feat: add icon selector demo.

demo/Ursa.Demo/Converters/TimelineIconConverter.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+using Ursa.Controls;
+
+namespace Ursa.Demo.Converters;
+
+public class TimelineIconConverter: IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is TimelineItemType t)
+        {
+            return t switch
+            {
+                TimelineItemType.Success => Brushes.Green,
+                TimelineItemType.Ongoing => Brushes.Blue,
+                TimelineItemType.Error => Brushes.Red,
+                _ => Brushes.Gray
+            };
+        }
+        return AvaloniaProperty.UnsetValue;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException();
+    }
+}

demo/Ursa.Demo/Pages/TimelineDemo.axaml

@@ -6,15 +6,29 @@
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:u="https://irihi.tech/ursa"
     xmlns:viewModels="clr-namespace:Ursa.Demo.ViewModels"
+    xmlns:selectors="clr-namespace:Ursa.Demo.TemplateSelectors"
     d:DesignHeight="450"
     d:DesignWidth="800"
     x:DataType="viewModels:TimelineDemoViewModel"
     x:CompileBindings="True"
     mc:Ignorable="d">
+    <UserControl.Resources>
+        <ResourceDictionary>
+            <selectors:TimelineIconTemplateSelector x:Key="IconSelector">
+                <Ellipse x:Key="Default" Width="12" Height="12" Fill="{DynamicResource SemiGray6}"></Ellipse>
+                <Ellipse x:Key="Ongoing" Width="12" Height="12" Fill="{DynamicResource SemiBlue6}"></Ellipse>
+                <Ellipse x:Key="Success" Width="12" Height="12" Fill="{DynamicResource SemiGreen6}"></Ellipse>
+                <Ellipse x:Key="Warning" Width="12" Height="12" Fill="{DynamicResource SemiOrange6}"></Ellipse>
+                <Ellipse x:Key="Error" Width="12" Height="12" Fill="{DynamicResource SemiRed6}"></Ellipse>
+            </selectors:TimelineIconTemplateSelector>
+        </ResourceDictionary>
+    </UserControl.Resources>
     <StackPanel>
         <u:Timeline ItemsSource="{Binding Items}"
                     HeaderMemberBinding="{ReflectionBinding Header}"
                     DescriptionMemberBinding="{ReflectionBinding Description}"
+                    IconMemberBinding="{ReflectionBinding ItemType}"
+                    IconTemplate="{StaticResource IconSelector}"
                     >
         </u:Timeline>
         <u:Timeline>

demo/Ursa.Demo/TemplateSelectors/TimelineIconTemplateSelector.cs

@@ -0,0 +1,30 @@
+using Avalonia.Controls;
+using Avalonia.Controls.Shapes;
+using Avalonia.Controls.Templates;
+using Avalonia.Media;
+using Ursa.Controls;
+
+namespace Ursa.Demo.TemplateSelectors;
+
+public class TimelineIconTemplateSelector: ResourceDictionary, IDataTemplate
+{
+    
+    public Control? Build(object? param)
+    {
+        if (param is TimelineItemType t)
+        {
+            string s = t.ToString();
+            if (ContainsKey(s))
+            {
+                object? o = this[s];
+                if (o is Control c) return c;
+            }
+        }
+        return null;
+    }
+
+    public bool Match(object? data)
+    {
+        return data is TimelineItemType;
+    }
+}

demo/Ursa.Demo/ViewModels/TimelineDemoViewModel.cs

@@ -22,7 +22,7 @@ public class TimelineDemoViewModel: ViewModelBase
             TimeFormat = "HH:mm:ss",
             Description = "Item 2",
             Header = "发布成功",
-            ItemType = TimelineItemType.Success,
+            ItemType = TimelineItemType.Ongoing,
         },
         new()
         {
@@ -30,7 +30,7 @@ public class TimelineDemoViewModel: ViewModelBase
             TimeFormat = "HH:mm:ss",
             Description = "Item 3",
             Header = "审核失败",
-            ItemType = TimelineItemType.Ongoing,
+            ItemType = TimelineItemType.Error,
         }
     };
 }

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

@@ -50,14 +50,11 @@
                             Classes="start"
                             Fill="{DynamicResource TimelineLineBrush}" />
                         <Panel Grid.Row="1">
-                            <Ellipse
+                            <ContentPresenter
-                                Name="PART_Indicator"
+                                Content="{TemplateBinding Icon}"
-                                Width="8"
-                                Height="8"
-                                Margin="2"
                                 HorizontalAlignment="Center"
-                                VerticalAlignment="Top"
+                                VerticalAlignment="Center"
-                                Fill="{DynamicResource DefaultTimelineIconForeground}" />
+                                ContentTemplate="{TemplateBinding IconTemplate}"/>
                         </Panel>
                         <Rectangle
                             Grid.Row="2"