Revert "Remove duplicate code for RoundLayoutValue"

This reverts commit 2edcb3b676.

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -2,11 +2,12 @@ using System;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Controls.Utils;
+using Avalonia.Data;
+using Avalonia.Input;
 using Avalonia.Layout;
 using Avalonia.LogicalTree;
 using Avalonia.Media;
 using Avalonia.Metadata;
-using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Presenters
 {
@@ -390,8 +391,8 @@ namespace Avalonia.Controls.Presenters
 
             if (useLayoutRounding)
             {
-                originX = MathUtilities.RoundLayoutValue(originX, scale);
-                originY = MathUtilities.RoundLayoutValue(originY, scale);
+                originX = LayoutHelper.RoundLayoutValue(originX, scale);
+                originY = LayoutHelper.RoundLayoutValue(originY, scale);
             }
 
             var boundsForChild =

src/Avalonia.Layout/LayoutHelper.cs

@@ -98,11 +98,48 @@ namespace Avalonia.Layout
         /// </remarks>
         public static Size RoundLayoutSize(Size size, double dpiScaleX, double dpiScaleY)
         {
-            var width = MathUtilities.RoundLayoutValue(size.Width, dpiScaleX);
-            var height = MathUtilities.RoundLayoutValue(size.Height, dpiScaleY);
-            return new Size(width, height);
+            return new Size(RoundLayoutValue(size.Width, dpiScaleX), RoundLayoutValue(size.Height, dpiScaleY));
         }
 
+        /// <summary>
+        /// Calculates the value to be used for layout rounding at high DPI.
+        /// </summary>
+        /// <param name="value">Input value to be rounded.</param>
+        /// <param name="dpiScale">Ratio of screen's DPI to layout DPI</param>
+        /// <returns>Adjusted value that will produce layout rounding on screen at high dpi.</returns>
+        /// <remarks>
+        /// This is a layout helper method. It takes DPI into account and also does not return
+        /// the rounded value if it is unacceptable for layout, e.g. Infinity or NaN. It's a helper
+        /// associated with the UseLayoutRounding property and should not be used as a general rounding
+        /// utility.
+        /// </remarks>
+        public static double RoundLayoutValue(double value, double dpiScale)
+        {
+            double newValue;
+
+            // If DPI == 1, don't use DPI-aware rounding.
+            if (!MathUtilities.AreClose(dpiScale, 1.0))
+            {
+                newValue = Math.Round(value * dpiScale) / dpiScale;
+
+                // If rounding produces a value unacceptable to layout (NaN, Infinity or MaxValue),
+                // use the original value.
+                if (double.IsNaN(newValue) ||
+                    double.IsInfinity(newValue) ||
+                    MathUtilities.AreClose(newValue, double.MaxValue))
+                {
+                    newValue = value;
+                }
+            }
+            else
+            {
+                newValue = Math.Round(value);
+            }
+
+            return newValue;
+        }
+
+
         /// <summary>
         /// Calculates the min and max height for a control. Ported from WPF.
         /// </summary>

src/Avalonia.Layout/Layoutable.cs

@@ -566,8 +566,8 @@ namespace Avalonia.Layout
                 if (UseLayoutRounding)
                 {
                     var scale = GetLayoutScale();
-                    width = MathUtilities.RoundLayoutValue(width, scale);
-                    height = MathUtilities.RoundLayoutValue(height, scale);
+                    width = LayoutHelper.RoundLayoutValue(width, scale);
+                    height = LayoutHelper.RoundLayoutValue(height, scale);
                 }
 
                 return NonNegative(new Size(width, height).Inflate(margin));
@@ -674,8 +674,8 @@ namespace Avalonia.Layout
 
                 if (useLayoutRounding)
                 {
-                    originX = MathUtilities.RoundLayoutValue(originX, scale);
-                    originY = MathUtilities.RoundLayoutValue(originY, scale);
+                    originX = LayoutHelper.RoundLayoutValue(originX, scale);
+                    originY = LayoutHelper.RoundLayoutValue(originY, scale);
                 }
 
                 Bounds = new Rect(originX, originY, size.Width, size.Height);