Этап 9

Minint.Core/Services/Impl/ImageEffectsService.cs

@@ -0,0 +1,38 @@
+using System;
+using Minint.Core.Models;
+
+namespace Minint.Core.Services.Impl;
+
+public sealed class ImageEffectsService : IImageEffectsService
+{
+    public void ApplyContrast(MinintDocument doc, double factor)
+    {
+        for (int i = 1; i < doc.Palette.Count; i++)
+        {
+            var c = doc.Palette[i];
+            doc.Palette[i] = new RgbaColor(
+                ContrastByte(c.R, factor),
+                ContrastByte(c.G, factor),
+                ContrastByte(c.B, factor),
+                c.A);
+        }
+        doc.InvalidatePaletteCache();
+    }
+
+    public void ApplyGrayscale(MinintDocument doc)
+    {
+        for (int i = 1; i < doc.Palette.Count; i++)
+        {
+            var c = doc.Palette[i];
+            byte gray = (byte)Math.Clamp((int)(0.299 * c.R + 0.587 * c.G + 0.114 * c.B + 0.5), 0, 255);
+            doc.Palette[i] = new RgbaColor(gray, gray, gray, c.A);
+        }
+        doc.InvalidatePaletteCache();
+    }
+
+    private static byte ContrastByte(byte value, double factor)
+    {
+        double v = ((value / 255.0) - 0.5) * factor + 0.5;
+        return (byte)Math.Clamp((int)(v * 255 + 0.5), 0, 255);
+    }
+}