Getting Bitmap from Canvas and converting it into image file format

[Nilesh Soni]

Hi all,
I am drawing some lines or any shapes in an applet. now i want to save that drawing or applet into an image like gif or jpeg. one funda is that we will click on one button on applet, it will contact a setvlet on the server and on the server i have to write some code.
I got reply from one of the javaranch member Tim Holloway as follows:
You'll need to convert the applet's canvas into a bitmap, convert the bitmap into JPEG or GIF format, then send the bitmap in a binary file transmission to the server. The server really can't do anything but catch the file - all the work has to be done on the client.
Can any one help me out in this regards.
------------------

[Nathan Pruett]

Someone posted this code a while back... it draws some text on a canvas and saves it as a JPEG image... it helped me understand what to do to generate an image file from an image...

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import com.sun.image.codec.jpeg.*;
public class Text2Image
{
    public static void main(String args[])
    {
        Frame myFrame = null;
        Canvas can = null;
        Graphics2D myGraphics = null;
        try
        {
            myFrame = new Frame();
            can = new Canvas();
            can.setSize( 400, 200 );
            myFrame.add( can );
            myFrame.setSize( 400, 200 );
            myFrame.setVisible( true );
            myFrame.addWindowListener( new WindowAdapter() {
                public void windowClosing( WindowEvent e )
                {
                    System.exit( 0 );
                }
            } );
            BufferedImage buffImage =
                    new BufferedImage(400, 200,
                    BufferedImage.TYPE_INT_RGB);
            BufferedOutputStream bos =
                    new BufferedOutputStream(
                    new FileOutputStream( "text.jpg" ) );
            myGraphics = buffImage.createGraphics();
            myGraphics.setFont(new Font("Serif", Font.ITALIC, 48));
            myGraphics.setColor(Color.red);
            myGraphics.drawString("Saidul Islam", 10, 50);
            //myGraphics.drawImage(offImage, 0, 0, myFrame);
            buffImage.createGraphics().drawImage(buffImage, 0, 0, myFrame);
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos);
            encoder.encode(buffImage);
 
            Toolkit tk = Toolkit.getDefaultToolkit();
            Image i = tk.getImage( "text.jpg" );
            MediaTracker mt = new MediaTracker( myFrame );
            mt.addImage( i, 0 );
            try
            {
                mt.waitForAll();
            }
            catch( InterruptedException x )
            {
                x.printStackTrace();
            }
 
            Graphics canGraphics = can.getGraphics();
            canGraphics.drawImage( i, 0, 0, myFrame );
            myFrame.repaint();
 
            System.out.println("gets here");
            bos.flush();
            System.out.println("flushed");
            bos.close();
            System.out.println("closed");
            buffImage.flush();
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            finally
            {
                System.out.println("final");
                if (myGraphics != null)
                {
                    myGraphics.dispose();
                    System.out.println("dispose");
                }
            }
            System.out.println("done!");
    } //end of main method
} //end of Text2Image class

It saves it as a JPEG because a JPEG encoder is shipped with the JDK by Sun... to save as a GIF file you'll either need to look at the Java Media Framework, or go with a 3rd party implementation...

-Nate