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Get current position in Metro app on Windows 8 freeze

Ati incercat pana acuma sa obtineti locatia GPS curenta intr-o aplicatie Metro pentru Windows 8?
Daca nu, trebuie sa stiti ca nu e deloc complicat, este chiar la mintea cocosului API-ul.
Geoposition currentPosition = await new Geolocator().GetGeopositionAsync();
Toate informatiile necesare o sa le puteti gasi intr-un obiect de tip Geoposition. Intr-o aplicatie simpla totul o sa mearga fara nici o problema. Apoi o sa ajungeti sa creati un provider de genul GPSProvider. Fiind o metoda asincrona, aceasta metoda o sa fie apelata cu await, iar codul vostru o sa arate in felul urmator:
public class GPSProvider
    public async Task<Geoposition> GetCurrentPositionAsync()
    // some code.
    return async _geoLocator.GetPositionAsync();
In unele cazuri, cand o sa rulati codul pe un alt thread decat cel principal o sa va treziti ca locatia GPS nu poate sa fie rezolvata, codul ingheata la metoda GetPositionAsync(). Cauza pentru care se intampla acest lucru este ca codul nu ruleaza intr-un mediu MTA (Multi Threaded Apartment) si nu intr-un mediu STA (Single Threaded Apartment).
Aceasta problema apare doar la primul apel, dupa acest apel, metoda poate sa fie apelata din orice locatie fara nici o problema. In specificatiile la acesta metoda se precizeaza ca aceasta trebuie sa fie apelata prima data dintr-un mediu STA, iar apoi o sa functioneze si dintr-un mediu MTA. In spate aceasta metoda apeleaza la randul ei un COM, din aceasta cauza apare aceasta restrictie.
From MSDN:
In apps that use C# or C++ in Windows 8 Consumer Preview, the first use of the Geolocator object to call GetGeopositionAsync should be on the STA thread. Calls from an MTA thread may result in undefined behavior.

Comportamentul este destul de ciudat si neasteptat. Solutia la aceasta problema este sa mutati codul care face apel la metoda GetPositionAsync in xaml.cs sau in orice loc care sa va asigure ca sunteti intr-un mediu STA. O alta solutie este sa va definiti o metoda de warm up, care este apelata din App.xaml.cs de exemplu.


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