/// <summary>
/// Returns a palette with the specified color count.
/// </summary>
/// <param name="colorCount">The maximum number of colors in the new palette.</param>
/// <returns></returns>
public IList <Color> GetPalette(int colorCount)
{
var result = new List <Color>();
int leafCount = Leaves.Count();
lastColorCount = leafCount;
int paletteIndex = 0;
// goes thru all the levels starting at the deepest, and goes upto a root level
for (int level = 6; level >= 0; level--)
{
// if level contains any node
if (levels[level].Count > 0)
{
// orders the level node list by pixel presence (those with least pixels are at the top)
IEnumerable <Node> sortedNodeList = levels[level].OrderBy(node => node.ActiveNodesPixelCount);
// removes the nodes unless the count of the leaves is lower or equal than our requested color count
foreach (Node node in sortedNodeList)
{
// removes a node
leafCount -= node.RemoveLeaves(level, leafCount, colorCount, this);
// if the count of leaves is lower then our requested count terminate the loop
if (leafCount <= colorCount)
{
break;
}
}
// if the count of leaves is lower then our requested count terminate the level loop as well
if (leafCount <= colorCount)
{
break;
}
// otherwise clear whole level, as it is not needed anymore
levels[level].Clear();
}
}
// goes through all the leaves that are left in the tree (there should now be less or equal than requested)
foreach (Node node in Leaves.OrderByDescending(node => node.ActiveNodesPixelCount))
{
if (paletteIndex >= colorCount)
{
break;
}
// adds the leaf color to a palette
if (node.IsLeaf)
{
result.Add(node.Color);
}
// and marks the node with a palette index
node.SetPaletteIndex(paletteIndex++);
}
// we're unable to reduce the Octree with enough precision, and the leaf count is zero
if (result.Count == 0)
{
throw new NotSupportedException("The Octree contains after the reduction 0 colors, it may happen for 1-16 colors because it reduces by 1-8 nodes at time. Should be used on 8 or above to ensure the correct functioning.");
}
// returns the palette
return(result);
}
