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Simplified MBTiles implementation

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ClemensFischer 2024-08-20 18:00:04 +02:00
parent 4343dd9e9a
commit 2b483b4a68
3 changed files with 101 additions and 181 deletions
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77
MBTiles/Shared/MBTileSource.cs
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@ -3,7 +3,10 @@
// Licensed under the Microsoft Public License (Ms-PL)
using System;
using System.Collections.Generic;
using System.Data.SQLite;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
#if WPF
using System.Windows.Media;
@ -19,19 +22,46 @@ namespace MapControl.MBTiles
{
public class MBTileSource : TileSource, IDisposable
{
public MBTileData TileData { get; }
private SQLiteConnection connection;
public MBTileSource(MBTileData tiledata)
public IDictionary<string, string> Metadata { get; } = new Dictionary<string, string>();
public async Task OpenAsync(string file)
{
var format = tiledata.Metadata["format"];
Close();
if (format == "png" || format == "jpg")
connection = new SQLiteConnection("Data Source=" + Path.GetFullPath(file));
await connection.OpenAsync();
using (var command = new SQLiteCommand("create table if not exists metadata (name string, value string)", connection))
{
TileData = tiledata;
await command.ExecuteNonQueryAsync();
}
else
using (var command = new SQLiteCommand("create table if not exists tiles (zoom_level integer, tile_column integer, tile_row integer, tile_data blob)", connection))
{
Debug.WriteLine($"MBTileSource: unsupported format '{format}'");
await command.ExecuteNonQueryAsync();
}
using (var command = new SQLiteCommand("select * from metadata", connection))
{
var reader = await command.ExecuteReaderAsync();
while (await reader.ReadAsync())
{
Metadata[(string)reader["name"]] = (string)reader["value"];
}
}
}
public void Close()
{
if (connection != null)
{
Metadata.Clear();
connection.Dispose();
connection = null;
}
}
@ -43,9 +73,21 @@ namespace MapControl.MBTiles
protected virtual void Dispose(bool disposing)
{
if (disposing && TileData != null)
if (disposing)
{
TileData.Dispose();
Close();
}
}
public async Task<byte[]> ReadImageBufferAsync(int x, int y, int zoomLevel)
{
using (var command = new SQLiteCommand("select tile_data from tiles where zoom_level=@z and tile_column=@x and tile_row=@y", connection))
{
command.Parameters.AddWithValue("@z", zoomLevel);
command.Parameters.AddWithValue("@x", x);
command.Parameters.AddWithValue("@y", (1 << zoomLevel) - y - 1);
return await command.ExecuteScalarAsync() as byte[];
}
}
@ -53,22 +95,19 @@ namespace MapControl.MBTiles
{
ImageSource image = null;
if (TileData != null)
try
{
var buffer = await TileData.ReadImageBufferAsync(x, y, zoomLevel);
var buffer = await ReadImageBufferAsync(x, y, zoomLevel);
if (buffer != null)
{
try
{
image = await ImageLoader.LoadImageAsync(buffer);
}
catch (Exception ex)
{
Debug.WriteLine($"MBTileSource : {ex.Message}");
}
image = await ImageLoader.LoadImageAsync(buffer);
}
}
catch (Exception ex)
{
Debug.WriteLine($"MBTileSource: {ex.Message}");
}
return image;
}