/// <summary>
/// Initializes the filter view model.
/// </summary>
protected override FilterControlVm CreateModel()
{
FilterControlVm vm = null;
filterPresenter = Parent == null ? null : FilterPresenter.TryGet(ParentCollection);
if (filterPresenter != null)
{
if (Key == null)
{
DataGridColumnHeader columnHeader = this.GetParent <DataGridColumnHeader>();
if (columnHeader == null)
{
return(null);
}
DataGridColumn column = columnHeader.Column;
if (column == null)
{
return(null);
}
DataGrid dataGrid = columnHeader.GetParent <DataGrid>();
if (dataGrid == null)
{
return(null);
}
if (column.DisplayIndex >= dataGrid.Columns.Count)
{
return(null);
}
IEnumerable <FilterInitializer> initializers = GetInitializers(column) ?? FilterInitializersManager;
string key = Key ?? GetColumnKey(column);
vm = filterPresenter.TryGetFilterControlVm(key, initializers);
}
else
{
IEnumerable <FilterInitializer> initializers = FilterInitializersManager;
vm = filterPresenter.TryGetFilterControlVm(Key, initializers);
}
if (vm != null)
{
vm.IsEnable = true;
}
}
return(vm);
}
// <summary>
// Returns FilterPresenter, connected to a pass source .
// If pass instance of ICollectionView, FilterPresenter connected to passed instance, otherwise, filterPresenter connected to default view for passed collection.
// </summary>
// <param name="source">ICollectionView for source or source</param>
// <returns>FilterPresenter, connected to source, or null if source is null.</returns>
public static FilterPresenter TryGet(IEnumerable source)
{
if (source == null)
{
return(null);
}
ICollectionView sourceCollectionView = source as ICollectionView;
if (sourceCollectionView == null)
{
sourceCollectionView = CollectionViewSource.GetDefaultView(source);
}
FilterPresenter instance = null;
//GC.Collect();
foreach (var entry in filterPresenters.ToArray())
{
if (!entry.Value.IsAlive)
{
filterPresenters.Remove(entry.Key);
}
}
if (filterPresenters.ContainsKey(sourceCollectionView))
{
var wr = filterPresenters[sourceCollectionView];
instance = wr.Target as FilterPresenter;
}
if (instance == null)
{
instance = new FilterPresenter(sourceCollectionView);
if (filterPresenters.ContainsKey(sourceCollectionView))
{
filterPresenters[sourceCollectionView] = new WeakReference(instance);
}
else
{
filterPresenters.Add(sourceCollectionView, new WeakReference(instance));
}
}
return(instance);
}