CD Ware Multimedia 1999 February/CDW0299.iso/Demos/Cafe/PDESAMPL.BIN/JmScale.java

Java Source | 1997-09-06 | 8.7 KB | 332 lines

/*
 *  JmScale.java
 *
 *  JmScale provides a slider bar with numeric output display on
 *  top of the thumb and a label below it.
 */

package samples.conversion;

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.util.Vector;

public class JmScale extends Canvas
{
    private int width = 120;
    private int height = 48;

    private final int BUFFER = 2;
    private final int THUMB_SIZE = 10;

    private final int TEXT_HEIGHT = 16;
    private final int TEXT_BUFFER = 3;

    private int minWidth;
    private int minHeight;

    private int barHeight;
    private int titlePosX = 0;
    private int titlePosY = 0;

    private int min, max, value, point;
    private int minPoint, maxPoint;
    private int decPt;

    private Color backgroundColor;
    private Color thumbColor;
    private Color barColor;
    private Color slashColor;
    private Color textColor;
    private Font font;
    private String title;

    private boolean holdThumb = false;
    private Image image;
    private Graphics imageGC;
    private Vector listeners = new Vector();

    public JmScale( String s, int min, int max, int x, int dec, int w, int h )
    {
        title = new String( s );
        width = w;
        height = h;
        font = new Font( "TimesRoman", Font.PLAIN, 12 );
        backgroundColor = Color.lightGray;
        thumbColor = Color.lightGray;
        barColor = Color.lightGray;
        slashColor = Color.black;
        textColor = Color.black;
        this.min = min;
        this.max = max;
        decPt = dec;
        setValue( x );
        setSize( width, height );
        addMouseListener( new MouseAdapter() );
        addMouseMotionListener( new MouseAdapter() );
    }

    public void addNotify()
    {
        super.addNotify();
        image = createImage( width, height );
        imageGC = image.getGraphics();
    }

    public void setValue( int num )
    {
       /*
        *  This method determines the value of point.
        *  point is where the thumb slider is drawn.
        */

        value = num;

        if( value < min )
            value = min;
        else if( value > max )
            value = max;

        if( value != min )
            point = (int) Math.round( ( (double)( value - min ) /
                                        (double)( max - min )
                                      ) * (double)( maxPoint - minPoint )
                                    ) + minPoint;
        else
            point = minPoint;
        repaint();
    }

    public int getValue()
    {
        return value;
    }

    public void paint( Graphics gc )
    {
       /*
        *  Clear the whole slider.
        */

        imageGC.setColor( backgroundColor );
        imageGC.fillRect( 0, 0, width, height );

       /*
        *  Draw the bar.
        */

        imageGC.setColor( barColor );
        imageGC.fill3DRect( 0, TEXT_HEIGHT, width, barHeight, false );

       /*
        *  Draw the thumb.
        */

        imageGC.setColor( thumbColor );
        imageGC.fill3DRect( point - THUMB_SIZE, TEXT_HEIGHT + BUFFER,
                     THUMB_SIZE * 2 + 1, barHeight - 2 * BUFFER,
                     true );

        imageGC.setColor( slashColor );
        imageGC.drawLine( point, TEXT_HEIGHT + BUFFER,
                           point, TEXT_HEIGHT + barHeight - 2 * BUFFER );

       /*
        *  Draw the value.  Check for decimal places.
        */

        imageGC.setColor( textColor );
        imageGC.setFont( font );

        String str;
        if( decPt > 0 )
        {
            double fpvalue = (double) value / Math.pow( 10.0, (double) decPt );
            str = String.valueOf( fpvalue );
            if( str.indexOf( '.' ) == -1 )
                str += ".0";
        }
        else
            str = String.valueOf( value );

        imageGC.drawString( str,
            point - (int)( getFontMetrics( font ).stringWidth( str ) / 2 ),
            TEXT_HEIGHT - TEXT_BUFFER );

       /*
        *  Draw the title.
        */

        imageGC.drawString( title, titlePosX, titlePosY );

        gc.drawImage( image, 0, 0, this );
    }

    public void update( Graphics g )
    {
        paint( g );
    }

    public void setSize( int w, int h )
    {
       /*
        *  This method resizes the whole component.
        *  It also computes for the variables needed
        *  for calculating the display.
        */

        width = w;
        height = h;
        super.setSize( width, height );

        minWidth = 2 * (THUMB_SIZE + BUFFER) + 1;

        minHeight = 2 * (BUFFER + 1) + 2 * TEXT_HEIGHT;
        barHeight = height - 2 * TEXT_HEIGHT;

        titlePosX = ( width / 2 ) -
            (int)( getFontMetrics( font ).stringWidth( title ) / 2 );
        titlePosY = TEXT_HEIGHT + barHeight - TEXT_BUFFER +
                      getFontMetrics( font ).getHeight();

        if( width < minWidth )
            width = minWidth;
        if( height < minHeight )
            height = minHeight;

        minPoint = THUMB_SIZE + BUFFER;
        maxPoint = width - THUMB_SIZE - BUFFER - 1;

        setValue( value );
    }

    public synchronized void addActionListener( ActionListener l )
    {
        listeners.addElement( l );
    }

    public synchronized void removeActionListener( ActionListener l )
    {
        listeners.removeElement( l );
    }

    public void postAction()
    {
       /*
        *  This method gets called when an event occurs
        *  that this object is interested in and will
        *  propagate the event to all of its listeners.
        */

        Vector targets;
        synchronized( this )
        {
            targets = (Vector) listeners.clone();
        }

        ActionEvent e = new ActionEvent( this, 0, title );

        for( int i = 0; i < targets.size(); i++ )
        {
            ActionListener target = (ActionListener) targets.elementAt( i );
            target.actionPerformed( e );
        }
    }

    class MouseAdapter implements MouseListener, MouseMotionListener
    {
       /*
        *  inner class MouseAdapter handles the mouse events
        *  for class JmScale.
        */

        Cursor prevCursor = getCursor();
        Cursor handCursor = new Cursor( Cursor.HAND_CURSOR );

        public void mouseClicked( MouseEvent e ){}

        public void mouseEntered( MouseEvent e )
        {
            prevCursor = getCursor();
            setCursor( handCursor );
        }

        public void mouseExited( MouseEvent e )
        {
            setCursor( prevCursor );
        }

        public void mousePressed( MouseEvent e )
        {
            int x = e.getX();
            int y = e.getY();

            if( ( y >= TEXT_HEIGHT ) &&
                ( y <= barHeight + TEXT_HEIGHT ) &&
                ( x < ( point + THUMB_SIZE ) ) &&
                ( x > ( point - THUMB_SIZE ) ) )
                holdThumb = true;
        }

        public void mouseReleased( MouseEvent e )
        {
           /*
            *  Set the value on the mouse click.
            *  And call postEvent() to pass event out.
            */

            int x = e.getX();
            int y = e.getY();

            if( holdThumb )
            {
                setValue( value );
                postAction();
            }
            else if( ( y >= TEXT_HEIGHT ) && ( y <= barHeight + TEXT_HEIGHT ) )
            {
                if( x > point )
                    setValue( value + 1 );
                else if ( x < point )
                    setValue( value - 1 );
                postAction();
            }

            holdThumb = false;
        }

        public void mouseMoved( MouseEvent e ){}

        public void mouseDragged( MouseEvent e )
        {
           /*
            *  When thumb is being dragged,
            *  compute for value and repaint.
            */

            int x = e.getX();
            int y = e.getY();

            if( ( y >= TEXT_HEIGHT ) &&
                ( y <= barHeight + TEXT_HEIGHT ) )
            {
                double percent;
                point = Math.max( x, minPoint );
                point = Math.min( point, maxPoint );

                if( point != minPoint )
                    percent = (double)( point - minPoint ) /
                              (double)( maxPoint - minPoint );
                else
                    percent = 0;

                value = (int) Math.round( percent *
                               (double)( max - min ) ) +
                               min;
                repaint();
            }
        }
    }
}