Silverlight：绑定到涉及属性的计算结果

Question

我想做的不仅是将属性 X 绑定到滑块，还将涉及 X 的计算结果绑定到饼图，因此当用户滑动滑块时，饼图会自动更新.

以下是我现在所拥有的。当我滑动“食物”滑块时，饼图会相应更新。但是，如果移动“租用”滑块，则不会发生任何事情。我猜renterInsurance.Value = rent.Value * 0.1 只被评估一次，所以在执行之后的任何rent.Value 变化都不会影响renterInsurance.Value。我如何实现我所需要的？实际计算可能涉及其他属性/变量。

public partial class MainPage : UserControl
{       
    public class Expense : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private string _Name;
        public string Name
        {
            get { return _Name; }
            set
            {
                _Name = value;
                NotifyPropertyChanged("Name");
            }
        }

        private double _Value;
        public double Value
        {
            get { return _Value; }
            set
            {
                _Value = value;
                NotifyPropertyChanged("Value");
            }
        }

        public void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }             

    public MainPage()
    {
        InitializeComponent();

        PieSeries ps = exampleChart.Series[0] as PieSeries;

        List<Expense> expenses = new List<Expense>();  

        Expense food = new Expense();
        food.Name = "Food";
        food.Value = 50;
        sliderFood.DataContext = food;
        expenses.Add(food);

        Expense rent = new Expense();
        rent.Name = "Rent";
        rent.Value = 100;
        sliderRent.DataContext = rent;

        Expense renterInsurance = new Expense();
        renterInsurance.Name = "Renter's Insurance";
        renterInsurance.Value = rent.Value * 0.1;
        expenses.Add(renterInsurance);
        ps.ItemsSource = expenses;


    }       
}

XAML：

<Grid x:Name="LayoutRoot" Background="White" Height="700" Width="600">
    <Canvas Height="700" Width="600">                

    <toolkit:Chart Name="exampleChart" Height="300" Width="300" Canvas.Left="150" Canvas.Top="5">
        <toolkit:Chart.Series>
            <toolkit:PieSeries IndependentValueBinding="{Binding Name}" DependentValueBinding="{Binding Value}" />                                    
        </toolkit:Chart.Series>
    </toolkit:Chart>

    <Slider Canvas.Left="11" Canvas.Top="65" Height="23" HorizontalAlignment="Left" Margin="158,254,0,0" Name="sliderFood" VerticalAlignment="Top" Width="100" Minimum="0" Maximum="100" 
            Value="{Binding Value, Mode=TwoWay}"/>
    <Slider Height="23" HorizontalAlignment="Left" Margin="158,12,0,0" Name="sliderRent" VerticalAlignment="Top" Width="100" Minimum="0" Maximum="100" Canvas.Left="154" Canvas.Top="307" 
            Value="{Binding Value,Mode=TwoWay}"/>
        </Canvas>
</Grid>

Answer 1

您需要修改费用类别，以便它可以订阅其他费用类别的 propertyChanged 事件，这样您就可以将租房者保险连接到租金类别，并让它在看到该租金时更新自己的值。值变化。

我相信这条线应该可行。您可以将其添加到构造函数的底部。

rent.PropertyChanged += (sender, args) => {
  if (args.PropertyName == "Value")
    renterInsurance.Value = ((Expense)sender).Value * 0.1;
};