Re: What are the options for serializing a BufferedImage?

From:

"Matt Humphrey" <matth@iviz.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 11 Jun 2009 07:28:32 -0400

Message-ID:

<o7ednVBPod7_d63X4p2dnAA@giganews.com>

"Qu0ll" <Qu0llSixFour@gmail.com> wrote in message
news:4a3096a5$0$32375$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Qu0ll" <Qu0llSixFour@gmail.com> wrote in message
news:4a309500$0$32382$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Matt Humphrey" <matth@iviz.com> wrote in message
news:rNqdnXm47qnIX7LX4p2dnAA@giganews.com...

"Matt Humphrey" <matth@iviz.com> wrote in message
news:7IqdnUbpuNDkJbLX4p2dnAA@giganews.com...

There are image encoders for PNG, GIF, JPG, etc such as
http://www.acme.com/java/software/Acme.JPM.Encoders.GifEncoder.html
and I think some are actually built into Java now. These have
streaming methods which you can then use to create a byte array or some
other format, or to stream directly out of a servlet (see below). One
advantage of using a standard encoder is that you can just display the
image if you want to, without having to reinterpret it.

Here's a reference to some sample code. In a servlet they create a
BufferedImage, draw stuff to it and then direct it to the servlet output
via a JPEG encoder. Note the servlet response content type is set to
image/jpg.

http://javahowto.blogspot.com/2008/04/sample-servlet-that-dynamically-creates.html

Thank you Matt - that looks like the way to go and is probably what I
will use.

The only problem is that there appear to be no codecs for PNG or GIF - is
that correct? How would I handle those file types if required?

I'm using Java 1.6_04 under Eclipse 3.3.1 and it reports the following
built-in codecs:
jpg, BMP, bmp, JPG, jpeg, wbmp, png, JPEG, PNG, WBMP, GIF, gif

Java Image / IO docs are here
http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/imageio_guideTOC.fm.html

Try this code to see what codecs are available on your system:

  public static final void main (String [] args) {
    try {
      String [] formatNames = ImageIO.getWriterFormatNames();
      if (formatNames.length == 0) {
        System.out.println("No output formats available.");
        return;
      }
      System.out.print ("Available formats: ");

      for (int i = 0; i < formatNames.length; ++i) {
        if (i > 0) System.out.print (", ");
        System.out.print (formatNames[i]);
      }
      System.out.println ("");

      BufferedImage image = new BufferedImage(300, 300,
          BufferedImage.TYPE_BYTE_INDEXED);
      Graphics graphics = image.getGraphics();
      graphics.setColor(Color.blue);
      graphics.fillRect(0, 0, image.getWidth(), image.getHeight());
      graphics.setColor(Color.green);
      graphics.fillRect(20, 60, 120, 170);

      Iterator<ImageWriter> iws = ImageIO.getImageWritersByFormatName
("png");
      if (! iws.hasNext()) {
        System.out.println ("No available image writer");
      }

      ImageWriter iw = iws.next();

      FileOutputStream fos = new FileOutputStream ("image1.png");
      MemoryCacheImageOutputStream mos = new MemoryCacheImageOutputStream
(fos);
      iw.setOutput(mos);
      iw.write(image);
      mos.close ();

    } catch (Exception ex) {
      ex.printStackTrace ();
    }
    System.out.println ("Done");
  }

There are plenty of 3rd party encoders--there's probably a free one out
there GIYF.

Matt Humphrey http://www.iviz.com/