is not used in this implementation. It is included for completeness, and 
	if a future expansion of the package requires it.
	*/
	protected class LinkClick implements  HyperlinkListener{
		public void hyperlinkUpdate(HyperlinkEvent e){
			if (e.getEventType()== HyperlinkEvent.EventType.ACTIVATED)	{
				try	{
					html.setPage(e.getURL());
				}
				
				catch(IOException x2){
					System.err.println(e.getURL());
				}

				html.repaint();
				html.revalidate();
			}
		}

	}//ends linkClick

}//ends class