AC＃Windows Store应用程序中带有SQLite的MBTiles数据库

Question

I am doing a windows store (8.1) app in c# Xaml to generate maps using the Bing Maps for c# extension with a mbtiles file, I've already used the project Portable Basemap Server to do the work but now I'm trying access the data in the mbtiles file by myself with SQLite.

I managed to get tiles from that kind of files in WPF but I don't know how to do it in a windows store project;

My code in WPF :

        SQLiteConnection _sqlcon;
        using (_sqlcon = new SQLiteConnection(String.Format("Data Source={0};Version=3;", "PATH_TO_MBTILES")))
        {
            _sqlcon.Open();
            SQLiteCommand cmd = new SQLiteCommand(string.Format("SELECT tile_data FROM tiles WHERE tile_column={0} AND tile_row={1} AND zoom_level={2}", 2, 5, 3), _sqlcon);
            object o = cmd.ExecuteScalar();

            if (o != null)
            {
                byte[] c = (byte[])o;
                using (MemoryStream stream = new MemoryStream(c))
                {
                    BitmapImage bmp = new BitmapImage();
                    bmp.BeginInit();
                    bmp.CacheOption = BitmapCacheOption.OnLoad;
                    bmp.StreamSource = stream;
                    bmp.EndInit();
                    img.Source = bmp;
                }
            }
        }

With that code I get the tile at column 2 row 5 and zoom level 3.

But in windows store app I get a SQLiteException "Could not open database file" when I try to create a SQLiteConnection with the same file (I am using the NuGet sqlite-net and the SqLite for Windows Runtime 8.1 extension)

My code in Windows Store App :

        SQLiteConnection _sqlcon;
        using (_sqlcon = new SQLiteConnection(String.Format("Data Source={0};Version=3;", "PATH_TO_MBTILES"))) //SQLiteExeption here
        {
            SQLiteCommand cmd = new SQLiteCommand(string.Format("SELECT tile_data FROM tiles WHERE tile_column={0} AND tile_row={1} AND zoom_level={2}", 2, 5, 3), _sqlcon);
            byte[] o = cmd.ExecuteScalar<byte[]>();
            //etc...
        }

The debugger of Visual Studio send me to the SQLite.cs file of the sqlite-net NuGet :

    public SQLiteConnection (string databasePath, SQLiteOpenFlags openFlags, bool storeDateTimeAsTicks = false)
    {
        if (string.IsNullOrEmpty (databasePath))
            throw new ArgumentException ("Must be specified", "databasePath");

        DatabasePath = databasePath;

#if NETFX_CORE
        SQLite3.SetDirectory(/*temp directory type*/2, Windows.Storage.ApplicationData.Current.TemporaryFolder.Path);
#endif

        Sqlite3DatabaseHandle handle;

#if SILVERLIGHT || USE_CSHARP_SQLITE
        var r = SQLite3.Open (databasePath, out handle, (int)openFlags, IntPtr.Zero);
#else
        // open using the byte[]
        // in the case where the path may include Unicode
        // force open to using UTF-8 using sqlite3_open_v2
        var databasePathAsBytes = GetNullTerminatedUtf8 (DatabasePath);
        var r = SQLite3.Open (databasePathAsBytes, out handle, (int) openFlags, IntPtr.Zero);
#endif

        Handle = handle;
        if (r != SQLite3.Result.OK) {
            throw SQLiteException.New (r, String.Format ("Could not open database file: {0} ({1})", DatabasePath, r));
        }
        _open = true; // Debugger Stops here !

        StoreDateTimeAsTicks = storeDateTimeAsTicks;

        BusyTimeout = TimeSpan.FromSeconds (0.1);
    }

I have found many examples of mbtiles files used in WPF but none in a windows store app.

Do the SQLite extensions for Windows store dev support MBTiles files as databases ? If yes what am I doing wrong ?

Answer 1

Windows Store apps can access only their own directories, but not the private files of the admin user.

Read the documentation , but you probably want to install the data as part of your app.