Question

我试图学习一致的反应，所以我想为Android制作简单的小费计算器应用程序。 ViewModel是：

public class TipCalcViewModel : ReactiveObject
{
    [IgnoreDataMember] private double _subtotal;

    [DataMember]
    public double Subtotal
    {
        get { return _subtotal; }
        set { this.RaiseAndSetIfChanged(ref _subtotal, value); }
    }

    [IgnoreDataMember] private int _percentage;

    [DataMember]
    public int Percentage
    {
        get { return _percentage; }
        set { this.RaiseAndSetIfChanged(ref _percentage, value); }
    }

    [IgnoreDataMember] private readonly ObservableAsPropertyHelper<double> _tipAmount;

    [DataMember]
    public double TipAmount
    {
        get { return _tipAmount.Value; }
    }

    [IgnoreDataMember] private readonly ObservableAsPropertyHelper<double> _total;

    [DataMember]
    public double Total
    {
        get { return _total.Value; }
    }

    public TipCalcViewModel(ITipCalcService service)
    {
        _tipAmount = this.WhenAnyValue(
            x => x.Subtotal,
            y => y.Percentage,
            service.CalculateTipAmount)
            .ToProperty(this, vm => vm.TipAmount);

        _total = this.WhenAnyValue(
            x => x.Subtotal,
            y => y.Percentage,
            service.CalculateTotal)
            .ToProperty(this, vm => vm.Total);
    }
}

活动看起来像这样：

public class TipCalcActivity : ReactiveActivity<TipCalcViewModel>
{
    public EditText SubTotal { get { return this.GetControl<EditText>(); } }
    public SeekBar Percentage { get { return this.GetControl<SeekBar>(); } }
    public TextView PercentageText { get { return this.GetControl<TextView>(); } }
    public TextView TipAmount { get { return this.GetControl<TextView>(); } }
    public TextView Total { get { return this.GetControl<TextView>(); } }

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);
        var service = new TipCalcService();
        ViewModel = new TipCalcViewModel(service);

        this.Bind(ViewModel, vm => vm.Subtotal, v => v.SubTotal.Text);
        //this.Bind(ViewModel, vm => vm.Percentage, v => v.Percentage.Progress);
        this.OneWayBind(ViewModel, vm => vm.Percentage, v => v.PercentageText.Text);
        this.OneWayBind(ViewModel, vm => vm.TipAmount, v => v.TipAmount.Text);
        this.OneWayBind(ViewModel, vm => vm.Total, v => v.Total.Text);

        var disposable = Observable.FromEventPattern<SeekBar.ProgressChangedEventArgs>(
            h => Percentage.ProgressChanged += h,
            h => Percentage.ProgressChanged -= h)
            .Throttle(TimeSpan.FromMilliseconds(500))
            .DistinctUntilChanged()
            .ObserveOn(RxApp.MainThreadScheduler)
            .Subscribe(x => 
                ViewModel.Percentage = x.EventArgs.Progress);
    }
}

所以问题：

如果我使用上面的注释绑定没有任何反应。因此，progress属性正在正确更改，但ViewModel的Percentage属性永远不会被设置。绑定正在从viewmodel工作到视图，但不是其他方式（EditText绑定在两个方向都正常工作）。如何解决这个问题？
如果我从ProgressChanged事件创建observable，我设法使它工作。但即使我不得不做这样的事情，我也不确定这是不是正确的方法。当活动被破坏或不被破坏时，我还必须处理订阅吗？
最后一件事。如果我想学习这个框架，最好的方法是什么？

Answer 1

SeekBar很可能不在支持的开箱即用控件列表中; Android没有内置的方法来观察视图属性，因此我们必须将它们硬编码为一次性。如果你写下这样的话，你可以使这个工作：

var progressChanged = Observable.FromEventPattern<SeekBar.ProgressChangedEventArgs>(
        h => Percentage.ProgressChanged += h,
        h => Percentage.ProgressChanged -= h);

this.Bind(ViewModel, 
    vm => vm.Percentage, 
    v => v.Percentage.Progress, 
    signalViewUpdate: progressChanged);

Reactiveui绑定不适用于SeekBar.Progress

1 个答案: