c# – 状态栏记录y的y

我想在StatusBar中显示’记录x的y’,因此,作为第一步,我尝试使用此XAML在网格中显示它：

<TextBlock Grid.Row="2" Grid.Column="3">
    <TextBlock Text="{Binding CurrentPosition}" /> <TextBlock Text="{Binding Count}" />
</TextBlock>

Count无问题地工作,并在添加新项目时自动更新.我的代码中定义的CurrentPosition不断保持为0.

如何使CurrentPosition自动更新？我希望不必使用INotify **,因为这已经是一个ObservableCollection.

我也没有任何代码隐藏,所以我希望它可以在我的类(或模型)和XAML中实现.

我确实尝试过使用CurrentChanged但没有成功：

public MyObservableCollection() : base() {
        this.GetDefaultView().CurrentChanged += MyObservableCollection_CurrentChanged;
    }

MyObservableCollection：

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace ToDoApplication.Models {
    public class MyObservableCollection<T> : ObservableCollection<T> {

        public MyObservableCollection() : base() {
        }

        public MyObservableCollection(List<T> list) : base(list) {
        }

        public MyObservableCollection(IEnumerable<T> collection) : base(collection) {
        }

        private System.ComponentModel.ICollectionView GetDefaultView() {
            return System.Windows.Data.CollectionViewSource.GetDefaultView(this);
        }

        public int CurrentPosition {
            get {
                return this.GetDefaultView().CurrentPosition;
            }
        }

        public void MoveFirst() {
            this.GetDefaultView().MoveCurrentToFirst();
        }
        public void MovePrevious() {
            this.GetDefaultView().MoveCurrentToPrevious();
        }
        public void MoveNext() {
            this.GetDefaultView().MoveCurrentToNext();
        }
        public void MoveLast() {
            this.GetDefaultView().MoveCurrentToLast();
        }

        public bool CanMoveBack() {
            return this.CurrentPosition > 0;
        }
        public bool CanMoveForward() {
            return (this.Count > 0) && (this.CurrentPosition < this.Count - 1);
        }
    }

    public enum Navigation {
        First,Previous,Next,Last,Add
    }
}

更新：我正在添加以下代码作为可能的解决方案,但我不是很喜欢它,我希望更好的一个出现,不需要我使用INotifyPropertyChanged – 我怀疑我将结束重复所有ObservableCollection应该已经具备的功能. (我也不知道为什么我需要重新通知Count更改.)

更新2：以下不是(完整)解决方案,因为它会干扰集合的其他行为(通知),但我保留了它,以防它包含任何有用的信息.

namespace ToDoApplication.Models {
    public class MyObservableCollection<T> : ObservableCollection<T>,INotifyPropertyChanged {
        public new event PropertyChangedEventHandler PropertyChanged;
        private int _currentPos = 1;

        public MyObservableCollection() : base() {
            this.GetDefaultView().CurrentChanged += MyObservableCollection_CurrentChanged;
            this.CollectionChanged += MyObservableCollection_CollectionChanged;
        }

        public MyObservableCollection(List<T> list) : base(list) {
            this.GetDefaultView().CurrentChanged += MyObservableCollection_CurrentChanged;
            this.CollectionChanged += MyObservableCollection_CollectionChanged;
        }
        public MyObservableCollection(IEnumerable<T> collection) : base(collection) {
            this.GetDefaultView().CurrentChanged += MyObservableCollection_CurrentChanged;
            this.CollectionChanged += MyObservableCollection_CollectionChanged;
        }

        void MyObservableCollection_CurrentChanged(object sender,EventArgs e) {
            this.CurrentPosition = this.GetDefaultView().CurrentPosition;
        }
        void MyObservableCollection_CollectionChanged(object sender,System.Collections.Specialized.NotifyCollectionChangedEventArgs e) {
            RaisePropertyChanged("Count");
        }

        private System.ComponentModel.ICollectionView GetDefaultView() {
            return System.Windows.Data.CollectionViewSource.GetDefaultView(this);
        }

        public int CurrentPosition {
            get {
                return _currentPos;
            }
            private set {
                if (_currentPos == value + 1) return;
                _currentPos = value + 1;
                RaisePropertyChanged("CurrentPosition");
            }
        }

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

        public void MoveFirst() {
            this.GetDefaultView().MoveCurrentToFirst();
        }
        public void MovePrevious() {
            this.GetDefaultView().MoveCurrentToPrevious();
        }
        public void MoveNext() {
            this.GetDefaultView().MoveCurrentToNext();
        }
        public void MoveLast() {
            this.GetDefaultView().MoveCurrentToLast();
        }

        public bool CanMoveBack() {
            return this.CurrentPosition > 1;
        }
        public bool CanMoveForward() {
            return (this.Count > 0) && (this.CurrentPosition < this.Count);
        }
    }

    public enum Navigation {
        First,Add
    }
}

有了这个,我可以在网格中显示“第1项3”：

<TextBlock Grid.Row="2" Grid.Column="3" x:Name="txtItemOf">Item 
            <TextBlock x:Name="txtItem" Text="{Binding CurrentPosition}" /> of 
            <TextBlock x:Name="txtOf" Text="{Binding Count}" />
    </TextBlock>

我不再需要这个TextBlock,因为我可以直接在(主)StatusBar中引用DataContext属性：

<StatusBar DockPanel.Dock="Bottom">
        Item <TextBlock Text="{Binding ElementName=vwToDo,Path=DataContext.CurrentPosition}" />
        Of <TextBlock Text="{Binding ElementName=vwToDo,Path=DataContext.Count}" />
    </StatusBar>

问题和解决方案

关注@JMarsch的回答：命名我的属性CurrentPosition正在屏蔽直接从DataContext可用的同名属性,因为绑定是集合的默认视图(具有此属性).

解决方案要么重命名为MyCurrentPosition,要么从StatusBar引用原始属性,或者像我一样,完全删除我的这个属性(和GetDefaultView)的版本：它们没有做任何特别有用的事情.

然后我使用以下简单的ValueConverter将0,1,2,..转换为1,3,..在StatusBar中.

[ValueConversion(typeof(int),typeof(int))]
class PositionConverter : IValueConverter {
    public object Convert(object value,Type targetType,object parameter,System.Globalization.CultureInfo culture) {
        return (int)value + 1;
    }

    public object ConvertBack(object value,System.Globalization.CultureInfo culture) {
        return (int)value - 1;
    }
}

状态栏：

<StatusBar DockPanel.Dock="Bottom" x:Name="status">
        Item <TextBlock Text="{Binding ElementName=vwToDo,Path=DataContext.CurrentPosition,Converter={StaticResource posConverter}}" />
        Of <TextBlock Text="{Binding ElementName=vwToDo,Path=DataContext.Count}" />
    </StatusBar>