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Implements the functionality common to all page transitions. Also: - Don't inherit from `PageSlide` in `Rotate3DTransition` - Don't use a nested enum for `PageSlide.Orientation`fixes/11167-pagetransition-flicker
Steven Kirk
3 years ago
8 changed files with 449 additions and 345 deletions
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using System; |
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using System.Collections.Generic; |
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using System.Threading; |
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using System.Threading.Tasks; |
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using Avalonia.Styling; |
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namespace Avalonia.Animation |
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{ |
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/// <summary>
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/// Base class for animations that transition between two controls.
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/// </summary>
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public abstract class PageTransition : IPageTransition |
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{ |
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private TimeSpan _duration; |
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private Animation? _hideVisibilityAnimation; |
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private Animation? _showVisibilityAnimation; |
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/// <summary>
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/// Initializes a new instance of the <see cref="PageTransition"/> class.
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/// </summary>
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public PageTransition() |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="PageTransition"/> class.
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/// </summary>
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/// <param name="duration">The duration of the animation.</param>
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public PageTransition(TimeSpan duration) |
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{ |
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_duration = duration; |
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} |
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/// <summary>
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/// Gets or sets the duration of the animation.
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/// </summary>
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public TimeSpan Duration |
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{ |
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get => _duration; |
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set |
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{ |
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if (_duration != value) |
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{ |
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_duration = value; |
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InvalidateCachedAnimations(); |
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} |
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} |
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} |
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/// <summary>
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/// Starts the animation.
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/// </summary>
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/// <param name="from">
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/// The control that is being transitioned away from. May be null.
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/// </param>
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/// <param name="to">
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/// The control that is being transitioned to. May be null.
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/// </param>
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/// <param name="cancellationToken">
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/// Animation cancellation.
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/// </param>
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/// <returns>
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/// A <see cref="Task"/> that tracks the progress of the animation.
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/// </returns>
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/// <remarks>
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/// The <paramref name="from"/> and <paramref name="to"/> controls will be made visible
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/// and <paramref name="from"/> transitioned to <paramref name="to"/>. At the end of the
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/// animation (when the returned task completes), <paramref name="from"/> will be made
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/// invisible but all other properties involved in the transition will have been left
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/// unchanged.
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/// </remarks>
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public Task Start(Visual? from, Visual? to, CancellationToken cancellationToken) |
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{ |
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return Start(from, to, true, cancellationToken); |
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} |
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/// <summary>
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/// Starts the animation.
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/// </summary>
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/// <param name="from">
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/// The control that is being transitioned away from. May be null.
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/// </param>
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/// <param name="to">
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/// The control that is being transitioned to. May be null.
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/// </param>
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/// <param name="forward">
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/// If the animation is bidirectional, controls the direction of the animation.
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/// </param>
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/// <param name="cancellationToken">
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/// Animation cancellation.
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/// </param>
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/// <returns>
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/// A <see cref="Task"/> that tracks the progress of the animation.
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/// </returns>
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/// <remarks>
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/// The <paramref name="from"/> and <paramref name="to"/> controls will be made visible
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/// and <paramref name="from"/> transitioned to <paramref name="to"/>. At the end of the
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/// animation (when the returned task completes), <paramref name="from"/> will be made
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/// invisible but all other properties involved in the transition will have been left
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/// unchanged.
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/// </remarks>
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public async Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken) |
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{ |
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if (cancellationToken.IsCancellationRequested) |
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return; |
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List<Task>? tasks = null; |
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if (from is not null) |
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{ |
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tasks ??= new(); |
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tasks.Add(GetHideVisibilityAnimation().RunAsync(from, null, cancellationToken)); |
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tasks.Add(GetHideAnimation(from, to, forward).RunAsync(from, null, cancellationToken)); |
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} |
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if (to is not null) |
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{ |
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tasks ??= new(); |
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tasks.Add(GetShowAnimation(from, to, forward).RunAsync(to, null, cancellationToken)); |
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tasks.Add(GetShowVisibilityAnimation().RunAsync(to, null, cancellationToken)); |
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} |
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if (tasks is not null) |
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await Task.WhenAll(tasks); |
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} |
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/// <summary>
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/// When implemented in a derived class, returns the animation used to transition away from
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/// the <paramref name="from"/> control.
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/// </summary>
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/// <param name="from">
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/// The control that is being transitioned away from. May be null.
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/// </param>
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/// <param name="to">
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/// The control that is being transitioned to. May be null.
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/// </param>
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/// <param name="forward">
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/// If the animation is bidirectional, controls the direction of the animation.
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/// </param>
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protected abstract Animation GetHideAnimation(Visual? from, Visual? to, bool forward); |
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/// <summary>
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/// When implemented in a derived class, returns the animation used to transition to the
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/// <paramref name="to"/> control.
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/// </summary>
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/// <param name="from">
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/// The control that is being transitioned away from. May be null.
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/// </param>
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/// <param name="to">
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/// The control that is being transitioned to. May be null.
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/// </param>
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/// <param name="forward">
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/// If the animation is bidirectional, controls the direction of the animation.
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/// </param>
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protected abstract Animation GetShowAnimation(Visual? from, Visual? to, bool forward); |
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/// <summary>
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/// Called when a property that affects the animation is changed.
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/// </summary>
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protected virtual void InvalidateCachedAnimations() |
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{ |
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if (_hideVisibilityAnimation is not null) |
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_hideVisibilityAnimation.Duration = _duration; |
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if (_showVisibilityAnimation is not null) |
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_showVisibilityAnimation.Duration = _duration; |
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} |
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private Animation GetHideVisibilityAnimation() |
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{ |
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return _hideVisibilityAnimation ??= CreateIsVisibleAnimation(Duration, false); |
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} |
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private Animation GetShowVisibilityAnimation() |
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{ |
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return _showVisibilityAnimation ??= CreateIsVisibleAnimation(Duration, true); |
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} |
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private static Animation CreateIsVisibleAnimation(TimeSpan duration, bool endState) |
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{ |
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return new() |
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{ |
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Duration = duration, |
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FillMode = FillMode.Forward, |
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Children = |
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{ |
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new KeyFrame() |
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{ |
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Setters = |
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{ |
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new Setter |
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{ |
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Property = Visual.IsVisibleProperty, |
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Value = true, |
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}, |
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}, |
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Cue = new Cue(0) |
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}, |
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new KeyFrame() |
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{ |
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Setters = |
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{ |
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new Setter |
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{ |
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Property = Visual.IsVisibleProperty, |
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Value = endState, |
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}, |
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}, |
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Cue = new Cue(1) |
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} |
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} |
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}; |
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} |
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} |
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} |
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