testencoder.java

PngEncoder - convert a Java Image to PNG PngEncoderB - convert a Java BufferedImage to PNG

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import java.io.*;
import com.keypoint.*;

/**
 * TestEncoder creates a PNG file that shows an analog clock
 * displaying the current time of day, optionally with an
 * alpha channel, and with the specified filter.
 *
 * The file name is in the format:
 * 
 *     clockHHMM_fNC
 *     alphaclockDHHMM_fNC
 *
 * HH = hours (24-hour clock), MM = minutes,
 *
 * N = filter level (0, 1, or 2)
 * C = compression level (0 to 9)
 *
 * "alpha" is prefixed to the name if alpha encoding
 * was used.
 *
 * This test program was written in a burning hurry, so
 * it is not a model of efficient, or even good, code.
 * Comments and bug fixes should be directed to:
 *
 *   [e-mail]
 *
 * @author J. David Eisenberg
 * @version 1.3, 6 April 2000
 */
public class TestEncoder extends Frame
{
    String          message;
    String          timeStr;
    Image           clockImage = null;
    int             hour, minute;
    boolean         encodeAlpha;
    int             filter;
    int             compressionLevel;
    int             pixelDepth;
    String          filename;
    boolean         fileSaved = false;

    public TestEncoder(String s)
    {
        super(s);
        setSize(200,200);
    }
    
    public void drawClockImage(int hour, int minute)
    {
        // variables used for drawing hands of clock
        Graphics g;
        Font smallFont = new Font("Helvetica", Font.PLAIN, 9 );
        FontMetrics fm;

        int x0, y0, x1, y1;
        double angle;
        
        g = clockImage.getGraphics();
        g.setFont( smallFont );
        fm = g.getFontMetrics();

        // draw the clock face; yellow for AM, blue for PM
        if (hour < 12)
        {
            g.setColor( new Color( 255, 255, 192 ) );
        }
        else
        {
            g.setColor( new Color( 192, 192, 255) );
        }
        g.fillOval(10, 10, 80, 80);
        g.setColor( Color.black );
        g.drawOval(10, 10, 80, 80);
        g.drawOval( 48, 48, 4, 4);
        
        /* draw the 12 / 3 / 6/ 9 numerals */
        g.setFont( smallFont );
        g.drawString( "12", 50-fm.stringWidth("12")/2, 11+fm.getAscent() );
        g.drawString( "3", 88-fm.stringWidth("3"), 50+fm.getAscent()/2 );
        g.drawString( "6", 50-fm.stringWidth("6")/2, 88 );
        g.drawString( "9", 12, 50+fm.getAscent()/2 );
        
        x0 = 50;
        y0 = 50;

        /* draw the hour hand */
        hour %= 12;
        angle = -(hour * 30 + minute/2) + 90;
        angle = angle * (Math.PI / 180.0);

        x1 = (int) (x0 + 28 * (Math.cos( angle ) ));
        y1 = (int) (y0 - 28 * (Math.sin( angle ) ));
        g.drawLine( x0, y0, x1, y1 );
        
        /* and the minute hand */
        angle = -(minute * 6) + 90;
        angle = angle * Math.PI / 180.0;
        x1 = (int) (x0 + 35 * (Math.cos( angle ) ));
        y1 = (int) (y0 - 35 * (Math.sin( angle ) )); 
        g.drawLine( x0, y0, x1, y1 );
    }

    public void addAlphaToImage()
    {
        int width=100;
        int height=100;
        int alphaMask = 0;
        int[] pixels = new int[width * height];

        PixelGrabber pg = new PixelGrabber(clockImage, 0, 0,
            width, height, pixels, 0, width);
        try {
            pg.grabPixels();
        }
        catch (InterruptedException e) {
            System.err.println("interrupted waiting for pixels!");
            return;
        }
        if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
            System.err.println("image fetch aborted or errored");
            return;
        }
        for (int i=0; i<width*height; i++)
        {
            if ((i % width) == 0)
            {
                alphaMask = (alphaMask >> 24) & 0xff;
                alphaMask += 2;
                if (alphaMask > 255)
                {
                    alphaMask = 255;
                }
                alphaMask = (alphaMask << 24) & 0xff000000;
            }
            pixels[i] = (pixels[i] & 0xffffff) | alphaMask;
        }
        clockImage= createImage(new MemoryImageSource(width, height, pixels,
            0, width));
    }

    public void paint( Graphics g )
    {
        if (clockImage == null)
        {
            clockImage = createImage( 100, 100 );
        }
        if (clockImage != null)
        {
            if (!fileSaved)
            {
                drawClockImage(hour, minute);
                if (encodeAlpha) { addAlphaToImage(); }
                saveClockImage();
                fileSaved = true;
            }
            g.drawImage( clockImage, 50, 20, null );
        }
        if (message != null)
        {
            g.drawString( message, 10, 140 );
        }
    }

    protected static void usage()
    {
        System.out.print("Usage: TestEncoder -alpha -filter n -compress c");
        System.out.println("-alpha means to use alpha encoding (default none)");
        System.out.println("n is filter number 0=none (default), 1=sub, 2=up");
        System.out.println("c is compression factor (0-9); 1 default");
        System.exit(0);
    }

    public static void main(String[] args)
    {
        int i;

        TestEncoder te = new TestEncoder("Test PNG Alpha/Filter Encoder");
        i = 0;
        te.encodeAlpha = false;
        te.filter = 0;
        te.pixelDepth = 24;
        te.compressionLevel = 1;
        while (i < args.length)
        {
            if (args[i].equals("-alpha"))
            {
                te.encodeAlpha = true;
                i++;
            }
            else if (args[i].equals("-filter"))
            {
                if (i != args.length-1)
                {
                    try
                    {
                        te.filter = Integer.parseInt(args[i+1]);
                    }
                    catch (Exception e)
                    {
                        usage();
                        break;
                    }
                }
                i += 2;
            }
            else if (args[i].equals("-compress"))
            {
                if (i != args.length-1)
                {
                    try
                    {
                        te.compressionLevel = Integer.parseInt(args[i+1]);
                    }
                    catch (Exception e)
                    {
                        usage();
                        break;
                    }
                }
                i += 2;
            }
            else
            {
                usage();
                break;
            }
        }
        if (te.pixelDepth == 8)
        {
            te.encodeAlpha = false;
        }
        te.doYourThing();
    }
    
    public void doYourThing()
    {
        Image   img;

        // The resultant PNG data will go into this array...
        
        Calendar cal = Calendar.getInstance();  

        hour = cal.get(Calendar.HOUR);
        if (cal.get(Calendar.AM_PM) == 1)
        {
            hour += 12;
        }
        hour %= 24;
        minute = cal.get(Calendar.MINUTE);

        /*
         * format the time to a string of the form
         *    hhmm
         * for use in the filename
         */
        
        timeStr = Integer.toString( minute );
        if (minute < 10)
        {
            timeStr = "0" + timeStr;
        }
        timeStr = Integer.toString( hour ) + timeStr;
        if (hour < 10)
        {
            timeStr = "0" + timeStr;
        }

        filename = (encodeAlpha) ? "alphaclock" : "clock";
        filename += timeStr + "_f" + filter + 
           compressionLevel + ".png";

        message =  "File: " + filename;


        WindowListener l = new WindowAdapter() {
                        public void windowClosing(WindowEvent e) {
                        System.exit(0);
                       }
        };
        addWindowListener(l);
        show();
    }
    
    public void saveClockImage()
    {
        byte[] pngbytes;
        PngEncoder png =  new PngEncoder( clockImage,
            (encodeAlpha) ? PngEncoder.ENCODE_ALPHA : PngEncoder.NO_ALPHA,
            filter, compressionLevel);

        try
        {
            FileOutputStream outfile = new FileOutputStream( filename );
            pngbytes = png.pngEncode();
            if (pngbytes == null)
            {
                System.out.println("Null image");
            }
            else
            {
                outfile.write( pngbytes );
            }
            outfile.flush();
            outfile.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }       

}