WPF combobox 圆角制作

修改ComboBox的Template, 在VS 2010或者Blend中你可以导出ComboBox的默认模板：
VS2010中：
然后修改里面的模板，比如：
<Window x:Class="WpfApplication3.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" xmlns:my="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero">
  <Window.Resources>
    <ControlTemplate x:Key="Template1" TargetType="ComboBox">
      <Grid Name="MainGrid" SnapsToDevicePixels="True">
        <Grid.ColumnDefinitions>
          <ColumnDefinition Width="*" />
          <ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0" />
        </Grid.ColumnDefinitions>
        <Popup AllowsTransparency="True" Grid.ColumnSpan="2" IsOpen="{Binding Path=IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" Name="PART_Popup" Placement="Bottom" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}">
　　　　　　<!--设置下拉列表样式-->          
　　　　　　<my:SystemDropShadowChrome Color="Transparent" MaxHeight="{TemplateBinding ComboBox.MaxDropDownHeight}" MinWidth="{Binding Path=ActualWidth, ElementName=MainGrid}" Name="Shdw">
            <Border Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" BorderThickness="1" Name="DropDownBorder"
                    CornerRadius="10" BorderBrush="Blue"> <!-- Here -->
              <ScrollViewer Name="DropDownScrollViewer" Margin="5"><!-- Here -->
                <Grid RenderOptions.ClearTypeHint="Enabled">
                  <Canvas Height="0" HorizontalAlignment="Left" VerticalAlignment="Top" Width="0">
                    <Rectangle Fill="{Binding Path=Background, ElementName=DropDownBorder}" Height="{Binding Path=ActualHeight, ElementName=DropDownBorder}" Name="OpaqueRect" Width="{Binding Path=ActualWidth, ElementName=DropDownBorder}" />
                  </Canvas>
                  <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" Name="ItemsPresenter" SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
                </Grid>
              </ScrollViewer>
            </Border>
          </my:SystemDropShadowChrome>
        </Popup>
        <ToggleButton Background="{TemplateBinding Control.Background}" BorderBrush="{TemplateBinding Control.BorderBrush}" Grid.ColumnSpan="2" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
          <ToggleButton.Style>
            <Style TargetType="ToggleButton">
              <Setter Property="FrameworkElement.OverridesDefaultStyle" Value="True" />
              <Setter Property="Control.IsTabStop" Value="False" />
              <Setter Property="UIElement.Focusable" Value="False" />
              <Setter Property="ButtonBase.ClickMode" Value="Press" />
              <Setter Property="Control.Template">
                <Setter.Value>
                  <ControlTemplate TargetType="ToggleButton">
                    <my:ButtonChrome Background="{TemplateBinding Control.Background}" BorderBrush="{TemplateBinding Control.BorderBrush}" Name="Chrome" RenderMouseOver="{TemplateBinding UIElement.IsMouseOver}" RenderPressed="{TemplateBinding ButtonBase.IsPressed}" SnapsToDevicePixels="True">
                      <!--设置下拉三角箭头样式-->
　　　　　　　　　　　　　<Grid HorizontalAlignment="Right" Background="#7e94a9" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
                          <!--画出下拉箭头-->
　　　　　　　　　　　　　　　<Path Data="M0,0L3.5,4 7,0z" Fill="Black" HorizontalAlignment="Center" Margin="3,1,0,0" Name="Arrow" VerticalAlignment="Center" />
                      </Grid>
                    </my:ButtonChrome>
                    <ControlTemplate.Triggers>
                      <Trigger Property="ToggleButton.IsChecked" Value="True">
                        <Setter Property="my:ButtonChrome.RenderPressed" TargetName="Chrome" Value="True" />
                      </Trigger>
                      <Trigger Property="UIElement.IsEnabled" Value="False">
                        <!--设置下拉箭头禁用时背景色-->
　　　　　　　　　　　　　　<Setter Property="Shape.Fill" TargetName="Arrow" Value="#FFAFAFAF" />
                      </Trigger>
                    </ControlTemplate.Triggers>
                  </ControlTemplate>
                </Setter.Value>
              </Setter>
            </Style>
          </ToggleButton.Style>
        </ToggleButton>
        <ContentPresenter Content="{TemplateBinding ComboBox.SelectionBoxItem}" ContentStringFormat="{TemplateBinding ComboBox.SelectionBoxItemStringFormat}" ContentTemplate="{TemplateBinding ComboBox.SelectionBoxItemTemplate}" HorizontalAlignment="{TemplateBinding Control.HorizontalContentAlignment}" IsHitTestVisible="False" Margin="{TemplateBinding Control.Padding}" SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding Control.VerticalContentAlignment}" />
      </Grid>
      <ControlTemplate.Triggers>
        <Trigger Property="Popup.HasDropShadow" SourceName="PART_Popup" Value="True">
          <Setter Property="FrameworkElement.Margin" TargetName="Shdw" Value="0,0,5,5" />
          <Setter Property="my:SystemDropShadowChrome.Color" TargetName="Shdw" Value="#71000000" />
        </Trigger>
        <Trigger Property="ItemsControl.HasItems" Value="False">
          <Setter Property="FrameworkElement.Height" TargetName="DropDownBorder" Value="95" />
        </Trigger>
        <Trigger Property="UIElement.IsEnabled" Value="False">
          <Setter Property="Control.Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
          <Setter Property="Control.Background" Value="#FFF4F4F4" />
        </Trigger>
        <Trigger Property="ItemsControl.IsGrouping" Value="True">
          <Setter Property="ScrollViewer.CanContentScroll" Value="False" />
        </Trigger>
        <Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="False">
          <Setter Property="Canvas.Top" TargetName="OpaqueRect" Value="{Binding Path=VerticalOffset, ElementName=DropDownScrollViewer}" />
          <Setter Property="Canvas.Left" TargetName="OpaqueRect" Value="{Binding Path=HorizontalOffset, ElementName=DropDownScrollViewer}" />
        </Trigger>
      </ControlTemplate.Triggers>
    </ControlTemplate>
  </Window.Resources>
  </Window>
使用方法，设置combobox的Template为 Temlate1
如果想全局的设置
则讲上述的 ControlTemplate
复制到app.xml中，外围节点为 <Style TargetType="ComboBox">
<Setter Property="Template">
<Setter.Value>
上述模板内容
</Setter.Value>
</Setter>
</Style>
app.xml头部不要忘记这个
xmlns:my="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Luna"