Question

我制作的Java应用程序可以显示文件夹中的某些GIF文件。我目前正在使用代码

  final JLabel imageLabel = new JLabel();
  imageLabel.setIcon(new ImageIcon(fileName));
  contentPane.add(imageLabel, java.awt.BorderLayout.CENTER);

这完美无缺，除了我的.GIF文件中有很多（数千）具有错误配置的帧速率，这使得它们以无限速度显示（frameDelay = 0），假设浏览器将自动修复此问题。默认情况下，Java不会这样做。如何覆盖frameDelay Java必须用于那些frameDelay = 0的GIF动画？

Answer 1

我找到了this，它对我试过的一个gif效果很好。

~~我不知道他到底做了什么，但是如果第一帧的延迟为0则一眼就看起来像~~它会覆盖所有10帧的延迟。然后他写道＆＃39;内存中的新GIF文件并加载到图像中。

[编辑]我把它打磨了一下并解决了这些错误。

没有专有API
不会检查第一帧以确定它是否有问题，
仅对其为零的帧替换延迟。

public static Image readImgFromFile(String filename, Component parent) {
    File file = new File(filename);
    if (!file.exists()) {
        return null;
    }

    // Fix for bug when delay is 0
    try {
        // Load anything but GIF the normal way
        if (!filename.substring(filename.length() - 4).equalsIgnoreCase(".gif")) {
            return ImageIO.read(file);
        }

        // Get GIF reader
        ImageReader reader = ImageIO.getImageReadersByFormatName("gif").next();
        // Give it the stream to decode from
        reader.setInput(ImageIO.createImageInputStream(file));

        int numImages = reader.getNumImages(true);

        // Get 'metaFormatName'. Need first frame for that.
        IIOMetadata imageMetaData = reader.getImageMetadata(0);
        String metaFormatName = imageMetaData.getNativeMetadataFormatName();

        // Find out if GIF is bugged
        boolean foundBug = false;
        for (int i = 0; i < numImages && !foundBug; i++) {
            // Get metadata
            IIOMetadataNode root = (IIOMetadataNode)reader.getImageMetadata(i).getAsTree(metaFormatName);

            // Find GraphicControlExtension node
            int nNodes = root.getLength();
            for (int j = 0; j < nNodes; j++) {
                Node node = root.item(j);
                if (node.getNodeName().equalsIgnoreCase("GraphicControlExtension")) {
                    // Get delay value
                    String delay = ((IIOMetadataNode)node).getAttribute("delayTime");

                    // Check if delay is bugged
                    if (Integer.parseInt(delay) == 0) {
                        foundBug = true;
                    }

                    break;
                }
            }
        }

        // Load non-bugged GIF the normal way
        Image image;
        if (!foundBug) {
            image = Toolkit.getDefaultToolkit().createImage(filename);
        } else {
            // Prepare streams for image encoding
            ByteArrayOutputStream baoStream = new ByteArrayOutputStream();
            try (ImageOutputStream ios = ImageIO.createImageOutputStream(baoStream)) {
                // Get GIF writer that's compatible with reader
                ImageWriter writer = ImageIO.getImageWriter(reader);
                // Give it the stream to encode to
                writer.setOutput(ios);

                writer.prepareWriteSequence(null);

                for (int i = 0; i < numImages; i++) {
                    // Get input image
                    BufferedImage frameIn = reader.read(i);

                    // Get input metadata
                    IIOMetadataNode root = (IIOMetadataNode)reader.getImageMetadata(i).getAsTree(metaFormatName);

                    // Find GraphicControlExtension node
                    int nNodes = root.getLength();
                    for (int j = 0; j < nNodes; j++) {
                        Node node = root.item(j);
                        if (node.getNodeName().equalsIgnoreCase("GraphicControlExtension")) {
                            // Get delay value
                            String delay = ((IIOMetadataNode)node).getAttribute("delayTime");

                            // Check if delay is bugged
                            if (Integer.parseInt(delay) == 0) {
                                // Overwrite with a valid delay value
                                ((IIOMetadataNode)node).setAttribute("delayTime", "10");
                            }

                            break;
                        }
                    }

                    // Create output metadata
                    IIOMetadata metadata = writer.getDefaultImageMetadata(new ImageTypeSpecifier(frameIn), null);
                    // Copy metadata to output metadata
                    metadata.setFromTree(metadata.getNativeMetadataFormatName(), root);

                    // Create output image
                    IIOImage frameOut = new IIOImage(frameIn, null, metadata);

                    // Encode output image
                    writer.writeToSequence(frameOut, writer.getDefaultWriteParam());
                }

                writer.endWriteSequence();
            }

            // Create image using encoded data
            image = Toolkit.getDefaultToolkit().createImage(baoStream.toByteArray());
        }

        // Trigger lazy loading of image
        MediaTracker mt = new MediaTracker(parent);
        mt.addImage(image, 0);
        try {
            mt.waitForAll();
        }
        catch (InterruptedException e) {
            image = null;
        }
        return image;
    }
    catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}

在Java中修复动画gif的帧速率

1 个答案: