Joh*_*zek 425
您可以创建可添加到TextBox附加属性的任何水印.以下是附属物业的来源:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
/// <summary>
/// Class that provides the Watermark attached property
/// </summary>
public static class WatermarkService
{
/// <summary>
/// Watermark Attached Dependency Property
/// </summary>
public static readonly DependencyProperty WatermarkProperty = DependencyProperty.RegisterAttached(
"Watermark",
typeof(object),
typeof(WatermarkService),
new FrameworkPropertyMetadata((object)null, new PropertyChangedCallback(OnWatermarkChanged)));
#region Private Fields
/// <summary>
/// Dictionary of ItemsControls
/// </summary>
private static readonly Dictionary<object, ItemsControl> itemsControls = new Dictionary<object, ItemsControl>();
#endregion
/// <summary>
/// Gets the Watermark property. This dependency property indicates the watermark for the control.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> to get the property from</param>
/// <returns>The value of the Watermark property</returns>
public static object GetWatermark(DependencyObject d)
{
return (object)d.GetValue(WatermarkProperty);
}
/// <summary>
/// Sets the Watermark property. This dependency property indicates the watermark for the control.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> to set the property on</param>
/// <param name="value">value of the property</param>
public static void SetWatermark(DependencyObject d, object value)
{
d.SetValue(WatermarkProperty, value);
}
/// <summary>
/// Handles changes to the Watermark property.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> that fired the event</param>
/// <param name="e">A <see cref="DependencyPropertyChangedEventArgs"/> that contains the event data.</param>
private static void OnWatermarkChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Control control = (Control)d;
control.Loaded += Control_Loaded;
if (d is ComboBox)
{
control.GotKeyboardFocus += Control_GotKeyboardFocus;
control.LostKeyboardFocus += Control_Loaded;
}
else if (d is TextBox)
{
control.GotKeyboardFocus += Control_GotKeyboardFocus;
control.LostKeyboardFocus += Control_Loaded;
((TextBox)control).TextChanged += Control_GotKeyboardFocus;
}
if (d is ItemsControl && !(d is ComboBox))
{
ItemsControl i = (ItemsControl)d;
// for Items property
i.ItemContainerGenerator.ItemsChanged += ItemsChanged;
itemsControls.Add(i.ItemContainerGenerator, i);
// for ItemsSource property
DependencyPropertyDescriptor prop = DependencyPropertyDescriptor.FromProperty(ItemsControl.ItemsSourceProperty, i.GetType());
prop.AddValueChanged(i, ItemsSourceChanged);
}
}
#region Event Handlers
/// <summary>
/// Handle the GotFocus event on the control
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="RoutedEventArgs"/> that contains the event data.</param>
private static void Control_GotKeyboardFocus(object sender, RoutedEventArgs e)
{
Control c = (Control)sender;
if (ShouldShowWatermark(c))
{
ShowWatermark(c);
}
else
{
RemoveWatermark(c);
}
}
/// <summary>
/// Handle the Loaded and LostFocus event on the control
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="RoutedEventArgs"/> that contains the event data.</param>
private static void Control_Loaded(object sender, RoutedEventArgs e)
{
Control control = (Control)sender;
if (ShouldShowWatermark(control))
{
ShowWatermark(control);
}
}
/// <summary>
/// Event handler for the items source changed event
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="EventArgs"/> that contains the event data.</param>
private static void ItemsSourceChanged(object sender, EventArgs e)
{
ItemsControl c = (ItemsControl)sender;
if (c.ItemsSource != null)
{
if (ShouldShowWatermark(c))
{
ShowWatermark(c);
}
else
{
RemoveWatermark(c);
}
}
else
{
ShowWatermark(c);
}
}
/// <summary>
/// Event handler for the items changed event
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="ItemsChangedEventArgs"/> that contains the event data.</param>
private static void ItemsChanged(object sender, ItemsChangedEventArgs e)
{
ItemsControl control;
if (itemsControls.TryGetValue(sender, out control))
{
if (ShouldShowWatermark(control))
{
ShowWatermark(control);
}
else
{
RemoveWatermark(control);
}
}
}
#endregion
#region Helper Methods
/// <summary>
/// Remove the watermark from the specified element
/// </summary>
/// <param name="control">Element to remove the watermark from</param>
private static void RemoveWatermark(UIElement control)
{
AdornerLayer layer = AdornerLayer.GetAdornerLayer(control);
// layer could be null if control is no longer in the visual tree
if (layer != null)
{
Adorner[] adorners = layer.GetAdorners(control);
if (adorners == null)
{
return;
}
foreach (Adorner adorner in adorners)
{
if (adorner is WatermarkAdorner)
{
adorner.Visibility = Visibility.Hidden;
layer.Remove(adorner);
}
}
}
}
/// <summary>
/// Show the watermark on the specified control
/// </summary>
/// <param name="control">Control to show the watermark on</param>
private static void ShowWatermark(Control control)
{
AdornerLayer layer = AdornerLayer.GetAdornerLayer(control);
// layer could be null if control is no longer in the visual tree
if (layer != null)
{
layer.Add(new WatermarkAdorner(control, GetWatermark(control)));
}
}
/// <summary>
/// Indicates whether or not the watermark should be shown on the specified control
/// </summary>
/// <param name="c"><see cref="Control"/> to test</param>
/// <returns>true if the watermark should be shown; false otherwise</returns>
private static bool ShouldShowWatermark(Control c)
{
if (c is ComboBox)
{
return (c as ComboBox).Text == string.Empty;
}
else if (c is TextBoxBase)
{
return (c as TextBox).Text == string.Empty;
}
else if (c is ItemsControl)
{
return (c as ItemsControl).Items.Count == 0;
}
else
{
return false;
}
}
#endregion
}
Attached Property使用一个名为的类WatermarkAdorner,这里是源:
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Media;
/// <summary>
/// Adorner for the watermark
/// </summary>
internal class WatermarkAdorner : Adorner
{
#region Private Fields
/// <summary>
/// <see cref="ContentPresenter"/> that holds the watermark
/// </summary>
private readonly ContentPresenter contentPresenter;
#endregion
#region Constructor
/// <summary>
/// Initializes a new instance of the <see cref="WatermarkAdorner"/> class
/// </summary>
/// <param name="adornedElement"><see cref="UIElement"/> to be adorned</param>
/// <param name="watermark">The watermark</param>
public WatermarkAdorner(UIElement adornedElement, object watermark) :
base(adornedElement)
{
this.IsHitTestVisible = false;
this.contentPresenter = new ContentPresenter();
this.contentPresenter.Content = watermark;
this.contentPresenter.Opacity = 0.5;
this.contentPresenter.Margin = new Thickness(Control.Margin.Left + Control.Padding.Left, Control.Margin.Top + Control.Padding.Top, 0, 0);
if (this.Control is ItemsControl && !(this.Control is ComboBox))
{
this.contentPresenter.VerticalAlignment = VerticalAlignment.Center;
this.contentPresenter.HorizontalAlignment = HorizontalAlignment.Center;
}
// Hide the control adorner when the adorned element is hidden
Binding binding = new Binding("IsVisible");
binding.Source = adornedElement;
binding.Converter = new BooleanToVisibilityConverter();
this.SetBinding(VisibilityProperty, binding);
}
#endregion
#region Protected Properties
/// <summary>
/// Gets the number of children for the <see cref="ContainerVisual"/>.
/// </summary>
protected override int VisualChildrenCount
{
get { return 1; }
}
#endregion
#region Private Properties
/// <summary>
/// Gets the control that is being adorned
/// </summary>
private Control Control
{
get { return (Control)this.AdornedElement; }
}
#endregion
#region Protected Overrides
/// <summary>
/// Returns a specified child <see cref="Visual"/> for the parent <see cref="ContainerVisual"/>.
/// </summary>
/// <param name="index">A 32-bit signed integer that represents the index value of the child <see cref="Visual"/>. The value of index must be between 0 and <see cref="VisualChildrenCount"/> - 1.</param>
/// <returns>The child <see cref="Visual"/>.</returns>
protected override Visual GetVisualChild(int index)
{
return this.contentPresenter;
}
/// <summary>
/// Implements any custom measuring behavior for the adorner.
/// </summary>
/// <param name="constraint">A size to constrain the adorner to.</param>
/// <returns>A <see cref="Size"/> object representing the amount of layout space needed by the adorner.</returns>
protected override Size MeasureOverride(Size constraint)
{
// Here's the secret to getting the adorner to cover the whole control
this.contentPresenter.Measure(Control.RenderSize);
return Control.RenderSize;
}
/// <summary>
/// When overridden in a derived class, positions child elements and determines a size for a <see cref="FrameworkElement"/> derived class.
/// </summary>
/// <param name="finalSize">The final area within the parent that this element should use to arrange itself and its children.</param>
/// <returns>The actual size used.</returns>
protected override Size ArrangeOverride(Size finalSize)
{
this.contentPresenter.Arrange(new Rect(finalSize));
return finalSize;
}
#endregion
}
现在你可以在任何TextBox上添加水印,如下所示:
<AdornerDecorator>
<TextBox x:Name="SearchTextBox">
<controls:WatermarkService.Watermark>
<TextBlock>Type here to search text</TextBlock>
</controls:WatermarkService.Watermark>
</TextBox>
</AdornerDecorator>
水印可以是你想要的任何东西(文字,图像......).除了使用TextBoxes之外,此水印还适用于ComboBoxes和ItemControls.
此代码改编自此博客文章.
apc*_*apc 260
只使用XAML,没有扩展,没有转换器:
<Grid>
<TextBox Width="250" VerticalAlignment="Center" HorizontalAlignment="Left" x:Name="SearchTermTextBox" Margin="5"/>
<TextBlock IsHitTestVisible="False" Text="Enter Search Term Here" VerticalAlignment="Center" HorizontalAlignment="Left" Margin="10,0,0,0" Foreground="DarkGray">
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding Text, ElementName=SearchTermTextBox}" Value="">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</Grid>
CSh*_*per 54
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.我在这里找到了它,但我认为这是最好的方法.
dai*_*ain 53
我无法相信没有人发布明显的扩展WPF工具包 -来自Xceed的WatermarkTextBox.它工作得很好,并且是开源的,以防您想要自定义.
Ren*_*ené 31
有关如何在"3行XAML"中执行此操作的CodeProject上有一篇文章.
<Grid Background="{StaticResource brushWatermarkBackground}">
<TextBlock Margin="5,2" Text="Type something..."
Foreground="{StaticResource brushForeground}"
Visibility="{Binding ElementName=txtUserEntry, Path=Text.IsEmpty,
Converter={StaticResource BooleanToVisibilityConverter}}" />
<TextBox Name="txtUserEntry" Background="Transparent"
BorderBrush="{StaticResource brushBorder}" />
</Grid>
好吧,但是它可能不是的XAML格式的3条线,但它是非常简单的.
但需要注意的一点是,它在Text属性上使用了非标准的扩展方法,称为"IsEmpty".你需要自己实现这个,但是文章似乎没有提到这一点.
Sef*_*fix 18
我看到约翰Myczek的解决方案,它的兼容性到的意见ComboBox和PasswordBox,所以我提高约翰Myczek的解决方案,在这里它是:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
/// <summary>
/// Class that provides the Watermark attached property
/// </summary>
public static class WatermarkService
{
/// <summary>
/// Watermark Attached Dependency Property
/// </summary>
public static readonly DependencyProperty WatermarkProperty = DependencyProperty.RegisterAttached(
"Watermark",
typeof(object),
typeof(WatermarkService),
new FrameworkPropertyMetadata((object)null, new PropertyChangedCallback(OnWatermarkChanged)));
#region Private Fields
/// <summary>
/// Dictionary of ItemsControls
/// </summary>
private static readonly Dictionary<object, ItemsControl> itemsControls = new Dictionary<object, ItemsControl>();
#endregion
/// <summary>
/// Gets the Watermark property. This dependency property indicates the watermark for the control.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> to get the property from</param>
/// <returns>The value of the Watermark property</returns>
public static object GetWatermark(DependencyObject d)
{
return (object)d.GetValue(WatermarkProperty);
}
/// <summary>
/// Sets the Watermark property. This dependency property indicates the watermark for the control.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> to set the property on</param>
/// <param name="value">value of the property</param>
public static void SetWatermark(DependencyObject d, object value)
{
d.SetValue(WatermarkProperty, value);
}
/// <summary>
/// Handles changes to the Watermark property.
/// </summary>
/// <param name="d"><see cref="DependencyObject"/> that fired the event</param>
/// <param name="e">A <see cref="DependencyPropertyChangedEventArgs"/> that contains the event data.</param>
private static void OnWatermarkChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Control control = (Control)d;
control.Loaded += Control_Loaded;
if (d is TextBox || d is PasswordBox)
{
control.GotKeyboardFocus += Control_GotKeyboardFocus;
control.LostKeyboardFocus += Control_Loaded;
}
else if (d is ComboBox)
{
control.GotKeyboardFocus += Control_GotKeyboardFocus;
control.LostKeyboardFocus += Control_Loaded;
(d as ComboBox).SelectionChanged += new SelectionChangedEventHandler(SelectionChanged);
}
else if (d is ItemsControl)
{
ItemsControl i = (ItemsControl)d;
// for Items property
i.ItemContainerGenerator.ItemsChanged += ItemsChanged;
itemsControls.Add(i.ItemContainerGenerator, i);
// for ItemsSource property
DependencyPropertyDescriptor prop = DependencyPropertyDescriptor.FromProperty(ItemsControl.ItemsSourceProperty, i.GetType());
prop.AddValueChanged(i, ItemsSourceChanged);
}
}
/// <summary>
/// Event handler for the selection changed event
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="ItemsChangedEventArgs"/> that contains the event data.</param>
private static void SelectionChanged(object sender, SelectionChangedEventArgs e)
{
Control control = (Control)sender;
if (ShouldShowWatermark(control))
{
ShowWatermark(control);
}
else
{
RemoveWatermark(control);
}
}
#region Event Handlers
/// <summary>
/// Handle the GotFocus event on the control
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="RoutedEventArgs"/> that contains the event data.</param>
private static void Control_GotKeyboardFocus(object sender, RoutedEventArgs e)
{
Control c = (Control)sender;
if (ShouldShowWatermark(c))
{
RemoveWatermark(c);
}
}
/// <summary>
/// Handle the Loaded and LostFocus event on the control
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="RoutedEventArgs"/> that contains the event data.</param>
private static void Control_Loaded(object sender, RoutedEventArgs e)
{
Control control = (Control)sender;
if (ShouldShowWatermark(control))
{
ShowWatermark(control);
}
}
/// <summary>
/// Event handler for the items source changed event
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="EventArgs"/> that contains the event data.</param>
private static void ItemsSourceChanged(object sender, EventArgs e)
{
ItemsControl c = (ItemsControl)sender;
if (c.ItemsSource != null)
{
if (ShouldShowWatermark(c))
{
ShowWatermark(c);
}
else
{
RemoveWatermark(c);
}
}
else
{
ShowWatermark(c);
}
}
/// <summary>
/// Event handler for the items changed event
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="ItemsChangedEventArgs"/> that contains the event data.</param>
private static void ItemsChanged(object sender, ItemsChangedEventArgs e)
{
ItemsControl control;
if (itemsControls.TryGetValue(sender, out control))
{
if (ShouldShowWatermark(control))
{
ShowWatermark(control);
}
else
{
RemoveWatermark(control);
}
}
}
#endregion
#region Helper Methods
/// <summary>
/// Remove the watermark from the specified element
/// </summary>
/// <param name="control">Element to remove the watermark from</param>
private static void RemoveWatermark(UIElement control)
{
AdornerLayer layer = AdornerLayer.GetAdornerLayer(control);
// layer could be null if control is no longer in the visual tree
if (layer != null)
{
Adorner[] adorners = layer.GetAdorners(control);
if (adorners == null)
{
return;
}
foreach (Adorner adorner in adorners)
{
if (adorner is WatermarkAdorner)
{
adorner.Visibility = Visibility.Hidden;
layer.Remove(adorner);
}
}
}
}
/// <summary>
/// Show the watermark on the specified control
/// </summary>
/// <param name="control">Control to show the watermark on</param>
private static void ShowWatermark(Control control)
{
AdornerLayer layer = AdornerLayer.GetAdornerLayer(control);
// layer could be null if control is no longer in the visual tree
if (layer != null)
{
layer.Add(new WatermarkAdorner(control, GetWatermark(control)));
}
}
/// <summary>
/// Indicates whether or not the watermark should be shown on the specified control
/// </summary>
/// <param name="c"><see cref="Control"/> to test</param>
/// <returns>true if the watermark should be shown; false otherwise</returns>
private static bool ShouldShowWatermark(Control c)
{
if (c is ComboBox)
{
return (c as ComboBox).SelectedItem == null;
//return (c as ComboBox).Text == string.Empty;
}
else if (c is TextBoxBase)
{
return (c as TextBox).Text == string.Empty;
}
else if (c is PasswordBox)
{
return (c as PasswordBox).Password == string.Empty;
}
else if (c is ItemsControl)
{
return (c as ItemsControl).Items.Count == 0;
}
else
{
return false;
}
}
#endregion
}
现在,ComboBox可也Editable,而PasswordBox可以也添加水印.不要忘记使用JoanComasFdz上面的评论来解决保证金问题.
而且,当然,所有的功劳都归功于John Myczek.
Nar*_*yal 11
<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>
https://code.msdn.microsoft.com/windowsdesktop/In-place-hit-messages-for-18db3a6c
Joh*_*son 10
这个图书馆有一个水印.
样品用法:
<TextBox adorners:Watermark.Text="Write something here"
adorners:Watermark.TextStyle="{StaticResource AdornerTextStyle}"
adorners:Watermark.VisibleWhen="EmptyAndNotKeyboardFocused"/>
我已经创建了siple代码实现,它也适用于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" />
使用带有绑定TextBox的@ john-myczek 代码时遇到了一些困难.由于TextBox在更新时不会引发焦点事件,因此水印将在新文本下方保持可见.要解决这个问题,我只需添加另一个事件处理程序
if (d is ComboBox || d is TextBox)
{
control.GotKeyboardFocus += Control_GotKeyboardFocus;
control.LostKeyboardFocus += Control_Loaded;
if (d is TextBox)
(d as TextBox).TextChanged += Control_TextChanged;
}
private static void Control_TextChanged(object sender, RoutedEventArgs e)
{
var tb = (TextBox)sender;
if (ShouldShowWatermark(tb))
{
ShowWatermark(tb);
}
else
{
RemoveWatermark(tb);
}
}
文本框水印的最简单方法
<Window.Resources>
<Style x:Key="MyWaterMarkStyle" TargetType="{x:Type TextBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<Grid>
<Border Background="White" BorderBrush="#FF7D8683" BorderThickness="1"/>
<ScrollViewer x:Name="PART_ContentHost" Margin="5,0,0,0" VerticalAlignment="Center" />
<Label Margin="5,0,0,0" x:Name="WaterMarkLabel" Content="{TemplateBinding Tag}" VerticalAlignment="Center"
Visibility="Collapsed" Foreground="Gray" FontFamily="Arial"/>
</Grid>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="Text" Value=""/>
</MultiTrigger.Conditions>
<Setter Property="Visibility" TargetName="WaterMarkLabel" Value="Visible"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Foreground" Value="DimGray"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
并添加文本框 StaticResource 样式
<TextBox
Style="{StaticResource MyWaterMarkStyle}"
Tag="Search Category"
Grid.Row="0"
Text="{Binding CategorySearch,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
TextSearch.Text="Search Category"
>
@Veton - 我真的很喜欢你的解决方案的简单性，但我的声誉还不够高，无法打击你。
@Tim Murphy - “双向绑定需要路径或 XPath”错误是一个简单的修复......更新的代码包括一些其他小调整（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);
}
}
}
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