WPF 搜索框控件样式

完全通过Xaml代码实现，使用了UserControl进行封装。功能包括聚焦时控件展开，输入为空时的文字提示，以及待选提示项列表等效果。实现效果如下图：

xaml代码

<UserControl x:Class="SearchBar.SearchBox"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:SearchBar"
             UseLayoutRounding="True"
             TextElement.FontSize="14"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="440">
    <UserControl.Resources>
        <SolidColorBrush x:Key="Control.BoderBrush" Color="#CBCBCB"/>
        <Style TargetType="{x:Type TextBox}">
            <Setter Property="Background" Value="#FFF2F3F4"/>
            <Setter Property="BorderBrush" Value="{StaticResource Control.BoderBrush}"/>
            <Setter Property="Foreground" Value="#515151"/>
            <Setter Property="VerticalContentAlignment" Value="Center"/>
            <Setter Property="Padding" Value="8 0 0 0"/>
            <Setter Property="BorderThickness" Value="1"/>
            <Setter Property="KeyboardNavigation.TabNavigation" Value="None"/>
            <Setter Property="HorizontalContentAlignment" Value="Left"/>
            <Setter Property="AllowDrop" Value="true"/>
            <Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
            <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type TextBox}">
                        <Border x:Name="border" CornerRadius="8" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" SnapsToDevicePixels="True">
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition/>
                                    <ColumnDefinition Width="44"/>
                                </Grid.ColumnDefinitions>
                                <Border x:Name="bdLeft" CornerRadius="8" Margin="4 4 8 4">
                                    <Grid>
                                        <ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                                        <TextBlock Text="输入搜索内容" VerticalAlignment="Center" Margin="10 0" Opacity="0.8">
                                            <TextBlock.Style>
                                                <Style TargetType="TextBlock">
                                                    <Setter Property="Visibility" Value="Collapsed" />
                                                    <Style.Triggers>
                                                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=TextBox},Path=Text}" Value="">
                                                            <Setter Property="Visibility" Value="Visible"/>
                                                        </DataTrigger>
                                                    </Style.Triggers>
                                                </Style>
                                            </TextBlock.Style>
                                        </TextBlock>
                                    </Grid>
                                </Border>

                                <Button Grid.Column="1" Margin="4">
                                    <Button.Style>
                                        <Style TargetType="Button">
                                            <Setter Property="Template">
                                                <Setter.Value>
                                                    <ControlTemplate TargetType="Button">
                                                        <Border x:Name="bd" CornerRadius="8" Background="Transparent">
                                                            <ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center"></ContentPresenter>
                                                        </Border>
                                                        <ControlTemplate.Triggers>
                                                            <Trigger Property="IsMouseOver" Value="True">
                                                                <Setter TargetName="bd" Property="Background" Value="#60CACACA"/>
                                                            </Trigger>
                                                        </ControlTemplate.Triggers>
                                                    </ControlTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </Button.Style>
                                    <Path Fill="#C9000000" Margin="8" Stretch="Uniform"  Data="M15.7 13.3l-3.81-3.83A5.93 5.93 0 0013 6c0-3.31-2.69-6-6-6S1 2.69 1 6s2.69 6 6 6c1.3 0 2.48-.41 3.47-1.11l3.83 3.81c.19.2.45.3.7.3.25 0 .52-.09.7-.3a.996.996 0 000-1.41v.01zM7 10.7c-2.59 0-4.7-2.11-4.7-4.7 0-2.59 2.11-4.7 4.7-4.7 2.59 0 4.7 2.11 4.7 4.7 0 2.59-2.11 4.7-4.7 4.7z"></Path>
                                </Button>
                            </Grid>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsEnabled" Value="false">
                                <Setter Property="Opacity" TargetName="border" Value="0.56"/>
                            </Trigger>
                            <Trigger Property="IsMouseOver" Value="true">
                                <Setter Property="Background" TargetName="border" Value="white"/>
                            </Trigger>
                            <Trigger Property="IsKeyboardFocused" Value="true">
                                <Setter Property="Background" TargetName="bdLeft" Value="#60CACACA"/>
                                <Setter Property="BorderBrush" TargetName="border" Value="Transparent"/>
                                <Setter Property="Background" TargetName="border" Value="white"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <MultiTrigger>
                    <MultiTrigger.Conditions>
                        <Condition Property="IsInactiveSelectionHighlightEnabled" Value="true"/>
                        <Condition Property="IsSelectionActive" Value="false"/>
                    </MultiTrigger.Conditions>
                    <Setter Property="SelectionBrush" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
                </MultiTrigger>
            </Style.Triggers>
        </Style>
    </UserControl.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="44"/>
            <RowDefinition Height="auto"/>
        </Grid.RowDefinitions>

        <Border Grid.RowSpan="2" BorderThickness="1" Background="White" BorderBrush="{StaticResource Control.BoderBrush}" CornerRadius="8">
            <Border.Effect>
                <DropShadowEffect Color="Gray" Opacity="0.2" ShadowDepth="0" BlurRadius="12"/>
            </Border.Effect>

            <Border.Style>
                <Style TargetType="Border">
                    <Setter Property="Visibility" Value="Collapsed"/>
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding ElementName=txtBox,Path=IsKeyboardFocused}" Value="True">
                            <Setter Property="Visibility" Value="Visible"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Border.Style>

            <Grid Margin="0 44 0 12">
                <ListBox BorderBrush="Transparent" Padding="4 0"
                         ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=local:SearchBox},Path=SearchList}">
                    <ListBox.ItemContainerStyle>
                        <Style TargetType="ListBoxItem">
                            <Setter Property="Padding" Value="8" />
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="{x:Type ListBoxItem}">
                                        <Border x:Name="Bd" SnapsToDevicePixels="true" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}">
                                            <ContentPresenter Opacity="0.8" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" x:Name="contentPresenter"/>
                                        </Border>
                                        <ControlTemplate.Triggers>
                                            <Trigger Property="IsMouseOver" Value="True">
                                                <Setter Property="Background" Value="#20808080"/>
                                            </Trigger>
                                            <Trigger Property="IsSelected" Value="True">
                                                <Setter Property="Background" Value="#20808080"/>
                                            </Trigger>
                                            <MultiTrigger>
                                                <MultiTrigger.Conditions>
                                                    <Condition Property="IsSelected" Value="true"/>
                                                    <Condition Property="Selector.IsSelectionActive" Value="false"/>
                                                </MultiTrigger.Conditions>
                                                <Setter Property="Background" TargetName="Bd" Value="#20808080"/>
                                            </MultiTrigger>
                                        </ControlTemplate.Triggers>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </ListBox.ItemContainerStyle>
                </ListBox>
            </Grid>
        </Border>
        <Grid>
            <TextBox x:Name="txtBox"/>
        </Grid>

        <Grid Grid.Row="1" Height="280"></Grid>
    </Grid>
</UserControl>

后台代码：

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace SearchBar
{
    /// <summary>
    /// SearchBox.xaml 的交互逻辑
    /// </summary>
    public partial class SearchBox : UserControl
    {
        public SearchBox()
        {
            InitializeComponent();
        }

        public ObservableCollection<string> SearchList
        {
            get { return (ObservableCollection<string>)GetValue(SearchListProperty); }
            set { SetValue(SearchListProperty, value); }
        }
        public static readonly DependencyProperty SearchListProperty =
            DependencyProperty.Register("SearchList", typeof(ObservableCollection<string>), typeof(SearchBox), new PropertyMetadata(new ObservableCollection<string>()));
    }
}

控件使用显示示例：

<Window x:Class="SearchBar.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:SearchBar"
        mc:Ignorable="d"
        Title="MainWindow" Height="500" Width="420">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="60"/>
            <RowDefinition/>
        </Grid.RowDefinitions>

        <local:SearchBox x:Name="searchbox" Grid.RowSpan="2" Margin="8" Panel.ZIndex="50">
        </local:SearchBox>
        
        <ListBox Grid.Row="1" Margin="16">
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
            <ListBoxItem Padding="8">AAA</ListBoxItem>
        </ListBox>
    </Grid>
</Window>