/// <summary>
/// Removes the specified item from the subset of this classification if that category is used.
/// Selected -> !Selected
/// Category[>0] -> Category[0]
/// Category[0] -> Null
/// Visible -> !Visible
/// Chunk -> -1 or basically a chunk index that is never drawn.
/// </summary>
/// <param name="item">The item to change the drawing state of</param>
/// <returns>Boolean, false if the item does not match the current grouping</returns>
/// <exception cref="ReadOnlyException">Occurs if this list is set to read-only in the constructor</exception>
public bool Remove(IFeature item)
{
if (_isReadOnly) throw new ReadOnlyException();
if (Contains(item) == false) return false;
IDrawnState previousState = _filter[item];
IFeatureCategory cat = previousState.SchemeCategory;
int chunk = previousState.Chunk;
bool sel = previousState.IsSelected;
bool vis = previousState.IsVisible;
if (_activeType == FilterTypes.Category)
{
cat = _category != _filter.DefaultCategory ? _filter.DefaultCategory : null;
}
if (_activeType == FilterTypes.Chunk)
{
// removing from a chunk effectively means setting to -1 so that it will not get drawn
// until it is added to a chunk again.
chunk = -1;
}
if (_activeType == FilterTypes.Selection)
{
sel = !_selected;
}
if (_activeType == FilterTypes.Visible)
{
vis = !_visible;
}
_filter[item] = new DrawnState(cat, sel, chunk, vis);
OnChanged();
return true;
}
/// <summary>
/// Adding a feature state sets the drawing state of the item to be
/// </summary>
/// <param name="item">The item to add to this category</param>
/// <exception cref="ReadOnlyException">Occurs if this list is set to read-only in the constructor</exception>
public void Add(IFeature item)
{
if (_isReadOnly) throw new ReadOnlyException();
IDrawnState previousState = _filter[item];
IFeatureCategory cat = previousState.SchemeCategory;
if (_useCategory) cat = _category;
bool sel = previousState.IsSelected;
if (_useSelection) sel = _selected;
int chunk = previousState.Chunk;
if (_useChunks) chunk = _chunk;
bool vis = previousState.IsVisible;
if (_useVisibility) vis = _visible;
_filter[item] = new DrawnState(cat, sel, chunk, vis);
OnChanged();
}