读取动画GIF中帧之间的延迟

问题描述

如何在每帧之间阅读动画GIF的控制块？我对每帧之间的延迟感兴趣。我已经查看了ImageReader的Javadoc，但是我没有看到任何内容。

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，我将如何增强它阅读有关动画GIF中嵌入的每一帧的元数据？

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

你将不得不寻找来自元数据节点的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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