Gestiti allegati nel form

SteUp.Maui/Core/Services/ImageThumb.cs

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+using SkiaSharp;
+
+namespace SteUp.Maui.Core.Services;
+
+public static class ImageThumb
+{
+    public static async Task CreateThumbnailAsync(
+        string inputPath,
+        string outputPath,
+        int maxSide = 320,
+        int quality = 70,
+        CancellationToken ct = default)
+    {
+        // Leggi bytes (meglio in async)
+        var data = await File.ReadAllBytesAsync(inputPath, ct);
+
+        using var codec = SKCodec.Create(new SKMemoryStream(data));
+        if (codec is null)
+            throw new InvalidOperationException("Formato immagine non supportato o file corrotto.");
+
+        // Decodifica
+        var info = codec.Info;
+        using var bitmap = SKBitmap.Decode(codec);
+        if (bitmap is null)
+            throw new InvalidOperationException("Impossibile decodificare l'immagine.");
+
+        // Calcola resize mantenendo aspect ratio
+        var w = bitmap.Width;
+        var h = bitmap.Height;
+
+        if (w <= 0 || h <= 0) throw new InvalidOperationException("Dimensioni immagine non valide.");
+
+        var scale = (float)maxSide / Math.Max(w, h);
+        if (scale > 1f) scale = 1f; // non ingrandire
+
+        var newW = Math.Max(1, (int)Math.Round(w * scale));
+        var newH = Math.Max(1, (int)Math.Round(h * scale));
+
+        using var resized = bitmap.Resize(new SKImageInfo(newW, newH), SKFilterQuality.Medium);
+        if (resized is null)
+            throw new InvalidOperationException("Resize fallito.");
+
+        using var image = SKImage.FromBitmap(resized);
+        using var encoded = image.Encode(SKEncodedImageFormat.Jpeg, quality);
+
+        Directory.CreateDirectory(Path.GetDirectoryName(outputPath)!);
+
+        await using var fs = File.Open(outputPath, FileMode.Create, FileAccess.Write, FileShare.None);
+        encoded.SaveTo(fs);
+        await fs.FlushAsync(ct);
+    }
+}