How to access the Rectangles width/height via C# code

问题

I have this page resource for my sliders. But I need to scale the thumb rectangles through the code behind in C#. How can I access the rects for the thumb definitions?

    <Page.Resources>

    <Style TargetType="Slider">

        <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
        <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
        <Setter Property="ManipulationMode" Value="None" />
        <Setter Property="UseSystemFocusVisuals" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Slider">
                    <Grid Margin="{TemplateBinding Padding}">
                        <Grid.Resources>
                            <Style TargetType="Thumb" x:Key="SliderThumbStyleVertical">
                                <Setter Property="BorderThickness" Value="0" />
                                <Setter Property="Background" Value="{ThemeResource SystemControlForegroundAccentBrush}" />
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="Thumb">

                                            <Rectangle Height="60" Width="30">
                                                <Rectangle.Fill>
                                                    <ImageBrush ImageSource="/Assets/Images/fader.png" Stretch="Uniform"/>
                                                </Rectangle.Fill>
                                            </Rectangle>

                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                            <Style TargetType="Thumb" x:Key="SliderThumbStyleHorizontal">
                                <Setter Property="BorderThickness" Value="0" />
                                <Setter Property="Background" Value="{ThemeResource SystemControlForegroundAccentBrush}" />
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="Thumb">

                                            <Rectangle x:Name="HorizontalThumbRect" Height="30" Width="60">
                                                <Rectangle.Fill>
                                                    <ImageBrush ImageSource="/Assets/Images/fader2.png" Stretch="Uniform"/>
                                                </Rectangle.Fill>
                                            </Rectangle>

                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                        </Grid.Resources>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto" />
                            <RowDefinition Height="*" />
                        </Grid.RowDefinitions>

                        <Grid x:Name="SliderContainer" Background="Transparent" Grid.Row="1" Control.IsTemplateFocusTarget="True">

                            <Grid x:Name="HorizontalTemplate">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="Auto" />
                                    <ColumnDefinition Width="Auto" />
                                    <ColumnDefinition Width="*" />
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="0" />
                                    <RowDefinition Height="Auto" />
                                    <RowDefinition Height="0" />
                                </Grid.RowDefinitions>
                                <Rectangle x:Name="HorizontalTrackRect"
                  Fill="DimGray"
                  Height="{ThemeResource SliderTrackThemeHeight}"
                  Grid.Row="1"
                  Grid.ColumnSpan="3" />
                  <Rectangle x:Name="HorizontalDecreaseRect" Fill="DimGray" Grid.Row="1" />
                  <Thumb x:Name="HorizontalThumb"
              Style="{StaticResource SliderThumbStyleHorizontal}"
              DataContext="{TemplateBinding Value}"
              Grid.Row="0"
              Grid.RowSpan="3"
              Grid.Column="1"
              AutomationProperties.AccessibilityView="Raw" />
                            </Grid>
                            <Grid x:Name="VerticalTemplate">
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="*" />
                                    <RowDefinition Height="Auto" />
                                    <RowDefinition Height="Auto" />
                                </Grid.RowDefinitions>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="0" />
                                    <ColumnDefinition Width="Auto" />
                                    <ColumnDefinition Width="0" />
                                </Grid.ColumnDefinitions>
                                <Rectangle x:Name="VerticalTrackRect"
                  Fill="DimGray"
                  Width="{ThemeResource SliderTrackThemeHeight}"
                  Grid.Column="1"
                  Grid.RowSpan="3" />
                                <Rectangle x:Name="VerticalDecreaseRect"
                  Fill="DimGray"
                  Grid.Column="1"
                  Grid.Row="2" />

                                <Thumb x:Name="VerticalThumb"

              Style="{StaticResource SliderThumbStyleVertical}"
              DataContext="{TemplateBinding Value}"
              Grid.Row="1"
              Grid.Column="0"
              Grid.ColumnSpan="3"
              AutomationProperties.AccessibilityView="Raw"/>
                            </Grid>
                        </Grid>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Page.Resources>

I've tried binding... but it seems that binding is not supported within a style? Is there another way I can access those rects?

来源：https://stackoverflow.com/questions/41812518/how-to-access-the-rectangles-width-height-via-c-sharp-code