WPF学习笔记——TextBox的一些问题

2022-10-24 18:04:08

1、如何判断TextBox是否为空？

if(textbox.Text != string.empty)

//或者

if（textbox.Text.Trim()!=""）

{

}

2、设置TextBox为空时，背景文字提示

参考博客：http://www.cnblogs.com/tsunami/archive/2011/09/16/2179170.html

<TextBox FontSize="17" Height="26" Margin="230,150,189,0" Name="txt_Account" VerticalAlignment="Top" Foreground="Indigo" TabIndex="0" BorderThickness="1">

            <TextBox.Resources>

                <VisualBrush x:Key="HelpBrush" TileMode="None" Opacity="0.3" Stretch="None" AlignmentX="Left">

                    <VisualBrush.Visual>

                        <TextBlock FontStyle="Italic" Text="请输入用户名"/>

                    </VisualBrush.Visual>

                </VisualBrush>

            </TextBox.Resources>

            <TextBox.Style>

                <Style TargetType="TextBox">

                    <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>

在*上的回答也很好http://*.com/questions/833943/watermark-hint-text-placeholder-textbox-in-wpf/21672408#21672408

以下这个回答使用资源实现

<Window.Resources>

    <Style x:Key="TextBoxUserStyle" BasedOn="{x:Null}" TargetType="{x:Type TextBox}">

      <Setter Property="Foreground" Value="Black"/>

      <Setter Property="HorizontalAlignment" Value="Center"/>

      <Setter Property="VerticalContentAlignment" Value="Center"/>

      <Setter Property="Width" Value="225"/>

      <Setter Property="Height" Value="25"/>

      <Setter Property="FontSize" Value="12"/>

      <Setter Property="Padding" Value="1"/>

      <Setter Property="Margin" Value="5"/>

      <Setter Property="AllowDrop" Value="true"/>

      <Setter Property="FocusVisualStyle" Value="{x:Null}"/>

      <Setter Property="Template">

        <Setter.Value>

          <ControlTemplate TargetType="{x:Type TextBox}">

            <Border x:Name="OuterBorder" BorderBrush="#5AFFFFFF" BorderThickness="1,1,1,1" CornerRadius="4,4,4,4">

              <Border x:Name="InnerBorder" Background="#FFFFFFFF" BorderBrush="#33000000" BorderThickness="1,1,1,1" CornerRadius="3,3,3,3">

                <ScrollViewer SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" x:Name="PART_ContentHost"/>

              </Border>

            </Border>

          </ControlTemplate>

        </Setter.Value>

      </Setter>

    </Style>

    <Style x:Key="PasswordBoxVistaStyle" BasedOn="{x:Null}" TargetType="{x:Type PasswordBox}">

      <Setter Property="Foreground" Value="Black"/>

      <Setter Property="HorizontalAlignment" Value="Center"/>

      <Setter Property="VerticalContentAlignment" Value="Center"/>

      <Setter Property="Width" Value="225"/>

      <Setter Property="Height" Value="25"/>

      <Setter Property="FontSize" Value="12"/>

      <Setter Property="Padding" Value="1"/>

      <Setter Property="Margin" Value="5"/>

      <Setter Property="AllowDrop" Value="true"/>

      <Setter Property="FocusVisualStyle" Value="{x:Null}"/>

      <Setter Property="Template">

        <Setter.Value>

          <ControlTemplate TargetType="{x:Type PasswordBox}">

            <Border x:Name="OuterBorder" BorderBrush="#5AFFFFFF" BorderThickness="1,1,1,1" CornerRadius="4,4,4,4">

              <Border x:Name="InnerBorder" Background="#FFFFFFFF" BorderBrush="#33000000" BorderThickness="1,1,1,1" CornerRadius="3,3,3,3">

                <Grid>

                  <Label x:Name="lblPwd" Content="Password" FontSize="11" VerticalAlignment="Center" Margin="2,0,0,0" FontFamily="Verdana" Foreground="#828385" Padding="0"/>

                  <ScrollViewer SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" x:Name="PART_ContentHost"/>

                </Grid>

              </Border>

            </Border>

            <ControlTemplate.Triggers>

              <Trigger Property="IsFocused" Value="True">

                <Setter Property="Visibility" TargetName="lblPwd" Value="Hidden"/>

              </Trigger>

            </ControlTemplate.Triggers>

          </ControlTemplate>

        </Setter.Value>

      </Setter>

    </Style>

  </Window.Resources>

        <PasswordBox Style="{StaticResource PasswordBoxVistaStyle}" Margin="169,143,22,0" Name="txtPassword" FontSize="14" TabIndex="2" Height="31" VerticalAlignment="Top" />

使用第一种方式实现PasswordBox的话需要设置依赖属性，因为PasswordBox中的Password不是依赖属性，需要自己实现。留作以后研究

3、自己写UserControl实现PasswordBox和TextBox的水印

参考博客：http://www.cnblogs.com/zhanglee/archive/2012/10/20/2732097.html

贴出PasswordBox的代码，侵删

<UserControl

    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"

    mc:Ignorable="d"

    x:Class="WpfApplication1.MyPassword"

    x:Name="UserControl"

    d:DesignWidth="150" d:DesignHeight="26">

    <Grid x:Name="LayoutRoot">

        <Border Background="White" Padding="2,3" Margin="1" d:LayoutOverrides="VerticalAlignment, GridBox"/>

        <TextBlock Text="请输入密码" x:Name="txtPasswordTip" Padding="7,3" Margin="1,3,1,1" FontFamily="SimSun" d:LayoutOverrides="VerticalAlignment, GridBox"/>

        <PasswordBox Padding="4,3,2,3"    Background="Transparent" x:Name="password" PasswordChanged="password_PasswordChanged" d:LayoutOverrides="GridBox" Password=""/>

    </Grid>

</UserControl>

using System;

using System.Collections.Generic;

using System.Text;

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 WpfApplication1

{

    /// <summary>

    /// MyPassword.xaml 的交互逻辑

    /// </summary>

    public partial class MyPassword : UserControl

    {

        public MyPassword()

        {

            this.InitializeComponent();

            if (string.IsNullOrWhiteSpace(TipContent))

            {

                _tipContent = "请输入密码";

            }

            txtPasswordTip.Text = TipContent;

        }

        string tip = string.Empty;

        private void password_PasswordChanged(object sender, RoutedEventArgs e)

        {

            if (password.Password.Length != )

            {

               // this.Content = password.Password;

                this._Password = password.Password;

                if (!string.IsNullOrWhiteSpace(txtPasswordTip.Text))

                    tip = txtPasswordTip.Text;

                txtPasswordTip.Text = string.Empty;

            }

            else { txtPasswordTip.Text = tip; }

        }

        private string _tipContent = string.Empty;

        public string TipContent

        {

            get

            {

                return _tipContent;

            }

            set

            {

                if (value != _tipContent)

                {

                    _tipContent = value;

                    txtPasswordTip.Text = TipContent;

                }

            }

        }

        private string _Password = string.Empty;

        public string Password

        {

            get

            {

                return _Password;

            }

            set

            {

                if (value != _Password)

                {

                    _Password = value;

                }

            }

        }

    }

}

待更新.......

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