private static uint ReadLength(ReaderState state)
{
return(state.IsImplicitVr ? state.Reader.ReadUInt32() : state.Reader.ReadUInt16());
}
private static Value[] ReadUShort(ReaderState state)
{
var length = ReadLength(state);
var count = length / 2;
var output = new Value[count];
for (var i = 0; i < count; i++)
{
output[i] = new Value { Long = state.Reader.ReadUInt16() };
}
return output;
}
private static Element ReadElement(ReaderState state, ushort groupId, ushort elementId)
{
var combinedId = ElementTag.GetCombinedId(groupId, elementId);
state.IsImplicitVr = state.UseImplicitVr && (groupId != 0x0002);
if (!state.IsImplicitVr && groupId != 0xfffe) // Sequence items are always implicit - hence 0xfffe.
{
state.ExplicitVr = new string(state.Reader.ReadChars(2));
}
// Always use Implicit VR if the tag is recognized in the dictionary.
var vr = ValueTypes.Unknown;
if (Dictionary.ContainsKey(combinedId))
{
var elementTag = Dictionary[combinedId];
vr = elementTag.VR;
Logger.Debug(elementTag.Name);
}
var value = new Value[0];
switch (vr)
{
case ValueTypes.String:
value = ReadString(state);
break;
case ValueTypes.DoubleString:
value = ReadDoubleString(state);
break;
case ValueTypes.UShort:
value = ReadUShort(state);
break;
case ValueTypes.Bytes:
value = ReadBytes(state);
break;
case ValueTypes.Item:
value = ReadItem(state);
break;
case ValueTypes.Separator:
value = ReadSeparator(state);
break;
default:
ReadUnknown(state);
break;
}
// TransferSyntaxUID - See if implicit is specified. We hate implicit because shit cannot always be understood!
state.UseImplicitVr = (combinedId == ReverseDictionary["TransferSyntaxUID"]) && (value[0].Text == "1.2.840.10008.1.2");
var tag = Dictionary.ContainsKey(combinedId) ? Dictionary[combinedId] : null;
return(new Element()
{
GroupId = groupId,
ElementId = elementId,
Value = value,
Tag = tag
});
}
private static Value[] ReadString(ReaderState state)
{
var length = ReadLength(state);
var chars = state.Reader.ReadChars((int)length);
var text = new string(chars);
var values = text.Split('\\');
var output = new Value[values.Length];
for (var i = 0; i < output.Length; i++)
{
var value = values[i];
while (value.EndsWith("\0"))
{
value = value.Substring(0, value.Length - 1);
}
output[i] = new Value { Text = value };
}
return output;
}
private static void ReadUnknown(ReaderState state)
{
uint length;
if (state.ExplicitVr == "OB" || state.ExplicitVr == "OW" ||
state.ExplicitVr == "UN" || state.ExplicitVr == "SQ")
{
state.Reader.ReadBytes(2);
length = state.Reader.ReadUInt32();
}
else
{
length = ReadLength(state);
}
if (state.ExplicitVr == "SQ")
{
var groupId = state.Reader.ReadUInt16();
var elementId = state.Reader.ReadUInt16();
ReadElement(state, groupId, elementId);
}
else
{
state.Reader.ReadBytes((int)length);
}
}
private static uint ReadLength(ReaderState state)
{
return state.IsImplicitVr ? state.Reader.ReadUInt32() : state.Reader.ReadUInt16();
}
private static Value[] ReadSeparator(ReaderState state)
{
var length = state.Reader.ReadUInt32();
return new[] { new Value { Long = length } };
}
private static Value[] ReadItem(ReaderState state)
{
Element element;
string elementName;
var items = new List<Element>();
var length = state.Reader.ReadUInt32();
var endItemPosition = length + state.Reader.BaseStream.Position;
do
{
var groupId = state.Reader.ReadUInt16();
var elementId = state.Reader.ReadUInt16();
element = ReadElement(state, groupId, elementId);
elementName = (element.Tag != null) ? element.Tag.Name : null;
items.Add(element);
} while (elementName != "ItemDelimitationItem" &&
state.Reader.BaseStream.Position < endItemPosition);
return new[] { new Value { Items = items } };
}
private static Element ReadElement(ReaderState state, ushort groupId, ushort elementId)
{
var combinedId = ElementTag.GetCombinedId(groupId, elementId);
state.IsImplicitVr = state.UseImplicitVr && (groupId != 0x0002);
if (!state.IsImplicitVr && groupId != 0xfffe) // Sequence items are always implicit - hence 0xfffe.
{
state.ExplicitVr = new string(state.Reader.ReadChars(2));
}
// Always use Implicit VR if the tag is recognized in the dictionary.
var vr = ValueTypes.Unknown;
if (Dictionary.ContainsKey(combinedId))
{
var elementTag = Dictionary[combinedId];
vr = elementTag.VR;
Logger.Debug(elementTag.Name);
}
var value = new Value[0];
switch (vr)
{
case ValueTypes.String:
value = ReadString(state);
break;
case ValueTypes.DoubleString:
value = ReadDoubleString(state);
break;
case ValueTypes.UShort:
value = ReadUShort(state);
break;
case ValueTypes.Bytes:
value = ReadBytes(state);
break;
case ValueTypes.Item:
value = ReadItem(state);
break;
case ValueTypes.Separator:
value = ReadSeparator(state);
break;
default:
ReadUnknown(state);
break;
}
// TransferSyntaxUID - See if implicit is specified. We hate implicit because shit cannot always be understood!
state.UseImplicitVr = (combinedId == ReverseDictionary["TransferSyntaxUID"]) && (value[0].Text == "1.2.840.10008.1.2");
var tag = Dictionary.ContainsKey(combinedId) ? Dictionary[combinedId] : null;
return new Element()
{
GroupId = groupId,
ElementId = elementId,
Value = value,
Tag = tag
};
}
private static Value[] ReadDoubleString(ReaderState state)
{
var values = ReadString(state);
var output = new Value[values.Length];
for (var i = 0; i < values.Length; i++)
{
output[i] = new Value { Double = double.Parse(values[i].Text, NumberFormatInfo.InvariantInfo) };
}
return output;
}
private static Value[] ReadBytes(ReaderState state)
{
byte[] data = null;
if (!state.IsImplicitVr)
{
state.Reader.ReadBytes(2);
}
var length = state.Reader.ReadUInt32();
if (length == 0xffffffff) // Check for compressed data.
{
throw new IOException("Unable to read compressed data. Use external converter!");
}
else
{
data = state.Reader.ReadBytes((int)length);
}
return new[] { new Value { Bytes = data } };
}
public static Dictionary<uint, Element> ReadFile(BinaryReader reader)
{
var state = new ReaderState()
{
UseImplicitVr = false,
IsImplicitVr = false,
Reader = reader,
};
reader.ReadBytes(128);
var magicBytes = reader.ReadChars(4);
var magicText = new string(magicBytes);
if (magicText != "DICM")
{
Logger.Error("Fileformat not recognized!");
return new Dictionary<uint, Element>();
}
var dicomData = new Dictionary<uint, Element>();
while (reader.BaseStream.Position < reader.BaseStream.Length)
{
var groupId = reader.ReadUInt16();
var elementId = reader.ReadUInt16();
var combinedId = ElementTag.GetCombinedId(groupId, elementId);
Logger.Debug("(0x{0:x4}, 0x{1:x4})", groupId, elementId);
var element = ReadElement(state, groupId, elementId);
if (element.Tag != null && element.Tag.VR != ValueTypes.Separator)
{
dicomData.Add(combinedId, element);
}
}
return dicomData;
}
