问题位图克隆 [英] Problem with Bitmap Cloning

问题描述

考虑这个code装载，修改和保存位图图像：

Consider this code for loading, modifying and saving a Bitmap image:

    using (Bitmap bmp = new Bitmap("C:\\test.jpg"))
    {
        bmp.RotateFlip(RotateFlipType.Rotate180FlipNone);
        bmp.Save("C:\\test.jpg");
    }

运行没有任何异常。
但考虑这个：

it runs without any exception. But consider this one:

    using (Bitmap bmp = new Bitmap("C:\\test.jpg"))
    {
        using (Bitmap bmpClone = (Bitmap)bmp.Clone())
        {
            //You can replace "bmpClone" in the following lines with "bmp",
            //exception occurs anyway                    
            bmpClone.RotateFlip(RotateFlipType.Rotate180FlipNone);
            bmpClone.Save("C:\\test.jpg");
        }
    }

它结束与该消息的ExternalException：GDI +中发生一般性错误。
什么是错在这里？任何一种在打开的文件锁？如果是这样，为什么第一个块的工作？什么是正确的code克隆一个System.Drawing.Bitmap，而我们可能需要编辑的主要对象或其克隆在内存中，仍然有他们两个在内存中加载？

It ends in an ExternalException with this message: "A generic error occurred in GDI+". What's wrong here? Any kind of lock on opened file? If so, why the first block works? What is the proper code for cloning a System.Drawing.Bitmap while we may need to edit main object or its clone in the memory and still have them both loaded in memory?

推荐答案

您也可以载入位图文件，而不使用简单的解决方法锁定：

You could also load the bitmap without file locking using the simple workaround:

using (Stream s = File.OpenRead(@"\My Documents\My Pictures\Waterfall.jpg"))
Bitmap _backImage = (Bitmap)Bitmap.FromStream(s);

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