知道内存中一个图片的指针IntPtr大小，转换成图片显示

//nSize 为总长度
//pImageData 为总数据
//nImageSize //一个图片的长度

[nImageSize];//
 //IntPtr infosIntptr = Marshal.AllocHGlobal(pImageData);
 Marshal.Copy(pImageData, _bytes, 0, nImageSize);//复制
 PtrMoveSize(ref pImageData, nImageSize);//丛总内存中去掉当前的图片所占内存
 nSize -= nImageSize;
 MemoryStream ms = new MemoryStream(_bytes);
 Image img = Image.FromStream(ms);
 ms.Close();
 ms.Dispose();
 pictureBox1.Image = img;
 pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;

  //指针偏移
  public static void PtrMoveSize(ref IntPtr pData, int nLength)
 {
     if (IntPtr.Size == sizeof(Int64))
       pData = new IntPtr(pData.ToInt64() + nLength);
     else
       pData = new IntPtr(pData.ToInt32() + nLength);
  }