update ChatBox

src/Shared/HandyControlDemo_Shared/UserControl/Basic/ChatBox.xaml

@@ -16,7 +16,7 @@
             <RowDefinition/>
             <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
-        <ListBox ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.CanContentScroll="False"  Background="Transparent" hc:ChatBubble.MaxWidth="300" BorderThickness="0" Style="{StaticResource StackPanelVerticalListBox}" ItemsSource="{Binding ChatInfos}">
+        <ListBox Name="ListBoxChat" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.CanContentScroll="False" Background="Transparent" hc:ChatBubble.MaxWidth="300" BorderThickness="0" Style="{StaticResource StackPanelVerticalListBox}" ItemsSource="{Binding ChatInfos}">
             <hc:Interaction.Triggers>
                 <hc:RoutedEventTrigger RoutedEvent="hc:ChatBubble.Selected">
                     <hc:EventToCommand Command="{Binding ReadMessageCmd}" PassEventArgsToCommand="True" />

src/Shared/HandyControlDemo_Shared/UserControl/Basic/ChatBox.xaml.cs

@@ -1,10 +1,27 @@
-namespace HandyControlDemo.UserControl
+using System.Windows.Controls;
+using HandyControl.Tools;
+
+namespace HandyControlDemo.UserControl
 {
     public partial class ChatBox
     {
+        private ScrollViewer _scrollViewer;
+
         public ChatBox()
         {
             InitializeComponent();
+
+            ListBoxChat.ItemContainerGenerator.ItemsChanged += ItemContainerGenerator_ItemsChanged;
+        }
+
+        private void ItemContainerGenerator_ItemsChanged(object sender, System.Windows.Controls.Primitives.ItemsChangedEventArgs e)
+        {
+            if (_scrollViewer == null)
+            {
+                _scrollViewer = VisualHelper.GetChild<ScrollViewer>(ListBoxChat);
+            }
+
+            _scrollViewer?.ScrollToBottom();
         }
     }
 }