Java ImageWriter BufferedImage到GIF [英] Java ImageWriter BufferedImage to GIF

问题描述

我希望你们能帮我这个忙.我不确定这是否是Java中的错误或我做错了什么，但我会选择后者.

I hope you guys can help me with this one. I'm not sure if it is a bug in Java or if I'm doing something wrong, but I'll go with the latter.

我想将BufferedImage转换为GIF图像.然后，我希望以字节数组的形式将GIF保留在内存中. (我不想将文件保存到磁盘)

I want to turn a BufferedImage into a GIF image. I then wish to keep the GIF in the memory in the form of a byte array. (I do not want to save the file to disk)

程序应捕获一个屏幕片段(仅用于创建快速图像)，然后使用ImageIO ImageWriter和ByteArrayOutputStream将其转换为GIF字节数组.

The program should capture a screen segment (just to create a quick image) and turn it into a GIF byte array using ImageIO ImageWriter and ByteArrayOutputStream.

下面的代码将向您显示错误.程序将崩溃并给出ArrayIndexOutOfBoundsException，并且数组保持为空.如果将"gif"替换为"png"，它将很好用，因此我很困惑.还！如果我使用

将图像保存到磁盘上的文件中

The code below will show you the bug. The program will crash and give an ArrayIndexOutOfBoundsException and the array remains empty. If you replace the "gif" with "png" it will work just fine, hence my confusion. Also! If I save the image to a file on disk with

write.setOutput(ImageIO.createImageOutputStream(new FileOutputStream(new File("C:/Image.gif")));

它将正确保存到.gif文件.

it will save it to a .gif file correctly.

所以我的问题是，在这段代码中我做错了什么?任何帮助将不胜感激！ :)

So my question is, what did I do wrong in this patch of code? Any help will be greatly appreciated! :)

注意:这不是动画GIF，也不涉及透明度.

Note: This is not an animated GIF, no transparency involved either.

    String format = "gif";
    Robot r = null;
    try {
        r = new Robot();
    } catch (AWTException e1) {
        e1.printStackTrace();
    }
    BufferedImage screen = r.createScreenCapture(new Rectangle(512,512));
    final BufferedImage gif = new BufferedImage(512,512,BufferedImage.TYPE_BYTE_INDEXED);
    Graphics2D g = gif.createGraphics();
    g.drawImage(screen,0,0,null);
    g.dispose();
    ImageWriter write = ImageIO.getImageWritersBySuffix(format).next();
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    try {
        write.setOutput(ImageIO.createImageOutputStream(out));
        write.write(gif);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    for(int i=0; i < 10; i++) {
        System.out.println(out.toByteArray()[i]);
    }

推荐答案

com.sun.imageio.plugins.gif.*中似乎有一些奇怪的(如果不是很明显的错误)流缓冲实现.如果不刷新或显式关闭ImageOutputStream，则即使在关闭基础流之后，也不会刷新内容..更改

It seems there is some strange (if not plainly buggy) implementation of stream bufferings in com.sun.imageio.plugins.gif.*. If you don't flush or close explicitly the ImageOutputStream, the contents doesn't get flushed, even after closing the underlying stream. Change

 write.setOutput(ImageIO.createImageOutputStream(out));
 write.write(gif);

到

   ImageOutputStream imageos = ImageIO.createImageOutputStream(out);
   write.setOutput(imageos);
   write.write(gif);
   imageos.close();  // or imageos.flush();

这篇关于Java ImageWriter BufferedImage到GIF的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！