我怎么能把一些文本放入一个文本框，这将被自动删除时，用户键入的东西在它?
当前回答
这是一个演示如何在WPF中创建水印文本框的示例:
<Window x:Class="WaterMarkTextBoxDemo.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WaterMarkTextBoxDemo"
Height="200" Width="400">
<Window.Resources>
<SolidColorBrush x:Key="brushWatermarkBackground" Color="White" />
<SolidColorBrush x:Key="brushWatermarkForeground" Color="LightSteelBlue" />
<SolidColorBrush x:Key="brushWatermarkBorder" Color="Indigo" />
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<local:TextInputToVisibilityConverter x:Key="TextInputToVisibilityConverter" />
<Style x:Key="EntryFieldStyle" TargetType="Grid" >
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="VerticalAlignment" Value="Center" />
<Setter Property="Margin" Value="20,0" />
</Style>
</Window.Resources>
<Grid Background="LightBlue">
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="{StaticResource brushWatermarkBackground}" Style="{StaticResource EntryFieldStyle}" >
<TextBlock Margin="5,2" Text="This prompt dissappears as you type..." Foreground="{StaticResource brushWatermarkForeground}"
Visibility="{Binding ElementName=txtUserEntry, Path=Text.IsEmpty, Converter={StaticResource BooleanToVisibilityConverter}}" />
<TextBox Name="txtUserEntry" Background="Transparent" BorderBrush="{StaticResource brushWatermarkBorder}" />
</Grid>
<Grid Grid.Row="1" Background="{StaticResource brushWatermarkBackground}" Style="{StaticResource EntryFieldStyle}" >
<TextBlock Margin="5,2" Text="This dissappears as the control gets focus..." Foreground="{StaticResource brushWatermarkForeground}" >
<TextBlock.Visibility>
<MultiBinding Converter="{StaticResource TextInputToVisibilityConverter}">
<Binding ElementName="txtUserEntry2" Path="Text.IsEmpty" />
<Binding ElementName="txtUserEntry2" Path="IsFocused" />
</MultiBinding>
</TextBlock.Visibility>
</TextBlock>
<TextBox Name="txtUserEntry2" Background="Transparent" BorderBrush="{StaticResource brushWatermarkBorder}" />
</Grid>
</Grid>
</Window>
TextInputToVisibilityConverter定义为:
using System;
using System.Windows.Data;
using System.Windows;
namespace WaterMarkTextBoxDemo
{
public class TextInputToVisibilityConverter : IMultiValueConverter
{
public object Convert( object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture )
{
// Always test MultiValueConverter inputs for non-null
// (to avoid crash bugs for views in the designer)
if (values[0] is bool && values[1] is bool)
{
bool hasText = !(bool)values[0];
bool hasFocus = (bool)values[1];
if (hasFocus || hasText)
return Visibility.Collapsed;
}
return Visibility.Visible;
}
public object[] ConvertBack( object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture )
{
throw new NotImplementedException();
}
}
}
注意:这不是我的代码。我是在这里找到的，但我认为这是最好的方法。
其他回答
MahApps。Metro for WPF有一个内置的水印控制，如果你不想自己滚动。使用起来相当简单。
<AdornerDecorator>
<TextBox Name="txtSomeText"
Width="200"
HorizontalAlignment="Right">
<Controls:TextBoxHelper.Watermark>I'm a watermark!</Controls:TextBoxHelper.Watermark>
</TextBox>
</AdornerDecorator>
namespace PlaceholderForRichTexxBoxInWPF
{
public MainWindow()
{
InitializeComponent();
Application.Current.MainWindow.WindowState = WindowState.Maximized;// maximize window on load
richTextBox1.GotKeyboardFocus += new KeyboardFocusChangedEventHandler(rtb_GotKeyboardFocus);
richTextBox1.LostKeyboardFocus += new KeyboardFocusChangedEventHandler(rtb_LostKeyboardFocus);
richTextBox1.AppendText("Place Holder");
richTextBox1.Foreground = Brushes.Gray;
}
private void rtb_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
if (sender is RichTextBox)
{
TextRange textRange = new TextRange(richTextBox1.Document.ContentStart, richTextBox1.Document.ContentEnd);
if (textRange.Text.Trim().Equals("Place Holder"))
{
((RichTextBox)sender).Foreground = Brushes.Black;
richTextBox1.Document.Blocks.Clear();
}
}
}
private void rtb_LostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
//Make sure sender is the correct Control.
if (sender is RichTextBox)
{
//If nothing was entered, reset default text.
TextRange textRange = new TextRange(richTextBox1.Document.ContentStart, richTextBox1.Document.ContentEnd);
if (textRange.Text.Trim().Equals(""))
{
((RichTextBox)sender).Foreground = Brushes.Gray;
((RichTextBox)sender).AppendText("Place Holder");
}
}
}
}
<TextBox x:Name="OrderTxt" HorizontalAlignment="Left" VerticalAlignment="Top" VerticalContentAlignment="Center" Margin="10,10,0,0" Width="188" Height="32"/>
<Label IsHitTestVisible="False" Content="Order number" DataContext="{Binding ElementName=OrderTxt}" Foreground="DarkGray">
<Label.Style>
<Style TargetType="{x:Type Label}">
<Setter Property="Visibility" Value="Collapsed"/>
<Setter Property="Width" Value="{Binding Width}"/>
<Setter Property="Height" Value="{Binding Height}"/>
<Setter Property="Margin" Value="{Binding Margin}"/>
<Setter Property="VerticalAlignment" Value="{Binding VerticalAlignment}"/>
<Setter Property="HorizontalAlignment" Value="{Binding HorizontalAlignment}"/>
<Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding Text}" Value="">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>
</Label>
这是一个演示如何在WPF中创建水印文本框的示例:
<Window x:Class="WaterMarkTextBoxDemo.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WaterMarkTextBoxDemo"
Height="200" Width="400">
<Window.Resources>
<SolidColorBrush x:Key="brushWatermarkBackground" Color="White" />
<SolidColorBrush x:Key="brushWatermarkForeground" Color="LightSteelBlue" />
<SolidColorBrush x:Key="brushWatermarkBorder" Color="Indigo" />
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<local:TextInputToVisibilityConverter x:Key="TextInputToVisibilityConverter" />
<Style x:Key="EntryFieldStyle" TargetType="Grid" >
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="VerticalAlignment" Value="Center" />
<Setter Property="Margin" Value="20,0" />
</Style>
</Window.Resources>
<Grid Background="LightBlue">
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="{StaticResource brushWatermarkBackground}" Style="{StaticResource EntryFieldStyle}" >
<TextBlock Margin="5,2" Text="This prompt dissappears as you type..." Foreground="{StaticResource brushWatermarkForeground}"
Visibility="{Binding ElementName=txtUserEntry, Path=Text.IsEmpty, Converter={StaticResource BooleanToVisibilityConverter}}" />
<TextBox Name="txtUserEntry" Background="Transparent" BorderBrush="{StaticResource brushWatermarkBorder}" />
</Grid>
<Grid Grid.Row="1" Background="{StaticResource brushWatermarkBackground}" Style="{StaticResource EntryFieldStyle}" >
<TextBlock Margin="5,2" Text="This dissappears as the control gets focus..." Foreground="{StaticResource brushWatermarkForeground}" >
<TextBlock.Visibility>
<MultiBinding Converter="{StaticResource TextInputToVisibilityConverter}">
<Binding ElementName="txtUserEntry2" Path="Text.IsEmpty" />
<Binding ElementName="txtUserEntry2" Path="IsFocused" />
</MultiBinding>
</TextBlock.Visibility>
</TextBlock>
<TextBox Name="txtUserEntry2" Background="Transparent" BorderBrush="{StaticResource brushWatermarkBorder}" />
</Grid>
</Grid>
</Window>
TextInputToVisibilityConverter定义为:
using System;
using System.Windows.Data;
using System.Windows;
namespace WaterMarkTextBoxDemo
{
public class TextInputToVisibilityConverter : IMultiValueConverter
{
public object Convert( object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture )
{
// Always test MultiValueConverter inputs for non-null
// (to avoid crash bugs for views in the designer)
if (values[0] is bool && values[1] is bool)
{
bool hasText = !(bool)values[0];
bool hasFocus = (bool)values[1];
if (hasFocus || hasText)
return Visibility.Collapsed;
}
return Visibility.Visible;
}
public object[] ConvertBack( object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture )
{
throw new NotImplementedException();
}
}
}
注意:这不是我的代码。我是在这里找到的，但我认为这是最好的方法。
嗨，我把这个任务变成了一个行为。你只需要在文本框中添加这样的东西
<i:Interaction.Behaviors>
<Behaviors:TextBoxWatermarkBehavior Label="Test Watermark" LabelStyle="{StaticResource StyleWatermarkLabel}"/>
</i:Interaction.Behaviors>
你可以在这里找到我的博客文章
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