// 

//  GifSequenceWriter.java

//  

//  Created by Elliot Kroo on 2009-04-25.

//  (modified here)

//

import javax.imageio.*;

import javax.imageio.metadata.*;

import javax.imageio.stream.*;

import java.awt.image.*;

sclass GifSequenceWriter implements AutoCloseable {

  protected ImageWriter gifWriter;

  protected ImageWriteParam imageWriteParam;

  protected IIOMetadata imageMetaData;

  ImageOutputStream stream;

  /**

   * Creates a new GifSequenceWriter

   * 

   * @param outputStream the ImageOutputStream to be written to

   * @param imageType one of the imageTypes specified in BufferedImage

   * @param timeBetweenFramesMS the time between frames in miliseconds

   * @param loopContinuously wether the gif should loop repeatedly

   * @throws IIOException if no gif ImageWriters are found

   *

   * @author Elliot Kroo (elliot[at]kroo[dot]net)

   */

  public GifSequenceWriter(

      ImageOutputStream outputStream,

      int imageType,

      int timeBetweenFramesMS,

      boolean loopContinuously) throws IIOException, IOException {

    // my method to create a writer

    stream = outputStream;

    gifWriter = getWriter(); 

    imageWriteParam = gifWriter.getDefaultWriteParam();

    ImageTypeSpecifier imageTypeSpecifier =

      ImageTypeSpecifier.createFromBufferedImageType(imageType);

    imageMetaData =

      gifWriter.getDefaultImageMetadata(imageTypeSpecifier,

      imageWriteParam);

    String metaFormatName = imageMetaData.getNativeMetadataFormatName();

    IIOMetadataNode root = (IIOMetadataNode)

      imageMetaData.getAsTree(metaFormatName);

    IIOMetadataNode graphicsControlExtensionNode = getNode(

      root,

      "GraphicControlExtension");

    graphicsControlExtensionNode.setAttribute("disposalMethod", "none");

    graphicsControlExtensionNode.setAttribute("userInputFlag", "FALSE");

    graphicsControlExtensionNode.setAttribute(

      "transparentColorFlag",

      "FALSE");

    graphicsControlExtensionNode.setAttribute(

      "delayTime",

      Integer.toString(timeBetweenFramesMS / 10));

    graphicsControlExtensionNode.setAttribute(

      "transparentColorIndex",

      "0");

    IIOMetadataNode commentsNode = getNode(root, "CommentExtensions");

    commentsNode.setAttribute("CommentExtension", "Created by MAH");

    IIOMetadataNode appEntensionsNode = getNode(

      root,

      "ApplicationExtensions");

    IIOMetadataNode child = new IIOMetadataNode("ApplicationExtension");

    child.setAttribute("applicationID", "NETSCAPE");

    child.setAttribute("authenticationCode", "2.0");

    int loop = loopContinuously ? 0 : 1;

    child.setUserObject(new byte[]{ 0x1, (byte) (loop & 0xFF), (byte)

      ((loop >> 8) & 0xFF)});

    appEntensionsNode.appendChild(child);

    imageMetaData.setFromTree(metaFormatName, root);

    gifWriter.setOutput(outputStream);

    gifWriter.prepareWriteSequence(null);

  }

  public void writeToSequence(RenderedImage img) throws IOException {

    gifWriter.writeToSequence(

      new IIOImage(

        img,

        null,

        imageMetaData),

      imageWriteParam);

  }

  /**

   * Now also closes the stream

   */

  public void close() throws IOException {

    gifWriter.endWriteSequence();    

    stream.close();

  }

  /**

   * Returns the first available GIF ImageWriter using 

   * ImageIO.getImageWritersBySuffix("gif").

   * 

   * @return a GIF ImageWriter object

   * @throws IIOException if no GIF image writers are returned

   */

  private static ImageWriter getWriter() throws IIOException {

    ret assertNotNull("No GIF Image Writers Exist",

      first(ImageIO.getImageWritersBySuffix("gif")));

  }

  /**

   * Returns an existing child node, or creates and returns a new child node (if 

   * the requested node does not exist).

   * 

   * @param rootNode the <tt>IIOMetadataNode</tt> to search for the child node.

   * @param nodeName the name of the child node.

   * 

   * @return the child node, if found or a new node created with the given name.

   */

  private static IIOMetadataNode getNode(

      IIOMetadataNode rootNode,

      String nodeName) {

    int nNodes = rootNode.getLength();

    for (int i = 0; i < nNodes; i++) {

      if (rootNode.item(i).getNodeName().compareToIgnoreCase(nodeName)

          == 0) {

        return((IIOMetadataNode) rootNode.item(i));

      }

    }

    IIOMetadataNode node = new IIOMetadataNode(nodeName);

    rootNode.appendChild(node);

    return(node);

  }

}