/* TextPanel class */import java.util.StringTokenizer;import java.awt.*;import java.io.*;import java.net.*;/** * Text panel to display the source code of the animation algorithm. * This class is initialized in the <code>TextFrame</code> class * construction during the main frame initialization. * Each line of the source code starting with <code>/*-</code> will be ignored. * The line after <code>/*-------</code> is considered as the first line of * text being displayed. * The line before <code>//-</code> is the last line of source code being * displayed. The text after this line will no longer be parsed. * See also <A href="AlgThread.html"><code>AlgThread</code></A> for special * symbol used in displaying source code in text panel. * @see TextFrame * @see AlgAnimFrame */public class TextPanel extends Panel {    String file_name;    String[] lines;    /**     * The number of lines of source code to be displayed on the text frame.     */    public int n_lines;    int highlight;    int width = 300;    int height = 400;    int delay = 400;    int max_lines = 1000;    Dimension offscreensize = null;    Image offscreen = null;    Graphics offGraphics = null;    static final int dx = 2;    Font font;    /**     * The number of pixels allocated for each line of text.     */    public int line_space = 14;    int font_size = 10;    /**     * This attribute is used to couple the text panel to a vertical scrollbar     * in the TextFrame. It indicates the first line of source code that     * will be displayed.     */    public int start;    static final String ignore_trigger = "/*-";    static final String start_sign = "/*-------";    static final String end_sign = "//-";    private StringBuffer trim(String s) {        int pos;        StringBuffer sb;        pos = s.indexOf(ignore_trigger);        if (pos >= 0) {            sb = new StringBuffer(s.substring(0,pos)); //sb.setLength(pos);        } else             sb = new StringBuffer( s );        return sb;    }                    private String expandtabs( StringBuffer sb ) {        int i, len;        len = sb.length();        i = 0;        while( i < len ) {            if ( sb.charAt( i ) == '\t' ) {	      for (int k = 0; k < 8; k++) {                sb.setCharAt(i,' ');                sb.insert(i,' ');                len++;	      }            }            i++;        }        return sb.toString();            }    private void SetFont( Graphics g ) {        FontMetrics fm;        this.setBackground( Color.white );        font = new Font( "Dialog", Font.PLAIN, font_size );        fm = g.getFontMetrics( font );        line_space = fm.getHeight() + 1;        g.setFont( font );    }    private int ReadSource( DataInputStream ds ) {        int cnt = 0;        StringBuffer sb;                        try {            while( true ) {                String s;                if ( (s = ds.readLine()) != null ) {                    if ( s.startsWith( start_sign ) ) {                        n_lines = 0;                        cnt = 0;                    } else if (s.trim().startsWith(ignore_trigger)) {                        continue;                    } else if (s.startsWith(end_sign)) {                        break;                    } else {                        sb = trim( s );                        /* Copy the buffer into a string */                        lines[cnt++] = expandtabs( sb );                    }                 } else                    break;            }        } catch( IOException e ) {}        return cnt;    }    /**     * Creates a text panel based on the source file specified in the String     * passed in as the parameter.     * @param fn Filename of the source code     */    public TextPanel( String fn ) {        FileInputStream instream;        file_name = fn;        File source = new File( file_name );                if ( source.exists() && source.isFile() ) {            try {                lines = new String[ max_lines ];                instream = new FileInputStream( source );            } catch( IOException e ) {}            /* Read the file */        } else            System.out.println("Cant access [" + file_name + "]");    }            /**     * Creates a text frame based on the URL specified by     * the parameter.     * @param sourceURL URL of the source code     * @see URL     */    public TextPanel( URL sourceURL) {        InputStream source = null;        StringBuffer sb;        n_lines = 0;	start = 0;        file_name = sourceURL.toString();	try {	    source = sourceURL.openStream();	} catch( IOException e ) {        }        if ( source != null ) {            lines = new String[ max_lines ];            /* Read the file */            DataInputStream ds = new DataInputStream( source );            n_lines = ReadSource( ds );        }                                 highlight = -1;            }    /**     * Highlight a certain line of the source code. The highlighted line     * is displayed in RED while the other normal lines are displayed     * in BLACK. The first line of the source has a line index of <b>0</b>.     * @param h The line to be highlighted     */    public void Highlight( int h ) {        highlight = h;        this.repaint();    }    /**     * Returns the initial dimension of the text panel. This method     * will be called by the layout manager during the corresponding     * frame initialization.     */    public Dimension getPreferredSize() {        int h = line_space * (n_lines + 1) - start * line_space;        return new Dimension( width, h );    }        /**     * Return the minimum allowed dimension of the text panel.     */    public Dimension getMinimumSize() {        int h = line_space * (n_lines + 1) - start * line_space;        return new Dimension( width, h );    }        /**     * This method is invoked when the <code>repaint()</code> method of the     * parent class is called. This method eliminates flashing during animation.     */    public void update(Graphics g) {        Dimension d = size();        if (d.width < 1 || d.height < 1)            return;        if ((offscreen == null) || (d.width != offscreensize.width) ||                (d.height != offscreensize.height)) {            offscreen = createImage(d.width, d.height);            offscreensize = d;            offGraphics = offscreen.getGraphics();        }        offGraphics.setColor(Color.white);        offGraphics.fillRect(0, 0, d.width, d.height);        paint(offGraphics);        g.drawImage(offscreen, 0, 0, null);    }        /**     * Set the first line to display.     * @param start First line to display     * @see TextPanel#start     */    public void setStart(int start) {	this.start = start;    }    /**     * This method print the source code starting from the first line specified     * by <code>setStart(int)</code> on the text panel.     * @param g Graphical context of the text panel.     */    public void paint( Graphics g ) {        int i, x, y;        SetFont( g );        x = dx; y = line_space;        g.setColor( Color.black );        for (i=start;i<n_lines;i++) {            if( i == highlight ) {                g.setColor( Color.red );            }            g.drawString( lines[i], x, y );            g.setColor( Color.black );            y += line_space;                        }        //g.drawString("EOF",x,y);    }}