Question

在我的应用中，我允许用户出于各种原因去市场。在加载市场时，如果用户非常快地点击后退按钮，它将尝试返回我保存的应用程序。来自iso-storage等的所有数据都加载得很好，但是屏幕被冻结了。我为各种枢轴项目设置了不同的应用程序栏，当我进行滑动动作时，我看到应用程序栏发生了变化，所以我知道应用程序是响应式的。

主要问题是屏幕卡在用户最初启动市场任务的位置。我理解在这个边缘情况下，我的App和Page构造函数没有触发，并且触发的事件是从导航，应用程序停用，应用程序激活和导航到。

我以为我可以使用布尔来基本涵盖市场任务被解雇时的情况，这样我就可以在on导航到方法中重新加载数据上下文并将其设置为我的视图模型。然而屏幕仍然冻结。

非常感谢有关此问题的任何帮助，感谢

编辑：这是一些相关的代码

private void Application_Activated(object sender, ActivatedEventArgs e)
{
    if (!App.ViewModel.IsDataLoaded)
    {
        App.ViewModel.LoadData();
    }

    DetermineIsTrial();
}

private void Application_Deactivated(object sender, DeactivatedEventArgs e)
{
    if (playerController.chapterPlayer != null)
    {
        var store = new PersistentDataStorage();
        store.Backup(StringResource.ChapterPosition, playerController.chapterPlayer.Position);
        store.Backup(StringResource.ChapterUriString, playerController.chapterPlayer.Source.OriginalString);
        store.Backup(StringResource.NaturalDuration, playerController.chapterPlayer.NaturalDuration.TimeSpan);
    }
}

主页XAML：

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    App.viewIdentifier = StringResource.MainPageView;

    if (App.firstTimeLoading == false && PivotBackground.SelectedItem != SuggestedPivotItem)
    {
        BuildApplicationBar();
    }
    else if (PivotBackground.SelectedItem == SuggestedPivotItem)
    {
        BuildMarketPlaceApplicationBar();
    }

    if (App.firstTimeLoading == true)
    {
        BuildApplicationBar(); //builds the application bar

        //Restore the state from tombstone and set the audioplayer.
        App.playerController = new PlayerButtonsController();
        App.playerController.SetMediaPlayer(App.MainAudioPlayer);
        RestoreState();
        ResourceDictionary appResourceList = App.Current.Resources;
        App.firstTimeLoading = false;
        //default source for chapter position
        App.AudioMgr.SetChapterSource(0);
    }
}

更多方法：

private void RestoreState()
{
    var store = new PersistentDataStorage();
    playerWasWhere = store.Restore<TimeSpan>(StringResource.ChapterPosition);
    naturalDuration = store.Restore<TimeSpan>(StringResource.NaturalDuration);
    currentAudioFile = store.Restore<String>(StringResource.ChapterUriString);
    SetAudioListScrollPosition();
    App.playerController.SetPositionFromIsoStorage(currentAudioFile, playerWasWhere, naturalDuration);
}

public void LoadData()
{

    CreateAudioPlayerGUIfromChapterList();
    CreateAboutMenuGUIfromExtrasData();
    CreateQuotesMenuGUIfromExtrasData();
    this.IsDataLoaded = true;
}

private void CreateAudioPlayerGUIfromChapterList()
{
    int numberOfChapters = 0;
    for (int i = 0; i < App.AudioMgr.Parts.Count; i++)
    {
        ObservableCollection<ItemViewModel> tempObservableCollection = new ObservableCollection<ItemViewModel>();
        for (int j = 0; j < App.AudioMgr.Parts[i].NumberOfChapters; j++)
        {
            tempObservableCollection.Add(new ItemViewModel()
            {
                LineOne = ProcessTitle(App.AudioMgr.Chapters[numberOfChapters + j].Title),
                LineTwo = App.AudioMgr.Chapters[numberOfChapters + j].StatusMessage,
                ItemAlpha = 0.0,
                ChapterForeground = ChapterInfo.StatusColor[(int)App.AudioMgr.Chapters[numberOfChapters + j].Status],
                Progress = 0,
                Width = 0,
                UserColorTheme = App.accentBrush,
                PlayIconVisible = Visibility.Collapsed,
                ChapterDurationProgressBarAdjacent = StringResource.Space,
                ContainingPart = i,
                MediaStateImageSource = StringResource.KJIcons + App.themeDir + StringResource.AppBarSpeaker
            });
        }
        numberOfChapters += App.AudioMgr.Parts[i].NumberOfChapters;

        //no parts header doesn't need spacing or border since its the first header.
        if (i == 0 && App.AudioMgr.Parts[i].Title == "")
        {
            Parts.Add(new PartsViewModel()
            {
                PartsHeader = StringResource.Space,
                ChapterForeground = App.defaultForeground,
                ChaptersInPart = tempObservableCollection,
                PartsBackgroundBrush = App.partsBackgroundBrush,
                PartsHeaderHeight = 0,
                PartsBorderThickness = new Thickness(0)
            });
        }
        //parts header needs spacing and border
        else if (App.AudioMgr.Parts[i].Title != "")
        {
            Parts.Add(new PartsViewModel()
            {
                PartsHeader = App.AudioMgr.Parts[i].Title,
                ChapterForeground = App.defaultForeground,
                ChaptersInPart = tempObservableCollection,
                PartsBackgroundBrush = App.partsBackgroundBrush,
                PartsHeaderHeight = double.NaN,
                PartsBorderThickness = new Thickness(0,0,0,2)
            });
        }
        else
        {
            Parts.Add(new PartsViewModel()
            {
                PartsHeader = StringResource.Space,
                ChapterForeground = App.defaultForeground,
                ChaptersInPart = tempObservableCollection,
                PartsBackgroundBrush = App.partsBackgroundBrush,
                PartsHeaderHeight = 0,
                PartsBorderThickness = new Thickness(0)
            });
        }
    }
}

private void CreateAboutMenuGUIfromExtrasData()
{
    int list_count = 0;

    for (int i = 0; i < 3; ++i)
    {
        switch (i)
        {
            //Evaluate number of Authors
            case 0:
                list_count = DictionaryIterator(App.Parser.AboutAuthorsArrayList);
                if (list_count == 1)
                {
                    this.About.Add(new ItemViewModel() { LineOne = StringResource.AboutAuthor }); //for one author
                }
                else if (list_count > 1)
                {
                    this.About.Add(new ItemViewModel() { LineOne = StringResource.AboutAuthors }); //for more than one author
                }
                break;

             //Evaluate number of books (should only be one)
            case 1:
                list_count = DictionaryIterator(App.Parser.AboutBookArrayList);
                if (list_count > 0)
                    this.About.Add(new ItemViewModel() { LineOne = StringResource.AboutBook });
                break;

            //Evaluate number of Readers
            case 2:
                list_count = DictionaryIterator(App.Parser.AboutNarratorsArrayList);
                if (list_count == 1)
                {
                    this.About.Add(new ItemViewModel() { LineOne = StringResource.AboutReader }); //for one reader
                }
                else if (list_count > 1)
                {
                    this.About.Add(new ItemViewModel() { LineOne = StringResource.AboutReaders}); //for more than one reader
                }
                break;
        }
    }
}

private void CreateQuotesMenuGUIfromExtrasData()
{
    int list_count = 0;

    for( int i = 0; i < 6; ++i )
    {
        switch( i )
        {
            case 0:
                list_count = DictionaryIterator(App.Parser.QuotesAuthorAboutArrayList);
                if (list_count == 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesAboutAuthor});
                else if(list_count > 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesAboutAuthors });
                break;

            case 1:
                list_count = DictionaryIterator(App.Parser.QuotesAuthorFromArrayList);
                if (list_count == 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesFromAuthor });
                else if (list_count > 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesFromAuthors});
                break;

            case 2:
                list_count = DictionaryIterator(App.Parser.QuotesBookAboutArrayList);
                if (list_count > 0)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesAboutBook });
                break;

            case 3:
                list_count = DictionaryIterator(App.Parser.QuotesBookFromArrayList);
                if (list_count > 0)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesFromBook });
                break;

            case 4:
                list_count = DictionaryIterator(App.Parser.QuotesReaderAboutArrayList);
                if (list_count == 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesAboutReader });
                else if (list_count > 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesAboutReaders });
                break;

            case 5:
                list_count = DictionaryIterator(App.Parser.QuotesReaderFromArrayList);
                if (list_count == 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesFromReader });
                else if (list_count > 1)
                    this.Quotes.Add(new ItemViewModel() { LineOne = StringResource.QuotesFromReaders });
                break;
        }
    }
}

Answer 1

基本上这是因为您的代码锁定了UI线程。它锁定它的原因是因为它方式减慢。

现在查看您的代码，这是一项疯狂的工作量，您应该从隔离存储中加载一个简单的数据。您需要将所有这些UI工作移至View，并在创建实际视图时首先处理它，而不是之前的，就像您现在正在做的那样。

我个人不喜欢将viewmodel与你的App类耦合的想法，我也认为使用Application_Activated/Deactivated进行墓碑化是没有意义的，而不是在OnNavigatedFrom和OnNavigatedTo处理持久性

我认为很难对导致问题的原因给出一个精确的答案，但我现在的猜测在于你正在使用墓碑化的过程来重新创建UI，而不是让它UIThread自己做的工作。

关于你在C＃中生成UI的整个部分是非常错误的。 XAML就是为此而制作的，并且非常擅长制作它。

Answer 2

如果代码真的被逻辑删除，你确定你只是恢复状态吗？

我怀疑你是在恢复状态之前回到你的应用程序，但仍在尝试恢复状态。您正在保存的内容以及如何恢复它将决定如何检查是否需要恢复它。检查null或不是defautl值可能是最简单的方法如果您只保存您必须拥有的任何状态，您也可以获得更好的性能。您还应该尝试在OnNavigatingFrom事件中保存State，而不是OnNavigatedFrom事件。

您保存给IS的是什么以及如何保存？为什么不使用Page.State对象？

在正确停用WP7之前激活

2 个答案: