48 lines
1.4 KiB
C#
48 lines
1.4 KiB
C#
using System;
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using System.IO;
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using SixLabors.ImageSharp;
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using SixLabors.ImageSharp.Formats.Png;
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using SixLabors.ImageSharp.Processing;
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namespace Gott.Services;
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public class ImageService
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{
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private const int MaxSideLength = 512;
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/// <summary>
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/// Nimmt eine Base64-Data-URL (z.B. "data:image/png;base64,..."), skaliert das Bild
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/// auf max 512px Seitenlänge und gibt eine neue Data-URL zurück.
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/// Gibt null zurück wenn input null/leer ist.
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/// </summary>
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public string ResizeDataUrl(string dataUrl)
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{
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if (string.IsNullOrEmpty(dataUrl)) return null;
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// Data-URL parsen: "data:<mediaType>;base64,<data>"
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var commaIndex = dataUrl.IndexOf(',');
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if (commaIndex < 0) return dataUrl;
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var base64 = dataUrl.Substring(commaIndex + 1);
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var bytes = Convert.FromBase64String(base64);
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using var image = Image.Load(bytes);
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// Nur skalieren wenn nötig
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if (image.Width <= MaxSideLength && image.Height <= MaxSideLength)
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return dataUrl;
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image.Mutate(x => x.Resize(new ResizeOptions
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{
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Size = new Size(MaxSideLength, MaxSideLength),
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Mode = ResizeMode.Max
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}));
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using var ms = new MemoryStream();
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image.Save(ms, new PngEncoder());
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var resizedBase64 = Convert.ToBase64String(ms.ToArray());
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return "data:image/png;base64," + resizedBase64;
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}
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}
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