src/main/java/eu/svjatoslav/meviz/htmlindexer/GifSequenceWriter.java

   1 package eu.svjatoslav.meviz.htmlindexer;
   2
   3 import javax.imageio.*;
   4 import javax.imageio.metadata.IIOInvalidTreeException;
   5 import javax.imageio.metadata.IIOMetadata;
   6 import javax.imageio.metadata.IIOMetadataNode;
   7 import javax.imageio.stream.ImageOutputStream;
   8 import java.awt.image.RenderedImage;
   9 import java.io.IOException;
  10
  11 /**
  12  * Source: https://memorynotfound.com/generate-gif-image-java-delay-infinite-loop-example/
  13  */
  14 public class GifSequenceWriter {
  15     protected ImageWriter writer;
  16     protected ImageWriteParam params;
  17     protected IIOMetadata metadata;
  18
  19     public GifSequenceWriter(ImageOutputStream out, int imageType, int delay, boolean loop) throws IOException {
  20         writer = ImageIO.getImageWritersBySuffix("gif").next();
  21         params = writer.getDefaultWriteParam();
  22
  23         ImageTypeSpecifier imageTypeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(imageType);
  24         metadata = writer.getDefaultImageMetadata(imageTypeSpecifier, params);
  25
  26         configureRootMetadata(delay, loop);
  27
  28         writer.setOutput(out);
  29         writer.prepareWriteSequence(null);
  30     }
  31
  32     private void configureRootMetadata(int delay, boolean loop) throws IIOInvalidTreeException {
  33         String metaFormatName = metadata.getNativeMetadataFormatName();
  34         IIOMetadataNode root = (IIOMetadataNode) metadata.getAsTree(metaFormatName);
  35
  36         IIOMetadataNode graphicsControlExtensionNode = getNode(root, "GraphicControlExtension");
  37         graphicsControlExtensionNode.setAttribute("disposalMethod", "none");
  38         graphicsControlExtensionNode.setAttribute("userInputFlag", "FALSE");
  39         graphicsControlExtensionNode.setAttribute("transparentColorFlag", "FALSE");
  40         graphicsControlExtensionNode.setAttribute("delayTime", Integer.toString(delay ));
  41         graphicsControlExtensionNode.setAttribute("transparentColorIndex", "0");
  42
  43         IIOMetadataNode commentsNode = getNode(root, "CommentExtensions");
  44         commentsNode.setAttribute("CommentExtension", "Created by: https://memorynotfound.com");
  45
  46         IIOMetadataNode appExtensionsNode = getNode(root, "ApplicationExtensions");
  47         IIOMetadataNode child = new IIOMetadataNode("ApplicationExtension");
  48         child.setAttribute("applicationID", "NETSCAPE");
  49         child.setAttribute("authenticationCode", "2.0");
  50
  51         int loopContinuously = loop ? 0 : 1;
  52         child.setUserObject(new byte[]{ 0x1, (byte) (loopContinuously & 0xFF), (byte) ((loopContinuously >> 8) & 0xFF)});
  53         appExtensionsNode.appendChild(child);
  54         metadata.setFromTree(metaFormatName, root);
  55     }
  56
  57     private static IIOMetadataNode getNode(IIOMetadataNode rootNode, String nodeName){
  58         int nNodes = rootNode.getLength();
  59         for (int i = 0; i < nNodes; i++){
  60             if (rootNode.item(i).getNodeName().equalsIgnoreCase(nodeName)){
  61                 return (IIOMetadataNode) rootNode.item(i);
  62             }
  63         }
  64         IIOMetadataNode node = new IIOMetadataNode(nodeName);
  65         rootNode.appendChild(node);
  66         return(node);
  67     }
  68
  69     public void writeToSequence(RenderedImage img) throws IOException {
  70         writer.writeToSequence(new IIOImage(img, null, metadata), params);
  71     }
  72
  73     public void close() throws IOException {
  74         writer.endWriteSequence();
  75     }
  76
  77 }