Activation before proper Deactivation WP7 - silverlight

Question

In my app I allow the user to go to the marketplace for various reasons. While loading the marketplace, if the user hits the back button very quickly it will try to go back to my apps saved stated. All my data from iso-storage etc is loaded just fine, but the screen is frozen. I have different application bars for various pivot items and as I do the swiping motion, I see the application bar changing, so I know the app is responsive.
The main problem is that the screen is stuck where the user initially launched the marketplace task. I understand that int this edge case, my App and Page constructors are not firing, and the events that are firing are on navigated from, application deactivated, application activated, and on navigated to.
I thought I could use a Boolean to basically cover the case for when a marketplace task has fired so that way I can reload the data context in the on navigated to method and set it to my view model. The screen however is still frozen.
Any help on this issue is greatly appreciated,
Thanks
Edit: Here is some relevant code
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);
}
}
Main Page 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);
}
}
More methods:
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

Basically this happens because your code is locking up the UI thread. And the reason it locks it up, is because it's way to slow.
And looking at your code now, it's a crazy amount of work you're doing in what should be a simple data loading from the isolated storage. You need to move all this UI work over to the View, and first handle it upon creation of the actual view, not before, as you're doing right now.
Personally I dislike the idea of coupling the viewmodel with your App class, and I also think it's pointless to use the Application_Activated/Deactivated for tombstoning, rather than handling persistence at OnNavigatedFrom and OnNavigatedTo.
I think it'll be difficult to give a precise answer to what is causing the problem, but my guess right now lies in that you're using the process for the tombstoning to re-create the UI, instead of letting the UIThread itself do the work.
The whole part about you're generating the UI in C# is just so plain wrong as it can be. XAML is made for this, and it's really good at what it's made for.

Answer 2

Are you sure that you're only restoring state if the code was actually tombstoned?
I suspect that you're coming back to your app before it is tombstoned but still trying to restore state. Quite what you're saving and how you restore it will determine how you can check if you need to restore it. Checking for null or if not the defautl value is probably the easiest way.
You may also get better performance if you only save the state of anything you absolutely have to. You should also try saving the State in the OnNavigatingFrom event, rather than the OnNavigatedFrom event.
What and how are you saving to IS?
Why not use the Page.State object?