Question

I am currently using javax.imageio.ImageIO to write a PNG file. I would like to include a tEXt chunk (and indeed any of the chunks listed here), but can see no means of doing so.

By the looks of com.sun.imageio.plugins.png.PNGMetadata it should be possible.

I should be most grateful for any clues or answers.

M.

Answer 1

The solution I struck upon after some decompilation, goes as follows …

RenderedImage image = getMyImage();          Iterator<ImageWriter> iterator = ImageIO.getImageWritersBySuffix( 'png' );  if(!iterator.hasNext()) throw new Error( 'No image writer for PNG' );  ImageWriter imagewriter = iterator.next(); ByteArrayOutputStream bytes = new ByteArrayOutputStream(); imagewriter.setOutput( ImageIO.createImageOutputStream( bytes ) );   // Create & populate metadata PNGMetadata metadata = new PNGMetadata(); // see http://www.w3.org/TR/PNG-Chunks.html#C.tEXt for standardized keywords metadata.tEXt_keyword.add( 'Title' ); metadata.tEXt_text.add( 'Mandelbrot' ); metadata.tEXt_keyword.add( 'Comment' ); metadata.tEXt_text.add( '...' ); metadata.tEXt_keyword.add( 'MandelbrotCoords' ); // custom keyword metadata.tEXt_text.add( fractal.getCoords().toString() );             // Render the PNG to memory IIOImage iioImage = new IIOImage( image, null, null ); iioImage.setMetadata( metadata ); // Attach the metadata imagewriter.write( null, iioImage, null );