本文实例为大家分享TextBox和PasswordBox加水印的方法，供大家参考，具体内容如下

Textbox加水印

Textbox加水印，需要一个VisualBrush和触发器验证Text是否为空，在空的时候设置背景的Brush就可以实现水印效果。

<TextBox Name="txtBoxName" Width="120" Height="23"> <TextBox.Resources> <VisualBrush x:Key="HelpBrush" TileMode="None" Opacity="0.3" Stretch="None" AlignmentX="Left"> <VisualBrush.Visual> <TextBlock Font Text="水印效果"/> </VisualBrush.Visual> </VisualBrush> </TextBox.Resources> <TextBox.Style> <Style TargetType="TextBox"> <Setter Property="Height" Value="23"/> <Setter Property="HorizontalAlignment" Value="Left"/> <Setter Property="VerticalAlignment" Value="Top"/> <Style.Triggers> <Trigger Property="Text" Value="{x:Null}"> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> <Trigger Property="Text" Value=""> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> </Style.Triggers> </Style> </TextBox.Style> </TextBox>

PasswordBox加水印

PasswordBox加水印，需要添加判断输入非空的依赖属性，因为PasswordBox本身没有这个属性。

通过一个PasswordLength函数判断密码框的长度是不是0，如果是0则显示背景水印，否则就隐藏。

属性部分代码，CS文件

public class PasswordBoxMonitor : DependencyObject { public static bool GetIsMonitoring(DependencyObject obj) { return (bool)obj.GetValue(IsMonitoringProperty); } public static void SetIsMonitoring(DependencyObject obj, bool value) { obj.SetValue(IsMonitoringProperty, value); } public static readonly DependencyProperty IsMonitoringProperty = DependencyProperty.RegisterAttached("IsMonitoring", typeof(bool), typeof(PasswordBoxMonitor), new UIPropertyMetadata(false, OnIsMonitoringChanged)); public static int GetPasswordLength(DependencyObject obj) { return (int)obj.GetValue(PasswordLengthProperty); } public static void SetPasswordLength(DependencyObject obj, int value) { obj.SetValue(PasswordLengthProperty, value); } public static readonly DependencyProperty PasswordLengthProperty = DependencyProperty.RegisterAttached("PasswordLength", typeof(int), typeof(PasswordBoxMonitor), new UIPropertyMetadata(0)); private static void OnIsMonitoringChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var pb = d as PasswordBox; if (pb == null) { return; } if ((bool)e.NewValue) { pb.PasswordChanged += PasswordChanged; } else { pb.PasswordChanged -= PasswordChanged; } } static void PasswordChanged(object sender, RoutedEventArgs e) { var pb = sender as PasswordBox; if (pb == null) { return; } SetPasswordLength(pb, pb.Password.Length); } }

XMAL代码

<PasswordBox Name="pb" Width="120" VerticalAlignment="Bottom" Height="35"> <PasswordBox.Style> <Style TargetType="PasswordBox"> <Setter Property="Height" Value="23"/> <Setter Property="HorizontalAlignment" Value="Left"/> <Setter Property="VerticalAlignment" Value="Top"/> <Setter Property="local:PasswordBoxMonitor.IsMonitoring" Value="True"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type PasswordBox}"> <Border Name="Bd" Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" SnapsToDevicePixels="True"> <Grid> <ScrollViewer x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/> <StackPanel Orientation="Horizontal" Visibility="Collapsed" Name="myStackPanel"> <TextBlock HorizontalAlignment="Left" VerticalAlignment="Center" Foreground="LightGray" Text="水印效果"/> </StackPanel> </Grid> </Border> <ControlTemplate.Triggers> <Trigger Property="IsEnabled" Value="false"> <Setter Property="Visibility" TargetName="myStackPanel" Value="Collapsed"/> </Trigger> <Trigger Property="local:PasswordBoxMonitor.PasswordLength" Value="0"> <Setter Property="Visibility" TargetName="myStackPanel" Value="Visible"/> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter> </Style> </PasswordBox.Style> </PasswordBox>

效果图

2016-09-07 新增内容

将TextBlock暴露出来，做一个可以修改水印的Textbox控件

<TextBox x:Class="OracleCodeGenerator.watermarkTextBox" 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:OracleCodeGenerator" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="300" Name="tb"> <TextBox.Resources> <VisualBrush x:Key="HelpBrush" TileMode="None" Opacity="0.3" Stretch="None" AlignmentX="Left"> <VisualBrush.Visual> <TextBlock Text="{Binding TbText,ElementName=tb}" Font/> </VisualBrush.Visual> </VisualBrush> </TextBox.Resources> <TextBox.Style> <Style TargetType="TextBox"> <Setter Property="Height" Value="23"/> <Setter Property="HorizontalAlignment" Value="Left"/> <Setter Property="VerticalAlignment" Value="Top"/> <Style.Triggers> <Trigger Property="Text" Value="{x:Null}"> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> <Trigger Property="Text" Value=""> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> </Style.Triggers> </Style> </TextBox.Style> </TextBox>

public partial class watermarkTextBox : TextBox { public watermarkTextBox() { InitializeComponent(); } private string tbText; public string TbText { get { return tbText; } set { tbText = value; } } }

调用只有一句话

复制代码 代码如下:<local:watermarkTextBox Width="150" TbText="我是水印"/>

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