c# - MemoryStream.CopyTo 不工作

Question

TiffBitmapDecoder decoder = new TiffBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);

using (MemoryStream allFrameStream = new MemoryStream())
{
    foreach (BitmapFrame frame in decoder.Frames)
    {
        using (MemoryStream ms= new MemoryStream())
        {
            JpegBitmapEncoder enc = new JpegBitmapEncoder();
            enc.Frames.Add(BitmapFrame.Create(frame));
            enc.Save(ms);
            ms.CopyTo(allFrameStream);
        }
    }

    Document documentPDF = new Document();
    PdfWriter writer = PdfWriter.GetInstance(documentPDF, allFrameStream);
}

总是所有 FrameStream 的 Length=0。但是每次迭代我都可以看到 ms.Length=989548。我的代码中有什么错误。为什么 ms.CopyTo(allFrameStream) 不工作？

Answer 1

填充后将 ms 的 Position 重置为 0:

enc.Save(ms);
ms.Position = 0;
ms.CopyTo(allFrameStream);

来自 Stream.CopyTo

Copying begins at the current position in the current stream