参数空异常位图保存到内存流

问题描述

我正在尝试将我的位图保存到 MemoryStream - 这段代码有什么问题?为什么它让我argumentnullexception ?

I'm trying to save my Bitmap to MemoryStream - what wrong in this code? Why it gets me argumentnullexception ??

private void insertBarCodesToPDF(Bitmap barcode)
    {

            .......
            MemoryStream ms = new MemoryStream();
            barcode.Save(ms, System.Drawing.Imaging.ImageFormat.MemoryBmp); //<----
            byte [] qwe = ms.ToArray();
            .......

    }

UPD: StackTraceSystem.Drawing.Image.Save(流流，ImageCodecInfo 编码器，EncoderParameters 编码器参数)在 WordTest.FormTestWord.insertBarCodesToPDF(位图条码)

UPD: StackTrace System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams) in WordTest.FormTestWord.insertBarCodesToPDF(Bitmap barcode)

推荐答案

我相信您的问题与您尝试保存到 MemoryStream 的图像类型有关.根据此代码项目文章:动态生成图标(安全)，一些 ImageFormat类型没有必要的编码器来允许保存功能保存为该类型.

I believe that your problem is related to the type of image you are trying to save to the MemoryStream as. According to this Code Project article: Dynamically Generating Icons (safely), some of the ImageFormat types do not have the necessary encoder to allow the Save function to save as that type.

我运行以下命令来确定哪些类型有效，哪些无效:

I ran the following to determine which types did and didn't work:

System.Drawing.Bitmap b = new Bitmap(10, 10);
foreach (ImageFormat format in new ImageFormat[]{
          ImageFormat.Bmp, 
          ImageFormat.Emf, 
          ImageFormat.Exif, 
          ImageFormat.Gif, 
          ImageFormat.Icon, 
          ImageFormat.Jpeg, 
          ImageFormat.MemoryBmp,
          ImageFormat.Png,
          ImageFormat.Tiff, 
          ImageFormat.Wmf}) 
{
  Console.Write("Trying {0}:", format);
  MemoryStream ms = new MemoryStream();
  bool success = true;
  try 
  {
    b.Save(ms, format);
  }
  catch (Exception) 
  {
    success = false;
  }
  Console.WriteLine("	{0}", (success ? "works" : "fails"));
}

结果如下:

Trying Bmp:       works
Trying Emf:       fails
Trying Exif:      fails
Trying Gif:       works
Trying Icon:      fails
Trying Jpeg:      works
Trying MemoryBMP: fails
Trying Png:       works
Trying Tiff:      works
Trying Wmf:       fails

有一个 Microsoft KB 文章，其中指出某些 ImageFormat类型是只读的.

There is a Microsoft KB Article which states that some of the ImageFormat types are read-only.