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WPF 控件Expander其实是由ToggleButton+ContentPresenter 组成的

Expander样式代码：

<Style x:Key="ExpanderStyle" TargetType="{x:Type Expander}">

   <Setter Property="Foreground" Value="#FF217cb5"/>    <Setter Property="FontFamily" Value="宋体" />    <Setter Property="FontSize" Value="14" />    <Setter Property="Background" Value="Transparent"/>    <Setter Property="HorizontalContentAlignment" Value="Stretch"/>    <Setter Property="VerticalContentAlignment" Value="Stretch"/>    <Setter Property="BorderBrush" Value="Transparent"/>    <Setter Property="BorderThickness" Value="0"/>    <Setter Property="Template">       <Setter.Value>          <ControlTemplate TargetType="{x:Type Expander}">             <Canvas Background="{TemplateBinding Background}" SnapsToDevicePixels="true">                <ToggleButton x:Name="HeaderSite"                            Canvas.Top="0"                           ContentTemplate="{TemplateBinding HeaderTemplate}"                            ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}"                           Content="{TemplateBinding Header}"                             IsChecked="{Binding IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"                                                             Style="{DynamicResource ToggleButtonStyle}" />                                           <Border x:Name="ExpandSite"  HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"                        VerticalAlignment="{TemplateBinding VerticalContentAlignment}"                                                   Visibility="Collapsed"                        Canvas.Top="35" Canvas.Left="0"                       Focusable="false"                       BorderBrush="{TemplateBinding BorderBrush}"                       BorderThickness="{TemplateBinding BorderThickness}"                        Width="{Binding ElementName=HeaderSite,Path=Width}"                       Background="#7Ae9f4fa"                                                   >                                        <ContentPresenter Margin="10 10"                            HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />                </Border>                                               </Canvas>             <ControlTemplate.Triggers>                <Trigger Property="IsExpanded" Value="true">                   <Setter Property="Visibility" TargetName="ExpandSite" Value="Visible"/>                </Trigger>                <Trigger Property="IsEnabled" Value="false">                   <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>                </Trigger>             </ControlTemplate.Triggers>          </ControlTemplate>       </Setter.Value>    </Setter> </Style>

ToggleButton样式代码：

<Style x:Key="ToggleButtonStyle" TargetType="{x:Type ToggleButton}">

   <Setter Property="FocusVisualStyle" Value="{x:Null}"/>    <Setter Property="Width" Value="245"/>    <Setter Property="Height" Value="35" />    <Setter Property="Background" Value="#7Ad2e7f4" />    <Setter Property="Foreground" Value="#FF217cb5"/>    <Setter Property="FontSize" Value="14" />    <Setter Property="FontFamily" Value="宋体" />    <Setter Property="FontWeight" Value="Bold" />    <Setter Property="BorderThickness" Value="0"/>    <Setter Property="HorizontalContentAlignment" Value="Left"/>    <Setter Property="VerticalContentAlignment" Value="Center"/>    <Setter Property="Padding" Value="10 10"/>    <Setter Property="Template">       <Setter.Value>          <ControlTemplate TargetType="{x:Type ToggleButton}">             <Canvas Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"                      Background="{TemplateBinding Background}" SnapsToDevicePixels="True">                <Canvas x:Name="canvNormal" Visibility="Visible"                       Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"                       Background="{TemplateBinding Background}" SnapsToDevicePixels="True" Canvas.Right="0">                   <Rectangle Width="15" Height="35" Fill="#FFc7ebff" Canvas.Right="0"/>                   <Line X1="0" Y1="0" X2="0" Y2="15" Stroke="#297eb4" StrokeThickness="3"                          Margin="6 10" StrokeDashArray="1" Canvas.Right="0"/>                </Canvas>                <Canvas x:Name="canvChecked" Visibility="Hidden"                       Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"                       Background="{TemplateBinding Background}" SnapsToDevicePixels="True" Canvas.Right="0">                   <Path Data="M13.494,10.697l-3.497-3.6l-3.497,3.6L6.494,8.328l3.503-3.631l3.48,3.592L13.494,10.697z" Fill="#297eb4" Canvas.Right="5" Canvas.Top="8"/>                   <Path Data="M13.494,10.697l-3.497-3.6l-3.497,3.6L6.494,8.328l3.503-3.631l3.48,3.592L13.494,10.697z" Fill="#297eb4" Canvas.Right="5" Canvas.Top="15"/>                   <Rectangle Width="{TemplateBinding Width}" Height="1" Canvas.Bottom="0" Fill="#FFbacfda" />                </Canvas>                                            <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"                       Margin="{TemplateBinding Padding}"                       RecognizesAccessKey="True"                       SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"                       VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>             </Canvas>                          <ControlTemplate.Triggers>                <Trigger Property="IsPressed" Value="true">                   <Setter Property="Background" Value="#FFd2e7f4" />                </Trigger>                <Trigger Property="IsChecked" Value="true">                   <Setter Property="Visibility" TargetName="canvChecked" Value="Visible" />                   <Setter Property="Visibility" TargetName="canvNormal" Value="Hidden" />                </Trigger>                <Trigger Property="IsEnabled" Value="false">                   <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>                </Trigger>             </ControlTemplate.Triggers>          </ControlTemplate>       </Setter.Value>    </Setter> </Style>

 主程序代码：

<Expander ExpandDirection="Down "

        HorizontalAlignment="Left" IsExpanded="true"          Margin="46,0,0,60" Style="{DynamicResource ExpanderStyle1}" Height="122.5" VerticalAlignment="Bottom" >    <Expander.Header>       <TextBlock Text="标题" />    </Expander.Header>    <Expander.Content>       <TextBlock Text="文本内容" TextWrapping="Wrap"  />           </Expander.Content> </Expander>

注：暂不清楚为什么ToggleButton样式中的字体对Expander起不到作用

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