将Bitmap保存到MemoryStream的GDI +异常

Question

我在Windows窗体应用程序中遇到问题,Bitmap.Save在保存到MemoryStream时失败.问题似乎只是间歇性地出现在一台机器上(到目前为止),而坏消息则出现在客户现场.我无法在机器上进行调试,但是我得到了一个堆栈跟踪,将问题缩小到一行代码.

这是我的代码的精简版本:

byte[] ConvertPixelsToBytes()
{
    // imagine a picture class that creates a 24 bbp image, and has
    // a method to get an unmanaged pixel buffer.
    // imagine it also has methods for getting the width,
    // height, pitch 

    // I suppose this line could return a bad address, but 
    // I would have expected that the Bitmap constructor would have 
    // failed if it was
    System.IntPtr pPixels = picture.GetPixelData();

    System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(
            picture.width(),
            picture.height(),
            picture.pitch(),
            System.Drawing.Imaging.PixelFormat.Format24bppRgb,
            pPixels );

    // This line doesn't actually free the memory, but it could be freed in a 
    // background thread
    // (2)
    picture.releasePixelData(pPixels);

    System.IO.MemoryStream memStream = new System.IO.MemoryStream();
    try
    {
        // I don't see how this line could fail, but it does
        // (3)
        bmp.Save(memStream, System.Drawing.Imaging.ImageFormat.Bmp);
        return memStream.ToArray();
    }
   catch(System.Runtime.InteropServices.ExternalException e)
   {
       // e.Message is the very helpful " A generic error occurred in GDI+."
   }
   finally
   {
       memStream.Dispose();
   }
   return new byte[0];
}

知道可能会发生什么吗？我很确定我的像素缓冲区是正确的,它总是适用于我们的开发/测试机器和其他客户站点.

我对失败的可能原因的看法是

一个.位图构造函数不复制像素数据,但保留对它的引用,并且由于释放内存而导致保存失败.我没有在这一点上找到MSDN文档清楚,但我假设Bitmap复制像素数据而不是假设它被锁定.

湾 像素数据无效,导致Save方法失败.我怀疑这是因为我的像素数据是每像素24位,所以据我所知它不应该是无效的.

C..NET框架存在问题.

我很感激任何关于其他可能的失败原因的想法,所以我可以添加额外的检查和记录信息到我的应用程序,所以我可以发送一些东西到现场.

Answer 1

毫无疑问,该Bitmap构造函数的MSDN文档是毫无疑问的:

备注 调用者负责分配和释放scan0参数指定的内存块,但是,在释放相关的Bitmap之前,不应释放内存.