在开发WPF自定义控件时，我注意到了奇怪的裁剪行为。当我将控件调整到一定的最小边界/门槛以下时，它会决定裁剪掉控件顶部24个像素，原因我不明白。
如果有人能够解释我如何在没有裁剪行为的情况下实现所需的图形效果，将不胜感激，如下图所示：
裁剪前：
裁剪后：
此行为发生在以下XAML中。请注意，该XAML已被简化，以符合标准.net 4.0控件的规范。
如果有人能够解释我如何在没有裁剪行为的情况下实现所需的图形效果，将不胜感激，如下图所示：
裁剪前：
裁剪后：
此行为发生在以下XAML中。请注意，该XAML已被简化，以符合标准.net 4.0控件的规范。 <Style x:Key="{ComponentResourceKey ResourceId=DataGridSelectAllButtonStyle, TypeInTargetAssembly={x:Type DataGrid}}" TargetType="{x:Type Button}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid>
<Rectangle x:Name="Border" Fill="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" SnapsToDevicePixels="True"/>
<Polygon x:Name="Arrow" Fill="Black" HorizontalAlignment="Right" Margin="8,8,3,3" Opacity="0.15" Points="0,10 10,10 10,0" Stretch="Uniform" VerticalAlignment="Bottom"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Stroke" TargetName="Border" Value="{DynamicResource {x:Static SystemColors.ControlDarkBrushKey}}"/>
</Trigger>
<Trigger Property="IsPressed" Value="True">
<Setter Property="Fill" TargetName="Border" Value="{DynamicResource {x:Static SystemColors.ControlDarkBrushKey}}"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Visibility" TargetName="Arrow" Value="Collapsed"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="DataGridStyle1" TargetType="{x:Type DataGrid}">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="BorderBrush" Value="#FF688CAF"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="RowDetailsVisibilityMode" Value="VisibleWhenSelected"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="ScrollViewer.PanningMode" Value="Both"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGrid}">
<Border Background="Transparent" Margin="0,24,0,0" >
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}"
SnapsToDevicePixels="True">
<ScrollViewer x:Name="DG_ScrollViewer" Focusable="false">
<ScrollViewer.Template>
<ControlTemplate TargetType="{x:Type ScrollViewer}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Button Grid.Row="0" Command="{x:Static DataGrid.SelectAllCommand}" Focusable="false" Style="{DynamicResource {ComponentResourceKey ResourceId=DataGridSelectAllButtonStyle, TypeInTargetAssembly={x:Type DataGrid}}}" Visibility="{Binding HeadersVisibility, ConverterParameter={x:Static DataGridHeadersVisibility.All}, Converter={x:Static DataGrid.HeadersVisibilityConverter}, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Width="{Binding CellsPanelHorizontalOffset, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/>
<DataGridColumnHeadersPresenter Grid.Row="0" x:Name="PART_ColumnHeadersPresenter" Grid.Column="1" Visibility="{Binding HeadersVisibility, ConverterParameter={x:Static DataGridHeadersVisibility.Column}, Converter={x:Static DataGrid.HeadersVisibilityConverter}, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/>
<Grid VerticalAlignment="Top" Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="1" ClipToBounds="False">
<Grid.RenderTransform>
<TranslateTransform Y="-24" />
</Grid.RenderTransform>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding NonFrozenColumnsViewportHorizontalOffset, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Rectangle Fill="Yellow" Grid.Row="1" Grid.ColumnSpan="3" Grid.Column="1" Height="48" />
</Grid>
</Grid>
</ControlTemplate>
</ScrollViewer.Template>
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</ScrollViewer>
</Border>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
</Style.Triggers>
</Style>
<DataGrid AutoGenerateColumns="False" HorizontalAlignment="Left" Margin="12,12,0,12" Name="dataGrid1" Width="868" FrozenColumnCount="2"
ScrollViewer.HorizontalScrollBarVisibility="Visible" CanUserSortColumns="False" CanUserReorderColumns="False"
AreRowDetailsFrozen="True" CanUserAddRows="False" Style="{StaticResource DataGridStyle1}"
ScrollViewer.VerticalScrollBarVisibility="Visible">
<DataGrid.Columns>
<DataGridTextColumn Header="Layer Name" Width="250" IsReadOnly="True" />
<DataGridHyperlinkColumn Header="" Width="150" IsReadOnly="True" />
<DataGridTemplateColumn Width="*" HeaderStyle="{StaticResource DataGridColumnHeaderStyle}" IsReadOnly="True">
<DataGridTemplateColumn.Header>
<Grid Height="18">
<TextBlock Text="100.0f" Margin="0,-10" />
</Grid>
</DataGridTemplateColumn.Header>
</DataGridTemplateColumn>
</DataGrid.Columns>
<DataGrid.GroupStyle>
<GroupStyle>
<GroupStyle.ContainerStyle>
<Style TargetType="{x:Type GroupItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type GroupItem}">
<StackPanel>
<TextBlock Text="test" />
<ItemsPresenter />
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</GroupStyle.ContainerStyle>
</GroupStyle>
</DataGrid.GroupStyle>
</DataGrid>