/// <summary>Flush the state and update the header</summary>
/// <returns>Slice contained the finished compressed bitmap</returns>
/// <remarks>You cannot write any more words after Packing, until <see cref="Reset"/> is called.</remarks>
public void Pack()
{
if (m_packed)
{
ThrowAlreadyPacked();
}
// flush any pending word
Flush();
if (m_words == 0)
{ // empty!
m_bounds = BitRange.Empty;
// there will be no header
m_writer.Position = m_head;
}
else
{
// we need to find the lowest and highest bits
m_bounds = CompressedBitmap.ComputeBounds(m_writer.ToMutableSlice(), m_words);
// update the header
int p;
m_writer.Rewind(out p, m_head);
//the last word is either a literal, or a 1-bit filler
m_writer.WriteFixed32(CompressedWord.MakeHeader(m_bounds.Highest));
m_writer.Position = p;
}
m_packed = true;
}
internal static Slice Pack([NotNull] CompressedWord[] words, int size, int highest)
{
Contract.Requires(size >= 0 && size <= words.Length);
if (size == 0)
{ // empty bitmap
return(Slice.Empty);
}
var writer = new SliceWriter(checked ((size + 1) << 2));
writer.WriteFixed32(CompressedWord.MakeHeader(highest));
for (int i = 0; i < size; i++)
{
writer.WriteFixed32(words[i].RawValue);
}
return(writer.ToSlice());
}