resizing animated GIF while keeping it's animation using java

Question

i am using Graphics2D in java to resize images, it works perfect with jpg,png and other formats. my problem is the animated GIF images, after re-sizing the animation is gone

Answer 1

I found two sources which when combined can be used to resize the image while keeping the animation.

On this question ( Convert each animated GIF frame to a separate BufferedImage ) look for the answer by Alex Orzechowski. His code takes a gif file and converts it to an array of ImageFrames (which is a class he made which wraps a BufferedImage). Then look at this code which converts a sequence of BufferedImages to a gif file ( http://elliot.kroo.net/software/java/GifSequenceWriter/ ).

As you could probably guess, all you need to do is upload the gif, use Alex's code to convert it to an array of ImageFiles/BufferedImages, use your Graphics2D code to resize each frame (you'll need to add a setImage method to Alex's ImageFrame class), then use Elliot's code to convert the array to a gif! Here is what mine looks like:

public static void main( String[] args )
{
  try {
     File imageFile = new File( "InputFile" );
     FileInputStream fiStream = new FileInputStream( imageFile );

     ImageFrame[] frames = readGif( fiStream );
     for( int i = 0; i < frames.length; i++ ){
        //code to resize the image
        BufferedImage image = ImageUtilities.resizeImage( frames[ i ].getImage(), newWidth, newHeight);
        frames[ i ].setImage( image );
   }

     ImageOutputStream output =
       new FileImageOutputStream( new File( "OutputFile" ) );

     GifSequenceWriter writer =
       new GifSequenceWriter( output, frames[0].getImage().getType(), frames[0].getDelay(), true );

     writer.writeToSequence( frames[0].getImage() );
     for ( int i = 1; i < frames.length; i++ ) {
        BufferedImage nextImage = frames[i].getImage();
        writer.writeToSequence( nextImage );
     }

     writer.close();
     output.close();
  }
  catch ( FileNotFoundException e ) {
     System.out.println( "File not found" );
  }
  catch ( IOException e ) {
     System.out.println( "IO Exception" );
  }
}

This code, however, does not account for gif images with different amount of time elapsing between frames.