WPF滑块控件(Slider)的自定义样式

前言

每次开发滑块控件的样式都要花很久去读样式代码，感觉有点记不牢，所以特此备忘。

自定义滑块样式

首先创建项目，添加Slider控件。

然后获取Slider的Window样式，如下图操作。

然后弹出界面如下.我们点击确定。

点击确定后，我们的页面的Resources中，增加了一系列样式代码，而滑块代码会被修改为如下样子：

1	`<Slider HorizontalAlignment="Left"` `Width="200"` `VerticalAlignment="Top"` `Style="{DynamicResource SliderStyle1}"/>`

可以看到，系统为我们的Slider控件增加了样式——Style="{DynamicResource SliderStyle1}"

现在我们查看样式SliderStyle1，F12跟踪到定义。

<Style x:Key="SliderStyle1" TargetType="{x:Type Slider}">
    <Setter Property="Stylus.IsPressAndHoldEnabled" Value="false"/>
    <Setter Property="Background" Value="Transparent"/>
    <Setter Property="BorderBrush" Value="Transparent"/>
    <Setter Property="Foreground" Value="{StaticResource SliderThumb.Static.Foreground}"/>
    <Setter Property="Template" Value="{StaticResource SliderHorizontal}"/>
    <Style.Triggers>
        <Trigger Property="Orientation" Value="Vertical">
            <Setter Property="Template" Value="{StaticResource SliderVertical}"/>
        </Trigger>
    </Style.Triggers>
</Style>

上述代码中我们可以看发现Slider使用的模板是SliderHorizontal，但当他的排列方向为Vertical时，则使用SliderVertical模板。

因为Slider控件默认是横向布局，所以我们先修改SliderHorizontal模板，对Slider进行下美化。

同样，我们继续F12跟进SliderHorizontal的定义。

<ControlTemplate x:Key="SliderHorizontal" TargetType="{x:Type Slider}">
           <Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
               <Grid>
                   <Grid.RowDefinitions>
                       <RowDefinition Height="Auto"/>
                       <RowDefinition Height="Auto" MinHeight="{TemplateBinding MinHeight}"/>
                       <RowDefinition Height="Auto"/>
                   </Grid.RowDefinitions>
                   <TickBar x:Name="TopTick" Fill="{TemplateBinding Foreground}" Height="4" Margin="0,0,0,2" Placement="Top" Grid.Row="0" Visibility="Collapsed"/>
                   <TickBar x:Name="BottomTick" Fill="{TemplateBinding Foreground}" Height="4" Margin="0,2,0,0" Placement="Bottom" Grid.Row="2" Visibility="Collapsed"/>
                   <Border x:Name="TrackBackground" BorderBrush="{StaticResource SliderThumb.Track.Border}" BorderThickness="1" Background="{StaticResource SliderThumb.Track.Background}" Height="4.0" Margin="5,0" Grid.Row="1" VerticalAlignment="center">
                       <Canvas Margin="-6,-1">
                           <Rectangle x:Name="PART_SelectionRange" Fill="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" Height="4.0" Visibility="Hidden"/>
                       </Canvas>
                   </Border>
                   <Track x:Name="PART_Track" Grid.Row="1">
                       <Track.DecreaseRepeatButton>
                           <RepeatButton Command="{x:Static Slider.DecreaseLarge}" Style="{StaticResource RepeatButtonTransparent}"/>
                       </Track.DecreaseRepeatButton>
                       <Track.IncreaseRepeatButton>
                           <RepeatButton Command="{x:Static Slider.IncreaseLarge}" Style="{StaticResource RepeatButtonTransparent}"/>
                       </Track.IncreaseRepeatButton>
                       <Track.Thumb>
                           <Thumb x:Name="Thumb" Focusable="False" Height="18" OverridesDefaultStyle="True" Template="{StaticResource SliderThumbHorizontalDefault}" VerticalAlignment="Center" Width="11"/>
                       </Track.Thumb>
                   </Track>
               </Grid>
           </Border>
           <ControlTemplate.Triggers>
               <Trigger Property="TickPlacement" Value="TopLeft">
                   <Setter Property="Visibility" TargetName="TopTick" Value="Visible"/>
                   <Setter Property="Template" TargetName="Thumb" Value="{StaticResource SliderThumbHorizontalTop}"/>
                   <Setter Property="Margin" TargetName="TrackBackground" Value="5,2,5,0"/>
               </Trigger>
               <Trigger Property="TickPlacement" Value="BottomRight">
                   <Setter Property="Visibility" TargetName="BottomTick" Value="Visible"/>
                   <Setter Property="Template" TargetName="Thumb" Value="{StaticResource SliderThumbHorizontalBottom}"/>
                   <Setter Property="Margin" TargetName="TrackBackground" Value="5,0,5,2"/>
               </Trigger>
               <Trigger Property="TickPlacement" Value="Both">
                   <Setter Property="Visibility" TargetName="TopTick" Value="Visible"/>
                   <Setter Property="Visibility" TargetName="BottomTick" Value="Visible"/>
               </Trigger>
               <Trigger Property="IsSelectionRangeEnabled" Value="true">
                   <Setter Property="Visibility" TargetName="PART_SelectionRange" Value="Visible"/>
               </Trigger>
               <Trigger Property="IsKeyboardFocused" Value="true">
                   <Setter Property="Foreground" TargetName="Thumb" Value="Blue"/>
               </Trigger>
           </ControlTemplate.Triggers>
       </ControlTemplate>

SliderHorizontal模板的定义比较多，这里直接定义到重点内容——轨道。

首先定位到代码【Border x:Name="TrackBackground"】，这里的TrackBackground是控制滑块背景颜色的，我们修改其背景颜色和边框颜色。

<Border x:Name="TrackBackground" BorderBrush="Red" BorderThickness="1" Background="Yellow" Height="4.0" Margin="5,0" Grid.Row="1" VerticalAlignment="center">
    <Canvas Margin="-6,-1">
        <Rectangle x:Name="PART_SelectionRange" Fill="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" Height="4.0" Visibility="Hidden"/>
    </Canvas>
</Border>

得到效果如下：

但我们有时候需要拖动前后颜色不一样，此时就靠背景修改就不够了。

在SliderHorizontal模板中找到DecreaseRepeatButton和IncreaseRepeatButton；这两个一个是拖动前覆盖颜色，一个是拖动后覆盖颜色。

修改代码如下：

<Track x:Name="PART_Track" Grid.Row="1">
    <Track.DecreaseRepeatButton>
        <RepeatButton Height="4" Background="Gray" Command="{x:Static Slider.DecreaseLarge}" Style="{StaticResource RepeatButtonTransparent}"/>
    </Track.DecreaseRepeatButton>
    <Track.IncreaseRepeatButton>
        <RepeatButton Height="4" Background="Green" Command="{x:Static Slider.IncreaseLarge}" Style="{StaticResource RepeatButtonTransparent}"/>
    </Track.IncreaseRepeatButton>
    <Track.Thumb>
        <Thumb x:Name="Thumb" Focusable="False" Height="18" OverridesDefaultStyle="True" Template="{StaticResource SliderThumbHorizontalDefault}" VerticalAlignment="Center" Width="11"/>
    </Track.Thumb>
</Track>

得到效果如下：

注意这里的Height一定要给值。

现在，我们设置好了轨道，可当前的滑块的颜色我们有点不太满意，所以我们再来处理下滑块。

滑块模板的模板是上方代码中粉色标记的代码——Thumb。

可以看到Thumb使用的是SliderThumbHorizontalDefault模板，所以，我们继续F12跟进SliderThumbHorizontalDefault查看它的定义。

<ControlTemplate x:Key="SliderThumbHorizontalDefault" TargetType="{x:Type Thumb}">
    <Grid HorizontalAlignment="Center" UseLayoutRounding="True" VerticalAlignment="Center">
        <Path x:Name="grip" Data="M 0,0 C0,0 11,0 11,0 11,0 11,18 11,18 11,18 0,18 0,18 0,18 0,0 0,0 z" Fill="{StaticResource SliderThumb.Static.Background}" Stretch="Fill" SnapsToDevicePixels="True" Stroke="{StaticResource SliderThumb.Static.Border}" StrokeThickness="1" UseLayoutRounding="True" VerticalAlignment="Center"/>
    </Grid>
    <ControlTemplate.Triggers>
        <Trigger Property="IsMouseOver" Value="true">
            <Setter Property="Fill" TargetName="grip" Value="{StaticResource SliderThumb.MouseOver.Background}"/>
            <Setter Property="Stroke" TargetName="grip" Value="{StaticResource SliderThumb.MouseOver.Border}"/>
        </Trigger>
        <Trigger Property="IsDragging" Value="true">
            <Setter Property="Fill" TargetName="grip" Value="{StaticResource SliderThumb.Pressed.Background}"/>
            <Setter Property="Stroke" TargetName="grip" Value="{StaticResource SliderThumb.Pressed.Border}"/>
        </Trigger>
        <Trigger Property="IsEnabled" Value="false">
            <Setter Property="Fill" TargetName="grip" Value="{StaticResource SliderThumb.Disabled.Background}"/>
            <Setter Property="Stroke" TargetName="grip" Value="{StaticResource SliderThumb.Disabled.Border}"/>
        </Trigger>
    </ControlTemplate.Triggers>
</ControlTemplate>

从上述代码中可以看到，滑块定义很简单，布局就是一个Grid里放了一个Path，事件响应只有3个。

下面为修改Path的Fill填充色和Stroke的划线颜色如下：

1	`<Path x:Name="grip"` `Data="M 0,0 C0,0 11,0 11,0 11,0 11,18 11,18 11,18 0,18 0,18 0,18 0,0 0,0 z"` `Fill="Red"` `Stretch="Fill"` `SnapsToDevicePixels="True"` `Stroke="Blue"` `StrokeThickness="1"` `UseLayoutRounding="True"` `VerticalAlignment="Center"/>`

得到效果如下：

现在，我们觉得矩形的滑块不好看，需要用椭圆形的滑块，那么，我们再来处理下滑块。

首先删除Thumb里定义的宽和高，因为不删除它们，模板里的宽高会受此限制。

删除后如下：

<Track.Thumb>
    <Thumb x:Name="Thumb" Focusable="False"   OverridesDefaultStyle="True" Template="{StaticResource SliderThumbHorizontalDefault}" VerticalAlignment="Center" />
</Track.Thumb>

现在我们再来修改SliderThumbHorizontalDefault模板。

在模板里找到Path，修改他的Data，之前他的Data是自己画的一个矩形，现在我们给他改为椭圆形，并且给Path重新设置宽高，如下：

<Path x:Name="grip" Width="20" Height="20" Fill="Red" Stretch="Fill" SnapsToDevicePixels="True" Stroke="Blue" StrokeThickness="1" UseLayoutRounding="True" VerticalAlignment="Center">
    <Path.Data>
        <EllipseGeometry Center="10,10" RadiusX="10" RadiusY="10"></EllipseGeometry>
    </Path.Data>
</Path>

我们得到效果如下：

可以看到，图中的滑块是个圆形，而我们需要的是一个椭圆形。

处理很简单，修改Path的Width即可，我们该为14，得到效果如下：

当然，我们既然可以通过修改样式设计椭圆形滑块，就也可以设计其他形状滑块，比如，我们修改Path如下，获得斜角四边形滑块：

<Path x:Name="grip" Width="14" Height="20" Fill="Red" Stretch="Fill" SnapsToDevicePixels="True" Stroke="Blue" StrokeThickness="1" UseLayoutRounding="True" VerticalAlignment="Center">
    <Path.Data>
        <PathGeometry>
            <PathGeometry.Figures>
                <PathFigure StartPoint="0,0" IsClosed="True">
                    <LineSegment Point="0,0" />
                    <LineSegment Point="110,0" />
                    <LineSegment Point="70,40" />
                    <LineSegment Point="-40,40" />
                </PathFigure>
            </PathGeometry.Figures>
        </PathGeometry>
    </Path.Data>
</Path> 

效果图如下：

修改代码如下，设置三角形滑块：

<Path x:Name="grip" Width="14" Height="20" Fill="Red" Stretch="Fill" SnapsToDevicePixels="True" Stroke="Blue" StrokeThickness="1" UseLayoutRounding="True" VerticalAlignment="Center">
    <Path.Data>
        <PathGeometry>
            <PathGeometry.Figures>
                <PathFigure StartPoint="0,0" IsClosed="True">
                    <LineSegment Point="30,0" />
                    <LineSegment Point="15,100" />
                </PathFigure>
            </PathGeometry.Figures>
        </PathGeometry>
    </Path.Data>
</Path> 

效果图如下：

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上述代码设置的都是水平方向的滑块样式，垂直方向的滑块样式设置同理，只要从模板SliderVertical开始，以此处理修改即可。

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特殊图形我们看到，在图形后面还有一个小背景色在显示，解决方法：修改TrackBackground的背景色为透明。

<Border x:Name="TrackBackground" BorderBrush="{StaticResource SliderThumb.Track.Border}" BorderThickness="0" Background="Transparent" Height="4.0" Margin="5,0" Grid.Row="1" VerticalAlignment="center">
                   <Canvas Margin="-6,-1">
                       <Rectangle x:Name="PART_SelectionRange" Fill="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" Height="4.0" Visibility="Hidden"/>
                   </Canvas>
</Border>