WP8 - 绑定ProgressBar可见性(WP8 - Bind ProgressBar visibility)

 我有一个简单的代码，我检查了其他问题，但还没有。 
 
 我有一个应用程序，它从Web检索的xml文件中加载一些数据，然后在longlistselector中显示它。 
 
 我做到了，它的工作原理，现在我想添加一个不确定的进度条，它一直保持活动状态，直到我完成数据加载。 
 
 我将进度条包含在我的longlistselector之前的stackpanel中，并且我将其可见性限制在函数ProgressBarVisibility中（参见下面的代码）。 
 
        <phone:PivotItem Header="Status">
            <StackPanel>
            <ProgressBar Value ="0" IsIndeterminate="True" Visibility="{Binding ProgressBarVisibility}"/>
            <phone:LongListSelector Margin="0,0,-12,0" ItemsSource="{Binding PivotOne}">
                <phone:LongListSelector.ItemTemplate>
                    <!-- lots of code here -->
                </phone:LongListSelector.ItemTemplate>
            </phone:LongListSelector>
            </StackPanel>
        </phone:PivotItem>
 
 在MainViewModel.cs中，这就是我写的东西。 
 
    using System.Windows;


    public class MainViewModel : INotifyPropertyChanged
    {
    public MainViewModel()
    {
        this.PivotOne = new ObservableCollection<ItemViewModel>();
        this.PivotTwo = new ObservableCollection<ItemViewModel>();
        this.PivotThree = new ObservableCollection<ItemViewModel>();
    }

    /// <summary>
    /// A collection for ItemViewModel objects.
    /// </summary>
    public ObservableCollection<ItemViewModel> PivotOne { get; private set; }
    public ObservableCollection<ItemViewModel> PivotTwo { get; private set; }
    public ObservableCollection<ItemViewModel> PivotThree { get; private set; }

    private string _detailPageTitle = "Default";
    /// <summary>
    /// DetailPageTitle ritorna il titolo della pagina di dettaglio. Viene settato nella funzione che carica la pagina secondaria
    /// </summary>
    /// <returns></returns>
    public string DetailPageTitle
    {
        get
        {
            return _detailPageTitle;
        }
        set
        {
            if (value != _detailPageTitle)
            {
                _detailPageTitle = value;
                NotifyPropertyChanged("DetailPageTitle");
            }
        }
    }

    public bool IsDataLoaded
    {
        get;
        private set;
    }


    private Visibility _progressBarVisibility = Visibility.Collapsed;

    public Visibility ProgressBarVisibility
    {
        get
        {
            return _progressBarVisibility;
        }
        set
        {
            if (value != _progressBarVisibility)
            {
                _progressBarVisibility = value;
                NotifyPropertyChanged("ProgressBarVisibility");
            }
        }
    }


    private Visibility _progressBarVisibility = Visibility.Visible;

    public Visibility ProgressBarVisibility
    {
        get
        {
            return _progressBarVisibility;
        }
        set
        {
            if (value != _progressBarVisibility)
            {
                _progressBarVisibility = value;
                NotifyPropertyChanged("ProgressBarVisibility");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(String propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (null != handler)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    public void LoadData()
    {
        //progressbar is visible, data not loaded
        this.IsDataLoaded = false;
        ProgressBarVisibility = Visibility.Visible;

        // Load Static and dynamic data -- populate the different pivots
        LoadStaticData();
        LoadXMLFile();

        // data loaded, progressbar collapsed
        this.IsDataLoaded = true;
        ProgressBarVisibility = Visibility.Collapsed;
    }
 
 所以我包括了system.windows库，并使用了可见性类。 无论如何，当加载完成时，我无法让进度条消失，它会继续运行。 
 
 有什么建议吗？ 我在哪里做错了？ 
 
 提前致谢！ 
 
 解决方案：在应用程序激活时执行loaddata，因此此时内容甚至无法呈现。 

I have a simple thing to code, i checked other questions but couldn't it yet.
 
I have an application which loads some data from an xml file retrieved from the web, and then displays it inside a longlistselector.
 
I did it, it works, now i would like to add an indeterminate progressbar which stays active until I finished the data loading.
 
I enclosed the progressbar in a stackpanel, before my longlistselector, and i bound its visibility to the function ProgressBarVisibility (see code below).
 
        <phone:PivotItem Header="Status">
            <StackPanel>
            <ProgressBar Value ="0" IsIndeterminate="True" Visibility="{Binding ProgressBarVisibility}"/>
            <phone:LongListSelector Margin="0,0,-12,0" ItemsSource="{Binding PivotOne}">
                <phone:LongListSelector.ItemTemplate>
                    <!-- lots of code here -->
                </phone:LongListSelector.ItemTemplate>
            </phone:LongListSelector>
            </StackPanel>
        </phone:PivotItem>
 
In the MainViewModel.cs , that's how i wrote the thing.
 
    using System.Windows;


    public class MainViewModel : INotifyPropertyChanged
    {
    public MainViewModel()
    {
        this.PivotOne = new ObservableCollection<ItemViewModel>();
        this.PivotTwo = new ObservableCollection<ItemViewModel>();
        this.PivotThree = new ObservableCollection<ItemViewModel>();
    }

    /// <summary>
    /// A collection for ItemViewModel objects.
    /// </summary>
    public ObservableCollection<ItemViewModel> PivotOne { get; private set; }
    public ObservableCollection<ItemViewModel> PivotTwo { get; private set; }
    public ObservableCollection<ItemViewModel> PivotThree { get; private set; }

    private string _detailPageTitle = "Default";
    /// <summary>
    /// DetailPageTitle ritorna il titolo della pagina di dettaglio. Viene settato nella funzione che carica la pagina secondaria
    /// </summary>
    /// <returns></returns>
    public string DetailPageTitle
    {
        get
        {
            return _detailPageTitle;
        }
        set
        {
            if (value != _detailPageTitle)
            {
                _detailPageTitle = value;
                NotifyPropertyChanged("DetailPageTitle");
            }
        }
    }

    public bool IsDataLoaded
    {
        get;
        private set;
    }


    private Visibility _progressBarVisibility = Visibility.Collapsed;

    public Visibility ProgressBarVisibility
    {
        get
        {
            return _progressBarVisibility;
        }
        set
        {
            if (value != _progressBarVisibility)
            {
                _progressBarVisibility = value;
                NotifyPropertyChanged("ProgressBarVisibility");
            }
        }
    }


    private Visibility _progressBarVisibility = Visibility.Visible;

    public Visibility ProgressBarVisibility
    {
        get
        {
            return _progressBarVisibility;
        }
        set
        {
            if (value != _progressBarVisibility)
            {
                _progressBarVisibility = value;
                NotifyPropertyChanged("ProgressBarVisibility");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(String propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (null != handler)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    public void LoadData()
    {
        //progressbar is visible, data not loaded
        this.IsDataLoaded = false;
        ProgressBarVisibility = Visibility.Visible;

        // Load Static and dynamic data -- populate the different pivots
        LoadStaticData();
        LoadXMLFile();

        // data loaded, progressbar collapsed
        this.IsDataLoaded = true;
        ProgressBarVisibility = Visibility.Collapsed;
    }
 
So i included system.windows library, and used the visibility class. Anyway, i cannot get the progressbar to disappear when the loading is done, it keeps going.
 
Any suggestion? where am i doing it wrong?
 
Thanks in advance!
 
Solution: loaddata is executed on the app activation, so the content is not even rendered at that moment. 

原文：https://stackoverflow.com/questions/18298263