86 lines
3.1 KiB
C#
86 lines
3.1 KiB
C#
namespace Caliburn.Micro {
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using System.Collections.Specialized;
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using System.Linq;
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using System.Windows;
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using System.Windows.Interactivity;
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using Caliburn.Micro.Core;
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/// <summary>
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/// A collection that can exist as part of a behavior.
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/// </summary>
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/// <typeparam name="T">The type of item in the attached collection.</typeparam>
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public class AttachedCollection<T> : FreezableCollection<T>, IAttachedObject
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where T : DependencyObject, IAttachedObject {
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DependencyObject associatedObject;
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/// <summary>
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/// Creates an instance of <see cref="AttachedCollection{T}"/>
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/// </summary>
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public AttachedCollection() {
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((INotifyCollectionChanged)this).CollectionChanged += OnCollectionChanged;
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}
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/// <summary>
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/// Attached the collection.
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/// </summary>
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/// <param name="dependencyObject">The dependency object to attach the collection to.</param>
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public void Attach(DependencyObject dependencyObject) {
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WritePreamble();
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associatedObject = dependencyObject;
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WritePostscript();
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this.Apply(x => x.Attach(associatedObject));
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}
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/// <summary>
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/// Detaches the collection.
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/// </summary>
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public void Detach() {
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this.Apply(x => x.Detach());
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WritePreamble();
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associatedObject = null;
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WritePostscript();
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}
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DependencyObject IAttachedObject.AssociatedObject {
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get { return associatedObject; }
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}
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/// <summary>
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/// Called when an item is added from the collection.
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/// </summary>
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/// <param name="item">The item that was added.</param>
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protected virtual void OnItemAdded(T item) {
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if (associatedObject != null)
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item.Attach(associatedObject);
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}
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/// <summary>
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/// Called when an item is removed from the collection.
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/// </summary>
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/// <param name="item">The item that was removed.</param>
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protected virtual void OnItemRemoved(T item) {
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if(item.AssociatedObject != null)
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item.Detach();
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}
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void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e) {
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switch(e.Action) {
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case NotifyCollectionChangedAction.Add:
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e.NewItems.OfType<T>().Where(x => !Contains(x)).Apply(OnItemAdded);
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break;
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case NotifyCollectionChangedAction.Remove:
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e.OldItems.OfType<T>().Apply(OnItemRemoved);
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break;
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case NotifyCollectionChangedAction.Replace:
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e.OldItems.OfType<T>().Apply(OnItemRemoved);
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e.NewItems.OfType<T>().Where(x => !Contains(x)).Apply(OnItemAdded);
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break;
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case NotifyCollectionChangedAction.Reset:
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this.Apply(OnItemRemoved);
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this.Apply(OnItemAdded);
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break;
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}
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}
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}
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} |