public HistoryMementoDeleteKeyframe(Metadata metadata, Guid keyframeId)
{
this.metadata = metadata;
this.keyframeId = keyframeId;
// TODO: save the complete keyframe to XML (including the thumbnail).
// Including all drawings and trackable drawings associated with these drawings.
Keyframe keyframe = metadata.GetKeyframe(keyframeId);
if (keyframe == null)
{
throw new NullReferenceException("keyframe");
}
data = KeyframeSerializer.SerializeMemento(metadata, keyframe);
}