63 lines
2.1 KiB
C#
63 lines
2.1 KiB
C#
using Avalonia;
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using ReactiveUI;
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using Ursa.Controls;
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/* These codes are ported from Avalonia.ReactiveUI.
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* **/
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namespace Ursa.ReactiveUIExtension;
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/// <summary>
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/// A ReactiveUI <see cref="UrsaView"/> that implements the <see cref="IViewFor{TViewModel}"/> interface and
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/// will activate your ViewModel automatically if the view model implements <see cref="IActivatableViewModel"/>.
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/// When the DataContext property changes, this class will update the ViewModel property with the new DataContext
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/// value, and vice versa.
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/// </summary>
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/// <typeparam name="TViewModel">ViewModel type.</typeparam>
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public class ReactiveUrsaView<TViewModel> : UrsaView, IViewFor<TViewModel> where TViewModel : class
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{
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[System.Diagnostics.CodeAnalysis.SuppressMessage("AvaloniaProperty", "AVP1002", Justification = "Generic avalonia property is expected here.")]
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public static readonly StyledProperty<TViewModel?> ViewModelProperty = AvaloniaProperty
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.Register<ReactiveUrsaView<TViewModel>, TViewModel?>(nameof(ViewModel));
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/// <summary>
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/// Initializes a new instance of the <see cref="ReactiveUrsaView{TViewModel}"/> class.
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/// </summary>
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public ReactiveUrsaView()
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{
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// This WhenActivated block calls ViewModel's WhenActivated
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// block if the ViewModel implements IActivatableViewModel.
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this.WhenActivated(disposables => { });
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}
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/// <summary>
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/// The ViewModel.
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/// </summary>
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public TViewModel? ViewModel
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{
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get => GetValue(ViewModelProperty);
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set => SetValue(ViewModelProperty, value);
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}
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object? IViewFor.ViewModel
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{
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get => ViewModel;
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set => ViewModel = (TViewModel?)value;
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}
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protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
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{
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base.OnPropertyChanged(change);
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if (change.Property == DataContextProperty) {
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if (ReferenceEquals(change.OldValue, ViewModel)
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&& change.NewValue is null or TViewModel) {
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SetCurrentValue(ViewModelProperty, change.NewValue);
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}
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}
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else if (change.Property == ViewModelProperty) {
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if (ReferenceEquals(change.OldValue, DataContext)) {
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SetCurrentValue(DataContextProperty, change.NewValue);
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}
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}
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}
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} |