wip: more properties.

demo/Ursa.Demo/Pages/FormDemo.axaml

@@ -9,10 +9,10 @@
              x:CompileBindings="True"
              x:Class="Ursa.Demo.Pages.FormDemo">
     <StackPanel>
-        <u:Form DataContext="{Binding Model}" >
+        <u:Form DataContext="{Binding Model}" LabelWidth="Auto">
             <u:FormGroup Header="Information">
-                <TextBox u:Form.Label="Name" Text="{Binding Name}"/>
+                <TextBox u:Form.Label="Name" Text="{Binding Name}" Width="300"/>
-                <TextBox u:Form.Label="Email" Text="{Binding Email}"/>
+                <TextBox u:Form.Label="Email" Text="{Binding Email}" Width="300"/>
             </u:FormGroup>
             <u:FormItem>
                 <CalendarDatePicker u:Form.Label="Date" SelectedDate="{Binding Date}" />

demo/Ursa.Demo/ViewModels/FormDemoViewModel.cs

@@ -40,4 +40,9 @@ public partial class DataModel : ObservableObject
         get => _date;
         set => SetProperty(ref _date, value);
     }
+
+    public DataModel()
+    {
+        Date = DateTime.Today;
+    }
 }

src/Ursa.Themes.Semi/Controls/Form.axaml

@@ -5,7 +5,9 @@
     <ControlTheme x:Key="{x:Type u:Form}" TargetType="u:Form">
         <Setter Property="Template">
             <ControlTemplate TargetType="u:Form">
-                <ItemsPresenter ItemsPanel="{TemplateBinding ItemsPanel}"></ItemsPresenter>
+                <DataValidationErrors>
+                    <ItemsPresenter ItemsPanel="{TemplateBinding ItemsPanel}"></ItemsPresenter>
+                </DataValidationErrors>
             </ControlTemplate>
         </Setter>
     </ControlTheme>

src/Ursa/Controls/Form/Form.cs

@@ -1,14 +1,17 @@
 using Avalonia;
 using Avalonia.Controls;
+using Ursa.Common;
 
 namespace Ursa.Controls;
 
 public class Form: ItemsControl
 {
-    public static readonly AttachedProperty<string> LabelProperty =
+    #region Attached Properties
-        AvaloniaProperty.RegisterAttached<Form, Control, string>("Label");
+
-    public static void SetLabel(Control obj, string value) => obj.SetValue(LabelProperty, value);
+    public static readonly AttachedProperty<object?> LabelProperty =
-    public static string GetLabel(Control obj) => obj.GetValue(LabelProperty);
+        AvaloniaProperty.RegisterAttached<Form, Control, object?>("Label");
+    public static void SetLabel(Control obj, object? value) => obj.SetValue(LabelProperty, value);
+    public static object? GetLabel(Control obj) => obj.GetValue(LabelProperty);
     
 
     public static readonly AttachedProperty<bool> IsRequiredProperty =
@@ -16,6 +19,37 @@ public class Form: ItemsControl
     public static void SetIsRequired(Control obj, bool value) => obj.SetValue(IsRequiredProperty, value);
     public static bool GetIsRequired(Control obj) => obj.GetValue(IsRequiredProperty);
 
+    public static readonly AttachedProperty<GridLength> LabelWidthProperty =
+        AvaloniaProperty.RegisterAttached<Form, Control, GridLength>("LabelWidth");
+
+    public static void SetLabelWidth(Control obj, GridLength value) => obj.SetValue(LabelWidthProperty, value);
+    public static GridLength GetLabelWidth(Control obj) => obj.GetValue(LabelWidthProperty);
+
+    #endregion
+    
+
+    public static readonly StyledProperty<Position> LabelPositionProperty = AvaloniaProperty.Register<Form, Position>(
+        nameof(LabelPosition));
+    /// <summary>
+    /// Only Left and Top work.
+    /// </summary>
+    public Position LabelPosition
+    {
+        get => GetValue(LabelPositionProperty);
+        set => SetValue(LabelPositionProperty, value);
+    }
+
+    public static readonly StyledProperty<Position> LabelAlignmentProperty = AvaloniaProperty.Register<Form, Position>(
+        nameof(LabelAlignment));
+    /// <summary>
+    /// Only Left and Right work. 
+    /// </summary>
+    public Position LabelAlignment
+    {
+        get => GetValue(LabelAlignmentProperty);
+        set => SetValue(LabelAlignmentProperty, value);
+    }
+
     protected override bool NeedsContainerOverride(object? item, int index, out object? recycleKey)
     {
         recycleKey = null;
@@ -25,8 +59,30 @@ public class Form: ItemsControl
     protected override Control CreateContainerForItemOverride(object? item, int index, object? recycleKey)
     {
         if (item is not Control control) return new FormItem();
-        string label = GetLabel(control);
+        return new FormItem()
-        bool isRequired = GetIsRequired(control);
+        {
-        return new FormItem() { Label = label, IsRequired = isRequired, Content = control };
+            Content = control,
+            [!LabelProperty] = control.GetObservable(Form.LabelProperty).ToBinding(),
+            [!IsRequiredProperty] = control.GetObservable(Form.IsRequiredProperty).ToBinding(),
+        };
+    }
+
+    protected override void PrepareContainerForItemOverride(Control container, object? item, int index)
+    {
+        base.PrepareContainerForItemOverride(container, item, index);
+        if (container is FormGroup group)
+        {
+            if (!group.IsSet(FormGroup.LabelWidthProperty))
+            {
+                group[!LabelWidthProperty] = this.GetObservable(LabelWidthProperty).ToBinding();
+            }
+        }
+        else if (container is FormItem formItem)
+        {
+            if(!formItem.IsSet(FormItem.LabelWidthProperty))
+            {
+                formItem[!LabelWidthProperty] = this.GetObservable(LabelWidthProperty).ToBinding();
+            }
+        }
     }
 }

src/Ursa/Controls/Form/FormGroup.cs

@@ -1,21 +1,41 @@
-using Avalonia.Controls;
+using Avalonia;
+using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
 
 namespace Ursa.Controls;
 
 public class FormGroup: HeaderedItemsControl
 {
+    public static readonly StyledProperty<GridLength> LabelWidthProperty = Form.LabelWidthProperty.AddOwner<FormGroup>();
+
+    public GridLength LabelWidth
+    {
+        get => GetValue(LabelWidthProperty);
+        set => SetValue(LabelWidthProperty, value);
+    }
     protected override bool NeedsContainerOverride(object? item, int index, out object? recycleKey)
     {
         recycleKey = null;
-        return item is not FormItem or FormGroup;
+        return item is not FormItem;
     }
 
     protected override Control CreateContainerForItemOverride(object? item, int index, object? recycleKey)
     {
         if (item is not Control control) return new FormItem();
-        var label = Form.GetLabel(control);
+        return new FormItem
-        var isRequired = Form.GetIsRequired(control);
+        {
-        return new FormItem() { Label = label, IsRequired = isRequired, Content = control };
+            Content = control,
+            [!FormItem.LabelProperty] = control.GetObservable(Form.LabelProperty).ToBinding(),
+            [!FormItem.IsRequiredProperty] = control.GetObservable(Form.IsRequiredProperty).ToBinding(),
+        };
+    }
+
+    protected override void PrepareContainerForItemOverride(Control container, object? item, int index)
+    {
+        base.PrepareContainerForItemOverride(container, item, index);
+        if (container is FormItem formItem)
+        {
+            formItem.LabelWidth = LabelWidth;
+        }
     }
 }

src/Ursa/Controls/Form/FormItem.cs

@@ -6,10 +6,10 @@ namespace Ursa.Controls;
 
 public class FormItem: ContentControl
 {
-    public static readonly StyledProperty<string> LabelProperty = AvaloniaProperty.Register<FormItem, string>(
+    public static readonly StyledProperty<object?> LabelProperty = AvaloniaProperty.Register<FormItem, object?>(
         nameof(Label));
 
-    public string Label
+    public object? Label
     {
         get => GetValue(LabelProperty);
         set => SetValue(LabelProperty, value);
@@ -24,4 +24,23 @@ public class FormItem: ContentControl
         set => SetValue(IsRequiredProperty, value);
     }
 
+    public static readonly StyledProperty<GridLength> LabelWidthProperty = AvaloniaProperty.Register<FormItem, GridLength>(
+        nameof(LabelWidth));
+
+    public GridLength LabelWidth
+    {
+        get => GetValue(LabelWidthProperty);
+        set => SetValue(LabelWidthProperty, value);
+    }
+    
+    static FormItem()
+    {
+        LabelWidthProperty.Changed.AddClassHandler<FormItem, GridLength>((x, args) => x.LabelWidthChanged(args));
+    }
+
+    private void LabelWidthChanged(AvaloniaPropertyChangedEventArgs<GridLength> args)
+    {
+        GridLength? length = args.GetNewValue<GridLength>();
+        
+    }
 }