动画 GIF 中帧之间的读取延迟 [英] Read delay between frames in animated GIF

问题描述

你如何读取每帧之间的动画 GIF 的控制块?我对每帧之间的延迟感兴趣.我查看了 ImageReader 的 Javadoc，但没有看到任何内容.

How do you read the animated GIF's control block between each frame? I'm interested in the delay between each frame. I've looked at the Javadoc for ImageReader and I'm not seeing anything.

这是我从动画 GIF 中读取所有帧的代码，我将如何增强它以读取有关嵌入在动画 GIF 中的每个帧的元数据?

Here's my code for reading all the frames from the animated GIF, how would I enhance it to read the metadata about each frame embedded in the animated GIF?

    List<BufferedImage> list = new ArrayList<BufferedImage>();
    try {
        ImageReader reader = ImageIO.getImageReadersBySuffix("gif").next();
        reader.setInput(ImageIO.createImageInputStream(urlImage.openStream()));
        int i = reader.getMinIndex();
        int numImages = reader.getNumImages(true);
        while (i < numImages)
        {
            list.add(reader.read(i++));
        }

        // do stuff with frames of image...

    } catch (Exception e) {
        e.printStackTrace();
    }

推荐答案

您必须从元数据节点中找出 "delayTime" 属性.使用以下工作示例来理解:

You will have to seek out "delayTime" attribute from metadata node. Use the following working example to understand:

public class GiffTest {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        ImageReader reader = ImageIO.getImageReadersBySuffix("gif").next();
        reader.setInput(ImageIO.createImageInputStream(new FileInputStream("H:\\toonGif.gif")));
        int i = reader.getMinIndex();
        int numImages = reader.getNumImages(true);

        IIOMetadata imageMetaData =  reader.getImageMetadata(0);
        String metaFormatName = imageMetaData.getNativeMetadataFormatName();

    IIOMetadataNode root = (IIOMetadataNode)imageMetaData.getAsTree(metaFormatName);

    IIOMetadataNode graphicsControlExtensionNode = getNode(root, "GraphicControlExtension");

        System.out.println(graphicsControlExtensionNode.getAttribute("delayTime"));
    }

    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);
  }
}

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