c# - 将多个复选框绑定(bind)到 ViewModel 中的单个属性

Question

我想将多个 CheckBox 项(IsChecked 属性)绑定(bind)到我的 ViewModel 中的单个属性。

ViewModel 属性称为 SelectedWeekdays (int)，是所有选定工作日的总和。这个想法是工作日值的每一种可能组合都将始终产生唯一的总和。工作日在枚举中定义如下:

public enum Weekdays
{
    Monday = 1
    Tuesday = 2
    Wednesday = 4
    Thursday = 8
    Friday = 16
    Saturday = 32
    Sunday = 64
}

例如，如果在 View 上选择了星期二和星期四，这应该导致 ViewModel 属性值为 10。

同样，如果 ViewModel 属性更改为 3，则应选中星期一和星期二的复选框。

我查看了 MultiBindings，但似乎我只能使用它来将单个 CheckBox 绑定(bind)到多个值。你能给我指出正确的方向吗？

Answer 1

这对你有用吗？我没有实现 ConvertBack。这应该很容易。

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = this;

        SelectedWeekday = Weekdays.Tuesday;
    }

    private Weekdays _selectedWeekday;
    public Weekdays SelectedWeekday
    {
        get { return _selectedWeekday; }
        set
        {
            _selectedWeekday = value;
            if(PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("SelectedWeekday"));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

[Flags]
public enum Weekdays
{
    Monday = 1,
    Tuesday = 2,
    Wednesday = 4,
    Thursday = 8,
    Friday = 16,
    Saturday = 32,
    Sunday = 64
}

public class WeekdayConverter : IValueConverter, INotifyPropertyChanged
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var day = (Weekdays)value;
        if ((day & Weekday) != 0)
            return true;
        return false;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        //Implement convertback
        throw new NotImplementedException();
    }

    private Weekdays _weekday;
    public Weekdays Weekday
    {
        get { return _weekday; }
        set
        {
            _weekday = value;
            if(PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("Weekday"));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

XAML:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:view="clr-namespace:WpfApplication2"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <view:WeekdayConverter x:Key="MondayConverter" Weekday="Monday"></view:WeekdayConverter>
        <view:WeekdayConverter x:Key="TuesdayConverter" Weekday="Tuesday"></view:WeekdayConverter>
    </Window.Resources>
    <StackPanel>
        <CheckBox Content="Monday" IsChecked="{Binding SelectedWeekday, Converter={StaticResource MondayConverter}}" />
        <CheckBox Content="Tuesday" IsChecked="{Binding SelectedWeekday, Converter={StaticResource TuesdayConverter}}" />
    </StackPanel>
</Window>