/// <summary>
/// Extracts a MDX4TagTableHeader from a Stream
/// </summary>
/// <param name="Reader">The BinaryReader that contains the MDX4TTH structure</param>
/// <param name="LengthOfTags">The total length of a single MDX4TTH structrue + overhead</param>
/// <param name="StreamPosition">The start position in the stream</param>
/// <returns>An MDX4TagTableHeader structure or null (if the operation failed)</returns>
public static MDX4TagTableHeader Read(BinaryReader Reader, byte LengthOfTags, int StreamPosition)
{
GCHandle handle;
byte[] buffer;
Reader.BaseStream.Position = StreamPosition;
buffer = Reader.ReadBytes(LengthOfTags);
handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
MDX4TagTableHeader TempObject = (MDX4TagTableHeader)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(MDX4TagTableHeader));
handle.Free();
return(TempObject);
}
/// <summary>
/// Read the MDX subentry from the parent MDXFile structure
/// </summary>
/// <param name="Reader">A binary reader that contains the filestream of the MDX File</param>
/// <param name="LengthOfTagTableHeader">The byte length of the TagTableHeader</param>
/// <param name="StartPosition">The start position of the first tag table header</param>
/// <returns>"True" if the operation was successfull</returns>
public bool Read(BinaryReader Reader, byte LengthOfTagTableHeader, int StartPosition)
{
bool Successfull = true;
//Read the TagTableHeader
this.objTagDescription = MDX4TagTableHeader.Read(Reader, LengthOfTagTableHeader, StartPosition);
// Read the TagHeader
this.objTagHeader = MDXTagHeader.Read(Reader, this.objTagDescription.tagHeaderPageNumber*512);
//Fill Index (base) with values from the Header
base.shortKeysPerNode = this.objTagHeader.maxNumberOfKeysPage;
base.shortKeyLength = this.objTagHeader.indexKeyLength;
base.objKeyType = this.objTagHeader.keyType;
base.unique_key = this.objTagHeader.uniqueFlag;
int Index_record = (int) objTagHeader.pointerToRootPage;
int reading = Index_record;
//Read Nodes
MNode llNode = null;
while (reading > 0)
{
if (topNode == null)
{
(objNode = new MNode(shortKeysPerNode, shortKeyLength, objKeyType, Index_record, false)).Read(Reader);
}
else
{
llNode = new MNode(shortKeysPerNode, shortKeyLength, objKeyType, Index_record, false);
objNode.Read(Reader);
objNode.PreviousNode = llNode;
objNode = (MNode) llNode;
} /* endif */
workNode = objNode;
objNode.Position = 0;
objNode.Read(Reader);
if (reading > 0)
{
/* if reading is zero we're still reading Nodes, when < 0 then read
/* a leaf */
Index_record = objNode.LowerLevel;
if (Index_record == 0)
{
Index_record = objNode.KeyRecordNumber;
reading = 0; /* read a leaf so last time in loop */
objNode.Position = 0; // /* so sequentially reads get first record */
} /* Index = 0 then it's a leaf pointer */
} /* reading > 0 */
if (topNode == null)
topNode = (MNode) objNode.Clone();
}
return Successfull;
}
