WIP

samples/TreeDataGridDemo/Models/Country.cs

@@ -14,7 +14,7 @@ internal class Country
         public double? NetMigration { get; private set; }
         //per 1000 births
         public double? InfantMortality { get; private set; }
-        public int GDP { get; private set; }
+        public int GDP { get; set; }
         public double? LiteracyPercent { get; private set; }
         //per 1000
         public double? Phones { get; private set; }

samples/TreeDataGridDemo/ViewModels/CountriesPageViewModel.cs

@@ -30,12 +30,12 @@ public CountriesPageViewModel()
                     new TextColumn<Country, int>("Population", x => x.Population, new GridLength(3, GridUnitType.Star),
                         new TextColumnOptions<Country> { StringFormat = "{0:N}" }),
                     new TextColumn<Country, int>("Area", x => x.Area, new GridLength(3, GridUnitType.Star)),
-                    new TextColumn<Country, int>("GDP", x => x.GDP, new GridLength(3, GridUnitType.Star), new()
+                    new TextColumn<Country, int>("GDP", x => x.GDP, (o, v) => o.GDP = v, new GridLength(3, GridUnitType.Star), new()
                     {
                         TextAlignment = Avalonia.Media.TextAlignment.Right,
                         MaxWidth = new GridLength(150),
                         StringFormat = "{0:C}", // Format as Currency
-                        FormatCultureInfo = CultureInfo.GetCultureInfo("en-US"), // Format this as USD
+                        Culture = CultureInfo.GetCultureInfo("en-US"), // Format this as USD
                     }),
                 }
             };

src/Avalonia.Controls.TreeDataGrid/Models/TreeDataGrid/ITextCell.cs

@@ -14,16 +14,6 @@ public interface ITextCell : ICell
         /// </summary>
         string? Text { get; set; }
 
-        /// <summary>
-        /// Format to use for the string
-        /// </summary>
-        string StringFormat { get; }
-
-        /// <summary>
-        /// Culture info used in conjunction with <see cref="StringFormat"/>
-        /// </summary>
-        CultureInfo FormatCultureInfo { get; }
-
         /// <summary>
         /// Gets the cell's text trimming mode.
         /// </summary>

src/Avalonia.Controls.TreeDataGrid/Models/TreeDataGrid/ITextCellOptions.cs

@@ -7,14 +7,14 @@ namespace Avalonia.Controls.Models.TreeDataGrid
     public interface ITextCellOptions : ICellOptions
     {
         /// <summary>
-        /// Format to use for the string
+        /// Gets the format string to be used to format the cell value.
         /// </summary>
         string StringFormat { get; }
 
         /// <summary>
-        /// Culture info used in conjunction with <see cref="StringFormat"/>
+        /// Gets the culture to be used in conjunction with <see cref="StringFormat"/>.
         /// </summary>
-        CultureInfo FormatCultureInfo { get; }
+        CultureInfo Culture { get; }
 
         /// <summary>
         /// Gets the text trimming mode for the cell.

src/Avalonia.Controls.TreeDataGrid/Models/TreeDataGrid/TextCell.cs

@@ -43,16 +43,22 @@ public TextCell(
         public bool CanEdit => !IsReadOnly;
         public BeginEditGestures EditGestures => _options?.BeginEditGestures ?? BeginEditGestures.Default;
         public bool IsReadOnly { get; }
-        public string StringFormat => _options?.StringFormat ?? "{0}";
-        public CultureInfo FormatCultureInfo => _options?.FormatCultureInfo ?? CultureInfo.InvariantCulture;
         public TextTrimming TextTrimming => _options?.TextTrimming ?? TextTrimming.None;
         public TextWrapping TextWrapping => _options?.TextWrapping ?? TextWrapping.NoWrap;
         public TextAlignment TextAlignment => _options?.TextAlignment ?? TextAlignment.Left;
 
         public string? Text
         {
-            get => _value?.ToString();
-            set{
+            get
+            {
+                if (_options?.StringFormat is { } format)
+                    return string.Format(_options.Culture ?? CultureInfo.CurrentCulture, format, _value);
+                else
+                    return _value?.ToString();
+            }
+
+            set
+            {
                 if (string.IsNullOrEmpty(value))
                 {
                     Value = default(T?);

src/Avalonia.Controls.TreeDataGrid/Models/TreeDataGrid/TextColumnOptions.cs

@@ -23,7 +23,7 @@ public class TextColumnOptions<TModel> : ColumnOptions<TModel>, ITextCellOptions
         /// <summary>
         /// Culture info used in conjunction with <see cref="StringFormat"/>
         /// </summary>
-        public CultureInfo FormatCultureInfo { get; set; } = CultureInfo.InvariantCulture;
+        public CultureInfo Culture { get; set; } = CultureInfo.InvariantCulture;
 
         /// <summary>
         /// Gets or sets the text trimming mode for the cells in the column.

src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridTextCell.cs

@@ -1,26 +1,13 @@
 using System.ComponentModel;
 using System.Globalization;
-
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Controls.Selection;
-using Avalonia.Input;
-using Avalonia.Interactivity;
 using Avalonia.Media;
 
 namespace Avalonia.Controls.Primitives
 {
     public class TreeDataGridTextCell : TreeDataGridCell
     {
-        public static readonly DirectProperty<TreeDataGridTextCell, string> StringFormatProperty =
-            AvaloniaProperty.RegisterDirect<TreeDataGridTextCell, string>(
-                nameof(StringFormat),
-                o => o.StringFormat);
-
-        public static readonly DirectProperty<TreeDataGridTextCell, CultureInfo> FormatCultureInfoProperty =
-            AvaloniaProperty.RegisterDirect<TreeDataGridTextCell, CultureInfo>(
-                nameof(FormatCultureInfo),
-                o => o.FormatCultureInfo);
-
         public static readonly DirectProperty<TreeDataGridTextCell, TextTrimming> TextTrimmingProperty =
             AvaloniaProperty.RegisterDirect<TreeDataGridTextCell, TextTrimming>(
                 nameof(TextTrimming),
@@ -44,25 +31,11 @@ public class TreeDataGridTextCell : TreeDataGridCell
                 (o,v)=> o.TextAlignment = v);
 
         private string? _value;
-        private string _stringFormat = "{0}";
-        private CultureInfo _formatCultureInfo = CultureInfo.InvariantCulture;
         private TextBox? _edit;
         private TextTrimming _textTrimming = TextTrimming.CharacterEllipsis;
         private TextWrapping _textWrapping = TextWrapping.NoWrap;
         private TextAlignment _textAlignment = TextAlignment.Left;
 
-        public string StringFormat
-        {
-            get => _stringFormat;
-            set => SetAndRaise(StringFormatProperty, ref _stringFormat, value);
-        }
-
-        public CultureInfo FormatCultureInfo
-        {
-            get => _formatCultureInfo;
-            set => SetAndRaise(FormatCultureInfoProperty, ref _formatCultureInfo, value);
-        }
-
         public TextTrimming TextTrimming
         {
             get => _textTrimming;
@@ -90,17 +63,15 @@ public TextAlignment TextAlignment
             get => _textAlignment;
             set => SetAndRaise(TextAlignmentProperty, ref _textAlignment, value);
         }
+
         public override void Realize(
             TreeDataGridElementFactory factory,
             ITreeDataGridSelectionInteraction? selection,
             ICell model,
             int columnIndex,
             int rowIndex)
         {
-            var format = (model as ITextCell)?.StringFormat ?? "{0}";
-            var culture = (model as ITextCell)?.FormatCultureInfo ?? CultureInfo.InvariantCulture;
-
-            Value = string.Format(culture, format, model.Value);
+            Value = (model as ITextCell)?.Text;
             TextTrimming = (model as ITextCell)?.TextTrimming ?? TextTrimming.CharacterEllipsis;
             TextWrapping = (model as ITextCell)?.TextWrapping ?? TextWrapping.NoWrap;
             TextAlignment = (model as ITextCell)?.TextAlignment ?? TextAlignment.Left;
@@ -131,11 +102,8 @@ protected override void OnModelPropertyChanged(object? sender, PropertyChangedEv
         {
             base.OnModelPropertyChanged(sender, e);
 
-            if (e.PropertyName != nameof(ITextCell.Value)) return;
-            var format = (Model as ITextCell)?.StringFormat ?? "{0}";
-            var culture = (Model as ITextCell)?.FormatCultureInfo ?? CultureInfo.InvariantCulture;
-
-            Value = string.Format(culture, format, Model?.Value);
+            if (e.PropertyName == nameof(ITextCell.Value))
+                Value = Model?.Value?.ToString();
         }
     }
 }

tests/Avalonia.Controls.TreeDataGrid.Tests/Models/TextCellTests.cs

@@ -95,5 +95,46 @@ public void Modified_Value_Is_Not_Written_To_Binding_On_CancelEdit()
             Assert.Equal("initial", target.Value);
             Assert.Equal(new[] { "initial" }, result);
         }
+
+        public class StringFormat
+        {
+            [AvaloniaFact(Timeout = 10000)]
+            public void Initial_Int_Value_Is_Formatted()
+            {
+                var binding = new BehaviorSubject<BindingValue<int>>(42);
+                var target = new TextCell<int>(binding, true, GetOptions());
+
+                Assert.Equal("foo42", target.Text);
+                Assert.Equal(42, target.Value);
+            }
+
+            [AvaloniaFact(Timeout = 10000)]
+            public void Int_Value_Is_Formatted_After_Editing()
+            {
+                var binding = new BehaviorSubject<BindingValue<int>>(42);
+                var target = new TextCell<int>(binding, false);
+                var result = new List<int>();
+
+                binding.Subscribe(x => result.Add(x.Value));
+
+                target.BeginEdit();
+                target.Text = "43";
+
+                Assert.Equal("43", target.Text);
+                Assert.Equal(43, target.Value);
+                Assert.Equal(new[] { 42 }, result);
+
+                target.EndEdit();
+
+                Assert.Equal("43.0", target.Text);
+                Assert.Equal(43, target.Value);
+                Assert.Equal(new[] { 42, 43 }, result);
+            }
+
+            private ITextCellOptions? GetOptions(string format = "foo{0}")
+            {
+                return new TextColumnOptions<int> { StringFormat = format };
+            }
+        }
     }
 }

tests/Avalonia.Controls.TreeDataGrid.Tests/Primitives/TreeDataGridTextCellTests.cs

@@ -71,7 +71,7 @@ private static TreeDataGridTextCell SetupCellForType<T>(T input, CultureInfo? cu
                 options.StringFormat = formatString;
 
             if (cultureInfo is not null)
-                options.FormatCultureInfo = cultureInfo;
+                options.Culture = cultureInfo;
             var model = new TextCell<T>(subject, true, options);
             subject.OnNext(new BindingValue<T>(input));
             cell.Realize(new TestElementFactory(), null, model, 0, 0);