/// <summary>
/// Returns the template element with specified name and type, or throws an exception if not found.
/// </summary>
/// <param name="nameScope">The NameScope used to find the element.</param>
/// <param name="name">The name of the element to find.</param>
/// <typeparam name="T">The type of the element to find.</typeparam>
/// <returns>The element found.</returns>
/// <exception cref="InvalidCastException">The element is not found.</exception>
public static T FindOrThrow <T>(this INameScope nameScope, string name)
where T : class
{
var part = nameScope.Find <T>(name);
if (part == null)
{
throw new InvalidCastException(string.Format(CultureInfo.InvariantCulture,
Properties.Resources.TemplateElementNotFound, name, nameof(T)));
}
return(part);
}
public object Find(string name)
{
var found = _inner.Find(name);
if (found != null)
{
return(found);
}
if (_inner.IsCompleted)
{
return(_parentScope.Find(name));
}
return(null);
}
/// <summary>
/// Finds a named element in an <see cref="INameScope"/>.
/// </summary>
/// <typeparam name="T">The element type.</typeparam>
/// <param name="nameScope">The name scope.</param>
/// <param name="name">The name.</param>
/// <returns>The named element or null if not found.</returns>
public static T Find <T>(this INameScope nameScope, string name)
where T : class
{
Contract.Requires <ArgumentNullException>(nameScope != null);
Contract.Requires <ArgumentNullException>(name != null);
var result = nameScope.Find(name);
if (result != null && !(result is T))
{
throw new InvalidOperationException(
$"Expected control '{name}' to be '{typeof(T)} but it was '{result.GetType()}'.");
}
return((T)result);
}
/// <summary>
/// Gets a named element from an <see cref="INameScope"/> or throws if no element of the
/// requested name was found.
/// </summary>
/// <typeparam name="T">The element type.</typeparam>
/// <param name="nameScope">The name scope.</param>
/// <param name="name">The name.</param>
/// <returns>The named element.</returns>
public static T Get <T>(this INameScope nameScope, string name)
where T : class
{
_ = nameScope ?? throw new ArgumentNullException(nameof(nameScope));
_ = name ?? throw new ArgumentNullException(nameof(name));
var result = nameScope.Find(name);
if (result == null)
{
throw new KeyNotFoundException($"Could not find control '{name}'.");
}
if (!(result is T))
{
throw new InvalidOperationException(
$"Expected control '{name}' to be '{typeof(T)} but it was '{result.GetType()}'.");
}
return((T)result);
}
private void Update()
{
if (_name != null)
{
_nameScope = _relativeTo.FindNameScope();
if (_nameScope != null)
{
_nameScope.Registered += Registered;
_nameScope.Unregistered += Unregistered;
_value = _nameScope.Find <ILogical>(_name);
}
else
{
_value = null;
}
}
else
{
_value = _relativeTo.GetLogicalAncestors()
.Where(x => _ancestorType?.GetTypeInfo().IsAssignableFrom(x.GetType().GetTypeInfo()) ?? true)
.ElementAtOrDefault(_ancestorLevel);
}
}
/// <inheritdoc/>
protected override void OnTemplateApplied(INameScope nameScope)
{
Presenter = nameScope.Find <IItemsPresenter>("PART_ItemsPresenter");
}
/// <inheritdoc/>
protected override void OnTemplateApplied(INameScope nameScope)
{
Presenter = nameScope.Find<IItemsPresenter>("PART_ItemsPresenter");
}
/// <inheritdoc/>
protected override void OnTemplateApplied(INameScope nameScope)
{
// We allow ContentControls without ContentPresenters in the template. This can be
// useful for e.g. a simple ToggleButton that displays an image. There's no need to
// have a ContentPresenter in the visual tree for that.
Presenter = nameScope.Find<ContentPresenter>("PART_ContentPresenter");
}