58 lines
2.0 KiB
C#
58 lines
2.0 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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using System.ComponentModel;
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#pragma warning disable CA1001
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namespace CommunityToolkit.Common.Deferred;
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/// <summary>
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/// <see cref="EventArgs"/> which can retrieve a <see cref="EventDeferral"/> in order to process data asynchronously before an <see cref="EventHandler"/> completes and returns to the calling control.
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/// </summary>
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public class DeferredEventArgs : EventArgs
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{
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/// <summary>
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/// Gets a new <see cref="DeferredEventArgs"/> to use in cases where no <see cref="EventArgs"/> wish to be provided.
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/// </summary>
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public static new DeferredEventArgs Empty => new();
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private readonly object eventDeferralLock = new();
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private EventDeferral? eventDeferral;
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/// <summary>
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/// Returns an <see cref="EventDeferral"/> which can be completed when deferred event is ready to continue.
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/// </summary>
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/// <returns><see cref="EventDeferral"/> instance.</returns>
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public EventDeferral GetDeferral()
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{
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lock (this.eventDeferralLock)
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{
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return this.eventDeferral ??= new EventDeferral();
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}
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}
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/// <summary>
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/// DO NOT USE - This is a support method used by <see cref="EventHandlerExtensions"/>. It is public only for
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/// additional usage within extensions for the UWP based TypedEventHandler extensions.
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/// </summary>
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/// <returns>Internal EventDeferral reference</returns>
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[Browsable(false)]
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[EditorBrowsable(EditorBrowsableState.Never)]
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[Obsolete("This is an internal only method to be used by EventHandler extension classes, public callers should call GetDeferral() instead.")]
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public EventDeferral? GetCurrentDeferralAndReset()
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{
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lock (this.eventDeferralLock)
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{
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EventDeferral? eventDeferral = this.eventDeferral;
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this.eventDeferral = null;
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return eventDeferral;
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}
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}
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}
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