Add image processor and tests

StabilityMatrix.Core/Helper/ImageProcessor.cs

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+using SixLabors.ImageSharp;
+using StabilityMatrix.Core.Extensions;
+
+namespace StabilityMatrix.Core.Helper;
+
+public static class ImageProcessor
+{
+    /// <summary>
+    /// Get the dimensions of a grid that can hold the given amount of images.
+    /// </summary>
+    public static (int rows, int columns) GetGridDimensionsFromImageCount(int count)
+    {
+        if (count <= 1) return (1, 1);
+        if (count == 2) return (1, 2);
+        
+        // Prefer one extra row over one extra column,
+        // the row count will be the floor of the square root
+        // and the column count will be floor of count / rows
+        var rows = (int) Math.Floor(Math.Sqrt(count));
+        var columns = (int) Math.Floor((double) count / rows);
+        return (rows, columns);
+    }
+    
+    public static Image<TPixel> CreateImageGrid<TPixel>(
+        IReadOnlyList<Image<TPixel>> images, 
+        int spacing = 0) where TPixel : unmanaged, IPixel<TPixel>
+    {
+        var (rows, columns) = GetGridDimensionsFromImageCount(images.Count);
+
+        var singleWidth = images[0].Width;
+        var singleHeight = images[0].Height;
+        
+        // Make output image
+        var output = new Image<TPixel>(
+            singleWidth * columns + spacing * (columns - 1), 
+            singleHeight * rows + spacing * (rows - 1));
+        
+        
+        // Draw images
+        foreach (var (row, column) in 
+                 Enumerable.Range(0, rows).Product(Enumerable.Range(0, columns)))
+        {
+            // Stop if we have drawn all images
+            var index = row * columns + column;
+            if (index >= images.Count) break;
+                
+            // Get image
+            var image = images[index];
+                
+            // Draw image
+            output.Mutate(op =>
+            {
+                op.DrawImage(image,
+                    new Point(singleWidth * column + spacing * column,
+                        singleHeight * row + spacing * row), 1);
+            });
+        }
+
+        return output;
+    }
+}

StabilityMatrix.Tests/Core/ImageProcessorTests.cs

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+using StabilityMatrix.Core.Helper;
+
+namespace StabilityMatrix.Tests.Core;
+
+[TestClass]
+public class ImageProcessorTests
+{
+    [DataTestMethod]
+    [DataRow(0, 1, 1)]
+    [DataRow(1, 1, 1)]
+    [DataRow(4, 2, 2)]
+    [DataRow(8, 2, 4)]
+    [DataRow(12, 3, 4)]
+    [DataRow(20, 4, 5)]
+    public void TestGetGridDimensionsFromImageCount(int count, int expectedRow, int expectedCols)
+    {
+        var result = ImageProcessor.GetGridDimensionsFromImageCount(count);
+        Assert.AreEqual(expectedRow, result.rows);
+        Assert.AreEqual(expectedCols, result.columns);
+    }
+}