Arrange items in a panel like a thumbnails manager

arrangeItems.cs

public static void Arrange(Control container, int horizontalGap, int verticalGap, float aspectRatio)
        {
            var H = container.Height;
            var W = container.Width;
            var N = container.Controls.OfType<Control>().Count(c => c.Visible);
            
            if (N == 0)
                return;

            var bestSizedItem = (

                // Try n rows
                Enumerable.Range(1, N).Select(testRowCount =>
                {
                    var testItemHeight = (H - verticalGap * (testRowCount - 1)) / testRowCount;

                    return new
                    {
                        testColCount = (int)Math.Ceiling((double)N / testRowCount),
                        testRowCount = testRowCount,
                        testItemHeight = (int)testItemHeight,
                        testItemWidth = (int)(testItemHeight * aspectRatio)
                    };
                })

                // Try n columns
                .Concat(
                Enumerable.Range(1, N).Select(testColCount =>
                {
                    var testItemWidth = (W - horizontalGap * (testColCount - 1)) / testColCount;

                    return new
                    {
                        testColCount = testColCount,
                        testRowCount = (int)Math.Ceiling((double)N / testColCount),
                        testItemHeight = (int)(testItemWidth / aspectRatio),
                        testItemWidth = (int)testItemWidth
                    };
                })))

                // Remove when it's too big
                .Where(item => item.testItemWidth * item.testColCount + horizontalGap * (item.testColCount - 1) <= W &&
                               item.testItemHeight * item.testRowCount + verticalGap * (item.testRowCount - 1) <= H)

                // Get the biggest area
                .OrderBy(item => item.testItemHeight * item.testItemWidth)
                .LastOrDefault();

            Debug.Assert(bestSizedItem != null);

            if (bestSizedItem == null)
                return;

            // Centering

            int xCenter = (W - (bestSizedItem.testItemWidth * bestSizedItem.testColCount + bestSizedItem.testColCount * horizontalGap - horizontalGap)) / 2;
            int x = xCenter;

            int yCenter = (H - (bestSizedItem.testItemHeight * bestSizedItem.testRowCount + bestSizedItem.testRowCount * verticalGap - verticalGap)) / 2;
            int y = yCenter;

            container.SuspendLayout();
            foreach (var control in container.Controls.OfType<Control>().Where(c => c.Visible))
            {
                control.SetBounds(x, y,
                    bestSizedItem.testItemWidth,
                    bestSizedItem.testItemHeight);

                x += bestSizedItem.testItemWidth + horizontalGap;
                if (x + bestSizedItem.testItemWidth - horizontalGap > W)
                {
                    x = xCenter;
                    y += bestSizedItem.testItemHeight + verticalGap;
                }
            }
            container.ResumeLayout(false);
        }