fix: fix panel format change handling.

demo/Ursa.Demo/Pages/TimePickerDemo.axaml

@@ -11,21 +11,36 @@
     <StackPanel HorizontalAlignment="Left">
         <ToggleSwitch Name="needConfirm" Content="Need Confirm" />
         <TextBlock Text="{Binding #picker.SelectedTime}" />
+        <TextBox
+            Name="displayFormat"
+            Width="300"
+            InnerLeftContent="Display Format"
+            Text="HH 时 mm 分 ss 秒" />
+        <TextBox
+            Name="panelFormat"
+            Width="300"
+            InnerLeftContent="Panel Format"
+            Text="tt HH mm ss" />
         <u:TimePicker
             Name="picker"
             Width="200"
             HorizontalAlignment="Left"
+            DisplayFormat="{Binding #displayFormat.Text}"
             NeedConfirmation="{Binding #needConfirm.IsChecked}"
-            PanelFormat="hh mm tt" />
+            PanelFormat="{Binding #panelFormat.Text}" />
+
         <u:TimePicker
             Width="300"
-            Classes="ClearButton"
-            DisplayFormat="HH 时 mm 分 ss 秒"
-            PanelFormat="tt HH mm ss"
             HorizontalAlignment="Left"
-            NeedConfirmation="True"
+            Classes="ClearButton"
+            DisplayFormat="{Binding #displayFormat.Text}"
             InnerLeftContent="时刻"
-            InnerRightContent="截止" />
+            InnerRightContent="截止"
-        <u:TimeRangePicker Width="300"></u:TimeRangePicker>
+            NeedConfirmation="True"
+            PanelFormat="{Binding #panelFormat.Text}" />
+        <u:TimeRangePicker
+            Width="300"
+            DisplayFormat="{Binding #displayFormat.Text}"
+            PanelFormat="{Binding #panelFormat.Text}" />
     </StackPanel>
 </UserControl>

src/Ursa/Controls/DateTimePicker/TimePickerPresenter.cs

@@ -141,6 +141,8 @@ public class TimePickerPresenter : TemplatedControl
         foreach (var part in parts)
         {
             if (part.Length < 1) continue;
+            try
+            {
                 if ((part.Contains('h') || part.Contains('H')) && !panels.Contains(_hourScrollPanel))
                 {
                     panels.Add(_hourScrollPanel);
@@ -168,6 +170,11 @@ public class TimePickerPresenter : TemplatedControl
                     _ampmSelector?.SetValue(DateTimePickerPanel.ItemFormatProperty, part);
                 }
             }
+            catch
+            {
+                
+            }
+        }
 
         if (panels.Count < 1) return;
         IsVisibleProperty.SetValue(false, _hourScrollPanel, _minuteScrollPanel, _secondScrollPanel, _ampmScrollPanel,