kmpdfkit_demo/Demo/Examples/Compdfkit_Tools/PDFView/PDFSearch/PDFSearchUI/CPDFSearchInputUI.xaml

<UserControl x:Class="Compdfkit_Tools.PDFControlUI.CPDFSearchInputUI"
             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:Compdfkit_Tools.PDFControlUI"
             xmlns:common="clr-namespace:Compdfkit_Tools.Common"
             mc:Ignorable="d">
    <UserControl.Resources>
        <ResourceDictionary>
            <common:TextLengthToVisibilityConverter x:Key="TextLengthToVisibilityConverter"/>
            <common:InvertTextLengthToVisibilityConverter x:Key="InvertTextLengthToVisibilityConverter"/>
            <common:TextLengthToBoolConverter x:Key="TextLengthToBoolConverter"/>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="../../../Asset/Styles/ButtonStyle.xaml"></ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <Grid Margin="5">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"></ColumnDefinition>
            <ColumnDefinition Width="auto"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Grid Margin="0,0,8,0">
            <TextBox Name="SearchTextBox" VerticalContentAlignment="Center" TextChanged="SearchTextBox_TextChanged" Height="30" KeyDown="SearchTextBox_KeyDown" Padding="5,0,30,0"></TextBox>
            <TextBlock VerticalAlignment="Center" IsHitTestVisible="False" Margin="10,0,0,0" 
                       Visibility="{Binding ElementName=SearchTextBox,Path=Text,Converter={StaticResource TextLengthToVisibilityConverter}}">Search</TextBlock>
            
            <Border Visibility="{Binding ElementName=SearchTextBox,Path=Text,Converter={StaticResource InvertTextLengthToVisibilityConverter}}"
                    HorizontalAlignment="Right" VerticalAlignment="Center" Margin="0,0,10,0"
                    Background="#01000000" MouseLeftButtonDown="TextClear_MouseLeftButtonDown">
                <Path Fill="Black" IsHitTestVisible="False">
                    <Path.Data>
                        M12.5762 3.95117L8.5332 8L12.5762 12.0488L12.0488 12.5762L8 8.5332L3.95117 12.5762L3.42383 12.0488L7.4668 8L3.42383 3.95117L3.95117 3.42383L8 7.4668L12.0488 3.42383L12.5762 3.95117Z
                    </Path.Data>
                </Path>
            </Border>
        </Grid>
        <Button Name="SearchBtn" Style="{StaticResource ButtonStyle}" Grid.Column="1" Width="56" Height="30" FontSize="14" Click="SearchBtn_Click"
                IsEnabled="{Binding ElementName=SearchTextBox,Path=Text,Converter={StaticResource TextLengthToBoolConverter}}">
            Done
        </Button>
    </Grid>
</UserControl>