fix non-fixed star column width measurement

The child elements in non-fixed Start columns should get always double.PositiveInfinity width on its Measure call, because the column.ActualCurrentWidth at the Measure phase may be narrow than the finalRect.Width in Arrange phase.

Author: 9rnsr

components/DataTable/src/DataTable/DataRow.cs

@@ -131,7 +131,11 @@ protected override Size MeasureOverride(Size availableSize)
 
                 double width = column.ActualCurrentWidth;
 
-                if (column.IsAuto && !column.IsFixed)
+                if (column.IsFixed)
+                {
+                    child.Measure(new Size(width, availableSize.Height));
+                }
+                else
                 {
                     // We should get the *required* width from the child.
                     child.Measure(new Size(double.PositiveInfinity, availableSize.Height));
@@ -142,15 +146,11 @@ protected override Size MeasureOverride(Size availableSize)
 
                     // If the adjusted column width is smaller than the current cell width,
                     // we should call DataTable.MeasureOverride() again to extend it.
-                    if (!(width >= childWidth))
+                    if (column.IsAuto && !(width >= childWidth))
                     {
                         _parentTable.InvalidateMeasure();
                     }
                 }
-                else
-                {
-                    child.Measure(new Size(width, availableSize.Height));
-                }
 
                 maxHeight = Math.Max(maxHeight, child.DesiredSize.Height);
             }

components/DataTable/src/DataTable/DataTable.cs

@@ -238,6 +238,7 @@ protected override Size ArrangeOverride(Size finalSize)
                 width = starUnit * column.DesiredWidth.Value;
 
                 // Store the actual star column width.
+                //Debug.WriteLine($"  Column[{i}] ({column.DesiredWidth}) width is re-adjusted to: {width}");
                 column.CurrentWidth = width;
             }