/// <summary>
/// Removes the placeholder from an empty category.
/// </summary>
private void RemoveEmptyPlaceholder()
{
// Quit if the placeholder is not present
if (emptyPlaceholderModel is null)
{
return;
}
// Ignore changes to the children collection caused by the removal of the placeholder
ignoreChildrenCollectionChanged = true;
try {
this.Children.Remove(emptyPlaceholderModel);
emptyPlaceholderModel = null;
}
finally {
ignoreChildrenCollectionChanged = false;
}
}
/////////////////////////////////////////////////////////////////////////////////////////////////////
// NON-PUBLIC PROCEDURES
/////////////////////////////////////////////////////////////////////////////////////////////////////
/// <summary>
/// Adds the placeholder to an empty category.
/// </summary>
private void AddEmptyPlaceholder()
{
// Quit if the placeholder already exists
if ((emptyPlaceholderModel != null) && this.Children.Contains(emptyPlaceholderModel))
{
return;
}
if (emptyPlaceholderModel is null)
{
emptyPlaceholderModel = CreateEmptyPlaceholderTreeNodeModel();
}
// Ignore changes to the children collection caused by the addition of the placeholder
ignoreChildrenCollectionChanged = true;
try {
this.Children.Add(emptyPlaceholderModel);
}
finally {
ignoreChildrenCollectionChanged = false;
}
}