aistudio-wpf-diagram/AIStudio.Wpf.DiagramDesigner/Styles/TextBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:dd="clr-namespace:AIStudio.Wpf.DiagramDesigner">
    <!--TextBox水印样式-->
    <Style TargetType="{x:Type TextBox}" x:Key="WaterTextBox">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="TextWrapping" Value="Wrap"/>
        <Setter Property="Width" Value="Auto"/>
        <Setter Property="HorizontalAlignment" Value="Stretch"/>
        <Setter Property="VerticalAlignment" Value="Stretch"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <Grid x:Name="PART_Root">
                        <Border x:Name="Bg" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                    BorderBrush="{TemplateBinding BorderBrush}" 
                                    BorderThickness="{TemplateBinding BorderThickness}" 
                                    Background="{TemplateBinding Background}" />
                        <Grid x:Name="PART_InnerGrid">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition  Width="Auto" />
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition  Width="Auto" />
                            </Grid.ColumnDefinitions>

                            <!--内容区域-->
                            <ScrollViewer x:Name="PART_ContentHost" BorderThickness="0" Grid.Column="1" IsTabStop="False" Margin="2"
                                          VerticalAlignment="Stretch" Background="{x:Null}" >
                            </ScrollViewer>
                            <!--水印-->
                            <TextBlock x:Name="Message"  Padding="{TemplateBinding Padding}" Visibility="Collapsed"
                                       Text="{TemplateBinding dd:ControlAttachProperty.Watermark}" Grid.Column="1"
                                       Foreground="{TemplateBinding Foreground}" IsHitTestVisible="False" Opacity="0.5"
                                       HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                       VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Margin="5,2,5,2" />
                        </Grid>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <!--显示水印-->
                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Text}" Value="">
                            <Setter TargetName="Message" Property="Visibility" Value="Visible" />
                        </DataTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <!--TextBox水印，阴影样式-->
    <Style TargetType="{x:Type TextBox}" x:Key="WaterTextBoxWithEffect">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="TextWrapping" Value="Wrap"/>
        <Setter Property="Width" Value="Auto"/>
        <Setter Property="HorizontalAlignment" Value="Stretch"/>
        <Setter Property="VerticalAlignment" Value="Stretch"/>
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <Grid x:Name="PART_Root">
                        <Border x:Name="Bg" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                    BorderBrush="{TemplateBinding BorderBrush}" 
                                    BorderThickness="{TemplateBinding BorderThickness}" 
                                    Background="{TemplateBinding Background}" />
                        <Grid x:Name="PART_InnerGrid">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition  Width="Auto" />
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition  Width="Auto" />
                            </Grid.ColumnDefinitions>

                            <!--内容区域-->
                            <ScrollViewer x:Name="PART_ContentHost" BorderThickness="0" Grid.Column="1" IsTabStop="False" Margin="2"
                                          VerticalAlignment="Stretch" Background="{x:Null}" >
                                <ScrollViewer.Effect>
                                    <DropShadowEffect x:Name="effect" Color="{Binding FontViewModel.TextEffectColor}" ></DropShadowEffect>
                                </ScrollViewer.Effect>
                            </ScrollViewer>
                            <!--水印-->
                            <TextBlock x:Name="Message"  Padding="{TemplateBinding Padding}" Visibility="Collapsed"
                                       Text="{TemplateBinding dd:ControlAttachProperty.Watermark}" Grid.Column="1"
                                       Foreground="{TemplateBinding Foreground}" IsHitTestVisible="False" Opacity="0.5"
                                       HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                       VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Margin="5,2,5,2" />
                        </Grid>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <!--显示水印-->
                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Text}" Value="">
                            <Setter TargetName="Message" Property="Visibility" Value="Visible" />
                        </DataTrigger>
                        <DataTrigger Binding="{Binding FontViewModel.TextEffectColor}" Value="Transparent">
                            <Setter TargetName="PART_ContentHost" Property="Effect" Value="{x:Null}"/>
                        </DataTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>