/// <summary>
/// Patches the file segments in a stream.
/// </summary>
/// <param name="changes">The changes to make to the segments and their data.</param>
/// <param name="stream">The stream to write changes to.</param>
public static void PatchSegments(IEnumerable <SegmentChange> changes, IStream stream)
{
// Sort changes by their offsets
var changesByOffset = new SortedList <uint, SegmentChange>();
foreach (SegmentChange change in changes)
{
changesByOffset[change.OldOffset] = change;
}
// Now adjust each segment
foreach (SegmentChange change in changesByOffset.Values)
{
// Resize it if necessary
if (change.NewSize != change.OldSize)
{
if (change.ResizeAtEnd)
{
stream.SeekTo(change.NewOffset + change.OldSize);
}
else
{
stream.SeekTo(change.NewOffset);
}
StreamUtil.Insert(stream, change.NewSize - change.OldSize, 0);
}
// Patch its data
DataPatcher.PatchData(change.DataChanges, change.NewOffset, stream);
}
}
/// <summary>
/// Compresses and saves data for a resource.
/// </summary>
/// <param name="inStream">The stream open on the resource data. It must have read/write access.</param>
/// <param name="resourceIndex">The index of the resource to edit.</param>
/// <param name="data">The data to compress.</param>
/// <returns>The total size of the compressed resource in bytes.</returns>
public uint Compress(Stream inStream, int resourceIndex, byte[] data)
{
if (resourceIndex < 0 || resourceIndex > _resources.Count)
{
throw new ArgumentOutOfRangeException("resourceIndex");
}
// Compress the data (just use a single chunk)
var compressed = LZ4Codec.EncodeHC(data, 0, data.Length);
// Resize the resource's data so that the chunk can fit
var resource = _resources[resourceIndex];
var newSize = (uint)compressed.Length + ChunkHeaderSize;
var roundedSize = (newSize + 0xF) & ~0xFU; // Round up to a multiple of 0x10
var sizeDelta = (int)(roundedSize - resource.Size);
if (sizeDelta > 0)
{
// Resource needs to grow
inStream.Position = resource.Offset + resource.Size;
StreamUtil.Insert(inStream, sizeDelta, 0);
}
else
{
// Resource needs to shrink
inStream.Position = resource.Offset + roundedSize;
StreamUtil.Remove(inStream, -sizeDelta);
}
// Write the chunk in
inStream.Position = resource.Offset;
var writer = new BinaryWriter(inStream);
writer.Write(data.Length);
writer.Write(compressed.Length);
writer.Write(compressed, 0, compressed.Length);
StreamUtil.Fill(inStream, 0, (int)(roundedSize - newSize)); // Padding
// Adjust resource offsets
for (var i = resourceIndex + 1; i < _resources.Count; i++)
{
_resources[i].Offset = (uint)(_resources[i].Offset + sizeDelta);
}
UpdateResourceTable(writer);
return((uint)compressed.Length + ChunkHeaderSize);
}