mirror of https://github.com/dahall/Vanara.git
97 lines
5.0 KiB
C#
97 lines
5.0 KiB
C#
using System.Collections;
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using System.Collections.Generic;
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using System.Collections.Specialized;
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using System.ComponentModel;
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using System.IO;
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using System.Linq;
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using Vanara.Collections;
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using static Vanara.PInvoke.Shell32;
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namespace Vanara.Windows.Shell;
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/// <summary>The navigation log is a history of the locations visited by a shell view object.</summary>
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public class ShellNavigationHistory : IHistory<ShellItem>
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{
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private readonly History<PIDL> pidls = new();
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/// <summary>Initializes a new instance of the <see cref="ShellNavigationHistory"/> class.</summary>
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public ShellNavigationHistory()
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{
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pidls.CollectionChanged += (s, e) => CollectionChanged?.Invoke(this, e);
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pidls.PropertyChanged += (s, e) => PropertyChanged?.Invoke(this, e);
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}
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/// <summary>Occurs when an item is added, removed, changed, moved, or the entire list is refreshed.</summary>
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public event NotifyCollectionChangedEventHandler? CollectionChanged;
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/// <summary>Occurs when a property value changes.</summary>
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public event PropertyChangedEventHandler? PropertyChanged;
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/// <summary>Indicates the presence of items in the history that can be reached by calling <see cref="M:Vanara.Collections.IHistory`1.SeekBackward"/>.</summary>
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/// <value><see langword="true"/> if this instance can seek backward; otherwise, <see langword="false"/>.</value>
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public bool CanSeekBackward => pidls.CanSeekBackward;
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/// <summary>Indicates the presence of items in the history that can be reached by calling <see cref="M:Vanara.Collections.IHistory`1.SeekForward"/>.</summary>
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/// <value><see langword="true"/> if this instance can seek forward; otherwise, <see langword="false"/>.</value>
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public bool CanSeekForward => pidls.CanSeekForward;
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/// <summary>Gets the items in the history.</summary>
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/// <value>The number of items.</value>
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public int Count => pidls.Count;
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/// <summary>Gets the shell object in the Locations collection pointed to by CurrentLocationIndex.</summary>
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public ShellItem? Current => pidls.Current is null ? null : new(pidls.Current);
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/// <summary>
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/// Adds the specified item as the last history entry and sets the <see cref="P:Vanara.Collections.IHistory`1.Current"/> property to
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/// it's value.
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/// </summary>
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/// <param name="item">The item to add to the history.</param>
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public void Add(ShellItem item) => pidls.Add(item.PIDL, true);
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/// <summary>Clears the history of all items.</summary>
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public void Clear() => pidls.Clear();
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/// <summary>Returns an enumerator that iterates through the collection.</summary>
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/// <returns>A <see cref="IEnumerator{T}"/> that can be used to iterate through the collection.</returns>
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public IEnumerator<ShellItem> GetEnumerator() => pidls.WhereNotNull().Select(p => new ShellItem(p)).GetEnumerator();
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/// <summary>Gets a specified number of items starting at a location within the history.</summary>
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/// <param name="count">The maximum number of items to retrieve. The actual number of items returned may be less if not avaialable.</param>
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/// <param name="origin">The reference point within the history at which to start fetching items.</param>
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/// <returns>A read-only list of items.</returns>
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public IReadOnlyList<ShellItem> GetItems(int count, SeekOrigin origin) => new List<ShellItem>(pidls.GetItems(count, origin).Select(ShIFromPIDL).WhereNotNull());
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/// <summary>
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/// Seeks through the history a given number of items starting at a known location within the history. This updates the <see
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/// cref="P:Vanara.Collections.IHistory`1.Current"/> property.
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/// </summary>
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/// <param name="count">The number of items to move. This value can be negative to search backwards or positive to search forwards.</param>
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/// <param name="origin">The reference point within the history at which to start seeking.</param>
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/// <returns>The value at the new current pointer position.</returns>
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public ShellItem? Seek(int count, SeekOrigin origin) => ShIFromPIDL(pidls.Seek(count, origin));
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/// <summary>Seeks one position backwards.</summary>
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/// <returns>The value at the new current pointer position.</returns>
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public ShellItem? SeekBackward() => ShIFromPIDL(pidls.SeekBackward());
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/// <summary>Seeks one position forwards.</summary>
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/// <returns>The value at the new current pointer position.</returns>
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public ShellItem? SeekForward() => ShIFromPIDL(pidls.SeekForward());
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/// <summary>
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/// Adds the specified item as the last history entry and sets the <see cref="P:Vanara.Collections.IHistory`1.Current"/> property to
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/// it's value.
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/// </summary>
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/// <param name="item">The item to add to the history.</param>
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/// <param name="removeForwardItems">
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/// <see langword="true"/> indicates to remove all items forward of the current pointer; <see langword="false"/> leaves the history intact.
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/// </param>
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void IHistory<ShellItem>.Add(ShellItem? item, bool removeForwardItems) => pidls.Add(item?.PIDL, removeForwardItems);
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IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
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internal void Add(PIDL pidl) => pidls.Add(pidl, true);
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private static ShellItem? ShIFromPIDL(PIDL? pidl) => pidl is null ? null : new ShellItem(pidl);
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} |