public virtual DCMAbstractType Decode(byte[] data, ref uint idx)
{
//为节省资源，在构造函数中创建内存流
MemoryStream ms = new MemoryStream();
//流赋值
ms.Write(data, 0, data.Length);
ms.Position = idx;
//reader选用
BinaryReader reader = Select(ms);//此处ppt错误，定义为StreamReader。是困惑源。
//element初始化
DCMDataElement element = new DCMDataElement();
//1.解码tag
ParseTag(ref idx, ref element, reader);
//2.解码VR
ParseVR(ref element, reader);
//3.解码值长度
ParseVLength(ref element, reader, ms);
//4.解码值
GetValue(ref element, reader);
//结束
idx = (uint)ms.Position; //此处ppt错误 ms.Position为Long，不能直接赋值。
reader.Close();
ms.Close(); //回收内存流空间
return(element);
}
public void LookupDictionary(ref DCMDataElement element)//未将对象引用设置到对象的实例 原为保护方法
{
//查数据字典得到VR,Name,VM
DicomDictionaryEntry entry = dictionary.GetEntry(element.gtag, element.etag);
if (entry != null)
{
if (element.vr == "" || element.vr == null)
{
element.vr = entry.VR;
}
element.name = entry.Name;
element.vm = entry.VM;
}
else if (element.vr == "" && element.etag == 0)
{
element.vr = "UL";
}
else
{
Console.WriteLine("tag不存在");
}
//得到VR对象实例
element.vrparser = vrfactory.GetVR(element.vr);
//Console.WriteLine("LookUpDic");
}
public DCMDataElement ParseTag(ref uint idx, ref DCMDataElement element, BinaryReader reader)
{
element.gtag = reader.ReadUInt16();
element.etag = reader.ReadUInt16();
//Console.WriteLine("tag");
return(element);
}
public void GetValue(ref DCMDataElement element, BinaryReader reader)
{
if (element.length == 0xffffffff) //undefined length
{
element.value = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
}
else
{
element.value = reader.ReadBytes((int)element.length);
}
Console.WriteLine(BitConverter.ToString((byte[])element.value));
}
public DCMDataElement ParseVR(ref DCMDataElement element, BinaryReader reader)
{
if (element.gtag == 0xfffe)
{
element.vr = "Undefined";
return(element);
}
else if (isExplicit)
{
element.vr = Encoding.Default.GetString(reader.ReadBytes(2));
LookupDictionary(ref element);
//Console.WriteLine("vrE");
return(element);
}
else
{
LookupDictionary(ref element);
return(element);
}
}
public void ParseVLength(ref DCMDataElement element, BinaryReader reader, MemoryStream ms)
{
bool IsSixByte = element.vr == "OB" || element.vr == "OF" || element.vr == "OW" || element.vr == "SQ" || element.vr == "UT" || element.vr == "UN";
if (!isExplicit || element.gtag == 0xfffe)
{
element.length = reader.ReadUInt32();
//Console.WriteLine("length_I");
}
else if (IsSixByte)
{
ms.Position += 2; //skip two bytes
element.length = reader.ReadUInt32();
//Console.WriteLine("length_six");
}
else
{
element.length = reader.ReadUInt16();
//Console.WriteLine("length_other");
}
}
