/// <summary>
/// Add data to the image archive
/// </summary>
/// <param name="Key"></param>
/// <param name="Bytes"></param>
public void Add(string Key, byte[] Bytes)
{
lock (this)
{
if (this.archiveIndexKey.ContainsKey(Key))
{
throw new Exception("Key already exists: " + Key);
}
MD5Checksum md5 = MD5Checksum.Generate(Bytes);
ImageArchiveEntry entry;
if (this.archiveIndexMD5.ContainsKey(md5))
{
ImageArchiveEntry oldiae = this.archiveIndexMD5[md5];
entry = new ImageArchiveEntry
{
Key = Key,
BytePositionStart = oldiae.BytePositionStart,
Size = oldiae.Size,
MD5 = md5
};
}
else
{
entry = new ImageArchiveEntry
{
Key = Key,
BytePositionStart = this.archiveFile.Position,
Size = Bytes.Length,
MD5 = md5
};
//Add the entry to the MD5 index.
this.archiveIndexMD5.Add(md5, entry);
//Add to memorystream
this.archiveFile.Write(Bytes, 0, Bytes.Length);
}
//Add to key index
this.archiveIndexKey.Add(Key, entry);
}
}
/// <summary>
/// Remove the specific key from index.
/// </summary>
/// <param name="Key"></param>
public void Remove(string Key)
{
lock (this)
{
if (!this.archiveIndexKey.ContainsKey(Key))
{
throw new Exception("Key not found: " + Key);
}
ImageArchiveEntry removedEntry = this.archiveIndexKey[Key];
this.archiveIndexKey.Remove(Key);
//Browse through each ImageArchiveEntry we have, to find out if we can remove this image from the stream.
bool removeStream = true;
foreach (KeyValuePair <string, ImageArchiveEntry> kvp in this.archiveIndexKey)
{
if (kvp.Value.MD5 == removedEntry.MD5)
{
removeStream = false;
//Replace representation in MD5 index
this.archiveIndexMD5[removedEntry.MD5] = kvp.Value;
break;
}
}
//If we can remove the stream
if (removeStream)
{
//Adjust position mapping of entries after removed entry, but only if the removed entry isn't the last entry.
if ((removedEntry.BytePositionStart + removedEntry.Size) == this.archiveFile.Length)
{
foreach (KeyValuePair <string, ImageArchiveEntry> kvp in this.archiveIndexKey)
{
if (kvp.Value.BytePositionStart > removedEntry.BytePositionStart)
{
kvp.Value.BytePositionStart -= removedEntry.Size;
}
}
}
//Remove this part of the stream.
MemoryStream ms = new MemoryStream();
byte[] buffer;
//Part before removed entry.
if (removedEntry.BytePositionStart > 0)
{
buffer = new byte[removedEntry.BytePositionStart];
this.archiveFile.Read(buffer, 0, (int)removedEntry.BytePositionStart);
ms.Write(buffer, 0, buffer.Length);
}
//Part after removed entry.
if ((removedEntry.BytePositionStart + removedEntry.Size) <= this.archiveFile.Length)
{
int startpos = (int)removedEntry.BytePositionStart + removedEntry.Size;
int length = (int)this.archiveFile.Length - startpos;
buffer = new byte[length];
this.archiveFile.Read(buffer, startpos, length);
ms.Write(buffer, 0, buffer.Length);
}
}
}
}
