CheckBox样式

<Style x:Key="chkBase" TargetType="CheckBox">
            <Setter Property="IsChecked" Value="False"/>
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="Foreground" Value="#999"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="CheckBox">
                        <DockPanel  Background="{TemplateBinding Background}" ToolTip="{TemplateBinding Content}" LastChildFill="False" Width="{TemplateBinding Width}">
                            <Image Margin="2 0 0 0" DockPanel.Dock="Left" x:Name="_img"  Stretch="None" Source="/Images/chk_no.png"/>
                            <TextBlock DockPanel.Dock="Left" Foreground="{TemplateBinding Foreground}" Margin="2 0 0 0" VerticalAlignment="Center" Text="{Binding Content,RelativeSource={RelativeSource TemplatedParent}}" />
                        </DockPanel>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="_img" Property="Source" Value="/Images/chk_yes.png"/>
                            </Trigger>
                            <Trigger Property="IsChecked" Value="{x:Null}">
                                <Setter TargetName="_img" Property="Source" Value="/Images/chk_null.png"/>
                            </Trigger>
                       </ControlTemplate.Triggers>
                  </ControlTemplate>
             </Setter.Value>
       </Setter>
 </Style>