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TileImageLoader

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ClemensFischer 2025-11-13 19:25:11 +01:00
parent 76f920a053
commit b44018ac8f
2 changed files with 37 additions and 32 deletions
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3
MapControl/Shared/Tile.cs
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@ -19,10 +19,11 @@ namespace MapControl
public int Y { get; } = y;
public int Column { get; } = ((x % columnCount) + columnCount) % columnCount;
public int Row => Y;
public bool IsPending { get; set; } = true;
/// <summary>
/// Runs a tile image download Task and marshals the result to the UI thread.
/// Runs a tile image download Task and passes the result to the UI thread.
/// </summary>
public abstract Task LoadImageAsync(Func<Task<ImageSource>> loadImageFunc);
}

66
MapControl/Shared/TileImageLoader.cs
View file

@ -10,11 +10,14 @@ using System.Threading.Tasks;
namespace MapControl
{
/// <summary>
/// Loads and optionally caches map tile images for a MapTilePyramidLayer.
/// </summary>
public interface ITileImageLoader
{
/// <summary>
/// Loads all pending tiles from the tiles collection. Tile image caching is enabled
/// when cacheName is a non-empty string and tiles are loaded from http or https Uris.
/// Starts asynchronous loading of all pending tiles from the tiles collection.
/// Caching is enabled when cacheName is a non-empty string and tiles are loaded from http or https Uris.
/// </summary>
void BeginLoadTiles(IEnumerable<Tile> tiles, TileSource tileSource, string cacheName, IProgress<double> progress);
@ -24,9 +27,6 @@ namespace MapControl
void CancelLoadTiles();
}
/// <summary>
/// Loads and optionally caches map tile images for a MapTilePyramidLayer.
/// </summary>
public class TileImageLoader : ITileImageLoader
{
private static ILogger logger;
@ -122,6 +122,7 @@ namespace MapControl
if (tileQueue.Count > 0)
{
tile = tileQueue.Dequeue();
tile.IsPending = false;
return true;
}
@ -135,35 +136,12 @@ namespace MapControl
while (TryDequeueTile(out Tile tile))
{
tile.IsPending = false;
Logger?.LogDebug("Thread {thread,2}: Loading tile ({zoom}/{column}/{row})",
Environment.CurrentManagedThreadId, tile.ZoomLevel, tile.Column, tile.Row);
try
{
// Pass image loading callbacks to platform-specific method
// tile.LoadImageAsync(Func<Task<ImageSource>>) for completion in the UI thread.
Logger?.LogDebug("Thread {thread,2}: Loading tile ({zoom}/{column}/{row})",
Environment.CurrentManagedThreadId, tile.ZoomLevel, tile.Column, tile.Row);
var uri = tileSource.GetUri(tile.ZoomLevel, tile.Column, tile.Row);
if (uri == null)
{
await tile.LoadImageAsync(() => tileSource.LoadImageAsync(tile.ZoomLevel, tile.Column, tile.Row)).ConfigureAwait(false);
}
else if (uri.Scheme != "http" && uri.Scheme != "https" || string.IsNullOrEmpty(cacheName))
{
await tile.LoadImageAsync(() => ImageLoader.LoadImageAsync(uri)).ConfigureAwait(false);
}
else
{
var buffer = await LoadCachedBuffer(tile, uri, cacheName).ConfigureAwait(false);
if (buffer != null)
{
await tile.LoadImageAsync(() => ImageLoader.LoadImageAsync(buffer)).ConfigureAwait(false);
}
}
await LoadTileImage(tile, tileSource, cacheName);
}
catch (Exception ex)
{
@ -174,6 +152,32 @@ namespace MapControl
}
}
private static async Task LoadTileImage(Tile tile, TileSource tileSource, string cacheName)
{
// Pass image loading callbacks to platform-specific method
// tile.LoadImageAsync(Func<Task<ImageSource>>) for completion in the UI thread.
var uri = tileSource.GetUri(tile.ZoomLevel, tile.Column, tile.Row);
if (uri == null)
{
await tile.LoadImageAsync(() => tileSource.LoadImageAsync(tile.ZoomLevel, tile.Column, tile.Row)).ConfigureAwait(false);
}
else if (uri.Scheme != "http" && uri.Scheme != "https" || string.IsNullOrEmpty(cacheName))
{
await tile.LoadImageAsync(() => ImageLoader.LoadImageAsync(uri)).ConfigureAwait(false);
}
else
{
var buffer = await LoadCachedBuffer(tile, uri, cacheName).ConfigureAwait(false);
if (buffer != null)
{
await tile.LoadImageAsync(() => ImageLoader.LoadImageAsync(buffer)).ConfigureAwait(false);
}
}
}
private static async Task<byte[]> LoadCachedBuffer(Tile tile, Uri uri, string cacheName)
{
var extension = Path.GetExtension(uri.LocalPath).ToLower();