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
@Veton -我真的很喜欢你的解决方案的简单性，但我的声誉还没有高到足以撞到你。
@Tim Murphy -“双向绑定需要Path或XPath”的错误很容易修复…更新的代码，包括一些其他的小调整(仅WPF测试):
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
public class TextBoxWatermarked : TextBox
{
public string Watermark
{
get { return (string)GetValue(WaterMarkProperty); }
set { SetValue(WaterMarkProperty, value); }
}
public static readonly DependencyProperty WaterMarkProperty =
DependencyProperty.Register("Watermark", typeof(string), typeof(TextBoxWatermarked), new PropertyMetadata(new PropertyChangedCallback(OnWatermarkChanged)));
private bool _isWatermarked = false;
private Binding _textBinding = null;
public TextBoxWatermarked()
{
Loaded += (s, ea) => ShowWatermark();
}
protected override void OnGotFocus(RoutedEventArgs e)
{
base.OnGotFocus(e);
HideWatermark();
}
protected override void OnLostFocus(RoutedEventArgs e)
{
base.OnLostFocus(e);
ShowWatermark();
}
private static void OnWatermarkChanged(DependencyObject sender, DependencyPropertyChangedEventArgs ea)
{
var tbw = sender as TextBoxWatermarked;
if (tbw == null || !tbw.IsLoaded) return; //needed to check IsLoaded so that we didn't dive into the ShowWatermark() routine before initial Bindings had been made
tbw.ShowWatermark();
}
private void ShowWatermark()
{
if (String.IsNullOrEmpty(Text) && !String.IsNullOrEmpty(Watermark))
{
_isWatermarked = true;
//save the existing binding so it can be restored
_textBinding = BindingOperations.GetBinding(this, TextProperty);
//blank out the existing binding so we can throw in our Watermark
BindingOperations.ClearBinding(this, TextProperty);
//set the signature watermark gray
Foreground = new SolidColorBrush(Colors.Gray);
//display our watermark text
Text = Watermark;
}
}
private void HideWatermark()
{
if (_isWatermarked)
{
_isWatermarked = false;
ClearValue(ForegroundProperty);
Text = "";
if (_textBinding != null) SetBinding(TextProperty, _textBinding);
}
}
}
其他回答
<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" />
这可以帮助检查您的代码。当应用到密码框时，它将显示密码，当用户输入时，它将消失。
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
@Veton -我真的很喜欢你的解决方案的简单性，但我的声誉还没有高到足以撞到你。
@Tim Murphy -“双向绑定需要Path或XPath”的错误很容易修复…更新的代码，包括一些其他的小调整(仅WPF测试):
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
public class TextBoxWatermarked : TextBox
{
public string Watermark
{
get { return (string)GetValue(WaterMarkProperty); }
set { SetValue(WaterMarkProperty, value); }
}
public static readonly DependencyProperty WaterMarkProperty =
DependencyProperty.Register("Watermark", typeof(string), typeof(TextBoxWatermarked), new PropertyMetadata(new PropertyChangedCallback(OnWatermarkChanged)));
private bool _isWatermarked = false;
private Binding _textBinding = null;
public TextBoxWatermarked()
{
Loaded += (s, ea) => ShowWatermark();
}
protected override void OnGotFocus(RoutedEventArgs e)
{
base.OnGotFocus(e);
HideWatermark();
}
protected override void OnLostFocus(RoutedEventArgs e)
{
base.OnLostFocus(e);
ShowWatermark();
}
private static void OnWatermarkChanged(DependencyObject sender, DependencyPropertyChangedEventArgs ea)
{
var tbw = sender as TextBoxWatermarked;
if (tbw == null || !tbw.IsLoaded) return; //needed to check IsLoaded so that we didn't dive into the ShowWatermark() routine before initial Bindings had been made
tbw.ShowWatermark();
}
private void ShowWatermark()
{
if (String.IsNullOrEmpty(Text) && !String.IsNullOrEmpty(Watermark))
{
_isWatermarked = true;
//save the existing binding so it can be restored
_textBinding = BindingOperations.GetBinding(this, TextProperty);
//blank out the existing binding so we can throw in our Watermark
BindingOperations.ClearBinding(this, TextProperty);
//set the signature watermark gray
Foreground = new SolidColorBrush(Colors.Gray);
//display our watermark text
Text = Watermark;
}
}
private void HideWatermark()
{
if (_isWatermarked)
{
_isWatermarked = false;
ClearValue(ForegroundProperty);
Text = "";
if (_textBinding != null) SetBinding(TextProperty, _textBinding);
}
}
}
我已经创建了一个简单的代码实现，它适用于WPF和Silverlight:
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
public class TextBoxWatermarked : TextBox
{
#region [ Dependency Properties ]
public static DependencyProperty WatermarkProperty = DependencyProperty.Register
(
"Watermark",
typeof(string),
typeof(TextBoxWatermarked),
new PropertyMetadata(new PropertyChangedCallback(OnWatermarkChanged))
);
#endregion
#region [ Fields ]
private bool _isWatermarked;
private Binding _textBinding;
#endregion
#region [ Properties ]
protected new Brush Foreground
{
get { return base.Foreground; }
set { base.Foreground = value; }
}
public string Watermark
{
get { return (string)GetValue(WatermarkProperty); }
set { SetValue(WatermarkProperty, value); }
}
#endregion
#region [ .ctor ]
public TextBoxWatermarked()
{
Loaded += (s, ea) => ShowWatermark();
}
#endregion
#region [ Event Handlers ]
protected override void OnGotFocus(RoutedEventArgs e)
{
base.OnGotFocus(e);
HideWatermark();
}
protected override void OnLostFocus(RoutedEventArgs e)
{
base.OnLostFocus(e);
ShowWatermark();
}
private static void OnWatermarkChanged(DependencyObject sender, DependencyPropertyChangedEventArgs ea)
{
var tbw = sender as TextBoxWatermarked;
if (tbw == null) return;
tbw.ShowWatermark();
}
#endregion
#region [ Methods ]
private void ShowWatermark()
{
if (string.IsNullOrEmpty(base.Text))
{
_isWatermarked = true;
base.Foreground = new SolidColorBrush(Colors.Gray);
var bindingExpression = GetBindingExpression(TextProperty);
_textBinding = bindingExpression == null ? null : bindingExpression.ParentBinding;
if (bindingExpression != null)
bindingExpression.UpdateSource();
SetBinding(TextProperty, new Binding());
base.Text = Watermark;
}
}
private void HideWatermark()
{
if (_isWatermarked)
{
_isWatermarked = false;
ClearValue(ForegroundProperty);
base.Text = "";
SetBinding(TextProperty, _textBinding ?? new Binding());
}
}
#endregion
}
用法:
<TextBoxWatermarked Watermark="Some text" />
使用风格的简单解决方案:
<TextBox>
<TextBox.Style>
<Style TargetType="TextBox" xmlns:sys="clr-namespace:System;assembly=mscorlib">
<Style.Resources>
<VisualBrush x:Key="CueBannerBrush" AlignmentX="Left" AlignmentY="Center" Stretch="None">
<VisualBrush.Visual>
<Label Content="MM:SS:HH AM/PM" Foreground="LightGray" />
</VisualBrush.Visual>
</VisualBrush>
</Style.Resources>
<Style.Triggers>
<Trigger Property="Text" Value="{x:Static sys:String.Empty}">
<Setter Property="Background" Value="{StaticResource CueBannerBrush}" />
</Trigger>
<Trigger Property="Text" Value="{x:Null}">
<Setter Property="Background" Value="{StaticResource CueBannerBrush}" />
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="True">
<Setter Property="Background" Value="White" />
</Trigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
伟大的解决方案:
https://code.msdn.microsoft.com/windowsdesktop/In-place-hit-messages-for-18db3a6c
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