Re: Why there's a little delay after I save JPGs using ImageWriter

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 19 May 2008 16:38:15 +0100

Message-ID:

<Pine.LNX.4.64.0805191634030.17002@urchin.earth.li>

On Mon, 19 May 2008, ZelluX wrote:

I want to save the image on a JPanel to a JPG file, here is my code

ImageWriter iw = ImageIO.getImageWritersByFormatName("jpg").next();
BufferedImage bi = new BufferedImage(panel.getWidth(),
panel.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
panel.paintComponent(g);
ImageOutputStream ios = ImageIO.createImageOutputStream(new
FileOutputStream(path));
iw.setOutput(ios);
iw.write(bi);
g.dispose();
iw.dispose();
ios.close();

After this snippet of code finished, I clicked the created .jpg file,
but it showed nothing. After several seconds, I clicked again, and
this time the image turned up.
Can I diminish such delay?

Your ImageOutputStream is writing to a FileOutputStream, which is in turn
writing to disk. My guess would be that the ImageOutputStream is not
flushing the FileOutputStream when you close() it, and so data is staying
in a buffer until the FileOutputStream gets garbage collected and its
finalizer runs. Try this:

OutputStream fout = new FileOutputStream(path) ; // keep a reference to the FileOutputStream
ImageOutputStream ios = ImageIO.createImageOutputStream(fout) ;
iw.setOutput(ios) ;
iw.write(bi) ;
g.dispose() ;
iw.dispose() ;
ios.close() ;
fout.close() ; // explicitly close the FileOutputStream

Alternatively, an ios.flush() might do the job.

Many thanks and sorry for my poor English

Your english is fine!

tom

--
It is better to create badly than to appreciate well. -- Gareth Jones