feat: improve range picker context initialization.

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

@@ -66,7 +66,7 @@
                                 Name="{x:Static u:DateRangePicker.PART_Button}"
                                 Grid.Column="3"
                                 Padding="8,0"
-                                Content="{DynamicResource TimePickerIconGlyph}"
+                                Content="{DynamicResource CalendarDatePickerIconGlyph}"
                                 Focusable="False"
                                 Theme="{DynamicResource InnerIconButton}" />
                         </Grid>
@@ -87,6 +87,30 @@
                                 BoxShadow="{DynamicResource ComboBoxPopupBoxShadow}"
                                 ClipToBounds="True"
                                 CornerRadius="6">
+                                <DockPanel>
+                                    <!--
+                                    <StackPanel DockPanel.Dock="Bottom" IsVisible="{TemplateBinding NeedConfirmation}">
+                                        <Button
+                                            Margin="8"
+                                            HorizontalAlignment="Right"
+                                            Command="{Binding $parent[u:TimeRangePicker].Confirm}"
+                                            Content="{DynamicResource STRING_DATE_TIME_CONFIRM}" />
+                                    </StackPanel>
+                                    -->
+                                    <ContentPresenter
+                                        Name="PART_PopupHeader"
+                                        Margin="8,8,8,0"
+                                        Content="{TemplateBinding PopupInnerTopContent}"
+                                        DockPanel.Dock="Top"
+                                        IsVisible="{TemplateBinding PopupInnerTopContent,
+                                                                    Converter={x:Static ObjectConverters.IsNotNull}}" />
+                                    <ContentPresenter
+                                        Name="PART_PopupFooter"
+                                        Margin="8,0,8,8"
+                                        Content="{TemplateBinding PopupInnerBottomContent}"
+                                        DockPanel.Dock="Bottom"
+                                        IsVisible="{TemplateBinding PopupInnerBottomContent,
+                                                                    Converter={x:Static ObjectConverters.IsNotNull}}" />
                                     <Grid ColumnDefinitions="*, *">
                                         <u:CalendarView
                                             Name="{x:Static u:DateRangePicker.PART_StartCalendar}"
@@ -105,6 +129,7 @@
                                             FirstDayOfWeek="{TemplateBinding FirstDayOfWeek}"
                                             IsTodayHighlighted="{TemplateBinding IsTodayHighlighted}" />
                                     </Grid>
+                                </DockPanel>
                             </Border>
                         </Popup>
                     </Panel>

src/Ursa/Controls/DateTimePicker/CalendarContext.cs

@@ -13,4 +13,9 @@ public class CalendarContext(int? year = null, int? month = null, int? day = nul
     {
         return new CalendarContext(Year, Month, Day) { StartYear = StartYear, EndYear = EndYear };
     }
+
+    public static CalendarContext Today()
+    {
+        return new CalendarContext(DateTime.Today.Year, DateTime.Today.Month, 1);
+    }
 }

src/Ursa/Controls/DateTimePicker/DateRangePicker.cs

@@ -217,26 +217,37 @@ public class DateRangePicker : DatePickerBase
 
             if (_endCalendar is not null)
             {
-                var date2 = SelectedEndDate ?? SelectedStartDate ?? DateTime.Today;
+                var date2 = SelectedEndDate;
-                _endCalendar.ContextCalendar = new CalendarContext(date2.Year, date2.Month, 1);
+                if (date2 is null || (date2.Value.Year==SelectedStartDate?.Year && date2.Value.Month == SelectedStartDate?.Month))
+                {
+                    date2 = SelectedStartDate ?? DateTime.Today;
+                    date2 = date2.Value.AddMonths(1);
+                }
+                _endCalendar.ContextCalendar = new CalendarContext(date2?.Year, date2?.Month, 1);
                 _endCalendar.UpdateDayButtons();
             }
         }
         else if (sender == _endTextBox)
         {
             _start = false;
-            if (_startCalendar is not null)
-            {
-                var date2 = SelectedStartDate ?? SelectedEndDate ?? DateTime.Today;
-                _startCalendar.ContextCalendar = new CalendarContext(date2.Year, date2.Month, 1);
-                _startCalendar.UpdateDayButtons();
-            }
             if (_endCalendar is not null)
             {
                 var date = SelectedEndDate ?? DateTime.Today;
                 _endCalendar.ContextCalendar = new CalendarContext(date.Year, date.Month, 1);
                 _endCalendar.UpdateDayButtons();
             }
+            if (_startCalendar is not null)
+            {
+                var date2 = SelectedStartDate;
+                if (date2 is null || (date2.Value.Year==SelectedEndDate?.Year && date2.Value.Month == SelectedEndDate?.Month))
+                {
+                    date2 = SelectedStartDate ?? DateTime.Today;
+                    date2 = date2.Value.AddMonths(-1);
+                }
+                _startCalendar.ContextCalendar = new CalendarContext(date2?.Year, date2?.Month, 1);
+                _startCalendar.UpdateDayButtons();
+            }
+            
         }
         SetCurrentValue(IsDropdownOpenProperty, true);
     }