/// <summary>
/// Sorts the elements in a range of elements in an ObservableCollection using the specified
/// System.Collections.Generic.IComparer`1 generic interface.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="lstCollection">The ObservableCollection to sort.</param>
/// <param name="index">The starting index of the range to sort.</param>
/// <param name="length">The number of elements in the range to sort.</param>
/// <param name="objComparer">The System.Collections.Generic.IComparer`1 generic interface
/// implementation to use when comparing elements, or null to use the System.IComparable`1 generic
/// interface implementation of each element.</param>
public static void Sort <T>(this BindingList <T> lstCollection, int index, int length, IComparer <T> objComparer = null) where T : IComparable
{
if (lstCollection == null)
{
throw new ArgumentNullException(nameof(lstCollection));
}
if (index < 0)
{
throw new ArgumentOutOfRangeException(nameof(index));
}
if (length < 0)
{
throw new ArgumentOutOfRangeException(nameof(length));
}
if (index + length > lstCollection.Count)
{
throw new ArgumentException(nameof(length));
}
if (length == 0)
{
return;
}
T[] aobjSorted = new T[length];
for (int i = 0; i < length; ++i)
{
aobjSorted[i] = lstCollection[index + i];
}
Array.Sort(aobjSorted, objComparer);
bool blnOldRaiseListChangedEvents = lstCollection.RaiseListChangedEvents;
BitArray ablnItemChanged = blnOldRaiseListChangedEvents ? new BitArray(aobjSorted.Length) : null;
// We're going to disable events while we work with the list, then call them all at once at the end
lstCollection.RaiseListChangedEvents = false;
for (int i = 0; i < aobjSorted.Length; ++i)
{
int intOldIndex = lstCollection.IndexOf(aobjSorted[i]);
int intNewIndex = index + i;
if (intOldIndex == intNewIndex)
{
continue;
}
if (intOldIndex > intNewIndex)
{
// Account for removal happening before removal
intOldIndex -= 1;
if (blnOldRaiseListChangedEvents)
{
for (int j = intNewIndex; j <= intOldIndex; ++j)
{
ablnItemChanged[j] = true;
}
}
}
else
{
// Account for removal happening before removal
intNewIndex -= 1;
if (blnOldRaiseListChangedEvents)
{
for (int j = intOldIndex; j <= intNewIndex; ++j)
{
ablnItemChanged[j] = true;
}
}
}
lstCollection.RemoveAt(intOldIndex);
lstCollection.Insert(intNewIndex, aobjSorted[i]);
}
lstCollection.RaiseListChangedEvents = blnOldRaiseListChangedEvents;
if (!blnOldRaiseListChangedEvents)
{
return;
}
// If at least half of the list was changed, call a reset event instead of a large amount of ItemChanged events
if (ablnItemChanged.CountTrues() >= ablnItemChanged.Length / 2)
{
lstCollection.ResetBindings();
}
else
{
for (int i = 0; i < ablnItemChanged.Length; ++i)
{
if (ablnItemChanged[i])
{
lstCollection.ResetItem(i);
}
}
}
}
