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69 行
2.2 KiB

using System.Collections.Generic;
using Unity.UIWidgets.foundation;
namespace Unity.UIWidgets.widgets {
public delegate bool NotificationListenerCallback<T>(T notification) where T : Notification;
public abstract class Notification {
protected virtual bool visitAncestor(Element element) {
if (element is StatelessElement) {
StatelessWidget widget = (StatelessWidget) element.widget;
var listener = widget as _NotificationListener;
if (listener != null) {
if (listener._dispatch(this, element)) {
return false;
}
}
}
return true;
}
public void dispatch(BuildContext target) {
target?.visitAncestorElements(this.visitAncestor);
}
public override string ToString() {
var description = new List<string>();
this.debugFillDescription(description);
return $"{this.GetType()}({string.Join(", ", description.ToArray())})";
}
protected virtual void debugFillDescription(List<string> description) {
}
}
interface _NotificationListener {
bool _dispatch(Notification notification, Element element);
}
public class NotificationListener<T> : StatelessWidget, _NotificationListener where T : Notification {
public NotificationListener(
Key key = null,
Widget child = null,
NotificationListenerCallback<T> onNotification = null) : base(key) {
this.child = child;
this.onNotification = onNotification;
}
public readonly Widget child;
public readonly NotificationListenerCallback<T> onNotification;
bool _NotificationListener._dispatch(Notification notification, Element element) {
if (this.onNotification != null && notification is T) {
bool result = this.onNotification((T) notification);
return result;
}
return false;
}
public override Widget build(BuildContext context) {
return this.child;
}
}
public class LayoutChangedNotification : Notification {
}
}