Added Image DownScaler

image down scaling integration

src/Client/ShareLoc.Client.App/ViewModels/CreatePlaceViewModel.cs

@@ -20,21 +20,23 @@ public sealed partial class CreatePlaceViewModel : BaseViewModel
 	private readonly IOptions<ServerOptions> _serverOptions;
 	private readonly ModelMapper _modelMapper;
 	private readonly IMediator _mediator;
+	private readonly ImageDownScaler _imgDownScaler;
 
 	[ObservableProperty]
 	private PlaceDetailViewModel _placeDetailViewModel;
 
-	public CreatePlaceViewModel(ApiClient apiClient, INavigationService navigationService, LocalDbService localDbService, IAlertService alertService, PlaceDetailViewModel placeDetailViewModel, IOptions<ServerOptions> serverOptions, ModelMapper modelMapper, IMediator mediator)
+	public CreatePlaceViewModel(ApiClient apiClient, INavigationService navigationService, LocalDbService localDbService, IAlertService alertService, PlaceDetailViewModel placeDetailViewModel, IOptions<ServerOptions> serverOptions, ModelMapper modelMapper, IMediator mediator, ImageDownScaler imgDownScaler)
 	{
 		_apiClient = apiClient;
 		_navigationService = navigationService;
 		_localDbService = localDbService;
 		_alertService = alertService;
 		_serverOptions = serverOptions;
 		_modelMapper = modelMapper;
+		_mediator = mediator;
+		_imgDownScaler = imgDownScaler;
 
 		PlaceDetailViewModel = placeDetailViewModel;
-		_mediator = mediator;
 	}
 
 	protected override async Task LoadAsync(CancellationToken ct)
@@ -74,8 +76,7 @@ protected override async Task LoadAsync(CancellationToken ct)
 			return null;
 
 		using var stream = await photo.OpenReadAsync();
-		var buffer = new byte[stream.Length];
-		await stream.ReadAsync(buffer.AsMemory(0, (int)stream.Length), ct);
+		var buffer = await _imgDownScaler.ScaleDownAsync(stream, ct);
 		return buffer;
 	}
 

src/Client/ShareLoc.Client.BL/Extensions/ServiceCollectionExtensions.cs

@@ -17,6 +17,7 @@ public static IServiceCollection AddBL(this IServiceCollection serviceCollection
 
 		return serviceCollection
 			.AddSingleton<EntityMapper>()
+			.AddSingleton(new ImageDownScaler(400 * 1024, [1.0, 0.5, 0.25, 0.18]))
 			.AddScoped<LocalDbService>();
 	}
 }

src/Client/ShareLoc.Client.BL/Services/ImageDownScaler.cs

@@ -0,0 +1,86 @@
+using SkiaSharp;
+
+namespace ShareLoc.Client.BL.Services;
+
+public sealed class ImageDownScaler
+{
+	private readonly int _maxSize;
+	private readonly double[] _compressionLevels;
+
+	public ImageDownScaler(int maxSize, int runCount, double initialCompressionLevel)
+	{
+		_maxSize = maxSize;
+
+		_compressionLevels = new double[runCount];
+		_compressionLevels[0] = initialCompressionLevel;
+		for (int i = 1; i < runCount; i++)
+		{
+			_compressionLevels[i] = _compressionLevels[i - 1] / 2;
+		}
+	}
+
+	public ImageDownScaler(int maxSize, double[] compressionLevels)
+	{
+		_maxSize = maxSize;
+		_compressionLevels = compressionLevels;
+	}
+
+	public Task<byte[]> ScaleDownAsync(Stream imageStream, CancellationToken ct)
+	{
+		return Task.Run(() =>
+		{
+			var bufferCount = imageStream.Length;
+			if (bufferCount < _maxSize)
+			{
+				using var newImageStream = new MemoryStream(_maxSize);
+				imageStream.CopyToAsync(newImageStream, ct);
+				return newImageStream.ToArray();
+			}
+
+			using var image = SKImage.FromEncodedData(imageStream);
+			using var original = SKBitmap.FromImage(image);
+
+			byte[] imageBuffer = [];
+			foreach (var compressionLevel in _compressionLevels)
+			{
+				//size could be > max size
+				imageBuffer = ScaleDown(original, bufferCount, compressionLevel);
+				if (imageBuffer.Length > 0)
+					return imageBuffer;
+			}
+
+			//100% size < max size
+			return ScaleDown(original, bufferCount, null);
+		}, ct);
+	}
+
+	private byte[] ScaleDown(SKBitmap original, long bufferCount, double? compressionLevel)
+	{
+		var bytesPerPixel = original.BytesPerPixel;
+
+		var rawByteCount = original.Width * original.Height * bytesPerPixel;
+		var compressionRatio = compressionLevel switch
+		{
+			null => 1,
+			_ => (double)rawByteCount / bufferCount * compressionLevel
+		};
+
+		var newWidth2 = (double)(_maxSize * original.Width * compressionRatio) / (original.Height * bytesPerPixel);
+		var newWidth = (int)Math.Sqrt(newWidth2);
+		if (newWidth > original.Width)
+			return [];
+
+		var newHeight = newWidth * original.Height / original.Width;
+
+		using var newImageStream = new MemoryStream(_maxSize);
+		using var newBitmap = original.Resize(new SKImageInfo(newWidth, newHeight, original.ColorType, original.AlphaType, original.ColorSpace), SKFilterQuality.High);
+		using var image = SKImage.FromBitmap(newBitmap);
+		using var data = image.Encode(SKEncodedImageFormat.Png, 100);
+		data.SaveTo(newImageStream);
+
+		if (newImageStream.Length > _maxSize)
+			return [];
+
+		return newImageStream.ToArray();
+	}
+}

src/Client/ShareLoc.Client.BL/ShareLoc.Client.BL.csproj

@@ -11,6 +11,7 @@
     <PackageReference Include="Microsoft.Extensions.Http" Version="8.0.0" />
     <PackageReference Include="OneOf" Version="3.0.263" />
     <PackageReference Include="Riok.Mapperly" Version="3.2.0" />
+    <PackageReference Include="SkiaSharp" Version="2.88.6" />
   </ItemGroup>
 
   <ItemGroup>